JP2016079954A - Intake port heat insulation structure of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress vibration of a heat insulating member for insulating intake air from a wall surface of an intake port.SOLUTION: An intake port 30 is composed of a heat insulating member 44 disposed on a cylinder head 16 at a part of its wall surface. The heat insulating member 44 has an outer surface 4402 fitted to a recessed portion 46 of the cylinder head 16 and kept into contact with a wall surface of the recessed portion 46, and an inner surface 4404 forming a part of the wall surface of the intake port 30. A plurality of claw bodies 50 are disposed on the outer surface 4402 of the heat insulating member 44. As the claw bodies 50 are disposed in a state of projecting from the outer surface 4402 at a part of an upstream side of the intake air in the longitudinal direction with respect to a part at a downstream side, in a state of fitting the heat insulating member 44 to the recessed portion 46, movement in a direction toward an end face, of the heat insulating member 44 is prevented.SELECTED DRAWING: Figure 1

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-described structure, since the resin insertion portion is fitted and fixed in the recess formed in the intake port, a gap is generated between the resin insertion portion and the recess due to aging and tolerance. When such a gap has a large dimension, there is a concern that the resin insertion portion may move and vibrate in the gap due to intake pulsation.
The present invention has been made in view of the above circumstances, and can suppress the vibration of a heat insulating member that insulates intake air from the wall surface of the intake port, and promote fuel vaporization while suppressing an increase in intake air temperature. An object of the present invention is to provide an intake port heat insulation structure for an internal combustion engine that is advantageous in improving fuel consumption.

In order to achieve the above object, an invention according to claim 1 is an internal combustion engine comprising a heat insulating member that is incorporated in a cylinder head and has an outer surface that contacts the cylinder head and an inner surface that forms part of the wall surface of the intake port. In the intake port heat insulating structure, the outer surface of the heat insulating member has a length extending in a direction in which the intake air flows through the inner surface, and the upstream position of the intake air in the length direction is a downstream position. Further, a nail body protruding from the outer surface is provided.
The invention according to claim 2 is characterized in that the claw body exerts a biasing force that biases the outer surface away from the wall surface of the cylinder head with which the claw body contacts.
The invention according to claim 3 is characterized in that the claw body is provided at a portion of the outer surface located on the combustion chamber side.
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 extends downstream from the nozzle and forms a wall surface on the downstream side of the intake port, and the downstream side wall portion has a portion on the side where the injector is disposed. The injector nozzle hole is exposed in the intake port and extends in the direction in which the intake air flows and is provided with an open notch at the end of the downstream side wall portion away from the upstream side wall portion. The wall surface of the intake port on the side facing the injection port extends to a position just before the location where the sprayed fuel is attached.
According to a fifth aspect of the present invention, the claw body is constantly urged in a direction protruding from the outer surface, and the claw body includes a claw inner surface located on the outer surface side and a claw located on the opposite side of the claw inner surface. An outer surface, and the outer surface is provided with an accommodation recess for accommodating the nail body and positioning the outer surface of the nail and the outer surface on the same surface in a state where the nail body is accommodated. It is characterized by.

According to the first aspect of the present invention, the claw body prevents the heat insulating member from moving in the direction toward the outside of the cylinder head in a state where the heat insulating member is disposed on the cylinder head. Therefore, since the heat insulating member is incorporated in the cylinder head, even if a gap is generated between the heat insulating member and the cylinder head due to aging or tolerance, the movement of the heat insulating member in the longitudinal direction is prevented by the claw body. Therefore, it is suppressed that the heat insulating member moves and vibrates in the gap due to the intake pulsation.
According to the second aspect of the present invention, an air layer is formed between the outer surface of the heat insulating member and the wall surface of the cylinder head by the urging force of the claw body, the transfer of heat to the intake air is suppressed, and the temperature rise of the intake air is suppressed. This is advantageous for improving the fuel efficiency.
According to invention of Claim 3, an air layer is formed between the outer surface of a heat insulation member and the wall surface of the cylinder head by the side of the combustion chamber which becomes high temperature by the urging | biasing force of a nail | claw body, and the transmission to heat | fever intake is suppressed. Therefore, it is advantageous for suppressing the temperature rise of the intake air, and is advantageous for improving fuel consumption. Further, the outer surface of the heat insulating member is pressed against the wall surface of the cylinder head in the direction opposite to the combustion chamber side by the urging force of the claw provided only on the outer surface of the heat insulating member located on the combustion chamber side.
According to the fourth aspect of the present invention, the intake passage is formed by the upstream side wall portion of the heat insulating member on the upstream side of the intake port from the injection port of the injector, and downstream of the heat insulating member on the downstream side of the intake port from the injection port of the injector. The side wall extends downstream of the intake port to form a part of the wall surface of the intake passage, so that intake air flowing into the intake port can be prevented from receiving heat from the cylinder head, increasing intake charge efficiency. This is advantageous in improving combustion efficiency. In addition, by providing an opening notch at the end of the downstream side wall, a partial wall surface of the intake passage on the downstream side of the injector nozzle is formed by the inner wall of the intake port, that is, the cylinder head. Vaporization of the fuel injected from the cylinder is efficiently performed on the wall surface of the high-temperature cylinder head, which is advantageous in improving combustion efficiency.
According to the fifth aspect of the present invention, it is advantageous when the nail body is easily manufactured by making an oblique cut with respect to the surface of the heat insulating member formed of a synthetic resin using a blade.

