JP2001050105A - Method of forming intake or exhaust port and valve seat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fit a cylinder head therein with an intake or exhaust port which is asymmetric relative to the center line of a fluid passage in the port by machining the inner surface of a hole corresponding to the port and a valve sheet stock after the valve seat stock is diffusion-bonded to the combustion chamber side end part of the hole corresponding to the port, and the valve seat upon formation thereof, with a bonding depth which is circumferentially uniform. SOLUTION: The inner surface of a port corresponding hole 25 formed in a cylinder head material 26 before a valve seat material 27 is diffusion-bonded thereto, is formed, in a part thereof to which the valve seat material 27 is diffusion-bonded, in a curved shape that has a basic shape which is defined by superposing loci obtained by rotating the inner surface of the intake port 15 having a completed shape around the center line C of a passage, and that is convex toward the center line C of the passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a valve seat material which is diffused and bonded to a combustion chamber side end of a port corresponding hole provided in a cylinder head material corresponding to an intake or exhaust port. The inner surface and the valve seat material are machined to form a completed shape of an intake or exhaust port whose end inner surface on the combustion chamber side is asymmetric with respect to the center line of the flow path of the port, and that the port is on the combustion chamber side. The present invention relates to a method for forming a valve seat and an intake or exhaust port in which a valve seat is formed on the inner surface of the end of the valve seat.

[0002]

2. Description of the Related Art Conventionally, an intake or exhaust port and a valve seat are formed by such a method.
For example, it is already known in JP-A-7-103070.

[0003]

The valve seat is generally mounted on the cylinder head by press-fitting. However, in recent engine layouts, an intake valve and an exhaust valve are arranged close to each other, and a press-fit type Thus, there is little freedom in changing the layout around the combustion chamber in order to increase the valve diameter or increase the compression ratio. Therefore, in the technology disclosed in the above publication, after the valve seat material is diffused and bonded to the cylinder head material by applying a large current to the cylinder head material and pressing the valve seat material, the cylinder head material and the valve seat material The valve seat is formed by machining to obtain the completed shape of the intake or exhaust port, and the valve seat is thinned. The transmission is improved to improve the engine performance.

[0004] However, in order to further improve the engine output, the shape of the intake or exhaust port may be improved, and the shape of the intake or exhaust port is changed so that the inner surface of the intake or exhaust port at the end of the combustion chamber is reduced. May be asymmetric with respect to the center line of the distribution route. At this time, in the conventional method, as shown in FIG. 7, a port corresponding hole 25 'whose inner surface is formed with an extra thickness corresponding to the machining allowance is formed in the shape of the final intake or exhaust port 15 shown by a chain line.
Is provided on the cylinder head material 26 ', and the valve seat material 27 is pressed toward the cylinder head material 26' side along the flow path center line C of the intake or exhaust port 15 and diffusion bonded, and then the port corresponding hole is formed. By machining the inner surface of the valve seat 25 'and the valve seat blank 27, as shown in FIG. 8, the final shape intake or exhaust port 15 is formed in the cylinder head 13 and the thin valve seat 17' is formed. I have to.

However, since the port corresponding hole 25 'is asymmetrical with respect to the flow path center line C, the angle between the pressing direction of the valve seat material 27 and the contact surface between the valve seat material 27 and the cylinder head material 26' is formed. Is non-uniform in the circumferential direction of the port corresponding hole 25 ', and when the angle is larger (the angle indicated by β1), the valve seat material 2
7, the contact area increases sharply, and the resistance at the time of diffusion bonding increases, so that the heat generation and melting progress, so that the bonding depth of the valve seat material 27 increases as indicated by the arrow 31. On the other hand, when the angle is smaller (the angle indicated by β2), the increase in the contact area is small, so that heat generation and melting are small, and the joining depth of the valve seat material 27 is small as indicated by the arrow 32. . As a result, FIG.
In the completed shape indicated by, the joining depth d2 of the valve seat 17 'having the angle β2 is larger than the joining depth d of the valve seat 17' having the angle β1 larger than the angle B2.
It may be smaller than 1 and may not be able to function as a valve seat without obtaining a sufficient joint area.

The cylinder head 1 is located near the valve seat.
3 is provided with a water jacket for improving the cooling performance. As described above, when the inner surface of the port corresponding hole 25 'is formed only by the excess thickness corresponding to the machining allowance, the valve seat is provided. During diffusion bonding of the material 27, sufficient rigidity on the cylinder head material 26 'side cannot be secured, and the pressure applied during diffusion bonding deforms the cylinder head material 26',
In some cases, the current and the plastic flow resistance are biased, so that a sufficient joining cannot be obtained, or a spark is generated to make joining impossible.

The present invention has been made in view of such circumstances, and even if the inner surface of the intake port or exhaust port at the end of the combustion chamber side is asymmetrical with respect to the center line of the flow path,
It is an object of the present invention to provide a method of forming an intake or exhaust port and a valve seat, wherein a valve seat has a uniform joining depth in a circumferential direction and can be joined to a cylinder head with a reliable and sufficient joining strength. .

[0008]

In order to achieve the above object, the present invention provides a valve seat material provided at a combustion chamber side end of a port corresponding hole provided in a cylinder head material corresponding to an intake or exhaust port. After the diffusion bonding, the inner surface of the port corresponding hole and the valve seat material are machined to obtain a completed shape of the intake or exhaust port in which the inner surface at the end of the combustion chamber is asymmetric with respect to the center line of the flow path of the port. In a method of forming a valve seat and an intake or exhaust port, wherein a valve seat is formed on an inner surface of an end portion of the port on the combustion chamber side, the cylinder head material before diffusion bonding of the valve seat material is provided. A portion of the inner surface of the port corresponding hole for diffusion bonding of the valve seat material is flowed through the inner surface of the completed intake or exhaust port. Wherein the previously formed into a shape which is a curved surface bulging toward the flow path center line side and having a basic shape which is obtained by superposing a locus drawn by rotating around the center line.

According to such a method, before diffusion bonding of the valve seat material to the cylinder head material, the portion of the inner surface of the port corresponding hole where the valve seat material is diffusion bonded is located at the center of the flow path of the intake or exhaust port. Since the line is symmetrical, the angle between the contact surface of the valve seat material and cylinder head material and the center line of the flow path is uniform in the circumferential direction of the port corresponding hole, and the contact area increases due to the pressure of the valve seat material. Also in the circumferential direction of the port corresponding hole, the joint depth of the valve seat material can be made uniform in the circumferential direction. In addition, since a portion of the inner surface of the port corresponding hole that diffuses and joins the valve seat material is formed as a curved surface bulging toward the center line side of the flow path, the plastic fluid generated between the valve seat material and the cylinder head material is smoothly discharged. The valve seat material can be joined to the cylinder head material at a sufficient depth by good diffusion bonding. In other words, the curved surface whose central part is convex toward the center line of the flow path is more plastic than the one where the valve seat material is diffusion-bonded on the inner surface of the port corresponding hole to a simple conical surface. It is possible to increase the sliding speed of the fluid, and to positively discharge the plastic fluid, so that the valve seat material can be converted to the cylinder head material at a sufficient depth without increasing the pressing force. Joining becomes possible. In addition, it has a basic shape in which the trajectory drawn by rotating the inner surface of the completed intake port or exhaust port around the center line of the circulation path is overlapped with the part that diffuses and joins the valve seat material on the inner surface of the port corresponding hole. By doing so, it is possible to secure a sufficient thickness between the cylinder head material and the water jacket provided on the cylinder head. Thus, the valve seat material can be securely joined to the cylinder head material by preventing current and plastic flow resistance from being biased.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on one embodiment of the present invention shown in the attached drawings.

1 to 6 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a main part of a four-stroke engine, and FIG. 2 is a view showing a state immediately before diffusion bonding of a valve seat material to a cylinder head material. FIG. 3 is an explanatory view of the shape of the port corresponding hole, FIG. 4 is a view showing the structure on the front side of the casting, FIG.
Is a cross-sectional view corresponding to FIG. 2 after the completion of machining, and FIG. 6 is a view for explaining a sliding speed of a plastic fluid.

Referring first to FIG. 1, a piston (not shown) slidably fitted in a cylinder hole 12 provided in a cylinder block 11 of a four-cycle engine, and a cylinder head 13 coupled to the cylinder block 11 A combustion chamber 14 is formed between the cylinder heads 13 and 13.
Is provided with an intake port 15 and an exhaust port 16 that can communicate with the combustion chamber 14, and a water jacket 13a for improving cooling performance.

At the open ends of the intake port 15 and the exhaust port 16 to the combustion chamber 14, valve seats 17 and 18 are formed in the cylinder head 13, and a seat portion 19a which can be seated on the valve seats 17 and 18 is provided. , 20a of the intake valve 19 and the stem portion 19b of the exhaust valve 20 are slidably fitted to guide cylinders 21 and 22 provided on the cylinder head 13, respectively. Moreover, each of the stem portions 19b, 20b is provided with a guide cylinder 21,
2, each stem portion 19b,
Between the upper end of the cylinder head 20b and the cylinder head 13, the intake valve 19 and the exhaust valve 20 are urged upward, that is, the seat portions 19a and 20a are seated on the valve seats 17 and 18 to close the intake port 15 and the exhaust port 16. Springs 23 and 24 are provided. Also each stem part 1
A valve train (not shown) is connected to the upper ends of 9b and 20b, and the valve train drives the intake valve 19 and the exhaust valve 20 to open and close.

In FIG. 2, the intake port 15 and the exhaust port 16 and the valve seats 17 and 18 are provided with port corresponding holes 2 corresponding to the intake port 15 and the exhaust port 16.
5 are formed by subjecting a ring-shaped valve seat material 27 to a cylinder head material 26 having diffusion bonding and then mechanically working the inner surfaces of the port corresponding holes 25 and the valve seat material 27. Cylinder head 1
3, ie, a cylinder head material 26 is made of an aluminum alloy casting which is a lightweight and excellent heat transfer metal, and a valve seat material 27 is made of, for example, an iron-based sintered alloy having excellent wear resistance, cooling or the like. -A Cu-Be alloy or the like having excellent thermal conductivity is used.

The valve seat material 27 is diffusion-bonded to the cylinder head material 26 by being pressed toward the cylinder head material 26 in a heating state below the melting point of the valve seat material 27 and the cylinder head material 26. That is, according to the pressurization of the valve seat material 27 to the cylinder head material 26 side in a heated state, a sliding deformation occurs on the contact surface between the valve seat material 27 and the cylinder head material 26, and the valve seat material 27 and the cylinder head material 2
The oxide film, foreign matter and intermetallic compound on the surface of No. 6 are discharged from the bonding interface as a plastic fluid, and the fine irregularities and interatomic vacancies at the bonding interface disappear, and are extremely clean and free from atmospheric gas. A contact surface will be formed. In addition, free electrons in the metal are activated by the contact between the clean surfaces in the heated state, and intragranular / grain boundary diffusion of atoms occurs between the valve seat material 27 and the cylinder head material 26, so that the valve seat material 27 is formed. Cylinder head material 26
Diffusion bonding. In the heating state, when a large current is applied in a short time while the valve seat material 27 is in contact with the cylinder head material 26, the contact surface between the valve seat material 27 and the cylinder head material 26 generates heat by Joule heat. It can be obtained by:

Incidentally, at least one of the intake port 15 and the exhaust port 16, for example, the shape of the inner surface of the end of the intake port 15 on the combustion chamber side is asymmetrical with respect to the center line C of the flow path of the intake port 15 in order to improve the engine output. In such a case, the intake port 15 and the valve seat 17 are formed as follows.

First, before diffusion bonding of the valve seat material 27, the port corresponding holes 25 provided in the cylinder head material 26 are provided.
Of the inner surface of the valve seat material, for example, a range of about 2 mm in the pressing direction from the position where the valve seat material 27 first contacts when the valve seat material 27 is pressed against the cylinder head material 26 side. The inner surface of the port corresponding hole 25 is formed in advance to have a basic shape that is symmetrical with respect to the flow path center line C and a curved surface that is bulged toward the flow path center line C side.

As shown in FIG. 3, the basic shape is obtained by superimposing trajectories drawn by rotating the inner surface of the completed intake port 15 about the center line C of the circulation path.

The above-mentioned inner surface shape of the port corresponding hole 25 before diffusion bonding may be the same as the cast molding of the cylinder head material 26 or may be formed by machining after the casting. However, the surface roughness of the inner surface of the port corresponding hole 25 before diffusion bonding needs to be 25 μm or less, desirably about processing ▽▽, and if it remains as cast, it is JIS Class 1 or higher. In the case of machining, it is necessary to have a machining JIS class 2 or higher grade. If the surface roughness is determined in this way, the heat generated by the pressure, contact resistance, and energization during diffusion bonding will be uniform, and the discharge of plastic fluid containing oxides and impurities will be promoted, necessitating cleaning treatment. And a highly reliable bonding is possible.

If the above-mentioned inner surface shape of the port corresponding hole 25 before diffusion bonding is obtained while the cylinder head material 26 is cast and formed, the following effects can be obtained as compared with those obtained by machining. is there.

That is, (1) by joining after casting, it is possible to eliminate the processing and cleaning steps.
(2) If the joining is performed while the cylinder head material 26 is hot (for example, 150 ° C. or higher) after casting, the heating time by energization can be shortened and the joining energy for the initial resistance heat generation can be reduced. (3) Joining is possible by casting using a mold, but in particular, it has rheological properties generally called thixocast (semi-solid casting) and rheocast (semi-solid casting), and has no defects such as nests. In the case of casting, plastic flow becomes smooth due to the internal α-crystal structure, and energy at the time of joining can be reduced. In addition, as shown in FIG. 4, a eutectic structure called a chill layer is generated at the outermost surface of the casting by rapid cooling of the surface, and eutectic in which intermetallic compounds are scattered is formed inside the chill layer. An α-crystal structure is generated through the structure. However, the chill layer has a lower melting point than the α-crystal structure,
Resistance heating at the time of initial bonding in diffusion bonding is reduced,
Energy required for joining can be reduced.

The "energy" referred to in the above (2) and (3) includes applied pressure, current, voltage and temperature.

After the diffusion bonding of the valve seat material 27 to the cylinder head material 26 is completed, the inner surfaces of the port corresponding holes 25 and the valve seat material 27 are machined to form the combustion chamber 14 as shown in FIG. It is only necessary to form a completed shape of the intake port 15 in which the inner surface of the side end is asymmetric with respect to the flow path center line C, and to form a valve seat 17 on the inner surface of the end of the intake port 15 on the side of the combustion chamber 14.

Next, the operation of this embodiment will be described. Before the diffusion bonding of the valve seat material 27 to the cylinder head material 26, the portion of the inner surface of the port corresponding hole 25 where the valve seat material 27 is diffusion bonded is flowed. Since the valve seat material 27 is symmetrical with respect to the path center line C,
The angle formed by the contact surface of the cylinder head material 26 and the flow path center line C is uniform in the circumferential direction of the port corresponding hole 25. Accordingly, the degree of increase in the contact area due to the pressurization of the valve seat material 27 becomes uniform in the circumferential direction of the port corresponding hole 25, and the joining depth of the valve seat material 27 can be made uniform in the circumferential direction.

Moreover, since the portion of the inner surface of the port corresponding hole 25 where the valve seat material 27 is diffused and joined is formed as a curved surface bulging toward the center line C of the flow path, the portion is formed between the valve seat material 27 and the cylinder head material 26. The plastic fluid can be discharged smoothly, and the valve seat material 27 can be joined to the cylinder head material 26 at a sufficient depth by good diffusion joining. That is, FIG.
As shown in (a), the sliding distance L1 when the plastic fluid 33 slides on a curved surface is equal to the sliding distance L2 when sliding on a simple conical surface shown in FIG. In S, it becomes large (L1> L2), and the outer surface shape of the port corresponding hole 25 before joining at the portion where the valve seat material 27 is joined becomes a curved surface bulging toward the flow path center line C. In some cases, the sliding speed is higher than that of a simple conical surface, and the pressing force is increased by increasing the sliding speed of the plastic fluid 33 and positively discharging the plastic fluid 33. The valve seat material 27 can be joined to the cylinder head material 26 with a sufficient depth without increasing the size.

