JP6390339B2 - Intake port insulation structure of internal combustion engine - Google Patents

Description

  The present invention relates to an intake port structure of an internal combustion engine, and more particularly to an intake port heat insulation structure of a port injection type internal combustion engine.

In recent years, there has been a demand for an internal combustion engine having a high compression ratio with improved thermal efficiency from the viewpoint of improving fuel efficiency.
An internal combustion engine with a high compression ratio has a higher temperature of the air-fuel mixture after compression than an engine with a low compression ratio, so that it is easy to knock and the ignition timing must be retarded.
As a result, the fuel efficiency improvement effect is reduced, and it is necessary to suppress an increase in the intake air temperature and thus the mixture temperature.
Incidentally, the intake air is sucked into the combustion chamber via the intake passage of the intake manifold and the intake port provided in the cylinder head.
Since the intake manifold and the cylinder head are heated by the heat transmitted from the combustion chamber, the intake air inevitably rises in temperature by receiving heat from the intake manifold intake passage and the wall surface of the cylinder head intake port.
In view of this, an intake pipe mounting structure has been proposed in which an intake manifold is made of a heat-insulating resin material and a resin insertion portion of the intake manifold is inserted into an intake port (see Patent Document 1).
In this structure, the resin insertion portion is inserted into the intake port, and the area of the portion formed by the wall surface of the cylinder head in the wall surface of the intake port is reduced to suppress the rise in the intake air temperature.

JP 2007-285171 A

However, in the above structure, there is a limit to the heat insulating effect by the resin insertion portion, and there is room for improvement in further improving the heat insulating effect.
The present invention has been made in view of the above circumstances, and improves heat insulation by improving the heat insulation performance of insulating intake air from the wall surface of the intake port, while suppressing the rise in intake air temperature and promoting fuel vaporization. An object of the present invention is to provide an intake port heat insulation structure for an internal combustion engine that is advantageous in achieving the above.

In order to achieve the above object, a first aspect of the present invention includes a cylinder head disposed on a cylinder block and provided with an intake port, an outer surface incorporated in the cylinder head and in contact with the cylinder head, and the intake port An intake port heat insulating structure for an internal combustion engine, comprising a heat insulating member having an inner surface that forms a part of the wall surface of the cylinder head, and at least one of the location of the cylinder head that contacts the heat insulating member or the outer surface of the heat insulating member By providing an uneven structure that reduces the contact area between the cylinder head location and the outer surface, the contact area between the cylinder head location and the outer surface is in the overlapping direction of the cylinder head and the cylinder block. The location located on the cylinder block side is the location located on the side away from the cylinder block. Characterized in that is also small.
The invention according to claim 2 is characterized in that the contact area between the location of the cylinder head and the outer surface is smaller at a location located on the downstream side of the intake air than on a location located on the upstream side of the intake air.
The invention according to claim 3 is characterized in that the concavo-convex structure is formed of a plurality of convex portions projecting from the outer surface.
The invention according to claim 4 includes an injector that injects fuel into the intake port, and the heat insulating member includes an upstream side wall portion in which the inner surface forms a wall surface on the upstream side of the intake port from the injection port of the injector; The inner surface includes a downstream side wall portion that forms a wall surface on the downstream side of the intake port from the injection port, and intake air from the periphery of the injection port passes through the inner surface at a location on the downstream side wall portion where the injector is disposed. An open cutout is provided at the end of the downstream side wall extending in the flow direction and away from the upstream side wall, and the downstream side wall is sprayed on the wall surface of the intake port on the side facing the nozzle. This is characterized in that it extends up to the point where the fuel is attached.
According to a fifth aspect of the present invention, a cylinder head disposed on a cylinder block and provided with an intake port, an outer surface incorporated in the cylinder head and in contact with the cylinder head, and a part of a wall surface of the intake port are formed. An intake port heat insulating structure for an internal combustion engine comprising a heat insulating member having an inner surface, wherein the cylinder head portion and the outer surface of the heat insulating member are in contact with the cylinder head and the heat insulating member. By providing a concavo-convex structure for reducing the contact area of the outer surface, the location of the cylinder head and the contact area of the outer surface are larger than the location where the location located on the cylinder block side is located on the side away from the cylinder block. And an injector for injecting fuel into the intake port. An upstream side wall portion that forms a wall surface on the upstream side of the intake port from the injection port of the injector, and a downstream side wall portion that forms a wall surface on the downstream side of the intake port from the injection port, and the downstream side wall portion In the portion on the side where the injector is disposed, an open notch is provided at the end of the downstream side wall extending from the periphery of the nozzle hole in the direction in which the intake air flows through the inner surface and away from the upstream side wall. The downstream side wall portion extends to a position just before the location where the sprayed fuel is attached to the wall surface of the intake port on the side facing the nozzle hole.

