JPH0730687B2 - Valve holding structure for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a valve holding structure for an internal combustion engine that drives an automobile, a motorcycle, or the like.

[Conventional technology]

In recent years, higher performance is required for automobiles and motorcycles. By the way, in such a high-power engine, it is difficult to increase the size of the intake / exhaust port, and the required flow rate of intake / exhaust is large.

Therefore, in order to increase the press-fitting flow of the valve guide, by removing the part where the port wall surface was locally projected in the vicinity of the valve guide, the part of the port wall surface protruding into the port was minimized. Efforts are being made to reduce ventilation resistance.

[Problems to be solved by the invention]

However, when the valve guide is press-fitted with the wall surface of the port along the intake / exhaust flow, there is a disadvantage that the holding hole into which the valve stem of the valve guide is inserted is distorted. It is considered that this is because the axis of the press-fitting hole is inclined with respect to the port wall surface. That is, the press-fitting length of the valve guide is different at the opening portion of the press-fitting hole, and after the press-fitting, the valve guide is deformed due to the influence of the press-fitting margin.

[Means for solving problems]

The present invention has been made in view of the above circumstances, and provides a valve holding structure for an internal combustion engine capable of reducing ventilation resistance without causing distortion in a holding hole of a valve guide. In the valve holding structure for an internal combustion engine according to the present invention, the port wall surface is a surface along the flow of ventilation, and the valve guide press-fitting hole is formed obliquely with respect to the port wall surface. A clearance is provided between the hole wall surface of the opening and the valve, and this clearance is located on the port side of the plane that passes through the vicinity of the apex of the portion sandwiched by the press-fitting hole and the port and is orthogonal to the axis of the valve guide. It is arranged.

[Action]

In the present invention, ventilation is made to flow along the wall surface of the port, and the deformation due to press fitting of the valve guide is absorbed by the clearance portion.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a cross-sectional view showing a part of a cylinder head in which a valve holding structure for an internal combustion engine according to the present invention is implemented. In FIG. 1, reference numeral 1 indicates a cylinder head of an internal combustion engine for driving an automobile or a motorcycle. Indicates. This cylinder head 1
Forms a combustion chamber 2 by closing the upper side of a cylinder block (not shown). Reference numeral 3 denotes an intake port formed above the combustion chamber 2 for introducing intake air into the combustion chamber 2 from one side surface of the cylinder head 1. Reference numeral 4 also denotes an intake port formed above the combustion chamber 2 for combusting exhaust gas from the combustion chamber 2 into the cylinder. It is an exhaust port for discharging to the side surface on the opposite side of the head 1. These ports 3,4
Is bent so as to extend from the combustion chamber 2 to the both sides of the cylinder head 1, and valve seats 7 and 8 are press-fitted into the intake port 5 and the exhaust port 6, respectively.

Reference numeral 9 is an intake valve that is seated on the valve seat 7 to open and close the intake port 5. The intake valve 9 is slidably held so as to advance and retreat with respect to the valve seat 7 by a cylindrical valve guide 11 press-fitted into a press-fitting hole 10 of the cylinder head 1, and the intake port 5 is constantly maintained by a valve spring (not shown).
Is urged in the direction to close the. Although not shown, an exhaust valve for opening and closing the exhaust port 6 is held like the intake valve 9. These valves are driven by a valve operating mechanism to which the power of the crankshaft is transmitted.

The port wall surface 3a of the intake port 3 is formed smoothly along the flow of intake air flowing from the side of the cylinder head 1 toward the intake port 5. The axis of the press-fitting hole 10 is the port wall surface 3a
It is provided so as to be inclined with respect to and is opened above the intake port 5.

g is in the vicinity of the intake port 3 side of the valve guide 11, specifically, in the vicinity of the apex of the portion sandwiched between the press-fitting hole 10 and the intake port 3, in other words, through the upstream opening edge of the press-fitting hole 10 It is a gap provided on the intake port 3 side with respect to a plane P orthogonal to the axis of 11. This gap g constitutes the clearance portion according to the present invention. This gap g eliminates the influence of the valve guide 11 after the press-fitting in the vicinity of the intake port 3 due to the press-fitting margin for press-fitting the valve guide 11 into the cylinder head 1.

