JP2001003808A - Structure of valve guide press fitting part of cylinder head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the cracking caused by the concentration of stresses around a press-fit hole when a valve guide is press fit in a high port cylinder head. SOLUTION: The upper inner wall of an intake port 10 is swelled in the approximately arch-shape along a press-fit hole 19 of a valve guide 17, to form a padding part gradually and smoothly raised from a manifold side of the intake port 10 toward a combustion chamber 12 side and having a bearing surface 38 vertical to the press-fit hole 19 around an opening of the press-fit hole 19. By forming the bearing surface 38 vertical to the press-fit hole 19, an acute-angled part is not formed around the opening of the press-fit hole 19, which prevents the cracking caused by the concentration of the stress around the opening of the press-fit hole 19 in the drilling work of the press-fit hole 19 and the press-fitting of the valve guide 17. As the padding part 37 is gradually and smoothly raised from the manifold side toward the combustion chamber 12 side, the smooth intake flow in the intake port 10 is not disturbed thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a valve guide press-fitting structure of a cylinder head for press-fitting a valve guide for guiding an intake / exhaust valve of an engine of an automobile or the like into a cylinder head.

[0002]

2. Description of the Related Art As schematically shown in FIGS.
In order to guide a stem 3 of an intake / exhaust valve (only the intake valve 2 is shown), a cylinder head 1 of a four-cycle engine such as an automobile has a cylindrical shape toward an intake / exhaust port (only the intake port 4 is shown). The valve guide 5 is press-fitted.

Further, in recent engines, in order to increase the intake efficiency, the intake port 4 is made to have a high port, that is, the angle with respect to a horizontal plane (the joint surface between the cylinder head and the cylinder block) is increased (closer to the vertical).
That is being done. In FIG. 8, the intake port 4A of the conventional engine is represented by a phantom line, and the angle difference between the intake port 4 and the high-ported intake port 4 is indicated by a thick arrow.

[0004]

As the port of the intake port 4 becomes higher, the angle between the stem 5 of the intake valve 2 and the intake port 4 becomes smaller, and the valve guide 5 and the upper inner wall of the intake port 4 come into contact with each other. Becomes smaller. For this reason, when the valve guide 5 is press-fitted into the press-fitting hole 6 of the cylinder head 1, stress may be concentrated on the acute angle portion 7 of the angle α and a crack may be generated. In order to prevent such damage to the acute angle portion 7, it is necessary to strictly control the press-fitting allowance of the valve guide 5 to suppress the generation of stress, which causes a decrease in productivity.

[0005] The present invention has been made in view of the above points, and in a high ported cylinder head,
An object of the present invention is to provide a valve guide press-fitting structure of a cylinder head which prevents cracks around an opening of a valve guide press-in hole when a valve guide is press-fitted.

[0006]

According to a first aspect of the present invention, there is provided a valve guide press-fitting structure for a cylinder head, wherein an inner wall of an intake or exhaust port is formed in a cross section substantially along a press-fitting hole of a valve guide. The port is bulged in an arch shape, gradually and smoothly protrudes from the manifold side of the port toward the combustion chamber, and has a seating surface substantially perpendicular to the press-in hole around the opening of the press-in hole. It is characterized in that a built-up portion is formed.

[0007] With such a configuration, a seating surface substantially perpendicular to the press-fitting hole is formed around the opening of the press-fitting hole by the built-up portion, and no acute angle portion is formed. When the valve guide is press-fitted into the press-fitting hole, the stress is not concentrated around the opening of the press-fitting hole. Since the built-up portion is gradually and smoothly raised from the manifold side of the port toward the combustion chamber, it does not hinder a smooth flow in the port.

According to a second aspect of the present invention, in the structure of the first aspect, the periphery of the opening of the press-fitting hole in the seat surface is chamfered.

With this configuration, the stress generated around the opening of the press-fitting hole is dispersed by chamfering.

According to a third aspect of the present invention, in the valve guide press-fitting structure for a cylinder head, a recess is provided around the opening of the press-fitting hole of the valve guide on the inner wall of the intake or exhaust port, and the periphery of the opening of the press-fitting hole is provided. And a substantially vertical seating surface is formed in the press-fitting hole.

[0011] With this configuration, the recess forms a substantially vertical seating surface around the opening of the press-fitting hole and does not form an acute-angled portion. When press-fitting the valve guide into the press-fit hole,
Stress does not concentrate around the opening of the press-fitting hole.

According to a fourth aspect of the present invention, in the structure of the third aspect, the periphery of the opening of the press-fitting hole in the seat surface is chamfered.