According to the first aspect of the present invention, the heat conducted from the cylinder block side, which is at a high temperature, is located on the cylinder block side because the contact area between the location of the cylinder head that the heat insulating member contacts and the outer surface of the heat insulating member is small. It becomes difficult to be transmitted to the heat insulating member. Therefore, it is advantageous in improving the heat insulation performance for insulating the intake air from the wall surface of the intake port, suppressing the increase in intake air temperature, and improving the fuel consumption.
According to the second aspect of the present invention, the heat conducted from the combustion chamber side located on the downstream side of the intake air, which becomes high temperature, is not easily transmitted to the heat insulating member located on the downstream side. Therefore, it is more advantageous to improve the heat insulation performance for insulating the intake air from the wall surface of the intake port, to suppress the rise of the intake air temperature and to improve the fuel consumption.
According to the third aspect of the invention, it is advantageous to easily process the heat insulating member, and it is advantageous to reduce the manufacturing cost.
According to the fourth and fifth aspects of the invention, the wall surface of the intake port to which most of the fuel injected from the injection port adheres regardless of the operating state of the internal combustion engine is constituted by the cylinder head. The fuel adhering to the fuel is efficiently vaporized on the wall surface of the high-temperature cylinder head, which is advantageous for improving the combustion efficiency of the fuel. In addition, in the high-speed rotation range of the engine, the wall surface of the port, which is the location of the wall surface where most of the fuel injected from the nozzle hole does not adhere, is composed of a heat insulating member, so that the transfer of heat from the cylinder head to the intake air is suppressed. This is advantageous in suppressing the temperature rise of the intake air.

It is sectional drawing which shows the intake port structure of the internal combustion engine which concerns on embodiment. 1A is a cross-sectional view taken along line AA in FIG. 1, and FIG. 1B is a cross-sectional view taken along line BB in FIG. It is a perspective view of a heat insulation member.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the overall configuration of the internal combustion engine will be described.
As shown in FIG. 1, an internal combustion engine (hereinafter referred to as engine) 10 includes a cylinder block 14 in which a cylinder 12 is formed, a cylinder head 16 disposed on the cylinder block 14, and a piston disposed in the cylinder 12. 18.
An intake pipe 20 (intake manifold) and an exhaust pipe 22 (exhaust manifold) are connected to both sides of the cylinder head 16.
The combustion chamber 24 is constituted by the inner surface of the cylinder 12, the lower surface of the cylinder head 16, and the top surface of the piston 18, and the cylinder head 16 is provided with an ignition plug 26 so as to be positioned in the combustion chamber 24.
The piston 18 is connected to a crankshaft (not shown) via a connecting rod 28. In the figure, reference numerals 1802 and 1804 denote pressure rings, and reference numeral 1806 denotes an oil ring.

The cylinder head 16 is provided with an intake port 30 for supplying intake air to the combustion chamber 24 and an exhaust port 32 for discharging exhaust gas in the combustion chamber 24.
In the present invention, the intake port 30 refers to a portion located inside the cylinder head 16 in the intake passage that connects the intake port that opens to the outside and the combustion chamber 24.
An intake pipe 20 is connected to the intake port 30, and an exhaust pipe 22 is connected to the exhaust port 32.
The intake passage 2002 includes the intake pipe 20 and the intake port 30, and the exhaust passage 2202 includes the exhaust port 32 and the exhaust pipe 22.
An intake valve 34 is provided at the intake port 30 and an exhaust valve 36 is provided at the exhaust port 32. The intake valve 34 and the exhaust valve 36 are urged by valve springs 38 and 40 in the closing direction. The intake valve 34 and the exhaust valve 36 are driven by an intake / exhaust cam (not shown) to open and close the intake port 30 and the exhaust port 32.
In the figure, reference numeral 37 denotes a valve seat.