In the embodiment, a recess 12 is formed on the intake port 3 side of the holding hole 11a of the valve guide 11, and the recess 12 forms a gap g between the valve guide 11 and the valve stem 9a of the intake valve 9. In this case, the valve guide 11 may be bent due to the thickness of the press-fitted portion and may be separated from the wall surface of the press-fitting hole 10 at the tip end, so the gap g is set sufficiently larger than the press-fitting margin.

In the valve holding structure of the internal combustion engine thus configured, the intake valve 9 can be slidably held by the valve guide 11 press-fitted into the press-fitting hole 10 to open and close the intake port 5. Further, since the port wall surface 3a is formed as a surface along the flow of ventilation, the ventilation can smoothly flow along the port wall surface 3a, and the intake resistance can be reduced.

Further, since the gap g for removing the influence of the press-fitting margin is provided near the intake port 3, the deformation of the valve guide 11 caused by the press-fitting of the valve guide 11 can be absorbed by this gap g. Therefore, the holding hole 11a that holds the valve stem 9a is not deformed.

In the above embodiment, the gap g is set to the valve guide 11
The example provided between the valve stem 9a and the valve stem 9a has been described. However, the present invention is not limited to this, and as shown in FIGS.
It may be provided between and. That is, in order to provide the gap g, the recess 13 is formed on the outer peripheral surface of the valve guide 11 in the embodiment shown in FIG. 2, and the recess 14 is formed on the peripheral wall of the press-fitting hole 10 in the embodiment shown in FIG. .

Further, as shown in FIG. 4, the portion of the valve guide 11 projecting into the intake port 3 may be removed by the in-port valve guide cutter 15, which will further reduce the ventilation resistance. can do. In this case, the outer diameter of the cutter 15 is set to be slightly smaller than the inner diameter of the bent portion of the intake port 3, and the end surface 11b of the deleted valve guide 11 forms a part of the port wall surface 3a.

In the above embodiment, the example in which the intake valve 9 is held has been described, but the present invention is not limited to this, and the gap g is provided near the port side of the valve guide holding the exhaust valve. May be.

〔The invention's effect〕

As described above, according to the present invention, since the port wall surface is a surface along the flow of ventilation, ventilation can be smoothly flowed along the port wall surface. Also, a valve guide press-fitting hole is formed obliquely with respect to the port wall surface, and a clearance portion is provided between the valve wall surface of the port-side opening of the press-fitting hole and the valve. Since it is arranged on the port side with respect to the plane passing through the vicinity of the apex of the portion sandwiched by the port and orthogonal to the axis of the valve guide, the clearance absorbs the deformation caused by the press-fitting of the valve guide.

Therefore, the ventilation resistance can be reduced without causing distortion in the holding hole of the valve guide. Also, by adopting a configuration in which the clearance portion is arranged on the port side with respect to a plane that passes through the vicinity of the apex of the portion sandwiched by the press-fitting hole and the port and is orthogonal to the axis of the valve guide, the valve guide is press-fitted into the cylinder head. There is also an advantage that the valve guide can be reliably supported because the length of the closed portion can be made as long as possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a part of a cylinder head in which a valve holding structure for an internal combustion engine according to the present invention is implemented, and FIGS. 2 and 3 are main-part cross-sectional views showing another embodiment, and FIG. FIG. 7 is a sectional view showing a part of a cylinder head of another embodiment. 1 ... Cylinder head, 3 ... Intake port, 3a ... Port wall surface, 9 ... Intake valve, 10 ... Press-fit hole, 11 ... Valve guide, 12 ... Recess, g ... Gap.

Claims (3)

[Claims] 1. In an internal combustion engine in which a valve is slidably held by a valve guide press-fitted into a press-fitting hole of a cylinder head, a port wall surface is a surface along the flow of ventilation, and
The press-fitting hole is formed obliquely with respect to the port wall surface, and a clearance is provided between the valve and the hole wall surface of the port-side opening of the press-fitting hole. A valve holding structure for an internal combustion engine, characterized in that the valve holding structure is arranged on a port side with respect to a plane that passes through the vicinity of the apex of the portion sandwiched by and is orthogonal to the axis of the valve guide. 2. The valve holding structure for an internal combustion engine according to claim 1, wherein the clearance portion is provided between the valve guide and the valve. 3. The valve holding structure for an internal combustion engine according to claim 1, wherein the clearance portion is provided between the valve guide and the cylinder head.