JPH06185318A - Exhaust valve device of internal combustion engine - Google Patents

Abstract

PURPOSE:To provide an exhaust valve device of an internal combustion engine effectively restraining temperature rise of an exhaust valve while reducing exhaust resistance under a comparatively simple method. CONSTITUTION:On the upstream side of a valve stem 11 in the exhaust gas flowing direction, an upstream side straightening vane 6 approaching the valve stem 11 with a slight clearance and projecting from the inwall of an exhaust port 3 along the valve stem 11 is formed integrally with a cylinder head 1. The upstream side straightening vane 6, width of the proximate part of which is roughly the same as diameter of the valve stem 11, extends to the upstream in the flowing direction as it gradually reduces its width. A downstream side straightening vane 7 is also formed on the downstream in the flowing direction of the valve stem 11 in the same shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust valve device for an internal combustion engine.

[0002]

2. Description of the Related Art An exhaust valve of an internal combustion engine is exposed to heat generated by combustion of a valve umbrella, and hot exhaust gas is directly blown to an exposed portion of the exhaust port. For this reason, the temperature of the valve umbrella becomes high, the temperature of the air-fuel mixture sucked into the cylinder is excessively increased, and a heat spot is generated on a part of the valve umbrella, which causes knocking. This is a problem in that the valve shaft is broken due to the heat load, and it is necessary to suppress the temperature rise of the exhaust valve.

As a countermeasure against this, for example, there is an exhaust valve device as shown in FIG.
9).

The cylinder head 101 is provided with a combustion chamber 102 and an exhaust port 103 communicating with the combustion chamber 102. The exhaust valve 110 is made up of a valve shaft 111 protruding inside the exhaust port 103 and a valve umbrella 113 formed at the tip of the valve shaft 111. The valve shaft 111 is slidably supported by the valve guide 105 driven into the cylinder head 101, and the exhaust valve 110 reciprocates to open and close the exhaust port 103. In the valve guide 105, a cooling liquid passage 122 having a cooling liquid inlet 120 and a cooling liquid outlet 121 is formed.
Cooling 5 This conventional device is intended to suppress the temperature rise of the exhaust valve 110 by cooling the valve guide 105.

[0005]

However, in such a conventional exhaust valve device, only the upper portion of the valve shaft 111 of the exhaust valve 110, which is in contact with the valve guide 105, is cooled. Since it is not possible to directly cool the portion exposed to the gas and having a high temperature, the effect of suppressing the temperature rise of the valve umbrella surface 114 that influences knocking and the valve neck portion 112 having the largest heat load was not sufficient.
Further, in order to cool the valve shaft 111 as a whole with such a configuration, the valve guide 105 has to be largely projected into the exhaust port 103, and the exhaust resistance is greatly increased.

Further, there is a problem that the processing cost for installing the cooling liquid passage 122 becomes high.

It is an object of the present invention to provide an exhaust valve device that effectively suppresses the temperature rise of the exhaust valve while reducing the exhaust resistance by a relatively simple method.

[0008]

In order to solve the above-mentioned problems, the present invention is an exhaust valve comprising an exhaust port communicating with a combustion chamber and a valve umbrella formed at the tip of a valve shaft protruding into the exhaust port. An upstream rectifying wall which is located close to the exhaust gas flow direction upstream side of the valve shaft and projects from the inner wall of the exhaust port along the valve shaft, and is located close to the flow direction downstream side of the valve shaft. A downstream side straightening wall protruding from the inner wall of the exhaust port along the valve shaft, and the upstream side straightening wall has a width orthogonal to the flow at a portion close to the valve shaft, and the shaft of the valve shaft. The diameter is substantially the same as the diameter of the downstream side straightening wall, and the width of the downstream side straightening wall is substantially the same as the diameter of the valve shaft at a portion close to the valve shaft. The same, and decreases with increasing distance from the valve shaft downstream in the flow direction. Than it, characterized in that.

[0009]

The operation will be described based on the above configuration.

The hot exhaust gas discharged from the combustion chamber is
It flows into the exhaust port with a very large velocity. The flow toward the valve shaft is bisected in a direction orthogonal to the flow by the upstream flow straightening wall and flows along the flow straightening wall surface. Since the width of a portion of the upstream side rectifying wall that is close to the valve shaft is substantially the same as the valve shaft diameter, the two divided exhaust gas flows flow downstream of the valve shaft without being directly sprayed on the valve shaft. The downstream rectifying wall provided downstream of the valve shaft is close to the valve shaft and has a width substantially equal to the diameter of the valve shaft in the proximity portion, so that the flow is prevented from being disturbed by wrapping around the valve shaft. This allows
The downstream side of the valve shaft also does not come into direct contact with the exhaust gas flow.
The flow downstream of the valve shaft flows along the straightening wall surface and joins at the rear end of the straightening wall.

The exhaust gas flow around the valve shaft is directed as described above to prevent direct exposure of the valve shaft to the high temperature, high speed exhaust gas flow.

At the same time, the flow of the exhaust gas is rectified to suppress the occurrence of turbulence around the valve shaft.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment according to the present invention will be described with reference to FIGS.

