JP6512330B2 - Intake port 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 structure of a port injection type internal combustion engine.

BACKGROUND ART In recent years, an internal combustion engine with a high compression ratio with high thermal efficiency has been required from the viewpoint of fuel efficiency improvement.
An internal combustion engine with a high compression ratio has a high temperature of the air-fuel mixture after compression as compared to an engine with a low compression ratio, so it becomes easy to knock and it is necessary to retard the ignition timing.
As a result, since the improvement effect of the fuel consumption is reduced, it is necessary to suppress the rise of the intake air temperature and hence the mixture temperature.
The intake air is drawn into the combustion chamber via the intake passage of the intake manifold and an 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 temperature of the intake air is inevitably increased by receiving heat from the intake passage of the intake manifold and the wall surface of the intake port of the cylinder head.
Therefore, there has been proposed an attachment structure of an intake pipe in which an intake manifold is made of a resin material having a heat insulating property 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 wall surface of the intake port formed by the wall surface of the cylinder head is reduced to suppress the temperature rise of the intake air.

JP, 2007-285171, A

In the case of a port injection type internal combustion engine that injects fuel from the injector into the intake port, the fuel injected from the injector is vaporized by receiving heat from the wall surface of the cylinder head that constitutes the wall surface of the intake port and the intake valve. Promoted.
When the rotational speed of the internal combustion engine is increased and the intake speed is increased, the fuel injected from the injection port of the injector is received against the wall surface of the intake port on the side of the injection port located on the downstream side of the injection port. By doing this, vaporization is promoted.
In the case of the above-mentioned prior art, the resin insertion portion extends to the downstream side of the injection port, so the wall surface of the intake port on the side where the injection port is located among the wall surfaces of the intake port located downstream of the injection port The area of the wall portion of the cylinder head that constitutes the
For this reason, the fuel ejected from the injection port adheres to the portion of the wall surface constituted by the insertion portion made of resin, and vaporization of the fuel is suppressed, so the combustion efficiency is lowered and the fuel consumption is improved. It is disadvantageous on the top.
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an intake port structure of an internal combustion engine which is advantageous for improving fuel efficiency by promoting vaporization of fuel while suppressing an increase in intake temperature. With the goal.

In order to achieve the above object, the invention according to claim 1 comprises an injector disposed in the intake passage for supplying fuel, and a heat insulating member disposed in the intake port and forming the intake port and the intake passage. In the intake port heat insulating structure for an internal combustion engine, the heat insulating member includes an upstream side wall located upstream of the injection port of the injector and a downstream side wall located downstream of the injection port from the injection port. And a notch in the wall on the side where the injector is disposed, the notch being provided in a region surrounded by the downstream end of the upstream side wall portion and the upper edge of the downstream side wall portion , the downstream end of the upstream wall is located in the intake passage upstream of the injection port, the downstream wall is extended to a point where the fuel spray of the wall surface on the side facing the injection port is attached It is characterized in.
In the invention according to claim 2, the upstream side wall portion of the heat insulating member is formed in a substantially cylindrical shape, an inner peripheral surface constituting a wall surface of the intake port, and an outer peripheral surface fitted in a recess of the cylinder head The outer peripheral surface is formed by an inclined surface whose outer diameter dimension decreases as approaching the downstream portion.
The invention according to claim 3 is characterized in that the heat insulating member is constituted of a hollow member and a heat insulating material inserted into the hollow member.
The invention according to claim 4 is characterized in that the upstream side wall portion and the downstream side wall portion are separate bodies.

According to the invention of claim 1, the downstream end of the upstream side wall portion of the heat insulating member is located on the upstream side of the intake passage from the injection port, and on the side of the wall of the intake port located on the downstream side of the injection port Since the portion of the wall surface extending along the extension direction of the intake port from the injection port is formed by the cylinder head, the wall surface of the intake port downstream of the injection port is exposed.
Therefore, in the high-speed rotation range of the engine, the intake speed flowing through the intake port is increased, so most of the fuel injected from the injection port is extended along the extension direction of the intake port on the side where the injection port is located. By adhering to a portion and receiving heat from the wall surface, vaporization is efficiently performed in the intake port, which is advantageous in improving the combustion efficiency of the fuel. Further, the wall surface of the port, which is a portion of the wall surface to which most of the fuel injected from the injection port is not attached, is formed of a heat insulating member, which is advantageous in suppressing the temperature rise of the intake air. Therefore, it is advantageous to improve the fuel efficiency of the engine.
Further , in the low speed rotation region of the engine, the wall surface of the intake port to which most of the fuel injected from the injection nozzle adheres is formed by the cylinder head, so the cylinder head has a high temperature of vaporization of the fuel adhering to the wall surface of the intake port. This is done efficiently on the wall surface of the fuel cell, which is advantageous in improving the combustion efficiency of the fuel. Further, in the low-speed rotation region of the engine, the wall surface of the port, which is a portion of the wall surface to which most of the fuel injected from the injection port does not adhere, is made of a heat insulating member, so transmission of heat from the cylinder head to intake air is suppressed. It is advantageous in suppressing the temperature rise of the intake air. Therefore, it is advantageous to improve the fuel efficiency of the engine.
According to the second aspect of the present invention, when the upstream portion is fitted in the recess of the intake port, it is advantageous to fit the upstream portion without rattling.
According to the third aspect of the present invention, the temperature distribution of the cylinder head is selected by selecting the type of heat insulating material to be inserted into the hollow member or setting the number and thickness of the sheet-like heat insulating material. It is advantageous in corresponding and ensuring the heat insulation performance of the optimal intake port.
According to the invention as set forth in claim 4 , the heat insulating performance can be changed between the upstream portion and the downstream portion by changing the type of heat insulating material used for the upstream portion and the downstream portion, and the temperature distribution of the cylinder head can be matched. This is advantageous in securing the heat insulation performance of the optimum intake port.

FIG. 1 is a cross-sectional view showing an intake port structure of an internal combustion engine according to the present embodiment. (A) is a cross-sectional view taken along line AA of FIG. 1, (B) is a cross-sectional view taken along line BB of FIG. 1, and (C) is a cross-sectional view taken along line CC of FIG. It is a perspective view which shows the structure of a heat insulation member. It is sectional drawing which shows the structure 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 an engine) 10 has a cylinder block 14 in which a cylinder 12 is formed, a cylinder head 16 provided above the cylinder block 14, and a piston disposed in the cylinder 12. And 18 are included.
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 peripheral 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 a spark plug 26 so as to be located 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.
An intake passage 2002 of the intake pipe 20 is connected to the intake port 30, and an exhaust passage 2202 of the exhaust pipe 22 is connected to the exhaust port 32.
Further, an intake valve 34 is provided at the intake port 30, an exhaust valve 36 is provided at the exhaust port 32, and the intake valve 34 and the exhaust valve 36 are biased in the closing direction by valve springs 38 and 40. The intake valve 34 and the exhaust valve 36 are driven by an intake and exhaust cam (not shown) to open and close the intake port 30 and the exhaust port 32.

In the present embodiment, the engine 10 is a port injection type engine that injects fuel from the injector 42 into the intake port 30.
The injector 42 injects the fuel supplied from a pump (not shown), and is provided on a fuel injection nozzle 4204 with the injection port 4202 directed to the inside of the intake port 30 and the fuel injection nozzle 4204 and opens and closes the injection port 4202 by an actuator. And a needle valve (not shown).
In the port injection type engine, the intake air taken 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 air-fuel mixture It is supplied to the chamber 24.
Then, as the crankshaft rotates, the intake valve 34 and the exhaust valve 36 are opened and closed through the intake cam and the exhaust cam, and the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke are executed. During the injection, fuel is injected from the injection port 4202 into the intake port 30.

As shown in FIG. 1, a part of the wall surface of the intake port 30 is constituted by the heat insulating member 44 attached to the cylinder head 16, and the heat insulating member 44 is notched on the wall surface on the side where the injector 42 is disposed. It has 4402.
As shown in FIG. 2A, the intake port 30 is perpendicular to the height H between the wall surface on the side where the injection port 420 is located and the wall surface on the side facing the injection port 4202, and the height H It has an elongated shape having a width W larger than H.
In FIGS. 2A to 2C, a symbol C1 indicates a center line passing through the center of the height, a symbol C2 indicates a center line passing through the center of the width, and the intake port 30 is axisymmetrical to the center line C1. The shape is axisymmetric with respect to the center line C2, and the injection port 4202 is located on the center line C2.
The heat insulating member 44 has an upstream portion 46 located upstream of the injection nozzle 4202 of the intake air flowing through the intake port 30 and a downstream portion 48 located downstream of the injection nozzle 4202.
As shown in FIGS. 1, 2A, and 3, the upstream portion 46 is cylindrical, and the inner circumferential surface 4602 which constitutes the wall surface of the intake port 30 and the concave portion 1602 of the cylinder head 16 located opposite thereto. And an outer peripheral surface 4604 to be fitted.
The outer circumferential surface 4604 is formed by an inclined surface whose outer diameter dimension decreases as the downstream portion 48 is approached.
The inner circumferential surface 4602 of the upstream portion 46 is formed such that the intake port 30 extends with a uniform cross section, and constitutes the entire area of the wall surface 3002 of the intake port 30 located upstream of the injection port 4202.

