JP2006183550A - Intake and exhaust structure for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intake and exhaust structure for an internal combustion engine of high fuel atomization promotion effect without complicating a structure. <P>SOLUTION: This structure is provided with an intake valve 12 opening and closing an intake port 12, an intake valve seat 13 sticking to a valve face 12e of the intake valve 12 to keep air tightness of a combustion chamber, and an intake valve guide 14 having a valve stem 12a of the intake valve 12 inserted therethrough and guiding reciprocating motion of the intake valve 12. Heat transfer rate of the intake valve seat 13 is smaller than heat transfer rate of the intake valve 12 and heat transfer rate of the intake valve 12 is smaller than heat transfer rate of the intake valve guide 14. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an intake / exhaust structure for an internal combustion engine.

  In an internal combustion engine provided with an injector, an intake structure has been proposed in which fuel is injected toward the back surface of an umbrella of an intake valve, and fuel atomization is promoted using the temperature of the back surface of the umbrella. For example, in Patent Document 1, a heat pipe having a wick portion in which a working fluid flows and an evaporation portion in which the working fluid evaporates and vapor moves is incorporated in the umbrella portion of the intake valve. The lower part of the heat pipe serves as a heat receiving part that receives heat from the umbrella surface, and the upper part serves as a heat radiating part that condenses the evaporated working fluid. With such a structure, the heat received on the umbrella surface of the intake valve is conducted to the back surface of the umbrella through the heat pipe, and the atomization of the fuel is promoted by the heat.

  Further, an air layer is provided in the valve stem over the axial direction. Since this air layer acts as a heat insulating space, the thermal load on the valve stem can be reduced.

Furthermore, by increasing the contact surface of the valve with the valve seat, a large amount of heat from the valve escapes to the cylinder head via the valve seat.
Japanese Utility Model Publication No. 64-3008

  However, in the above-described conventional intake valve, since the heat pipe is built in a narrow space called the umbrella portion of the intake valve, the heat pipe capacity is small, the efficiency of the heat transfer cycle is low, and the fuel atomization promoting effect is small.

  In addition, it is difficult to embed a heat pipe in a narrow space called an umbrella portion of the intake valve or to form an air layer inside the valve stem, which increases the manufacturing cost.

  The present invention has been made paying attention to such a conventional problem, and an object thereof is to provide an intake / exhaust structure of an internal combustion engine having a high effect of promoting fuel atomization without complicating the structure. .

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention includes an intake valve (12) that opens and closes an intake port (11), an intake valve seat (13) that keeps an air tightness of a combustion chamber in close contact with a valve face (12e) of the intake valve (12), An intake valve guide (14) that guides the reciprocation of the intake valve (12) through the valve stem (12a) of the intake valve (12), and the heat transfer coefficient of the intake valve seat (13) is: The heat transfer coefficient of the intake valve (12) is smaller than the heat transfer coefficient of the intake valve guide (14).

  According to the present invention, the heat transfer coefficient of the intake valve seat is smaller than the heat transfer coefficient of the intake valve, so that the heat received on the umbrella surface of the intake valve is less likely to escape to the valve seat, and the inside of the intake valve Conducted, the back of the umbrella becomes hot, and fuel atomization is promoted.

  Further, since the heat transfer coefficient of the intake valve is made smaller than the heat transfer coefficient of the intake valve guide, the heat conducted through the valve stem is conducted from the insertion portion with the valve guide to the valve guide. Therefore, the thermal load on the valve stem can be reduced.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a view showing an embodiment of an intake / exhaust structure for an internal combustion engine according to the present invention.

The intake valve 12 controls the intake air by opening and closing the intake port 11 with the umbrella portion 12b. The valve seat 13 is in close contact with the valve face 12e formed on the umbrella back surface 12d of the umbrella portion 12b of the intake valve 12, and keeps the combustion chamber airtight. The umbrella surface 12c of the intake valve 12 receives heat from the combustion chamber. The valve guide 14 is inserted into the valve stem 12 a of the intake valve 12 and guides the reciprocating motion of the intake valve 12. The intake port 11 is provided with an injector 42. The injector 42 injects fuel supplied through a fuel supply pipe (delivery pipe) (not shown) into the intake port 11. The fuel injected from the injector 42 hits the umbrella portion 12b of the intake valve 12, and atomization is promoted.

The exhaust valve 22 controls the exhaust by opening and closing the exhaust port 21 by the umbrella portion 22b. The valve seat 23 is in close contact with the valve face 22e formed on the umbrella back surface 22d of the umbrella portion 22b of the exhaust valve 22, and keeps the combustion chamber airtight. The umbrella surface 22c of the exhaust valve 22 receives heat from the combustion chamber. The valve guide 24 is inserted through the valve stem 22a of the exhaust valve 22 to guide the reciprocation of the exhaust valve 22. When the piston 31 is near top dead center, the intake valve 12 and the exhaust valve 22 are closed, and the spark plug 41 Is ignited by.

  The present inventor obtained the heat flux diagram shown in FIG. 2 by analyzing the heat flow of the intake valve and the exhaust valve.

  As is apparent from this heat flux diagram, heat conducted through the valve 2 includes heat conducted downward along the section AA near the base of the umbrella 2b and heat conducted upward.

  Therefore, the present inventor, based on this analysis result, keeps the heat conducted below the intake valve 12 in the umbrella portion 12b as much as possible, and makes the umbrella back surface 12d high in temperature to use the heat of the injector 42. The atomization of the fuel injected from was promoted. The heat conducted above the intake valve 12 is released from the valve stem 12a to the valve guide 14 as much as possible to reduce the heat load on the intake valve 12.

  Therefore, in the present invention, the relationship of the thermal conductivity among the intake valve 12, the valve seat 13, and the valve guide 14 is as follows.

  The materials of the conventional intake valve 12, valve seat 13, and valve guide 14 are all made of steel such as heat-resistant steel, sintered alloy, cast iron and the like. Therefore, in the present invention, the valve seat 13 is made of a sintered alloy as usual, and the intake valve 12 is made of, for example, an aluminum alloy having a higher thermal conductivity. Further, the valve guide 14 is made of, for example, a copper alloy so as to have a higher thermal conductivity than the intake valve 12.

  Thus, by making the thermal conductivity of the valve seat 13 smaller than the thermal conductivity of the intake valve 12, the heat received by the umbrella surface 12c of the intake valve 12 becomes difficult to escape to the valve seat 13, and the intake valve 12 is conducted, the back surface 12d of the umbrella becomes high temperature, and fuel atomization can be promoted.

  On the other hand, since the heat conductivity of the valve guide 14 is made larger than the heat conductivity of the intake valve 12, the heat conducted through the valve stem 12a is conducted from the insertion portion with the valve guide 14 to the valve guide 14. Therefore, the thermal load on the valve stem 12a can be reduced.

  By making the intake valve 12 made of an aluminum alloy, there is a concern that the strength may be reduced as compared with an intake valve made of heat-resistant steel (standard (STD) type). Therefore, the shape was also reviewed. A specific shape is shown in FIG. FIG. 3 is a view showing the shape of the intake valve according to the present invention. In the figure, a solid line indicates an intake valve according to the present invention, and a broken line indicates a conventional heat-resistant steel intake valve.

  As shown in FIG. 3, when the umbrella back angle θ1 of the conventional valve, the umbrella back angle θ2 of the intake valve 12 according to the present invention, the umbrella head thickness T1 of the conventional valve, and the umbrella head thickness T2 of the intake valve 12 according to the present invention are used. The following relationship is satisfied.

θ1 × 2 ≦ θ2 ≦ θ1 × 3
T1 × 2 ≦ T2 ≦ T1 × 3
In this way, the thickness reduction can be prevented by increasing the thickness of the umbrella portion.

  Further, based on the analysis result of FIG. 2, the present inventor increases the heat load on the exhaust valve 22 by letting the exhaust valve 22 escape from the exhaust valve 22 as much as possible. I tried to reduce it.

  Therefore, in the present invention, the relationship of the thermal conductivity among the exhaust valve 22, the valve seat 23, and the valve guide 24 is as follows.

  Next, specific effects will be described.

  FIG. 4 is a diagram for explaining the fuel efficiency improvement effect. In the figure, the black circle ● is a conventional product, and the white circle ○ is an intake valve made of an aluminum alloy.

  By changing the material of the intake valve to an aluminum alloy that is a high thermal conductivity material, the umbrella back temperature of the intake valve increases (FIG. 4A). Thereby, the atomization of fuel can be accelerated | stimulated and an unburned rate falls (FIG. 4 (B)). As a result, the fuel consumption rate was improved (FIG. 4C).

  FIG. 5 is a diagram for explaining the knock improvement effect. In the figure, the black circle ● is a conventional product, and the white circle ○ is an intake valve made of an aluminum alloy.

  By changing the material of the intake valve to an aluminum alloy, the heat in the cylinder is easily conducted from the umbrella surface 12c to the umbrella back surface 12d, and this heat is consumed as vaporization heat that atomizes the fuel. As a result, the umbrella surface temperature decreases (FIG. 5B). Along with this, the temperature in the cylinder decreases, and knocking is less likely to occur (FIG. 5A).

  FIG. 6 is a diagram for explaining the exhaust gas reduction effect during cold operation. In the figure, the black circle ● is a conventional product, and the white circle ○ is an intake valve made of an aluminum alloy.

  By changing the material of the intake valve to an aluminum alloy, knocking is less likely to occur as described above (FIG. 5A), so that the ignition timing at which the same combustion stability is obtained can be delayed compared to the conventional product. Yes (FIG. 6C). By delaying the ignition timing, the exhaust temperature rises (FIG. 6B), and the hydrocarbon (HC) emissions can be reduced (FIG. 6A).

  FIG. 7 is a diagram showing a friction reducing effect. In the figure, the black circle ● is a conventional product, and the white circle ○ is an intake valve made of an aluminum alloy.

  By changing the material of the intake valve from heat-resistant steel to aluminum alloy, the mass of the intake valve is reduced, so that the spring constant of the spring that closes the intake valve can be reduced and the friction is also reduced (FIG. 7).

  The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea, and it is obvious that these are equivalent to the present invention.

  For example, in the above-described embodiment, the exhaust port 21 has the valve seat 23. However, the exhaust valve 21 does not have the valve seat 23, and the exhaust valve 22 directly contacts the opening of the exhaust port 21. There may be. In that case, the same effect can be obtained by making the heat transfer coefficient of the exhaust valve smaller than the heat transfer coefficient of the exhaust valve guide.

1 is a diagram showing an embodiment of an intake / exhaust structure of an internal combustion engine according to the present invention. It is a heat flux figure which shows the heat flow of an intake valve and an exhaust valve. It is a figure which shows the shape of the intake valve by this invention. It is a figure explaining the fuel consumption improvement effect. It is a figure explaining a knock improvement effect. It is a figure explaining the exhaust gas reduction effect at the time of cold machine. It is a figure which shows the friction reduction effect.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Intake port 12 Intake valve 12a Valve stem 12b Umbrella part 12c Umbrella surface 12d Umbrella back surface 12e Valve face 13 Valve seat 14 Valve guide 21 Exhaust port 22 Exhaust valve 23 Valve seat 24 Valve guide 42 Injector

Claims (4)

An intake valve that opens and closes the intake port;
An intake valve seat that is in close contact with the valve face of the intake valve to keep the combustion chamber airtight;
An intake valve guide for inserting the valve stem of the intake valve and guiding the reciprocation of the intake valve;
With
The heat transfer coefficient of the intake valve seat is smaller than the heat transfer coefficient of the intake valve,
The heat transfer coefficient of the intake valve is smaller than the heat transfer coefficient of the intake valve guide,
An intake structure for an internal combustion engine. An intake / exhaust structure for an internal combustion engine having the intake structure according to claim 1,
An exhaust valve that opens and closes the exhaust port;
An exhaust valve seat that is in close contact with the valve face of the exhaust valve to keep the combustion chamber airtight;
An exhaust valve guide for inserting the valve stem of the exhaust valve and guiding reciprocation of the exhaust valve;
With
The heat transfer coefficient of the exhaust valve is smaller than the heat transfer coefficient of the exhaust valve guide,
The heat transfer coefficient of the exhaust valve guide is smaller than the heat transfer coefficient of the exhaust valve seat,
An intake / exhaust structure for an internal combustion engine. An intake / exhaust structure for an internal combustion engine having the intake structure according to claim 1,
An exhaust valve that opens and closes the exhaust port and directly adheres to the opening of the exhaust port to keep the combustion chamber airtight;
An exhaust valve guide for inserting the valve stem of the exhaust valve and guiding reciprocation of the exhaust valve;
With
The heat transfer coefficient of the exhaust valve is smaller than the heat transfer coefficient of the exhaust valve guide,
An intake / exhaust structure for an internal combustion engine. An injector provided at the intake port;
An intake valve that opens and closes the intake port;
An intake valve seat that is in close contact with the valve face of the intake valve to keep the combustion chamber airtight, and has a thermal conductivity smaller than the heat transfer coefficient of the intake valve;
An intake valve guide that passes through the valve stem of the intake valve, guides the reciprocation of the intake valve, and has a heat transfer coefficient larger than the heat transfer coefficient of the intake valve;
With
The injector injects fuel toward the back of the umbrella of the intake valve to promote fuel vaporization;
A method for promoting fuel vaporization in an internal combustion engine.

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