A combustion chamber 2 and a combustion chamber 2 are provided on the cylinder head 1.
Is provided with an exhaust port 3. Exhaust valve 10
Is made up of a valve shaft 11 protruding inside the exhaust port 3 and a valve umbrella 13 formed at the tip of the valve shaft 11.
The valve guide 5 in which the valve shaft 11 is driven into the cylinder head 1.
Further, the exhaust port 10 is slidably supported, and the exhaust port 10 reciprocates to open and close the exhaust port 3. Reference numerals 4a to 4c are cooling liquid passages for cooling the cylinder head 1.

On the upstream side of the valve shaft 11 in the exhaust gas flow direction,
An upstream rectifying wall 6 is formed integrally with the cylinder head 1 so as to be close to the upstream side of the valve shaft 11 with a slight gap therebetween, and to project downward from the upper wall of the exhaust port 3 along the valve shaft 11. ing. The same applies to the downstream flow regulating wall 7 formed on the downstream side in the flow direction. The projecting height of each flow straightening wall 6, 7 into the exhaust port 3 is as large as possible within a range in which the lower ends of the flow straightening walls 6, 7 do not interfere with the valve neck portion 12 even when the exhaust valve 10 slides. The flow straightening walls 6 and 7 are extended to the lower side so as to entirely cover the upstream and downstream sides of the valve shaft 11. Further, as shown in FIG. 2, the protruding height of the downstream flow regulating wall 7 is reduced as the distance from the valve shaft 11 increases.

The upstream straightening wall 6 extending from just upstream of the valve shaft 11 in the upstream direction has a width perpendicular to the flow at a portion close to the valve shaft 11 as shown in section E of FIG. b1 is substantially the same as d, and has a shape that decreases with increasing distance from the valve shaft 11 in the upstream direction. The downstream flow straightening wall 7 also has a shape similar to that of the upstream flow straightening wall 6 and extends from immediately upstream of the valve shaft 11 toward the upstream direction, and the shape thereof is smoothly changed in the flow direction as a whole.

The operation will be described based on the above configuration.

The hot exhaust gas discharged from the combustion chamber is
It flows into the exhaust port 3 with a very large velocity. The flow toward the valve shaft 11 is divided into two in a direction orthogonal to the flow by the upstream flow straightening wall 6 and flows along the flow straightening wall surface. Since the width of a portion of the upstream side rectifying wall 6 which is close to the valve shaft 11 is b1 which is substantially the same as the valve shaft diameter d, both of the divided exhaust gas flows do not directly blow to the valve shaft 11. It flows downstream of the valve shaft 11. The downstream rectification wall 7 provided on the downstream side of the valve shaft 11 is close to the valve shaft 11 and has a width b2 that is substantially the same as the valve shaft diameter d in the proximity portion. Prevent from being disturbed. This allows
The downstream side of the valve shaft 11 also does not come into direct contact with the exhaust gas flow. The flow downstream of the valve shaft 11 flows along the straightening wall surface and joins at the rear end of the straightening wall.

The exhaust gas flow around the valve shaft 11 is directed as described above to prevent direct exposure of the valve shaft 11 to the high temperature, high speed exhaust gas flow. As a result, the amount of heat transferred from the exhaust gas to the valve shaft 11 can be reduced, and the temperature rise of the valve shaft 11 can be suppressed. Since each of the flow straightening walls 6 and 7 covers the upstream and downstream sides of the valve shaft 11 as a whole, the above-described action can be obtained by almost the entire valve shaft 11, and the temperature of the entire valve shaft 11 can be suppressed low. The heat of the valve umbrella 13 is easily conducted to the cylinder head 1 via the valve shaft 11. Therefore, the temperature of the valve umbrella surface 14 is lowered, and it is possible to suppress overheating of the intake air-fuel mixture that causes knocking and generation of a heat spot. Further, the heat from the valve umbrella 13 and the heat from the valve shaft 11 are concentrated to reduce the temperature rise of the valve neck portion 12 where the heat load becomes the largest, and the valve shaft 11 is prevented from being broken.

Each straightening wall 6, 7 is directly exposed to the flow of exhaust gas, and this portion is the cylinder head 1.
Since it is integrated with, the heat received from the exhaust gas is quickly diffused into the cylinder head 1. Further, the cylinder head 1 is provided with cooling liquid passages 4a and 4b on the upper side of the exhaust port 3, and since the cooling liquid passages 4a and 4b pass in the vicinity of the straightening walls 6 and 7, the straightening walls are formed. 6 and 7 do not cause a problematic temperature rise.

The flow regulating walls 6 and 7 regulate the flow of the exhaust gas, and in particular, the flow is restrained from being disturbed by entraining the valve shaft 11, and the flow resistance of the exhaust gas can be reduced. .

Since the flow-regulating walls 6 and 7 are formed so as to maintain a slight gap between them and the valve shaft 11, friction at the sliding portion does not increase when the exhaust valve 10 is opened and closed.

