JPH057480Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to the structure of an adiabatic engine equipped with an inverted cup-shaped head liner made of ceramics.

[Prior Art] An adiabatic engine using ceramics with excellent heat insulating properties for the lower surface of the cylinder head and the piston crown is disclosed in, for example, Japanese Patent Application Laid-Open No. 60-90955. In the above-mentioned prior art, as shown in FIG. 4, an inverted cup-shaped head liner 1 made of ceramic is fitted into the cylindrical portion 11 of the lower half of the cylinder head 2 made of metal, and a piston crown made of ceramic ( (not shown) makes the combustion chamber insulated.

A ceramic cylinder liner 19, into which the piston 4 is fitted, is fitted and supported on the metal cylinder body 3, and the cylinder head 2 is connected to the upper end wall 14 of the cylinder liner 19 by a head bolt (not shown). The inner peripheral surface 1a of the head liner 1 is continuous with the inner peripheral surface 19a of the cylinder liner 19, and the piston 4 fits into both of them to surround the combustion chamber 15.

An intake port 9 and an exhaust port (not shown) are provided on the upper wall 1b of the head liner 1, and a valve seat 10 that contacts the intake valve 8 and a valve seat that contacts the exhaust valve (not shown) are integrated at the lower end of these ports. is formed. The intake port 9 is an intake passage 1 provided in the cylinder head 2.
Connected to 2. The intake valve 8 is slidably supported on a valve guide 13 whose stem is connected to the cylinder head 2.

In order to form a heat insulating air layer between the cylindrical part 11 of the cylinder head 2 and the head liner 1, the inner diameter of the cylindrical part 11 is larger than the outer diameter of the head liner 1, and the depth of the cylindrical part 11 is set to the height of the head liner 1. It is made bigger than it is. A pair of upper and lower annular gaskets 22 and 23 are installed between the cylindrical portion 11 and the peripheral wall of the head liner 1 to form a heat insulating air layer 20. In addition, the upper wall 1b of the head liner 1 and the cylindrical portion 1
A seal ring 21 for sealing the connection between the gasket 35, the intake port 9, and the intake passage 12 is installed between the top wall 11a of the air insulator 1 and the air insulating air layer 20a. Similarly, although not shown, the intake port 9
A seal ring surrounding the connection portion between the intake passage 12 and the fuel injection nozzle and the intake hole of the fuel injection nozzle is also interposed.

The lower end of the head liner 1 is superimposed on the upper end surface of the cylinder liner 19 via the gasket 7 that engages with the annular groove in the upper end wall 14 of the cylinder body 3, and in this state, the head bolts between the cylinder body 3 and the cylinder head 2 Retained by bond.

According to the above-mentioned conventional technology, not only the lower surface of the cylinder head 2 but also a part of the cylinder and the piston crown are surrounded by ceramic material, and the combustion temperature is high during the combustion stroke (top dead center in terms of crank angle). The combustion chamber is insulated between 60 and 70 degrees before and after the
Not only can a good combustion state be obtained, but also the exhaust temperature can be increased. However, the lower end of the inverted cup-shaped head liner 1 is connected to the upper end wall 14 of the cylinder body 3, and the upper wall 1b is connected to the top wall 11 of the cylindrical portion 11 of the cylinder head 2 via a gasket 35.
As a result of being pinched by the head liner 1, stress concentration occurs at the corner portion a of the head liner 1 due to the explosive load during the combustion process, and there is a risk that cracks may occur from this portion.

That is, in a simplified manner, as shown in FIG. 5, the head liner 1 has a
Since the lower end is supported by the cylinder body 3 and the upper wall 1b is supported by the cylinder head 2, deformation as shown in FIG. 6a occurs during the combustion stroke. In this case, the load distribution from the lower end b of the inner peripheral surface 1a to the center c of the lower surface of the upper wall 1b via the corner part a is shown in Fig. 6b.
is represented by a solid line 35A. As a result, an excessive tensile load is generated at the corner portion a, and there is a fear that cracks may occur from the corner portion a.

During assembly, a tightening load of approximately 5 tons is applied to each of the six head bolts that connect the cylinder head 2 to the cylinder body 3, and a compressive load is applied to the corner a as shown by the broken line 35B. However, the peak of the tensile load during the combustion stroke, indicated by the solid line 35A, reaches as much as 150 kg/cm ² .

[Problems to be solved by the invention] Therefore, in view of the above-mentioned problems, the purpose of the present invention is to develop an adiabatic engine that takes into account the arrangement of the head liner so that the tensile load, which is the weak point of ceramics, does not act on the corners of the head liner. It's about providing structure.

[Means for Solving the Problems] In order to achieve the above object, the structure of the present invention includes a top wall of a cylindrical part provided on the lower wall of the cylinder head, and an inverted cup-shaped ceramic body fitted into the cylindrical part. An annular gasket with a diameter smaller than the inner diameter of the head liner is sandwiched concentrically with the upper wall of the head liner, and the lower end surface of the head liner is connected to the cylinder body and the cylinder body by the tightening force of the head bolt that fastens the cylinder head to the cylinder body. It is superimposed on the upper end surface of the cylinder liner.