In the present embodiment, engine 10 is a port injection engine that injects (sprays) fuel from injector 42 into intake port 30.
The injector 42 injects fuel supplied from a pump (not shown). The fuel injection nozzle 4204 directs the injection port 4202 into the intake port 30, and the injection port 4202 is provided in the fuel injection nozzle 4204 to open and close the injection port 4202. A needle valve (not shown) is included.
In the port injection type engine, the intake air sucked into the intake port 30 from the intake passage 2002 of the intake pipe 20 and the fuel injected from the injection port 4202 of the injector 42 are mixed in the intake port 30 to form an air-fuel mixture, and combustion It is supplied to the chamber 24.
When the crankshaft rotates, the intake valve 34 and the exhaust valve 36 are opened and closed via the intake cam and the exhaust cam, and the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke are executed. The fuel is injected into the intake port 30 from the nozzle 4202.

As shown in FIGS. 1 to 3, the intake port 30 is constituted by a heat insulating member 44 with a part of the wall surface attached to the cylinder head 16.
That is, a recess 46 is provided that opens on the end surface of the cylinder head 16 where the upstream end of the intake port 30 is located.
The heat insulating member 44 is incorporated in the cylinder head 16 and contacts the cylinder head 16, in other words, an outer surface 4402 that is fitted in the recess 46 and contacts the wall surface 4602 of the recess 46, and an inner surface that forms part of the wall surface of the intake port 30. 4404.
The heat insulating member 44 includes an upstream side wall portion 44A located on the end side, and a downstream side wall portion 44B extending in a direction in which intake air flows from the end portion of the upstream side wall portion 44A.
In the downstream side wall portion 44B where the injector 42 is disposed, the injection hole 4202 of the injector 42 is exposed in the intake port 30, and the downstream side wall portion 44B extending in the direction in which the intake air flows and away from the upstream side wall portion 44B is provided. An open notch 48 is provided at the end.
The range of the wall surface 3008 to which the fuel spray adheres at the location of the wall surface 3004 of the intake port 30 on the side facing the nozzle hole 4202 is constituted by the cylinder head 16.

Therefore, in the high-speed rotation region of the engine 10, the intake speed flowing through the intake port 30 is increased. Therefore, most of the fuel injected from the injection port 4202 is along the extending direction of the intake port 30 on the side where the injection port 4202 is located. It adheres to the location of the wall surface 3006 of the extending cylinder head 16.
In the present embodiment, a cutout 48 is provided at a location where the injector 42 is disposed on the downstream side wall 44 </ b> B, and on the side where the injection port 4202 is located on the wall surface of the intake port 30 positioned downstream of the injection port 4202. A portion of the wall surface 3006 extending along the extending direction of the intake port 30 is configured by the cylinder head 16.
Vaporization of the fuel injected from the nozzle 4202 is efficiently performed on the wall surface 3006 of the high-temperature cylinder head 16, which is advantageous for improving the combustion efficiency of the fuel. In particular, when the engine 10 is operating in a low / medium rotation range and a high load range, the flow rate of the intake air flowing into the intake port 30 becomes slow and the amount of fuel injected from the injector 42 increases. Part of the fuel injected from the fuel does not flow downstream of the intake port 30 together with the intake air, and adheres to the wall surface 3006 of the intake port 30. In this case, since the adhering fuel is efficiently vaporized by the wall surface 3006 of the high-temperature cylinder head 16, it is further advantageous in improving the combustion efficiency.
In addition, among the entire wall surface 3002 of the intake port 30 positioned upstream of the nozzle hole 4202 and the wall surface of the intake port 30 positioned downstream of the nozzle hole 4202, the position of the wall surface 3004 facing the nozzle hole 4202 is upstream. Since it is configured by the inner surface 4404 of the heat insulating member 44 composed of the side wall portion 44A and the downstream side wall portion 44B, the transfer of heat from the cylinder head 16 to the intake air is suppressed, which is advantageous in suppressing the temperature rise of the intake air. This is advantageous for improving the fuel consumption of the engine 10.
Therefore, the combustion efficiency can be improved while suppressing the temperature rise of the intake air, which is advantageous in improving the fuel consumption of the engine 10.

In particular, when the engine 10 is operating at a high load in the low and medium speed rotation region, the flow rate of the intake air flowing into the intake port 30 becomes slow and the amount of fuel injected from the injector 42 increases, so the fuel injected from the injection port 4202 May adhere to the wall surface 3008 of the cylinder head 16 and the intake valve 34 of the intake port 30 near the combustion chamber 24 on the side facing the injection nozzle 4202.
In the present embodiment, the downstream side wall 44 </ b> B extends from the location of the wall surface 3004 facing the nozzle hole 4202 to the front of the range of the wall surface 3008, and the range of the wall surface 3008 to which fuel spray adheres is configured by the cylinder head 16. ing.
Therefore, the vaporization of the fuel adhering to the wall surface 3008 of the intake port 30 is efficiently performed by the high-temperature cylinder head 16, which is advantageous for improving the fuel combustion efficiency.
Further, since the downstream side wall 44B extends from the location of the wall surface 3004 facing the nozzle hole 4202 to the front of the range of the wall surface 3008, the transfer of heat from the cylinder head 16 to the intake air is suppressed, and the temperature rise of the intake air is suppressed. It becomes more advantageous in suppressing.
Therefore, in the low-speed rotation region of the engine 10, the combustion efficiency can be further improved while further suppressing the rise in intake air temperature, which is further advantageous in improving the fuel consumption of the engine 10.

The heat insulating member 44 may be made of a hollow or solid synthetic resin material.
Alternatively, the heat insulating member 44 may be constituted by a hollow member and a heat insulating material inserted into the hollow member, and in this case, it is advantageous in securing optimum heat insulating performance.
Further, the upstream portion 44A and the downstream portion 44B of the heat insulating member 44 may be configured separately. In this case, the heat insulation performance can be changed by changing the kind of heat insulating material used for the upstream portion 44A and the downstream portion 44B.
For example, when the cooling water passage (high temperature) is disposed in the cylinder head 16 portion where the upstream portion 44A is disposed and the cylinder head 16 portion where the downstream portion 44B is disposed is at a lower temperature, the downstream portion 44B. The heat insulating material constituting the heat insulating member 44 can be selected or the density of the heat insulating material can be set so as to improve the heat insulating performance of the upstream portion 44A.
Therefore, it is advantageous in ensuring optimum heat insulation performance corresponding to the temperature distribution of the cylinder head 16.

As shown in FIGS. 1 to 3, the contact area between the wall surface 4602 and the outer surface 4402 is reduced to at least one of the wall surface 4602 of the recess 46 or the outer surface 4402 of the heat insulating member 44, which is the location of the cylinder head 16 with which the heat insulating member 44 contacts. By providing the concavo-convex structure 50, the contact area between the wall surface 4602 and the outer surface 4402 is smaller at the location located on the cylinder block 14 side than the location located on the side away from the cylinder block 14.
The concavo-convex structure 50 may be provided integrally with the cylinder head 16 and the heat insulating member 44 when the cylinder head 16 and the heat insulating member 44 are molded, or may be formed on the cylinder head 16 and the heat insulating member 44 by post-processing. May be.
In the present embodiment, the concavo-convex structure 50 is provided in a half portion of the heat insulating member 44 located on the cylinder block 14 side.
The concavo-convex structure 50 is composed of a plurality of convex portions 52 having a uniform outer shape protruding from the outer surface 4402 of the heat insulating member 44, and the convex portion 52 has a hemispherical cross section.
And the location where the location located on the cylinder block 14 side is located on the side away from the cylinder block 14 is the density of the convex portions 52 provided per unit area in the half portion located on the cylinder block 14 side of the heat insulating member 44. The contact area between the wall surface 4602 and the outer surface 4402 is set to be smaller at a location located on the cylinder block 14 side than at a location located away from the cylinder block 14.