Further, the locus drawn by rotating the inner surface of the completed intake port 15 about the center line C of the circulation path is superimposed on the portion of the inner surface of the port corresponding hole 25 where the valve seat material 27 is diffused and joined. By having the basic shape, it is possible to ensure a sufficient thickness between the cylinder head 13 and the water jacket 13a, and to sufficiently secure the rigidity of the cylinder head material 26 during diffusion bonding. Cylinder head material 26
The valve seat material 27 can be securely joined to the cylinder head material 26 by preventing the deformation of the valve seat material and preventing the current and the plastic flow resistance from being biased.

In this way, as shown in FIG. 5, the valve seat 17 can be joined to the cylinder head 13 with a uniform joining depth d in the circumferential direction and reliably and with sufficient joining strength. In the conventional method, the variation in the joining depth in the circumferential direction was 0.2 to 0.5 mm, whereas according to the present invention, the variation in the joining depth in the circumferential direction was ± 0. The present inventors have confirmed through experiments that the distance can be suppressed to .15 mm.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible to do.

For example, in the above embodiment, the intake port 15
And the valve seat 17 for the intake valve 19 have been described, but when the inner surface of the end of the exhaust port 16 on the combustion chamber 14 side is asymmetrical with respect to the flow path center line C, as in the above-described embodiment, Exhaust port 16 and exhaust valve 2
What is necessary is just to form the valve seat 18 for zero.

[0030]

As described above, according to the present invention, even if the inner shape of the end of the intake chamber or the exhaust port on the combustion chamber side is asymmetrical with respect to the center line of the flow path of the port, the valve seat can be evenly distributed in the circumferential direction. It is possible to join the cylinder head to the cylinder head with a sufficient joining strength with a sufficient joining depth.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of a four-cycle engine.

FIG. 2 is a longitudinal sectional view showing a state immediately before diffusion bonding of a valve seat material to a cylinder head material.

FIG. 3 is an explanatory diagram of a shape of a port corresponding hole.

FIG. 4 is a view showing a structure on a surface side of a casting.

FIG. 5 is a cross-sectional view corresponding to FIG. 2 after the completion of machining.

FIG. 6 is a diagram for explaining a sliding speed of a plastic fluid.

FIG. 7 is a longitudinal sectional view showing a state immediately before diffusion bonding of a valve seat material to a cylinder head material in a conventional technique.

FIG. 8 is a cross-sectional view corresponding to FIG. 7 after the completion of machining.

[Explanation of symbols]

 13: Cylinder head 14: Combustion chamber 15: Intake port 16: Exhaust port 25: Port corresponding hole 26: Cylinder head material 27: Valve seat material C: Distribution Route center line

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Ueda, Inventor 1-4-1 Chuo, Wako-shi, Saitama Pref. Inside Honda R & D Co., Ltd. (72) Inventor Makoto Sato 1-4-1, Chuo, Wako-shi, Saitama (72) Inventor Masakatsu Sato 1-4-1 Chuo, Wako-shi, Saitama F-term (reference) 3G024 AA14 AA15 CA05 DA03 FA06 GA00 GA01 GA10 HA00 HA20 4E067 BA00 EB00

Claims (1)

[Claims] A valve seat material (27) is provided at an end of a port corresponding hole (25) provided in a cylinder head material (26) corresponding to an intake or exhaust port (15, 16) on a combustion chamber (14) side. After diffusion bonding, the inner surface of the port corresponding hole (25) and the valve seat material (27) are machined so that the inner surface of the end on the combustion chamber (14) side flows through the ports (15, 16). A completed shape of the intake or exhaust port (15, 16) which is asymmetrical with respect to the path center line (C) is formed, and a valve seat (17) is formed on the inner surface of the end of the port (15, 16) on the combustion chamber (14) side. ,
In the method for forming an intake or exhaust port and a valve seat for forming the valve seat material (27), the cylinder head material (2) before diffusion bonding of the valve seat material (27).
6), the portion of the inner surface of the port corresponding hole (25) to which the valve seat material (27) is diffusion-bonded is connected to the inner surface of the completed intake or exhaust port (15, 16). ) Has a basic shape obtained by superimposing trajectories drawn by rotating around a center, and is formed in a shape that is a curved surface bulging toward the flow path center line (C) side. How to form intake or exhaust ports and valve seats.