JP2012002205A - Valve gear for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve gear for an internal combustion engine capable of restraining a valve stem from being vibrated at the time of intake or exhaust in the internal combustion engine, capable of preventing thereby the valve stem and a valve head from being abraded, and capable of prolonging a life of the valve gear.SOLUTION: The valve gear 1 for the internal combustion engine includes the valve stem 2 attached to a cylinder head 10 of the internal combustion engine and reciprocated by a valve gear linked to a crank shaft of the internal combustion engine, and the valve head 3 provided at an end of the valve stem 2 and having a seat face 4 at an outer periphery, and is constituted to open and close a gas passage 13 communicating with a combustion chamber 20 by attaching on and detaching from the seat face 4 of the valve head 3 to a valve seat 11 formed in the cylinder head 10. In the valve gear, a plurality of hole-like or groove-like recesses 5 is formed over the whole outer circumferential face periphery of the valve stem 2 in at least a portion exposed to the gas passage 13 of the valve stem 2, and a flow separation point in the valve stem 2 is positioned in a gas flowing directional rear side.

Description

  The present invention relates to a valve device for an internal combustion engine that is mounted on a cylinder head of an internal combustion engine and is reciprocated by a valve mechanism linked to a crankshaft to open and close an intake passage or an exhaust passage.

  In general, a valve device including an air supply valve or an exhaust valve of an internal combustion engine is reciprocally driven by a valve mechanism linked to a crankshaft of the internal combustion engine, and opens and closes a gas passage composed of an air supply passage or an exhaust passage by this reciprocating drive. It has a configuration. The valve device includes a valve stem that is slidably fitted into a cylinder head, and a valve head portion that is provided at an end of the valve stem and has a seat surface on the outer periphery thereof, and a valve seat formed on the cylinder head. The valve surface of the gas passage communicating with the combustion chamber is opened and closed by attaching and detaching the seat surface of the valve head part.

  In such a valve device, since the valve head part contacts the valve seat when opening and closing, the surface is worn when the internal combustion engine is operated for a long time due to the influence. In particular, at the time of air supply or exhaust, the gas flow rapidly increases in the gas passage, and excessive resistance is generated in the valve stem, so that an exciting force acts on the valve stem. As a result, the valve stem is swung while the valve device is open, and the seat surface of the valve head portion is vibrated, so that the surface of the valve head portion has a large contact force at the moment of seating. Slightly rubs while receiving, may cause premature wear.

  Therefore, in Patent Document 1 (Japanese Patent Laid-Open No. 2010-96137), as a valve device for reducing wear of the valve seat and the valve head portion, a contact surface that is attached to and detached from the seat surface of the valve head portion is attached to the valve seat of the cylinder head. In this contact surface, the rigidity of the inner contact part that contacts the inner diameter side of the seat surface is reduced, and when the seat surface is seated, the shape of the valve seat above the contact surface is changed, and the impact when seated at the valve seat portion A configuration is disclosed that absorbs.

JP 2010-96137 A

As described above, according to the valve device of Patent Document 1, it is possible to expect wear reduction of the valve seat and the valve umbrella portion by absorbing the impact at the time of seating at the valve seat portion. It does not suppress the vibration itself. FIG. 8 shows the locus of the central point of the valve head portion in the exhaust valve of the conventional internal combustion engine. As shown in the figure, the exhaust valve is shaken by about 1 mm during opening. Sitting in this state will cause premature wear. Further, when the valve stem vibrates, the contact with the portion supporting the valve stem becomes intense and the valve stem itself may be worn.
Therefore, it is desired to suppress the vibration of the valve stem in order to further suppress wear of the contact portion between the valve umbrella portion and the valve seat and the valve stem.

  In view of the problems of the prior art, the present invention can suppress the vibration of the valve stem during supply and exhaust of the internal combustion engine, thereby preventing the wear of the valve stem and the valve umbrella, and extending the life of the valve device. An object is to provide a valve device.

  In order to solve the above problems, an internal combustion engine valve device according to the present invention includes a valve rod mounted on a cylinder head of an internal combustion engine and driven reciprocally by a valve mechanism linked to a crankshaft of the internal combustion engine, A valve head portion having a seat surface on an outer periphery provided at an end portion of the valve stem, and a gas passage communicating with the combustion chamber by attaching and detaching the seat surface of the valve head portion to a valve seat formed on the cylinder head In the valve device for an internal combustion engine that opens and closes, a plurality of hole-shaped or groove-shaped recesses are formed over the entire outer peripheral surface of the valve rod at a portion exposed to the gas passage of the valve rod. To do.