It is sectional drawing which shows the intake port structure of the internal combustion engine which concerns on 1st Embodiment. FIG. 2 is a sectional view taken along line AA in FIG. 1. It is sectional drawing of a heat insulation member. It is an expanded sectional view around the nail | claw body of a heat insulation member. It is a perspective view which shows the structure of the heat insulation member in the intake port structure of the internal combustion engine which concerns on 2nd Embodiment. It is sectional drawing corresponding to FIG. 2 of the heat insulation member in the intake port structure of the internal combustion engine which concerns on 2nd Embodiment.

(First embodiment)
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 FIG. 1, 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 comes into contact with the cylinder head 16, in other words, an outer surface 4402 that is fitted in the recess 46 and contacts the wall surface of the recess 46, and an inner surface 4404 that forms a part of the wall surface of the intake port 30. And have.
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 other words, the heat insulating member 44 includes an upstream side wall portion 44A in which the inner surface 4404 forms a wall surface on the upstream side of the intake port 30 from the injection port 4202 of the injector 42, and the inner surface 4404 extends to the downstream side of the intake port 30 from the injection port 4202. And a downstream side wall portion 44B forming a downstream wall surface of the intake port 30.
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, the portion of the wall surface 3006 that extends along the extending direction of the intake port 30 on the side where the injection port 4202 is located out of the wall surface of the intake port 30 located downstream of the injection port 4202 is the cylinder head 16. It consists of
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. 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 located on the upstream side of the injection port 4202 and the wall surface of the intake port 30 located on the downstream side of the injection port 4202, the location of the wall surface 3004 on the side facing the injection port 4202 is upstream. Since the heat insulating member 44 includes the side wall portion 44A and the downstream side wall portion 44B, transmission of heat from the cylinder head 16 to the intake air is suppressed, which is advantageous in suppressing a rise in the intake air temperature. This is advantageous for improving fuel efficiency.
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 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, 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 on the side facing the nozzle hole 4202.
In the present embodiment, the range of the wall surface 3008 to which the fuel spray adheres at the location of the wall surface 3004 on the side facing the nozzle hole 4202 is constituted by the cylinder head 16.
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.
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, the combustion efficiency can be further improved while further suppressing the rise in the 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 50 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 and 3, a plurality of claws 50 are provided on the outer surface 4402 of the heat insulating member 44.
The claw body 50 has a length extending in the direction in which the intake air flows through the inner surface 4404, and is provided so that the upstream side portion of the intake air protrudes from the outer surface 4402 more than the downstream side in the length direction. .
In the present embodiment, the claw body 50 is provided only on the outer surface 4402 located on the combustion chamber 24 side in a state where the heat insulating member 44 is fitted in the recess 46.
In addition, the claw bodies 50 are provided at the center in the width direction of the outer surface 4402 of the downstream side wall portion 44B at intervals along the longitudinal direction of the downstream side wall portion 44B.

As shown in FIG. 4, the claw body 50 is constantly urged in a direction protruding from the outer surface 4402.
The claw body 50 has a claw inner surface 5002 positioned on the outer surface 4402 side and a claw outer surface 5004 positioned on the opposite side of the claw inner surface 5002.
The outer surface 4402 is provided with an accommodation recess 4410 that allows the nail body 50 to be accommodated so that the nail outer surface 5004 and the outer surface 4402 are positioned on the same surface in a state where the nail body 50 is accommodated.

As shown in FIG. 1 and FIG. 2B, the claw body 50 has an outer surface 4402 at a location on the upstream side of the intake air in the length direction rather than a location on the downstream side in a state where the heat insulating member 44 is fitted in the recess 46. Therefore, the movement in the direction toward the end face of the heat insulating member 44 is prevented.
Further, in a state where the heat insulating member 44 is fitted in the recess 46, the claw body 50 exerts a biasing force that biases the outer surface 4402 away from the wall surface of the recess 46 with which the claw body 50 contacts.

  In addition, the nail | claw body 50 may be formed by a part of heat insulation member 44 by making a cut | incision diagonally with respect to the surface of the heat insulation member 44 shape | molded with the synthetic resin using the cutter, or heat insulation. The claw body 50 made of synthetic resin may be formed separately from the member 44, and the claw body 50 may be joined to the surface of the heat insulating member 44 by an adhesive or welding.

According to the present embodiment, the outer surface 4402 of the heat insulating member 44 is provided with the claw body 50 in which the upstream side portion of the intake air protrudes from the outer surface 4402 more than the downstream side portion in the length direction. In a state where 44 is fitted, the claw body 50 prevents movement in the direction toward the end face of the heat insulating member 44.
Therefore, since the heat insulating member 44 is fitted into the concave portion 46 and fixed, even if a gap is generated between the heat insulating member 44 and the concave portion 46 due to aging deterioration and tolerance, the heat insulating member 44 is extended in the longitudinal direction. Since the movement is blocked by the claw body 50, the heat insulating member 44 is suppressed from moving and vibrating in the gap by the intake pulsation.