With this configuration, the stress generated around the opening of the press-fitting hole is dispersed by chamfering.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a cylinder head portion of an engine to which a valve guide press-fitting structure according to the present invention is applied. As shown in FIG.
Is a so-called four-valve engine. The cylinder head 9 has two intake ports 10 (only one is shown) and two exhaust ports 11 (only one is shown) arranged in parallel for each cylinder. Are provided, each of which communicates with a pent roof type combustion chamber 12. The intake port 10 and the exhaust port 11 are arranged in a so-called cross flow system, and the inlet of the intake port 10 and the exhaust port 11
Are opened at the side surface opposite to the cylinder head 9, and an intake manifold (not shown) and an exhaust manifold (not shown) are connected to these openings, respectively.

Each intake port 10 and exhaust port 11 have
An intake valve 13 and an exhaust valve 14 are provided, respectively. Stems 15, 16 of intake valve 13 and exhaust valve 14
Are extended upwardly through the intake port 10 and the exhaust port 11, respectively, and extend through the upper inner wall of each of the intake port 10 and the exhaust port 11, respectively.
18 extends to the top of the cylinder head 9. The valve guides 17 and 18 are press-fitted into press-fit holes 19 and 20 formed in the upper inner wall of the intake port 10 and the exhaust port 11, and slidably pass through the stems 15 and 16 of the intake and exhaust valves 13 and 14. Then, set the intake and exhaust valves 13 and 14 to the intake and exhaust port 1
The valve seats 21 and 22 of the valve 0 and 11 are guided so as to be able to move forward and backward to open and close the seats.

Each of the intake and exhaust valves 13 and 14 has a stem.
Tappets 27 and 28 are urged in the valve closing direction by valve springs 25 and 26 via retainers 23 and 24 attached to the upper ends of the stems 15 and 16 and contact the upper ends of the stems 15 and 16.
And cams 31 and 32 via shims 29 and 30
The valve is opened at a predetermined timing following the rotation of 33, 34. The four intake and exhaust valves 13 in the combustion chamber 12
An ignition plug (not shown) is arranged at the center of 14 (only one is shown). Also, the intake port 10
Is a high port, linearly extends from the opening on the side surface of the cylinder head 9 toward the combustion chamber 12, and
The angle θ between the intake valve 13 and the axis is 43 °. In FIG. 1, reference numeral 35 denotes a cylinder head cover,
Indicates a water jacket.

As shown in FIG. 2 to FIG.
A built-up portion 37 whose cross-sectional shape bulges in a substantially arch shape is formed on the upper inner wall of the press-fitting hole 19. Overlay 37
Is gradually and smoothly raised from the intake manifold side of the intake port 10 toward the combustion chamber 12 side, and the press-fit hole
A seating surface 38 having a flat surface perpendicular to the central axis is formed around the 19 opening. 3 and FIG. 4, the imaginary lines are the AA line, the BB line, and the CC line in FIG.
The cross-sectional shape of the intake port 10 is indicated by a line. Also,
A chamfer 39 is formed on the periphery of the opening on the seating surface 38 of the press-fitting hole 19. The build-up portion 37 can be formed together with the intake port 10 by using a core when casting the cylinder head 9, for example, and can be built-up after the cylinder head 9 is cast. 19 is drilled by machining using a drill or the like.

The operation of the first embodiment configured as described above will now be described. By providing a built-up portion 37 on the upper inner wall of the intake port 10 and forming a seating surface 38 having a flat surface perpendicular to the press-fitting hole 19, no acute angle portion is formed around the opening of the press-fitting hole 19, so that the press-fitting is performed. When the hole 19 is formed by a drill or the like, or when the valve guide 17 is press-fitted into the press-fitting hole 19, stress is not concentrated around the opening of the press-fitting hole 19, so that a crack does not occur. This facilitates the management of the press-fitting allowance of the valve guide 17, and improves the productivity. Furthermore, by applying a chamfer 39 to the opening of the press-fitting hole 19, it is possible to disperse the stress generated around the opening when the valve guide 17 is press-fitted, and to more effectively prevent the occurrence of cracks due to stress concentration. Can be. The built-up portion 37 is gradually and smoothly raised from the manifold side of the intake port 10 toward the combustion chamber, so that the
There is no obstruction to the smooth flow of intake air in 10.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. The second embodiment has the same structure as that of the first embodiment except that the structure of the valve guide press-fitting portion is different. Therefore, the same parts as those of the first embodiment are the same. Only different parts will be described in detail with reference numerals.

In the second embodiment, as shown in FIGS. 6 and 7, a recess 40A is provided around the opening of the press-fit hole 19 in the upper inner wall of the intake port 10, and the opening of the press-fit hole 19 is formed. A seat surface 40 having a flat surface perpendicular to the central axis is formed around the periphery. The periphery of the opening of the press-in hole 19 is chamfered 39 as in the first embodiment. The seating surface 40 can be formed together with the intake port 10 using a core when casting the cylinder head 9, for example, and formed by machining using an end mill or the like after casting the cylinder head 9. Thereafter, the press-fit hole 19 is formed by machining using a drill or the like.