In addition, the shape of the convex part 52 is not limited to hemisphere, For example, a cone shape, a truncated cone shape, a triangular pyramid shape, a triangular frustum shape, a quadrangular pyramid shape, a quadrangular frustum shape, a polygonal pyramid shape Various conventionally known shapes such as a polygonal pyramid trapezoidal shape, a columnar shape, a triangular prism shape, and a polygonal column shape can be employed.
Further, the convex portion 52 may be a protrusion that protrudes from the outer surface 4402 of the heat insulating member 44 and extends in the longitudinal direction of the heat insulating member 44 with an interval in a direction orthogonal to the longitudinal direction of the heat insulating member 44, or The protrusion may extend in the circumferential direction of the heat insulating member 44 with an interval in the longitudinal direction of the heat insulating member 44, and the cross-sectional shape thereof is arbitrary such as a triangle.
In addition, the concavo-convex structure 50 may be configured by providing a plurality of concave portions or a plurality of concave grooves whose outer surfaces are recessed instead of the plurality of convex portions 52.
Further, the concavo-convex structure 50 may be configured by providing a convex portion, a ridge, a concave portion, and a concave groove on the wall surface 4602 of the concave portion 46 of the cylinder head 16, and the outer surface 4402 of the heat insulating member 44 and the concave portion 46. The concavo-convex structure 50 may be provided on both the outer surface 4402 and the wall surface 4602, for example, by providing a recess and a groove on both the wall surfaces 4602.
In short, in the concavo-convex structure 50, the contact area between the wall surface 4602 of the recess 46 and the outer surface 4402 of the heat insulating member 44 is smaller at a location located on the cylinder block 14 side than on a location located on the side away from the cylinder block 14. What is necessary is just to be comprised.

In addition, the contact area between the wall surface 4602 of the recess 46 and the outer surface 4402 of the heat insulating member 44 is smaller at a location located on the downstream side of the intake air than on a location located on the upstream side of the intake air.
In the present embodiment, the density of the convex portions 52 provided per unit area of the outer surface 4402 of the heat insulating member 44 is smaller at the position located on the downstream side of the intake air than the position located on the upstream side of the intake air.

Note that the heat flow Q transferred from the high-temperature object to the low-temperature object between the two objects in contact with each other is proportional to the contact area A of the two objects.
Therefore, in order to reduce the heat flow between the wall surface 4602 of the recess 46 and the outer surface 4402 of the heat insulating member 44 and improve the heat insulating effect, it is preferable to make the contact area as small as possible.
In order to reduce the contact area between the wall surface 4602 of the recessed portion 46 and the outer surface 4402 of the heat insulating member 44, the wall surface 4602 of the recessed portion 46 and the outer surface 4402 of the heat insulating member 44 are in surface contact, the line contact state, It becomes increasingly advantageous in the order of point contact.
Therefore, in order to improve the heat insulation effect between the wall surface 4602 of the recessed portion 46 and the outer surface 4402 of the heat insulating member 44, the concavo-convex structure 50 is a line contact between the wall surface 4602 of the recessed portion 46 and the outer surface 4402 of the heat insulating member 44. It is more preferable, and it is more preferable that it is point contact.
Therefore, if the convex portion 52 has a hemispherical cross section as in the present embodiment, the convex portion 52 and the wall surface 4602 of the concave portion 46 are in point contact, so that the wall surface 4602 of the concave portion 46 and the outer surface of the heat insulating member 44 This is advantageous in improving the heat insulation effect with the 4402.

According to the present embodiment, the contact area between the wall surface 4602 and the outer surface 4402 is such that the location located on the cylinder block 14 side is greater than the location located on the side away from the cylinder block 14 by providing the uneven structure 50. It is getting smaller.
Therefore, the heat conducted from the cylinder block 14 side, which is at a high temperature, is hardly transmitted to the inner surface 4404 of the heat insulating member 44 located on the cylinder block 14 side. Therefore, it is advantageous in improving the heat insulating performance for insulating the intake air from the wall surface of the intake port 30 and suppressing the increase in the intake air temperature and improving the fuel consumption.

Further, in the present embodiment, the contact area between the wall surface 4602 of the recess 46 and the outer surface 4402 of the heat insulating member 44 is smaller at the location located on the downstream side of the intake air than on the location located on the upstream side of the intake air.
Therefore, the heat conducted from the combustion chamber side located on the downstream side of the intake air that becomes high temperature is not easily transmitted to the inner surface 4404 of the heat insulating member 44 located on the downstream side of the intake air. Therefore, it is more advantageous to improve the heat insulation performance for insulating the intake air from the wall surface of the intake port 30 and to suppress the rise of the intake air temperature and improve the fuel consumption.

In the present embodiment, the concavo-convex structure 50 is formed of a plurality of convex portions 52 that protrude from the outer surface 4402 of the heat insulating member 44.
Therefore, it is advantageous for easily processing the concavo-convex structure 50 and is advantageous for reducing the manufacturing cost.

10 Engine (Internal combustion engine)
14 Cylinder block 16 Cylinder head 20 Intake pipe 30 Intake port 3002 Wall surface 3004 Wall surface 3006 Wall surface 3008 Wall surface 42 Injector 4202 Injector 44 Thermal insulation member 4402 Outer surface 4404 Inner surface 44A Upstream side wall 44B Downstream side wall 46 Recess 4602 Wall 48 Notch 50 Uneven structure 52 Convex Part

Claims (5)

A cylinder head disposed on the cylinder block and provided with an intake port;
A heat insulating member having an outer surface built in a cylinder head and in contact with the cylinder head; and an inner surface forming a part of the wall surface of the intake port;
An intake port insulation structure for an internal combustion engine comprising:
At least one of the location of the cylinder head that contacts the heat insulation member or the outer surface of the heat insulation member is provided with a concavo-convex structure that reduces the contact area between the location of the cylinder head and the outer surface, thereby providing a location of the cylinder head. And the contact area of the outer surface is smaller in the overlapping direction of the cylinder head and the cylinder block than the portion located on the cylinder block side and located on the side away from the cylinder block.
An intake port heat insulation structure for an internal combustion engine. The area of contact between the cylinder head and the outer surface is smaller at the location located downstream of the intake air than the location located upstream of the intake air.
The intake port heat insulation structure for an internal combustion engine according to claim 1. The concavo-convex structure is formed of a plurality of convex portions protruding from the outer surface.
The intake port heat insulation structure for an internal combustion engine according to claim 1 or 2. An injector for injecting fuel into the intake port;
The heat insulating member includes an upstream side wall portion in which the inner surface forms a wall surface on the upstream side of the intake port from the injection port of the injector, and a downstream side wall portion in which the inner surface forms a wall surface on the downstream side of the intake port from the injection port. With
In the downstream side wall portion where the injector is disposed, the intake air extends from the periphery of the nozzle hole in the direction of flowing through the inner surface and is open at the end of the downstream side wall portion away from the upstream side wall portion. Notches are provided,
The downstream side wall portion extends to a position just before the location where the sprayed fuel adheres to the wall surface of the intake port on the side facing the nozzle hole.
The intake port heat insulation structure for an internal combustion engine according to any one of claims 1 to 3, wherein A cylinder head disposed on the cylinder block and provided with an intake port;
A heat insulating member having an outer surface built in a cylinder head and in contact with the cylinder head; and an inner surface forming a part of the wall surface of the intake port;
An intake port insulation structure for an internal combustion engine comprising:
At least one of the location of the cylinder head that contacts the heat insulation member or the outer surface of the heat insulation member is provided with a concavo-convex structure that reduces the contact area between the location of the cylinder head and the outer surface, thereby providing a location of the cylinder head. the contact area of the outer surface portions positioned on the cylinder block side, rather smaller than portions located on the side away from the cylinder block,
An injector for injecting fuel into the intake port;
The heat insulating member includes an upstream side wall portion in which the inner surface forms a wall surface on the upstream side of the intake port from the injection port of the injector, and a downstream side wall portion in which the inner surface forms a wall surface on the downstream side of the intake port from the injection port. With
In the downstream side wall portion where the injector is disposed, the intake air extends from the periphery of the nozzle hole in the direction of flowing through the inner surface and is open at the end of the downstream side wall portion away from the upstream side wall portion. Notches are provided,
The downstream side wall portion extends to a position just before the location where the sprayed fuel adheres to the wall surface of the intake port on the side facing the nozzle hole.
An intake port heat insulation structure for an internal combustion engine.

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