Further, the downstream portion 48 has an inner surface 4802 which constitutes a wall surface of the intake port 30 and an outer surface 4804 which is located opposite to the inner surface 4802 and fitted in the recess 1602 of the cylinder head 16.
The inner surface 4802 of the downstream portion 48 constitutes a portion of the wall surface 3004 of the wall surface of the intake port 30 positioned downstream of the injection port 4202 on the side facing the injection port 4202, and the intake port positioned downstream of the injection port 4202 The portion of the wall surface 3006 extending along the extension direction of the intake port 30 on the side where the injection port 4202 is located among the wall surfaces of the 30 is formed by the cylinder head 16.
Therefore, in the present embodiment, the notch 4402 is formed open toward the combustion chamber 24 in a region surrounded by the downstream end of the upstream portion 46 and the upper edge of the downstream portion 48.
The center in the width W direction of the inner surface of the downstream portion 48 is located on the center line C2, and in the present embodiment, as shown in FIG. 1, FIG. 2 (B), (C), and FIG. The width W1 of the inner surface and the height H1 of the inner surface of the downstream portion 48 gradually decrease toward the combustion chamber 24 side, and the area of the inner surface per unit length in the extension direction of the intake port 30 becomes the downstream of the intake flow It is formed to become smaller and smaller as it reaches the side.
In this manner, the width W1 and the height H1 of the inner surface 4802 of the downstream portion 48 gradually decrease toward the combustion chamber 24, and the area of the inner surface 4802 per unit length in the extension direction of the intake port 30 becomes the intake flow. It becomes smaller gradually toward the downstream side. As a result, the area in which the heat insulating member 44 is disposed in the vicinity of the combustion chamber 24 is minimized, which is advantageous in rapidly evaporating the fuel. Further, since the heat insulating member 44 is disposed in accordance with the spray shape of the fuel ejected from the injection port 4202, it is advantageous in promoting the vaporization of the fuel while thermally insulating the intake pipe 20.

According to the present embodiment, in the high-speed rotation range 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 located on the side 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 which extends along the extending direction.
Then, by receiving heat from the wall surface 3006, vaporization is promoted in the intake port 30, and it is drawn into the combustion chamber 24 as an air-fuel mixture mixed with the intake air, and the fuel not attached to the wall surface 3006 of the intake port 30 is the intake port. The air is mixed with the intake air within 30 and drawn into the combustion chamber 24.
In the present embodiment, in the wall surface of intake port 30 positioned downstream of injection port 4202, the location of wall surface 3006 extending along the extending direction of intake port 30 on the side where injection port 4202 is located is cylinder head 16 It consists of
Therefore, in the high-speed rotation range of the engine 10, the fuel adhering to the wall surface 3006 of the intake port 30 is efficiently vaporized by the wall surface 3006 of the high temperature cylinder head 16, which is advantageous in improving the combustion efficiency of the fuel.
Further, in the high-speed rotation range of engine 10, the entire area of wall surface 3002 of intake port 30 positioned upstream of injection port 4202, which is a portion of the wall surface to which most of the fuel injected from injection port 420 is not attached Of the wall surface of the intake port 30 located on the side, the portion of the wall surface 3004 on the side opposite to the injection port 4202 is constituted by the heat insulating member 44 consisting of the upstream portion 46 and the downstream portion 48. The transmission to the intake air is suppressed, which is advantageous in suppressing the temperature rise of the intake air, and advantageous in improving the fuel efficiency 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 efficiency of the engine 10.

Further, in the low speed rotation range of the engine 10, the majority of the fuel injected from the injection port 4202 adheres to the wall surface 3008 of the intake port 30 facing the injection port 4202 and the intake valve 34.
Then, by receiving heat from the wall surface 3008 and the intake valve 34, vaporization is promoted in the intake port 30, and it is drawn into the combustion chamber 24 as an air-fuel mixture mixed with the intake and does not adhere to the wall 3008 of the intake port 30. Is mixed with the intake air in the intake port 30 and drawn into the combustion chamber 24.
In the present embodiment, the range of the wall surface 3008 to which the fuel spray is attached at the portion of the wall surface 3004 opposite to the injection port 4202 is configured by the cylinder head 16.
The downstream portion 48 extends from the location of the wall surface 3004 facing the injection port 4202 to the front of the range of the wall surface 3008.
Therefore, in the low speed rotation range of the engine 10, the fuel adhering to the wall surface 3008 of the intake port 30 is efficiently vaporized, which is advantageous in improving the combustion efficiency of the fuel.
Further, since the downstream portion 48 extends from the location of the wall surface 3004 facing the injection port 4202 to the front of the range of the wall surface 3008, the heat transfer of the cylinder head 16 to the intake is suppressed, and the temperature rise of the intake is suppressed. It is more advantageous in doing
Therefore, in the low speed rotation region of the engine 10, the combustion efficiency can be further improved while suppressing the temperature rise of the intake air, which is further advantageous in improving the fuel efficiency of the engine 10.

  Further, since the outer peripheral surface 4604 of the upstream portion 46 is formed as an inclined surface whose outer diameter becomes smaller as it gets closer to the downstream portion 48, when the upstream portion 46 is fitted in the recess 1602 of the cylinder head 16, It is advantageous to fit the portion 46 without rattling.

In addition, when the upstream portion 46 and the downstream portion 48 are separately configured, the heat insulating performance can be changed by changing the type of heat insulating material used for the upstream portion 46 and the downstream portion 48.
For example, if the coolant water passage (high temperature) is disposed in the portion of the cylinder head 16 in which the upstream portion 46 is disposed, and the portion of the cylinder head 16 in which the downstream portion 48 is disposed is cooler, the portion is upstream of the downstream portion 48 The thermal insulation material comprising thermal insulation member 44 can be selected or the density of the thermal insulation material can be set to enhance the thermal insulation performance of portion 46.
Therefore, it is advantageous in ensuring the optimum heat insulation performance in accordance with the temperature distribution of the cylinder head 16.

Further, as shown in FIG. 4, the upstream portion 46 and the downstream portion 48 may each be formed of a hollow member and a heat insulating material 50 inserted inside the hollow member.
When a hollow member is used in this way, it is possible to use a sheet-like material, a powder, a liquid such as a liquid, or the like which does not have sufficient properties to constitute a wall surface as the heat insulating material 50 inserted into the hollow member. When the sheet-like heat insulation material 50 according to the desired heat insulation performance is selected, the number and thickness of the heat insulation material 50 can be set.
Therefore, it is advantageous in ensuring the optimum heat insulation performance in accordance with the temperature distribution of the cylinder head 16.

In addition, the material which comprises a hollow member can use conventionally well-known various materials, such as a synthetic resin material or a metal material.
Further, the heat insulating member 44 may be formed of a hollow or solid synthetic resin material in which the upstream portion 46 and the downstream portion 48 are integrally configured, or may be formed of a hollow metal material.
However, as in the present embodiment, when the upstream portion 46 and the downstream portion 48 of the heat insulating member 44 are respectively formed of a hollow member and the heat insulating material 50 inserted inside the hollow member, the optimum heat insulating performance is achieved. It is more advantageous in securing the

  Further, in the case where the plurality of intake ports 30 are branched from the opening on the intake pipe 20 side and the injectors 42 are provided in the respective intake ports 30, the upstream portion 46 and the downstream portion 48 are appropriately branched. The relative positional relationship between 42 and their branched downstream portions 48 is similar to that of the embodiment.

10 Engine (internal combustion engine)
16 cylinder head 30 intake port 3002 wall surface 3004 wall surface 3006 wall surface 3008 wall surface 42 injector 4202 injection port 44 heat insulating member 4402 notch 46 upstream portion 4602 inner circumferential surface 4604 outer circumferential surface 48 downstream portion 50 heat insulating material

Claims (4)

An intake port heat insulating structure for an internal combustion engine, comprising: an injector disposed in the intake passage for supplying fuel; and a heat insulating member disposed inside the intake port to form the intake port and the intake passage.
The heat insulating member has an upstream side wall portion located on the upstream side of the intake passage from the injection port of the injector, and a downstream side wall portion located on the downstream side of the intake passage from the injection port. Has a notch in the wall,
The notch is provided in a region surrounded by the downstream end of the upstream side wall portion and the upper edge of the downstream side wall portion,
The downstream end of the upstream side wall portion is located on the upstream side of the intake passage from the injection port ,
The intake port heat insulating structure for an internal combustion engine, wherein the downstream side wall portion is extended to a point where the fuel spray adheres to the wall surface on the side facing the injection port. The upstream side wall portion of the heat insulating member is formed in a substantially cylindrical shape, and has an inner peripheral surface forming a wall surface of the intake port and an outer peripheral surface fitted to a recess of the cylinder head.
The outer peripheral surface is formed by an inclined surface whose outer diameter dimension decreases as approaching the downstream portion.
Intake port structure for an internal combustion engine according to claim 1, wherein a. The heat insulating member is composed of a hollow member and a heat insulating material inserted into the hollow member.
The intake port structure of an internal combustion engine according to claim 1 or 2 , characterized in that: The upstream side wall portion and the downstream side wall portion are separate members,
An intake port structure for an internal combustion engine according to any one of claims 1 to 3 , characterized in that.

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