With this configuration, the press-fit hole 19
By forming the seating surface 40 having a flat surface perpendicular to the above, since no acute angle portion is formed around the opening of the press-in hole 19, when drilling the press-in hole 19 with a drill or the like,
When the valve guide 17 is press-fitted into the press-fitting hole 19, stress is not concentrated around the opening of the press-fitting hole 19 and cracks are not generated. Furthermore, by applying a chamfer 39 to the opening of the press-fitting hole 19, it is possible to disperse the stress generated around the opening when the valve guide 17 is press-fitted, and to more effectively prevent the occurrence of cracks due to stress concentration. Can be. The seat 40 is a recess
Since it is formed by providing 40A, it does not hinder a smooth intake flow in the intake port 10. In the case of the present embodiment, since the recess 40A is provided to form the seat surface 40, the valve guide 19
The length of the press-in allowance becomes smaller.

In the above embodiment, as an example, the case where the valve guide press-fitting portion structure of the cylinder head according to the present invention is applied to the valve guide press-fitting portion on the intake port side is described. However, the present invention can be similarly applied to a valve guide press-fitting portion on the exhaust port side.

[0023]

As described above in detail, according to the valve guide press-fitting structure of the cylinder head according to the first aspect, the seating surface substantially perpendicular to the press-fitting hole is formed around the opening of the press-fitting hole by the build-up portion. Is formed, and no acute angle portion is formed. Therefore, when drilling the press-fitting hole and press-fitting the valve guide into the press-fitting hole, stress is not concentrated around the opening of the press-fitting hole, so that a crack does not occur. In addition, since the built-up portion is gradually and smoothly raised from the manifold side of the port toward the combustion chamber, it does not hinder the smooth flow in the port.

According to the valve guide press-fitting structure of the cylinder head according to the second aspect, the stress generated around the opening of the press-fitting hole can be dispersed by chamfering.

According to the valve guide press-fitting structure of the cylinder head according to the third aspect, the recess forms a seat surface substantially perpendicular to the press-fitting hole around the opening of the press-fitting hole, thereby forming an acute angle portion. Therefore, when the press-fitting hole is formed and when the valve guide is press-fitted into the press-fitting hole, stress is not concentrated around the opening of the press-fitting hole, so that a crack does not occur.

According to the fourth aspect of the invention, the stress generated around the opening of the press-fitting hole can be dispersed by chamfering.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a cylinder head of an engine to which a valve guide press-fitting structure according to a first embodiment of the present invention is applied.

FIG. 2 is a cutaway perspective view showing a valve guide press-fitting portion of FIG. 1;

FIG. 3 is an enlarged view of a valve guide press-fitting portion of FIG. 1;

FIG. 4 is a diagram showing a cross-sectional shape of an intake port and a press-fit hole of a valve guide taken along lines AA, BB, and CC of FIG. 3;

FIG. 5 is a diagram showing a cross-sectional shape of the intake port along line AA, line BB, and line CC in the bottom view of FIG. 3;

FIG. 6 is a cutaway perspective view showing a valve guide press-fitting portion according to a second embodiment of the present invention.

FIG. 7 is a longitudinal sectional view of the valve guide press-fitting portion of FIG.

FIG. 8 is a schematic vertical sectional view of a conventional valve guide press-fitting portion of a high ported intake port.

FIG. 9 is a cutaway perspective view showing a valve guide press-fitting portion of a conventional high port intake port.

[Explanation of symbols]

 9 Cylinder head 10 Intake port 11 Exhaust port 12 Combustion chamber 17 Valve guide 19 Press-fit hole 37 Overlay 38,40 Seat 40A recess 39 Chamfer

Claims (4)

[Claims] An inner wall of an intake or exhaust port is bulged in a substantially arched cross section along a press-fit hole of a valve guide, and gradually and smoothly protrudes from a manifold side of the port toward a combustion chamber. A valve guide press-fitting structure for a cylinder head, wherein a built-up portion having a seat surface substantially perpendicular to the press-fitting hole is formed around the opening of the press-fitting hole. 2. The valve guide press-fitting structure for a cylinder head according to claim 1, wherein the periphery of the opening of the press-fitting hole in the seating surface is chamfered. 3. A recess is provided around the opening of the press-fit hole of the valve guide on the inner wall of the intake or exhaust port, and a seat surface substantially perpendicular to the press-fit hole is formed around the opening of the press-fit hole. A valve guide press-fitting structure for a cylinder head. 4. The valve guide press-fitting structure for a cylinder head according to claim 3, wherein the periphery of the opening of the press-fitting hole in the seating surface is chamfered.