JPH0221528Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of the invention] This invention relates to a valve seat for an internal combustion engine, and in particular, the invention relates to a valve seat for an internal combustion engine, and in particular, a method in which either the outer circumferential surface of the valve seat or the inner circumferential surface of the seat insertion hole is formed in a straight line. At the same time, by forming a gap on the combustion chamber side from the combustion chamber forming surface to a depth that is approximately half the depth of the seat insertion hole to separate one from the other, deformation of the valve seat is minimized. The present invention relates to a valve seat for an internal combustion engine that maintains good contact between the valve seat and intake/exhaust valves and can be easily processed.

[Technical background of the invention] In internal combustion engines, as shown in Figures 1 and 2,
Multiple intake ports 4 and exhaust ports 6 in the cylinder head 2
Valve seats 8 are inserted and fitted into the seat insertion holes formed in the respective holes.

This valve seat 8 protects against wear caused by impact with the intake and exhaust valves and damage caused by foreign objects being caught.
This prevents gas leakage. The valve seat 8 is formed into a ring shape using a metal different from the material of the cylinder head 2. For example, the valve seat 8 is formed from a metal with high strength, heat resistance, and durability, such as cast steel, copper impregnation, or a forged seat. has been done.

In addition, the valve seat 8 is as shown in FIG.
The outer peripheral surface is inserted and fitted in close contact with the entire inner peripheral surface of the seat insertion hole of the cylinder head 2, and is used as a seating member for the intake valve 10 in the intake port 4, for example.

[Problems with background technology]

By the way, the intake and exhaust ports of the cylinder head are structurally weak because they have large openings, and the combustion chamber-forming surface of the cylinder head comes into contact with the high-temperature combustion gas in the cylinder, so it becomes hot and the cylinder Since the temperature distribution within the head is complex and the temperature gradient is large, large deformations are likely to occur particularly near the intake and exhaust ports.

In particular, cylinder heads made of aluminum have a large coefficient of thermal expansion, so thermal deformation is large. Further, in the cylinder head of a four-valve internal combustion engine, the load is large both in terms of shape and temperature, and deformation tends to be large. When the cylinder head deforms in this way, the valve seat also deforms.
As a result, the contact with the intake/exhaust valves deteriorates, causing gas leakage, resulting in adverse effects such as unstable idling and reduced output of the internal combustion engine.

Therefore, in order to prevent this thermal deformation, it is possible to increase the rigidity of the valve seat.
Due to the shape and structure of the cylinder head, there is a limit to increasing the rigidity by increasing the thickness and height of the valve seat, and even if the rigidity of the valve seat is increased, it is not necessarily effective in preventing thermal deformation. I couldn't have expected it.

[Purpose of invention]

Therefore, the purpose of this invention is to form either the outer peripheral surface of the valve seat or the inner peripheral surface of the seat insertion hole into a straight line in order to eliminate the above-mentioned disadvantages, and to form a combustion chamber forming surface on the combustion chamber side. By forming a gap that separates one from the other at a depth that reaches approximately half the depth of the seat insertion hole, deformation of the valve seat is minimized and the relationship between the valve seat and the intake/exhaust valve is minimized. It is an object of the present invention to provide a valve seat for an internal combustion engine that can maintain a good contact state to prevent a decrease in output, and can be easily processed.

[Structure of the idea]

To achieve this objective, this invention provides a valve seat for an internal combustion engine that is fitted into a seat insertion hole formed around the intake and exhaust ports of the cylinder head of the internal combustion engine. The seat insertion hole is formed at a predetermined depth so as to be located in substantially the same plane as the combustion chamber forming surface of the cylinder head, and the outer circumferential surface of the valve seat and the inner circumferential surface of the seat insertion hole are formed. Either one of them is formed in a straight line, and a gap is formed on the combustion chamber side to separate the one from the other at a depth reaching approximately half the depth of the sheet insertion hole from the combustion chamber forming surface. It is characterized by

[Effect]

According to the configuration of this invention, the air gap reduces thermal deformation of the valve seat by blocking deformation and temperature around the intake/exhaust ports of the cylinder head from being transmitted to the valve seat, and also reduces thermal deformation of the valve seat. Even if the vicinity of the exhaust port is deformed due to heat, the valve seat is prevented from being deformed together with the deformation of the cylinder head. As a result, even if a valve seat with low rigidity is used, the contact between the valve seat and the intake/exhaust valve is good, preventing gas leakage, and stabilizing the idle operation of the internal combustion engine and improving output. can be achieved.

Further, since either the outer circumferential surface of the valve seat or the inner circumferential surface of the seat insertion hole is formed in a straight line, the number of processing steps is reduced and processing is facilitated.

[Example of idea]

Embodiments of this invention will be described in detail and specifically below based on the drawings.

1 and 3 show an embodiment of this invention. In FIG. 1, 2 is a cylinder head of a four-valve internal combustion engine, 4 is an intake port, and 6 is an exhaust port. A valve seat 8 is inserted and fitted around the intake port 4 and the exhaust port 6, respectively. As shown in FIG. 3, an intake valve 10 approaches and separates from the valve seat 8, for example, on the intake port 4 side.

As shown in FIG. 3, the valve seat 8 has a seat insertion hole 2a that is cut into the cylinder head 2 by the diameter of the combustion chamber side portion 8a, which is a concave portion, of the outer peripheral surface of the valve seat 8.
The diameter of the inner peripheral surface is cut to be smaller than the diameter of the inner peripheral surface. The height of the combustion chamber side portion 8a, that is, the depth L from the combustion chamber side surface 8e, is set to approximately half the predetermined depth H of the seat insertion hole 2a. Further, the sheet insertion hole 2a is formed in a straight line.

As a result, when the valve seat 8 is inserted and fitted into the seat insertion hole 2a, a gap 12 is formed between the combustion chamber side part 8a and the seat insertion hole 2a on the combustion chamber 14 side. Ru. That is, by forming the diameter of the combustion chamber side 8a smaller than the diameter of the inner circumferential surface of the seat insertion hole 2a, the gap 12 is formed so that the outer circumferential surface of the combustion chamber side 8a and the seat insertion hole are connected to each other. It is formed between the inner circumferential surfaces of the portions 2a and at a depth L from the combustion chamber forming surface 2e. As a result, the valve seat 8 is held by bringing the valve seat inner part 8b and the cylinder head hole inner part 2b into close contact, and since a gap 12 is formed on the combustion chamber 14 side, the outer circumferential surface of the valve seat 8 and the inner circumferential surface of the sheet insertion hole 2a are not in contact with each other.

Further, the seat insertion hole 2a is formed to a predetermined depth H so that the combustion chamber side surface 8e of the valve seat 8 is located substantially in the same plane as the combustion chamber forming surface 2e of the cylinder head 2. That is, the depth H of the seat insertion hole 2a and the axial length, which is the height of the valve seat 8, are formed to be the same. This prevents the valve seat 8 from unnecessarily protruding from the combustion chamber forming surface 2e.

Next, the operation of this embodiment will be explained.

As the internal combustion engine operates, the cylinder head 2 is exposed to high temperature combustion gas. especially,
The combustion chamber-forming surface 2e of the cylinder head 2, which is the part that directly contacts the high-temperature gas, has the highest temperature and the amount of deformation becomes large.

For this reason, in the past, as shown in FIG. 2, the entire outer circumferential surface of the valve seat 8 was tightly fitted into the inner circumferential surface of the seat insertion hole of the cylinder head 2. Due to the deformation, the valve seat 8 was also forcibly deformed significantly.

However, in this embodiment, as shown in FIG. 3, on the combustion chamber 14 side between the inner peripheral surface of the seat insertion hole 2a and the outer peripheral surface of the valve seat 8, the seat insertion hole is removed from the combustion chamber forming surface 2e. Depth H of 2a
Since the void 12 is formed at a depth L reaching approximately half of the cylinder head 2, the combustion chamber side portion 8a of the valve seat 8 is not deformed due to large thermal deformation of the cylinder head 2. Since the valve seat back part 8b of the valve seat 8 is firmly held in the small cylinder head back part 2b, it prevents the valve seat 8 from falling off and also prevents the valve seat part 8c of the valve seat 8 from being significantly deformed. It can be prevented.

That is, the intake port 4 and the exhaust port 6 of the cylinder head 2
The thermal deformation of the valve seat 8 is reduced by blocking the transmission of surrounding deformation and temperature to the valve seat 8, and even if the vicinity of the intake port 4 and exhaust port 6 of the cylinder head 2 are deformed due to heat, This prevents the valve seat 8 from deforming together with the deformation of the cylinder head 2, thereby improving the contact between the valve seat 8, the intake valve 10, and the exhaust valve, and preventing gas leakage. It is possible to stabilize the idle operation of the internal combustion engine, improve the output, and improve the driving performance.

Furthermore, by forming the air gap 12, the intake valve 10,
The propagation of the sound generated by the exhaust valve hitting the valve seat 8 is reduced, and quieter engine operation can be achieved. Moreover, by forming the void 12, the cylinder head 2
Since the temperature distribution of the valve seat 8 is less affected by this, the uneven temperature distribution of the valve seat 8 is alleviated, the deformation of the valve seat 8 is reduced, and the uniformity of the atomization of the air-fuel mixture is improved, thereby improving the combustion state. This has a positive effect on engine operation.

Furthermore, since either the outer circumferential surface of the valve seat 8 or the inner circumferential surface of the seat insertion hole 2a formed in the cylinder head 2 is formed to have the same diameter,
The valve seat 8 and cylinder head 2 can be easily processed.

Furthermore, since the combustion chamber side surface 8e of the valve seat 8 is located in substantially the same plane as the combustion chamber forming surface 2e of the cylinder head 2, the valve seat 8 does not protrude unnecessarily into the combustion chamber 14, and the part It is possible to prevent the temperature from reaching a high temperature, reduce the amount of thermal deformation, and extend the service life.

Note that this invention is not limited to the above-mentioned embodiments,
Of course, various applications and modifications are possible.

For example, as shown in FIG.
The seat insertion hole 2a to be cut is stepped,
It is also possible to form a gap 12 between the combustion chamber side 8a of the valve seat 8 and the cylinder head 2.

Further, as shown in FIG. 5, it is also possible to form the gap 12 by tapering and cutting the combustion chamber side portion 8a of the valve seat 8.

Furthermore, as shown in FIG. 6, it is also possible to form the gap 12 by cutting the seat insertion hole 2a of the cylinder head 2 into a tapered shape.

Furthermore, in the above-mentioned embodiment, a four-valve internal combustion engine has been described, but it goes without saying that the embodiment of this invention can be applied to other internal combustion engines having a different number of valves.

[Effect of idea]

As is clear from the above detailed explanation, according to this invention, a seat insertion hole is formed at a predetermined depth so that the side surface of the combustion chamber of the valve seat is located in substantially the same plane as the combustion chamber forming surface of the cylinder head. , one of the outer circumferential surface of the bulb seat and the inner circumferential surface of the seat insertion hole is formed in a straight line, and on the combustion chamber side, the depth reaches approximately half of the depth of the seat insertion hole from the combustion chamber forming surface. By forming a gap to separate one side from the other, approximately half of the axial length of the valve seat is formed from the combustion chamber side between a portion of the outer peripheral surface of the valve seat and the inner peripheral surface of the seat insertion hole. Even if there is deformation around the intake/exhaust ports of the cylinder head, the void formed at the depth prevents the valve seat from being deformed due to this deformation, and also blocks heat transfer from the cylinder head. Thermal deformation of the valve seat is minimized, and even if the vicinity of the intake/exhaust port of the cylinder head is deformed due to heat, the valve seat is prevented from being deformed together with the deformation of the cylinder head. Good contact between the seat and the intake/exhaust valves,
By preventing gas leakage, it is possible to stabilize the idle operation of the internal combustion engine, improve the output, and improve the operating performance.

In addition, the formation of voids impairs the propagation of the sound produced by the intake and exhaust valves hitting the valve seats.
It is possible to achieve quieter engine operation.

Furthermore, since the non-uniform temperature distribution of the valve seat is alleviated, the uniformity of the atomization of the air-fuel mixture is improved, the combustion condition is improved, and this has a positive effect on engine operation.

Furthermore, since the outer peripheral surface of the valve seat and the inner peripheral surface of the seat insertion hole formed in the cylinder head are formed to have the same diameter, processing of the valve seat and cylinder head is facilitated.
It is advantageous in terms of production.

In addition, since the side surface of the combustion chamber of the valve seat is located on approximately the same plane as the combustion chamber forming surface of the cylinder head, the valve seat does not protrude unnecessarily into the combustion chamber, thereby preventing local high temperatures. At the same time, the amount of thermal deformation can be reduced, and the service life can be extended.

[Brief explanation of the drawing]

Figures 1 and 3 show an embodiment of this invention; Figure 1 is a plan view of the cylinder head seen from the cylinder side;
FIG. 3 is a sectional view of the valve seat fitted into the seat insertion hole of the cylinder head. Fourth
Figures 6 to 6 show other embodiments of this invention, and are partial sectional views of the valve seat in a fitted state. FIG. 2 is a sectional view taken along the - line in FIG. 1, showing a conventional valve seat fitted into a seat insertion hole. In the figure, 2 is a cylinder head, 4 is an intake port, 6 is an exhaust port, 8 is a valve seat, 12 is a gap, and 14 is a combustion chamber.

Claims (1)

[Scope of utility model registration request] In a valve seat for an internal combustion engine that is fitted into a seat insertion hole formed around an intake/exhaust port of a cylinder head of an internal combustion engine, the combustion chamber side surface of the valve seat is substantially the same as the combustion chamber forming surface of the cylinder head. The seat insertion hole is formed at a predetermined depth so as to be located in a plane, and either the outer peripheral surface of the valve seat or the inner peripheral surface of the seat insertion hole is formed in a straight line, and combustion is performed. A valve seat for an internal combustion engine, characterized in that a gap is formed on the chamber side from the combustion chamber forming surface to a depth reaching approximately half the depth of the seat insertion hole to separate the one from the other.