  Here, the valve device of the internal combustion engine according to the present invention is at least one of an air supply valve and an exhaust valve, and particularly preferably an exhaust valve that easily vibrates.

  According to the present invention, the separation point of the gas flow in the valve stem can be located on the rear side in the gas flow direction by the plurality of recesses formed in the valve stem, thereby reducing the resistance in the gas flow boundary layer of the valve stem. In addition, it is possible to reduce the excitation force applied to the valve stem when supplying and discharging the internal combustion engine. Note that “the separation point of the gas flow at the valve stem is located on the rear side in the gas flow direction” means that in the cross section perpendicular to the axial direction of the valve rod, the gas flow passes through the central axis of the valve rod. This means that the peeling point is located on the rear side of the line to be performed. As a result, the vibration of the valve device can be suppressed, so that the wear of the contact portion between the valve head portion and the valve seat is not accelerated by the vibration, and the life of the valve device can be extended. Furthermore, the recessed part located in the site | part which a valve stem and a cylinder head slide can improve the retainability of the lubricant in a sliding site | part.

Further, it is preferable that a guide pipe that slides on the outer peripheral surface of the valve rod is provided in the cylinder head, and the guide pipe extends to the gas passage.
In this way, by extending the guide tube to the gas passage, the excitation force applied to the valve stem by the guide tube can be reduced, and the vibration of the valve stem can be further suppressed. Here, it is considered that extending the guide tube increases the sliding area between the valve stem and the guide tube and reduces the slidability. Therefore, smooth sliding between the valve stem and the guide tube is possible.

The hole-shaped recess described above may be a plurality of dimples, which can increase the resistance reduction effect of the valve stem, suppress the vibration of the valve device, and improve the hardness of the valve stem. .
On the other hand, the groove-shaped recess described above may be formed so that the groove direction is parallel to the axial direction of the valve stem or has an angle of less than 90 degrees with respect to the axial direction. The resistance reduction effect of the valve stem can be enhanced, the vibration of the valve device can be suppressed, and since it is groove-shaped, the lubricant can be distributed substantially uniformly on the valve stem surface at the sliding portion.

  Furthermore, it is preferable that the concave portion is formed from the valve stem to the seat surface of the valve head portion. As a result, resistance due to gas flow can be reduced not only in the valve stem but also in the valve head portion, and vibration of the valve device can be further suppressed. In particular, the concave portion formed in the valve head portion is preferably a dimple, whereby the strength of the seat surface of the valve head portion can be improved and wear due to contact with the valve seat can be suppressed.

  As described above, according to the present invention, the separation point of the gas flow in the valve stem can be located on the rear side in the gas flow direction by the plurality of recesses formed in the valve stem. The resistance in the layer can be reduced, and the excitation force applied to the valve stem when supplying and discharging the internal combustion engine can be reduced. As a result, the vibration of the valve device can be suppressed, so that the wear of the contact portion between the valve head portion and the valve seat is not accelerated by the vibration, and the life of the valve device can be extended. Furthermore, the recessed part located in the site | part which a valve stem and a cylinder head slide can improve the retainability of the lubricant in a sliding site | part.

It is a side view which shows the valve apparatus of the internal combustion engine which concerns on embodiment of this invention. It is a figure explaining the opening / closing operation | movement of an air supply valve. It is the elements on larger scale which show the valve apparatus of the 1st structural example of this embodiment, (A) is sectional drawing of a recessed part, (B) is a side view of a valve stem. It is the elements on larger scale which show the valve apparatus of the 2nd structural example of this embodiment, (A) is sectional drawing of a convex part, (B) is a side view of a valve stem. It is a figure explaining the gas flow near a valve stem, (A) is a figure which shows the gas flow in the valve apparatus of this embodiment, (B) is a figure which shows the gas flow in the valve apparatus of a prior art example. It is a figure explaining the vibration suppression effect of a valve apparatus, and is a figure showing the locus of the central part of the valve head part in the exhaust valve of this embodiment. It is a side view which shows the application example of the valve apparatus of the internal combustion engine which concerns on embodiment of this invention. It is a figure which shows the locus | trajectory of the valve head center point in the exhaust valve of the conventional internal combustion engine.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

First, the configuration of a valve device for an internal combustion engine according to an embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a side view showing a valve device for an internal combustion engine according to an embodiment of the present invention. The valve device 1 mainly includes a valve rod 2 mounted on a cylinder head 10 of the internal combustion engine, and the valve rod 2. And the valve head part 3 provided at the end of the head.
The valve device 1 is at least one of an intake valve and an exhaust valve of an internal combustion engine, and is particularly preferably an exhaust valve that easily vibrates.

The valve stem 2 is slidably inserted into a valve insertion hole 16 formed in the cylinder head 10 and is driven to reciprocate by a valve mechanism linked to a crankshaft of the internal combustion engine. The valve operating mechanism is a mechanism that opens and closes the valve device 1 in accordance with the piston position of the internal combustion engine. Generally, the movement of a cam that is drivingly connected to a crankshaft (not shown) is moved via a tappet, a rocker arm, or the like. This is transmitted to the valve stem 2 to drive the valve device 1 back and forth.
The valve head portion 3 is provided at the gas passage 13 side end portion of the valve stem 2 and has a seat surface 4 on the outer periphery thereof. The seat surface 4 is attached to and detached from a valve seat 11 formed in the cylinder head 10. The gas passage 13 is an air supply passage in the air supply valve and an exhaust passage in the exhaust valve.

Here, with reference to FIG. 2, the opening / closing operation | movement of the valve apparatus 1 provided with an above-described structure is demonstrated. In the figure, as an example, the cylinder head 10 is shown with two supply valves 1. The left half of the figure shows a state where the supply valve is closed, and the right half shows the supply valve fully open. Shows the state.
The cylinder head 10 is provided with a fuel gas passage 15 for supplying fuel gas and an air supply passage 13. The fuel gas passage 15 and the air supply passage 13 are connected to the outer periphery of the valve rod 2 and the valve of the cylinder head 10. It communicates with the insertion hole 16 through a gap. Further, the air supply passage 13 communicates with the combustion chamber 20 through the valve hole 12.

When the air supply valve is closed, as shown in the left half of FIG. 2, the valve stem 2 moves upward, the seat surface 4 of the valve head 3 is seated on the valve seat 11, and the valve hole 12 is closed.
On the other hand, when the air supply valve is opened, as shown in the right half of FIG. 2, the valve stem 2 moves downward, the seat surface 4 of the valve head part 3 is separated from the valve seat 11, and the valve hole 12 is opened. Then, the combustion chamber 20 is supplied with air.

In addition to the above-described configuration, the valve device 1 of the present embodiment further includes the following configuration.
As shown in FIG. 1, the valve device 1 has a plurality of hole-like or groove-like recesses 5 over the entire outer peripheral surface of the valve stem 2 at a portion exposed to the gas passage 13 of the valve stem 2. ing. FIG. 1 shows a case where a hole-like recess 5 is provided as an example. The plurality of hole-like recesses 5 are preferably formed substantially uniformly over the entire outer peripheral surface of the valve stem 2. Moreover, the recessed part 5 of a different shape and magnitude | size may be mixed.
The part exposed to the gas passage 13 is located in the valve insertion hole 16 when the valve is closed (see the left half of FIG. 2) in addition to the part of the valve rod 2 that is always located in the gas passage 13. However, when the valve is fully opened (refer to the right half of FIG. 2), a portion exposed to the gas passage 13 is included.

Next, a specific configuration example of the recess will be described with reference to FIGS.
3A and 3B are partial enlarged views showing the valve device of the first configuration example of the present embodiment, in which FIG. 3A is a sectional view of a recess, and FIG. 3B is a side view of a valve stem. The concave portion 5 is formed in a circular hole shape, and preferably the concave portion 5 is a dimple. A plurality of the dimples 5 are formed over the entire outer peripheral surface of the valve stem 2, and are formed by, for example, shot peening. By making the hole-like recesses into dimples as described above, the resistance reduction effect of the valve stem 2 as described later can be increased, the vibration of the valve device 1 can be suppressed, and the hardness of the valve stem 2 can be improved. is there.

Further, the plurality of dimples 5 may be arranged in a staggered manner or a row as shown in FIG. 3A, or may be arranged randomly as shown in FIG. More preferably, the plurality of dimples 5 may be arranged in a staggered manner because the manufacturing cost is low and the gas flow has a uniform effect.
For example, when the diameter Φ of the valve stem 2 is 18 to 20 mm, the dimple 5 has a diameter d of 0.5 to 1.5 mm and a depth h of 0.1 to 0.2 mm. arranged such that the density of 2 to 4 / cm ² on the outer peripheral surface. At this time, it is preferable that 7 to 10 dimples are disposed on the outer periphery of the valve stem 2.

  4A and 4B are partial enlarged views showing the valve device of the second configuration example of the present embodiment, in which FIG. 4A is a sectional view of a convex portion, and FIG. The recess 6 is formed in a groove shape, and a plurality of the recesses 6 are formed over the entire outer peripheral surface of the valve stem 2. Preferably, the groove-like recess 6 is formed so that the groove direction is parallel to the axial direction of the valve stem 2 or has an angle of less than 90 degrees with respect to the axial direction. As a result, the resistance reduction effect of the valve stem 2 as will be described later can be enhanced, the vibration of the valve device 1 can be suppressed, and since it is groove-shaped, the lubricant can be distributed substantially uniformly on the surface of the valve stem at the sliding portion. Is possible.

The grooved recess 6 is formed so that the groove direction is parallel to the axial direction of the valve stem 2 or has an angle of less than 90 degrees with respect to the axial direction. This is to make the unevenness along the flow direction exist, and in the groove perpendicular to the axial direction, the unevenness along the gas flow direction does not exist and it is difficult to obtain a resistance reduction effect. is there.
Furthermore, the groove-like recess 6 is preferably formed by knurling, whereby a plurality of groove-like recesses 6 can be easily formed and the manufacturing cost can be reduced.

4 has a groove-shaped recess 6a formed obliquely with respect to the axial direction of the valve stem 2, and a groove-shaped recess 6b formed symmetrically with respect to the groove-shaped recess 6a. The groove-shaped recesses 6a and 6b form a diamond-shaped protrusion 7 on the valve stem surface.
For example, when the diameter Φ of the valve stem 2 is 18 to 20 mm, the height h of the rhombus-shaped convex portion 7, that is, the depth of the groove-shaped concave portion 6 is 0.1 to 0.2 mm, and the axis of the rhombus-shaped convex portion 7 The direction length l is 2 to 3 mm, and the width w is 1 to 2 mm.

5A and 5B are diagrams for explaining the gas flow in the vicinity of the valve stem, FIG. 5A is a diagram showing the gas flow in the valve device of the present embodiment, and FIG. 5B is a diagram showing the gas flow in the conventional valve device. is there.
In the present embodiment, as described above, a plurality of hole-like recesses 5 or groove-like recesses 6 are formed over the entire outer peripheral surface of the valve stem 2, so that the separation point of the gas flow at the valve stem 2 is the gas flow. It can be located in the direction rear side.
Positioning the gas flow separation point on the valve stem 2 on the rear side in the gas flow direction means that the center of the valve stem 2 is in a cross section orthogonal to the axial direction of the valve stem 2 as shown in FIG. It means that the peeling point P is located behind the line (straight line L in the figure) perpendicular to the gas flow through the axis O.

As shown in FIG. 5B, in the conventional valve stem 2 in which the recesses 5 and 6 do not exist on the outer peripheral surface, the separation point P ′ in the gas flow boundary layer is the front side in the gas flow direction of the valve stem 2 (from the straight line L). Located on the front side. However, in this case, the resistance of the valve stem 2 is large, and the valve device 1 vibrates greatly during supply / discharge of the internal combustion engine due to an excessive excitation force applied to the valve stem 2.
As shown in FIG. 5A, in this embodiment, since the recesses 5 and 6 are formed on the outer peripheral surface of the valve stem 2 (see FIG. 3 or 4), the separation point P of the gas flow is set behind the gas flow. Can be located on the side. Therefore, the resistance in the gas flow boundary layer of the valve stem 2 can be reduced, and the excitation force applied to the valve stem 2 during supply / discharge of the internal combustion engine can be reduced. As a result, the vibration of the valve device 1 can be suppressed, so that the wear of the contact portion between the valve head portion 3 and the valve seat 11 is prevented from being accelerated by the vibration, and the life of the valve device 1 can be extended. Furthermore, the retention of the lubricant at the sliding portion can be enhanced by the recesses 5 and 6 formed at the portion where the valve stem 2 and the cylinder head 10 slide.

  Here, the vibration suppression effect of the valve device in the present embodiment will be described using FIGS. 6 and 8 in comparison with the conventional example. FIG. 6 is a diagram showing a locus of the central point of the valve head portion in the exhaust valve of the present embodiment. This exhaust valve has a valve stem 2 shown in FIG. 3, and a plurality of dimples 5 are formed on the surface of the valve stem. On the other hand, FIG. 8 is a diagram showing the locus of the central point of the valve head portion in the conventional exhaust valve. This exhaust valve is an exhaust valve having the same structure as that of the present embodiment, but has no recess formed on the surface of the valve stem. In both cases, the locus of the central point of the valve head when the exhaust valve is opened and exhausted is obtained from experiments.

As shown in the figure, the exhaust valve of the present embodiment has extremely small fluctuation and is stable, and the maximum fluctuation is about 0.5 mm, whereas the conventional exhaust valve does not always shake during exhaust. It occurs, and a shaking of 1 mm or more is also observed.
As is clear from the experimental results, according to the valve device 1 of the present embodiment, it is possible to significantly reduce the vibration of the valve device 1 as compared with the conventional example, and the wear of the valve device 1 is extended. It is speculated that it will greatly contribute to the extension of the service life.

The valve device 1 according to the present embodiment described above may further include the following configuration.
FIG. 7 is a side view showing an application example of the valve device of the internal combustion engine according to the embodiment of the present invention. As shown in the figure, the cylinder head 10 is provided with a guide tube 25 that slides on the outer peripheral surface of the valve rod 2, and the guide tube 25 extends to the gas passage 13.
In this way, by adopting a configuration in which the guide tube 25 is extended to the gas passage 13, the excitation force applied to the valve stem 2 by the guide tube 25 can be reduced, and the vibration of the valve stem 2 can be further suppressed. it can. Here, it is conceivable that extending the guide tube 25 increases the sliding area between the valve stem 2 and the guide tube 25 and lowers the slidability. Alternatively, since the retention of the lubricant can be enhanced by the groove-shaped recess 6, smooth sliding between the valve stem 2 and the guide tube 25 becomes possible.

The guide tube 25 can be designed based on its material strength, structural strength, etc., but is preferably formed to a length that reaches at least the center position of the gas flow path 13. Thereby, the exciting force which acts on the valve stem 2 can be reduced, and the vibration of the valve device 1 can be more reliably suppressed.
Furthermore, at least a part of the guide tube 25 on the gas passage 13 side may have a tapered shape whose outer peripheral surface is reduced in diameter toward the lower side. By forming the guide tube 25 in a tapered shape in this way, the resistance of the gas flow can be reduced by reducing the diameter while maintaining the strength of the guide tube 25.

In the present embodiment, the plurality of recesses 5 may be formed from the valve stem 2 to the seat surface 4 of the valve head portion 3. As a result, not only the valve stem 2 but also the valve head portion 3 can reduce the resistance caused by the gas flow, and the vibration of the valve device 1 can be further suppressed. In particular, the concave portion 5 formed in the valve head portion 3 is preferably a dimple, whereby the strength of the seat surface 4 of the valve head portion 3 can be improved and wear due to contact with the valve seat 11 can be suppressed.
Further, the recess 5 of the valve stem 2 may be formed up to a sliding portion with the cylinder head 10 above the valve stem 2 in addition to the portion exposed to the gas passage 13 of the valve stem 2. Thereby, the retainability of the lubricant at the sliding portion can be further enhanced.

DESCRIPTION OF SYMBOLS 1 Valve apparatus 2 Valve stick 3 Valve umbrella part 4 Seat surface 5 Hole-shaped recessed part 6 Groove-shaped recessed part 7 Diamond-shaped convex part 10 Cylinder head 11 Valve seat 12 Valve hole 13 Gas passage 20 Combustion chamber 25 Guide tube

Claims (5)

A valve stem mounted on a cylinder head of an internal combustion engine and reciprocally driven by a valve mechanism linked to a crankshaft of the internal combustion engine, and a valve umbrella portion provided at an end portion of the valve rod and having a seat surface on the outer periphery. In the valve device of the internal combustion engine that opens and closes the gas passage leading to the combustion chamber by attaching and detaching the seat surface of the valve head portion to the valve seat formed in the cylinder head,
A valve device for an internal combustion engine, wherein a plurality of hole-shaped or groove-shaped recesses are formed over the entire outer peripheral surface of the valve rod at a portion exposed to at least the gas passage of the valve rod.   The valve device for an internal combustion engine according to claim 1, wherein a guide pipe that slides on an outer peripheral surface of the valve rod is provided in the cylinder head, and the guide pipe extends to the gas passage.   The valve device for an internal combustion engine according to claim 1 or 2, wherein the hole-shaped recess is a plurality of dimples.   The groove-shaped recess is formed so that the groove direction is parallel to the axial direction of the valve stem or has an angle of less than 90 degrees with respect to the axial direction. 3. A valve device for an internal combustion engine according to 2.   The valve device for an internal combustion engine according to any one of claims 1 to 4, wherein the concave portion is formed from the valve stem to the seat surface of the valve head portion.

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