In addition, this embodiment has two conventional exhaust ports.
It is established only by providing one straightening wall 6 and 7, and does not cause a significant increase in cost.

A second embodiment according to the present invention will be described with reference to FIG.

In this embodiment, the valve guide 5 is provided between the valve shaft 11 and the valve guide 11.
The present invention is characterized in that a cooling liquid flow groove 8b is provided inside each of the straightening walls 6b and 7b formed in the same manner as in the first embodiment except that b is interposed, and this is connected to the cooling liquid passages 4a and 4b.

The cooling liquid flow groove 8b is provided in each of the straightening walls 6b and 7b.
Is provided in the center of the width of the straightening wall and has a shape along the outer shape of each of the straightening walls 6b and 7b.

The valve guide 5b has such a width that the upstream side thereof does not partially have a step with the upstream side straightening wall 6b, and the upstream side straightening wall 6b.
The valve shaft 11 and the upstream side straightening wall 6b
It comes in contact with both sides. The same applies to the downstream side.

The operation will be described based on the above configuration.

Each of the flow regulating walls 6b and 7b exhibits the same effect as that of the first embodiment. In addition, each straightening wall 6b, 7b
Is in contact with the valve shaft 11 as a whole through the valve guide 5b, so that more heat of the valve shaft 11 escapes to the flow straightening walls 6b and 7b. Further, since the cooling liquid flow groove 8b is provided inside each of the flow regulating walls 6b and 7b, the entire valve shaft 11 can be positively cooled. In particular, when the exhaust valve 10 is closed, it is possible to cool the vicinity of the valve neck portion 12 having the highest heat load.

A third embodiment of the present invention will be described with reference to FIG.

In this embodiment, the downstream flow straightening wall 7c is extended to the lower wall of the exhaust port 3, and a cooling liquid passage 4b is provided above and below the exhaust port 3 by a cooling liquid flow groove 8c provided therein. 4c is communicated. The other parts are configured similarly to the second embodiment.

The operation will be described based on the above configuration.

The operation relating to the cooling of the valve shaft 11 is the same as in the case of the second embodiment, but the cooling liquid flow groove 8c in the downstream side flow regulating wall 7c further connects the upper and lower cooling liquid passages 4b and 4c. Therefore, there is a flow of the cooling liquid from the cooling liquid passage 4c to the cooling liquid passage 4c in the cooling liquid flow groove 8c, and the cooling effect is greater.

By extending the downstream flow regulating wall 7c to the lower wall of the exhaust port 3, the flow passage cross-sectional area of the exhaust gas is reduced, but the main flow of the exhaust gas is along the upper wall surface of the exhaust port 3. And the downstream side straightening wall 7 extended downward.
The flow resistance is hardly increased by c, and the flow resistance is reduced by the rectification around the valve shaft 11, similar to the effects obtained in the first and second embodiments. Further, the effect of rectifying the turbulent flow around the valve umbrella 13 can be expected.

[0035]

As described above, according to the present invention, the upstream side rectification wall and the downstream side rectification wall provided on the upstream side and the downstream side of the valve shaft respectively cause the flow of the exhaust gas to the left and right of the valve shaft.
Therefore, the valve stem is not directly exposed to the high temperature, high velocity exhaust gas flow. With such a simple method, heat transfer from the exhaust gas to the valve shaft can be suppressed. As a result, excessive temperature rise of the valve shaft can be prevented, and the temperature rise of the entire valve can be effectively suppressed.

Further, the flow of exhaust gas can be rectified, and in particular, the flow can be prevented from being disturbed by involving the valve shaft, and the flow resistance of exhaust gas can be reduced.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a cylinder head exhaust valve showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing the details of the exhaust port and the upstream / downstream rectifying wall.

FIG. 3 is a sectional view showing a second embodiment of the present invention.

FIG. 4 is a sectional view showing a third embodiment of the present invention.

FIG. 5 is a sectional view showing a conventional example.

[Explanation of symbols]

 1 Cylinder Head 2 Combustion Chamber 3 Exhaust Port 6 Upstream Side Straightening Wall 7 Downstream Side Straightening Wall 10 Exhaust Valve 11 Valve Shaft 13 Valve Umbrella

Claims (1)

[Claims] 1. An exhaust port communicating with a combustion chamber, an exhaust valve formed by forming a valve umbrella at a tip of a valve shaft protruding into the exhaust port, and an exhaust valve close to an upstream side of the valve shaft in an exhaust gas flow direction. Upstream rectifying wall projecting from the inner wall of the exhaust port along the valve shaft, and downstream side projecting from the inner wall of the exhaust port along the valve shaft in proximity to the downstream side in the flow direction of the valve shaft. A flow straightening wall, the width of the upstream flow straightening wall orthogonal to the flow is substantially the same as the axial diameter of the valve shaft in the portion close to the valve shaft, and from the valve shaft to the upstream in the flow direction. The width of the downstream side straightening wall is substantially the same as the shaft diameter of the valve shaft in the portion close to the valve shaft, and the width decreases as the distance from the valve shaft toward the downstream in the flow direction increases. An exhaust valve device for an internal combustion engine, characterized in that: