JPH0723538Y2 - Reciprocating internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a structure of a reciprocating internal combustion engine, and more particularly to a structure of a joint portion between a cylinder and a cylinder head forming a combustion chamber.

[Conventional technology]

The reciprocating internal combustion engine is configured such that a combustion chamber is formed between a piston slidably fitted in a cylinder bore and an inner surface concave portion of the cylinder head, and power is obtained by explosion in the combustion chamber.

The reciprocating motion of the piston is usually converted into crank rotation via a connecting rod and output as a rotational force.

This reciprocating internal combustion engine can be divided into two cycles and four cycles or gasoline and diesel depending on the stroke and combustion system.

By the way, in the conventional reciprocating internal combustion engine, the joint surface of the cylinder and the cylinder head (usually joined through a sealing means such as a gasket or O-ring) is formed as a flat surface, and the horizontal positioning is For example, a method of fitting knock pins provided at two locations has been used.

In addition, the piston reaches the top dead center position for the purpose of improving combustion efficiency by directing the air-fuel mixture at the peripheral edge of the combustion chamber toward the ignition region (near the spark plug) by utilizing the piston rise in the compression stroke. A squish area is formed in the cylinder head so that the annular gap at the peripheral edge portion becomes small when the above is performed.

The squish area is intended to maintain a good ignition and combustion state by forming a flow of the air-fuel mixture from the peripheral portion to the central portion in the combustion chamber.

The above-mentioned reciprocating internal combustion engine is disclosed, for example, in Japanese Utility Model Publication No. Sho 63-16662.
No. 5 is disclosed.

FIG. 3 is a sectional view showing a structure of a joint portion between a cylinder and a cylinder head of a conventional reciprocating internal combustion engine.

In FIG. 3, a piston 3 is slidably fitted in a bore 2 of a cylinder 1, and an upper surface of the cylinder 1 is
The cylinder head 5 is joined via the gasket 4.

A recess 6 is formed on the inner surface of the cylinder head 5, a combustion chamber 8 is formed between the recess 6 and the top surface 7 of the piston 3, and an ignition plug 9 is mounted on the upper surface of the combustion chamber 8. ing.

Incidentally, FIG. 3 shows a state in which the piston 3 is at the top dead center.

A squish portion for forming a squish area 10 with the top surface 7 of the piston 3, that is, a clearance between the piston top surface 7 at the top dead center is formed in the peripheral edge portion of the recessed portion 6 of the cylinder head 5. A region 11 to be reduced is formed.

In addition, a surface treatment layer 12 is formed on the sliding surface of the cylinder bore 2 by a method such as bombardment or plating in order to secure wear resistance and lubricating oil retention.

[Technical issues to be solved by the device]

However, the conventional reciprocating internal combustion engine has the following technical problems.

i) Since the horizontal positioning of the cylinder 1 and the cylinder head 5 is performed by an indirect means (not shown) such as fitting a knock and a knock hole, the center of the cylinder bore 2 and the center of the cylinder head 5 are concentric. It is difficult to improve accuracy.

ii) Since it is difficult to increase the concentricity accuracy, in order to eliminate the possibility of contact between the piston 3 and the cylinder head 5 in the squish area 11, the combustion chamber 8 portion (inner surface concave portion) 6 of the cylinder head 5 is removed. It is necessary to make the outer diameter dimension D _b of the cylinder larger than the bore diameter D _a of the cylinder bore 2. Therefore, an annular gap 13 is formed at the peripheral edge of the combustion chamber, carbon tends to be deposited there, and the combustion state may be affected. There was a nature.

iii) The boundary of the surface treatment layer (generally a metal layer) 12 such as bombardment or plating of the upper end chamfered portion of the cylinder bore 2 is exposed in the combustion chamber 8, and the surface treatment layer may peel off. It was

The present invention has been made in view of such a technical problem, and a uniform and small squish area can be formed by easily increasing the concentricity accuracy of the cylinder bore and the cylinder head. Reciprocating internal combustion that can eliminate carbon deposits by eliminating the peripheral depressions and can improve the durability of the surface treatment layer of the cylinder bore without exposing the boundary of the surface treatment layer to the combustion chamber. The purpose is to provide an institution.

[Means for solving problems]

The present invention relates to a reciprocating internal combustion engine in which a piston is fitted in a cylinder bore and a cylinder head is joined to the upper surface of the cylinder to form a combustion chamber between the piston top surface and the cylinder bore. And a squish portion that forms a small gap between the piston head surface at the top dead center at the peripheral edge of the spigot portion of the cylinder head by fitting with almost no gap between the spigot portion and the piston. And a surface treatment layer such as bombardment or plating for ensuring wear resistance and lubricating oil retention of the piston sliding surface is formed in the cylinder bore up to the upper end of the cylinder bore, and the spigot part of the cylinder head is formed. Is fitted to the surface treatment layer forming portion of the cylinder bore, and a peripheral portion of the cylinder head outside the spigot portion is pressed against the upper end surface of the cylinder. In with the configuration for fixing the cylinder head to the cylinder, it is to achieve the above object.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 is a vertical sectional view of an embodiment of a two-cycle reciprocating internal combustion engine according to the present invention.

In FIG. 1, a piston 3 is slidably fitted in a bore 2 of a cylinder 1, and an upper surface of the cylinder 1 is
The cylinder head 5 is joined.

In the illustrated example, a sealing means having an O-ring 15 mounted in a ring groove 14 formed on the upper surface of the cylinder is provided.

A spigot portion 16 that fits into the cylinder bore 2 is formed in the cylinder head 5, and a recess 6 that is the upper surface of the combustion chamber 8 is formed on the inner surface of the spigot portion 16.

Therefore, the combustion chamber 8 is formed between the spigot portion 16 and the piston top surface 7, and the spark plug 9 is mounted on the upper surface of the combustion chamber 8.

The fitting portion between the spigot portion 16 and the cylinder bore 2 is
Although it is removable, it is set to a size that can regulate the concentricity with almost no gap.

Note that FIG. 1 shows a state in which the piston 3 is at the top dead center.

A squish portion for forming a squish area 10 with the top surface 7 of the piston 3, that is, a clearance between the top surface 7 of the piston 3 and the piston top surface 7 at the top dead center is formed in the peripheral portion of the recess 6 of the spigot portion 16. A region 11 to be reduced is formed.

In addition, a surface treatment layer 12 is formed on the sliding surface of the cylinder bore 2 by a method such as bombardment or plating in order to secure wear resistance and lubricating oil retention.

As described above, the reciprocating internal combustion engine of the present invention, that is, the piston 3 is fitted in the cylinder bore 2, the cylinder head 5 is joined to the cylinder upper surface, and the combustion chamber 8 is formed between the piston 3 and the piston top surface 7.
In the reciprocating internal combustion engine having the above-described structure, a reciprocating internal combustion engine having a structure in which a spigot portion 16 that fits into the cylinder bore 2 is provided around the combustion chamber 8 portion of the cylinder head 5.

In the illustrated example, a squish portion 11 that forms a small gap 10 between the spigot portion 16 of the cylinder head 5 and the piston top surface 7 at the top dead center is provided.

According to the embodiment described above, the combustion chamber portion 6 of the cylinder head 5 is fitted into the cylinder bore 2 by the spigot fitting and is positioned by the spigot portion 16, so that the following effects are obtained.

i) The concentricity between the cylinder bore 2 and the cylinder head 5 can be accurately obtained, and when the squish area 10 is provided, it is possible to form the squish area 10 with a uniform and small gap, thereby enhancing the squish effect. , The ignition and combustion conditions could be improved.

ii) Combustion chamber 8 at the joint between cylinder 1 and cylinder head 5
Since it is not necessary to provide a gap like the conventional concave portion 13 around, it was possible to reduce carbon deposition.

iii) Since the boundary of the surface treatment layer 12 such as bombardment or plating in the upper end chamfered portion 17 of the cylinder bore 2 is not exposed inside the combustion chamber 8, the durability of the surface treatment layer 12 (peeling resistance)
Was able to improve.

iv) Positioning of the cylinder 1 and the cylinder head 5 The nonque pin can be eliminated or reduced to one, and the cost can be reduced.

FIG. 2 is a longitudinal sectional view of an embodiment of a 4-cycle reciprocating internal combustion engine according to the present invention.

In this embodiment, an intake hole 18 and an exhaust hole 19 communicating with the combustion chamber 8 are formed in the cylinder head 5, and the intake and exhaust holes 18, 19 are opened and closed by intake and exhaust valves 20, 21 at a predetermined timing. .

The cylinder bore 2 is formed by a cylinder liner 22 press-fitted into the cylinder 1.

Further, on the joint surface between the cylinder 1 and the cylinder head 5,
An airtight gasket 4 is attached.

A spigot portion 16 that fits into the cylinder bore 2 is formed in the cylinder head 5, and a recess 6 that is the upper surface of the combustion chamber 8 is formed on the inner surface of the spigot portion 16.

Therefore, a combustion chamber 8 is formed between the spigot portion 16 and the piston top surface 7, and the intake / exhaust valves 20, 21 and a spark plug (not shown) are mounted on the upper surface of the combustion chamber 8. .

The fitting portion between the spigot portion 16 and the cylinder bore 2 is
Although it is removable, it has dimensions so that there is almost no gap and the concentricity can be regulated.

Note that FIG. 2 also shows a state in which the piston 3 is at the top dead center.

In addition, a squish portion for forming a squish area 10 with the top surface 7 of the piston 3, that is, the top surface 7 of the piston at the top dead center is formed on the peripheral portion of the recess 6 of the spigot portion 16.
A region 11 is formed to reduce the gap between and.

In addition, a surface treatment layer 12 is formed on the sliding surface of the cylinder bore 2 by a method such as bombardment or plating in order to secure wear resistance and lubricating oil retention.

Also in the embodiment described with reference to FIG. 2 above, the combustion chamber portion 6 of the cylinder head 5 is fitted into the cylinder bore 2 by the spigot fitting and is positioned by the spigot portion 16. Therefore, the embodiment of FIG. As in the case, the concentricity with the cylinder bore 2 and the cylinder head 5 can be accurately obtained, and when the squish area 10 is provided, it is possible to form the squish area 10 with a uniform and small gap,
The effect of enhancing the squish effect and improving the state of ignition and combustion was obtained.

Further, since it is not necessary to provide a gap like the conventional concave portion 13 around the combustion chamber 8 at the joint between the cylinder 1 and the cylinder head 5, it is possible to reduce carbon deposition.

Further, since the boundary of the surface treatment layer 12 such as bombardment or plating at the upper end part 17 of the cylinder bore 2 is not exposed in the combustion chamber 8, the durability of the surface treatment layer 12 (peeling resistance)
Was able to improve.

Moreover, the positioning pin for positioning the cylinder 1 and the cylinder head 5 can be eliminated or reduced to one, and the cost can be reduced accordingly.

It should be noted that the present invention can be similarly applied to both the 2-cycle and 4-cycle internal combustion engines as described above, and can also be applied to both the gasoline engine and the diesel engine.

Further, the present invention can be applied not only to one cylinder but also to a multi-cylinder internal combustion engine.

[Effect of device]

As is apparent from the above description, according to the present invention, in a reciprocating internal combustion engine in which a piston is fitted in a cylinder bore, and a cylinder head is joined to a cylinder upper surface to form a combustion chamber between the cylinder top and the piston top surface. A spigot portion that can be fitted to the cylinder bore with almost no clearance to regulate the concentricity is formed around the combustion chamber portion of the head, and a piston top surface at top dead center is formed at the peripheral edge of the spigot portion of the cylinder head. A squish portion that forms a small gap between the cylinder bore and a top surface of the cylinder bore is provided with a surface treatment layer such as bombardment or plating for ensuring abrasion resistance of the piston sliding surface and lubricating oil retention. And the fitting part of the cylinder head is fitted to the surface treatment layer forming part of the cylinder bore, and the periphery of the cylinder head outside the fitting part is formed. Since the cylinder head is fixed to the cylinder while being pressed against the upper end surface of the cylinder, the concentricity between the cylinder bore and the cylinder head can be accurately obtained to form a uniform and small squish area. As a result, the squish effect can be enhanced to improve the ignition and combustion conditions, and no gap is formed around the combustion chamber at the joint between the cylinder and the cylinder head. Since the boundary of the upper end of the surface treatment layer of the cylinder bore is not stored in the spigot fitting part and exposed to the combustion chamber, the peel resistance and durability of the surface treatment layer are improved. In addition, since the positioning knock pins for the cylinder and cylinder head can be eliminated, cost reduction can be achieved. Reciprocating internal combustion engine is provided which can be.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the reciprocating internal combustion engine according to the present invention, FIG. 2 is a vertical sectional view of another embodiment of the reciprocating internal combustion engine according to the present invention, and FIG. 3 is a vertical sectional view of a conventional reciprocating internal combustion engine. It is a side view. 1 ... Cylinder, 2 cylinder bore, 3 ... Piston, 5
...... Cylinder head, 6 ...... concave part, 7 ...... piston top surface, 8 ...... combustion chamber, 10 ...... squish area, 11 ...... squish part, 16 ...... spigot part.

Claims (1)

[Scope of utility model registration request] 1. A reciprocating internal combustion engine in which a piston is fitted in a cylinder bore and a cylinder head is joined to an upper surface of the cylinder to form a combustion chamber between the piston top surface and the piston. A squish that fits with the cylinder bore with almost no gap to form a spigot part that can regulate the concentricity, and forms a small gap with the top surface of the piston at the top dead center at the peripheral edge of the spigot part of the cylinder head. And a surface treatment layer such as bombardment or plating for ensuring abrasion resistance and lubricating oil retention of the piston sliding surface is formed in the cylinder bore up to the upper end of the cylinder bore, and Part was fitted to the surface treatment layer forming part of the cylinder bore, and the peripheral part outside the spigot part of the cylinder head was pressed against the upper end surface of the cylinder. Reciprocating internal combustion engine, characterized by fixing the cylinder head to the cylinder in state.