  Further, according to the present embodiment, with the heat insulating member 44 fitted in the recess 46, the claw body 50 biases the outer surface 4402 away from the wall surface of the recess 46 with which the claw body 50 contacts. As a result, an air layer is formed between the outer surface 4402 of the heat insulating member 44 and the wall surface of the recess 46 by the urging force of the claw body 50, so that the transfer of heat to the intake air is suppressed and the temperature rise of the intake air is suppressed. This is advantageous for improving the fuel consumption of the engine 10.

Further, according to the present embodiment, the claw body 50 is provided only at the location of the outer surface 4402 located on the combustion chamber 24 side in a state in which the heat insulating member 44 is fitted in the recess 46, and thus the claw body 50. Due to the urging force, an air layer is formed between the outer surface 4402 of the heat insulating member 44 and the wall surface of the concave portion 46 on the combustion chamber 24 side that becomes high temperature, and the transfer of heat to the intake air is suppressed, and the temperature rise of the intake air is suppressed. This is advantageous in improving the fuel consumption of the engine 10.
Further, the outer surface 4402 of the heat insulating member 44 is pressed against the wall surface of the recess 46 in the opposite direction to the combustion chamber 24 side by the urging force of the claw 50 provided only at the location of the outer surface 4402 located on the combustion chamber 24 side. Therefore, it is advantageous for suppressing vibration in the radial direction of the heat insulating member 44.

Further, according to the present embodiment, the nail body 50 is constantly urged in a direction protruding from the outer surface 4402, and the nail body 50 is disposed on the nail inner surface 5002 positioned on the outer surface 4402 side and on the side opposite to the nail inner surface 5002. The nail outer surface 5004 is positioned, and the outer surface 4402 has an accommodating recess 4410 that can accommodate the nail body 50 and positions the nail outer surface 5004 and the outer surface 4402 on the same surface in a state where the nail body 50 is accommodated. Is provided.
Therefore, it becomes advantageous when the nail | claw body 50 is manufactured easily by making a cut | incision diagonally with respect to the surface of the heat insulation member 44 shape | molded with the synthetic resin using the cutter.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS.
In 2nd Embodiment, the arrangement structure of the nail | claw body 50 differs from 1st Embodiment.
In the second embodiment, as shown in FIG. 5 and FIG. 6, the plurality of claws 50 are spaced along the width direction of the downstream side wall 44 </ b> B at an intermediate position in the longitudinal direction of the outer surface 4402 of the downstream side wall 44 </ b> B. May be provided.
The effect similar to 1st Embodiment is show | played also by such 2nd Embodiment.

10 Engine (Internal combustion engine)
16 Cylinder head 24 Combustion chamber 30 Intake port 3002 Wall surface 3004 Wall surface 3006 Wall surface 3008 Wall surface 42 Injector 4202 Injection hole 44 Heat insulation member 4402 Outer surface 4404 Inner surface 44A Upstream side wall portion 44B Downstream side wall portion 4410 Receiving recess 46 Recess 48 Notch 50 Nail body 5002 Nail inner surface 5004 Nail exterior

Claims (5)

An intake port heat insulating structure for an internal combustion engine comprising a heat insulating member having an outer surface incorporated in a cylinder head and in contact with the cylinder head and an inner surface forming a part of a wall surface of the intake port,
The outer surface of the heat insulating member has a length that extends in a direction in which the intake air flows through the inner surface, and a claw body in which the upstream side portion of the intake air protrudes from the outer surface more than the downstream side in the length direction Is provided,
An intake port heat insulation structure for an internal combustion engine. The claw body exerts a biasing force that biases the outer surface away from the wall surface of the cylinder head that the claw body contacts.
The intake port heat insulation structure for an internal combustion engine according to claim 1. The claw body is provided at the outer surface located on the combustion chamber side,
The intake port heat insulation structure for an internal combustion engine according to claim 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 upstream of the intake port from the injection port of the injector, and the inner surface extends downstream of the intake port from the injection port. A downstream side wall forming a downstream wall,
An end of the downstream side wall portion that is exposed in the intake port and extends in a direction in which the intake air flows and is separated from the upstream side wall portion at a location on the side where the injector is disposed in the downstream side wall portion The part is provided with an open notch,
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 The claw body is constantly urged in a direction protruding from the outer surface,
The claw body has a claw inner surface located on the outer surface side, and a claw outer surface located on the opposite side to the claw inner surface,
The outer surface is provided with an accommodation recess that allows the nail body to be accommodated and positions the outer surface of the nail and the outer surface on the same surface in a state where the nail body is accommodated.
The intake port heat insulation structure for an internal combustion engine according to any one of claims 1 to 4, wherein the intake port heat insulation structure is provided.

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