[Operation] When the position of the gasket between the upper wall of the head liner and the top wall of the cylinder head is shifted toward the cylinder center, no tensile load is applied to the corner portions of the head liner. In other words, by reducing the diameter of the annular gasket and sandwiching it between the upper wall of the head liner and the ceiling wall of the cylinder head at a portion inside the inner circumferential surface of the head liner, the explosive load acting on the head liner during the combustion process can be reduced. It is supported by the cylinder head using the gasket as a fulcrum, and in this case, no tensile load that would cause cracks is applied to the corner portion, but a compressive load is applied.

As a characteristic of ceramics, the compressive strength is about 10 times higher than the tensile strength, so when only compressive load is applied to the corners of the head liner during the combustion process, no force that would tear the corners is applied, and the head liner can eliminate cracks and other strength problems.

[Embodiment of the invention] As shown in FIGS. 1 and 2, the gasket 24 is disposed inside the circumferential surface 1a of the head liner 1. Each valve seat 1 is mounted on the upper wall 1b of the head liner 1.
An intake port 9 and an exhaust port 31 having a radius of A seal ring 21 is interposed between them. Similarly, a seal ring 34 is interposed between the upper end of the exhaust port 31 and the top wall 11a of the cylinder head 2.

Further, as shown in FIG. 1, a mounting hole 40 for a fuel injection nozzle is provided in the upper wall 1b. The intake port 9 and the exhaust port 31 are arranged on the inner circumferential surface 1a of the head liner 1 in order to maximize the passage area.
located close to. Therefore, in this part, the gasket 24 protrudes outside the inner circumferential surface 1a, but if two small-diameter intake ports 9 and two exhaust ports 31 are provided, the gasket 24 will fit between the upper wall 1b and the cylinder head. 2 ceiling wall 1
1a, it can be interposed concentrically with the head liner 1 inside the inner circumferential surface 1a of the head liner 1. The other configurations are almost the same as the conventional example shown in FIG.

According to the present invention, as described above, the gasket 24
By arranging the head liner 1 as shown by the imaginary line in FIG. 5 and sandwiching the head liner 1 between the cylinder head 2 and the cylinder body 3 with head bolts, the corner portion a is provided with the dashed line 24B shown in FIG. 3b during assembly. A compressive load is applied as shown in . The explosive force acting on the headliner 1 during the combustion process is the gasket 24.
At this time, the head liner 1 is deformed from the state shown by the broken line in FIG. 3a to the state shown by the solid line, and at the corner part a, as shown by the solid line 24A in FIG. The compressive load is only reduced and the tensile load does not act. Due to the characteristics of ceramics, its strength against compressive loads is approximately 10 times higher than that under tensile loads, and the strength at the corner a
When a tensile load is applied to the head liner 1, a force that would tear it apart is applied, but when a compressive load is applied, no force that would tear the corner part a is applied, which greatly increases the reliability of the strength of the head liner 1. will be improved.

Note that, as shown in FIG.
5, bending stress occurs in the upper wall 1b as shown in Fig. 7a and b, an excessive compressive load is applied to the corner part a, and an excessive tensile load is applied to the center c of the lower surface of the upper wall 1b. This may cause cracks to occur in the upper wall 1b.

Therefore, as is clear from the above explanation,
An annular gasket 2 interposed between the upper wall 1b of the head liner 1 and the top wall 11a of the cylinder head 2.
4 is essential to be arranged concentrically between the center of the peripheral wall 1c and the upper wall 1b, and according to the stress analysis results, it is arranged in a part that is slightly biased toward the center than the inner peripheral surface 1a. is optimal.

As described above, in the present invention, between the cylinder head 2 and the cylinder body 3, which receive the explosion load of the combustion chamber acting on the head liner 1, the gasket 24, which is a support point for the explosive force, is attached to the inner circumferential surface of the head liner 1. It is most preferable to place it between the upper wall 1b and the ceiling wall 11a at a part closer to the center than 1a, and since the load acting on corner part a can be converted from a tensile load to a compressive load, The force that would tear this apart is eliminated, and it is possible to prevent cracks from occurring at the corner portion a.

[Effects of the invention] As described above, the present invention has a structure in which a cylinder is provided between the top wall of the cylindrical part provided on the bottom wall of the cylinder head and the top wall of the inverted cup-shaped ceramic head liner fitted into the cylindrical part. An annular gasket with a diameter smaller than the inner diameter of the head liner is sandwiched concentrically with the head liner, and the lower end surface of the head liner is overlapped with the cylinder body and the upper end surface of the cylinder liner by the tightening force of the head bolt that fastens the cylinder head to the cylinder body. Therefore, a compressive load always acts on the corners of the headliner (the intersection of the peripheral wall and the top wall), which are most prone to cracking due to the structure, and tensile loads due to explosive force (forces that tear the corners) Since this does not work, it is possible to provide an adiabatic engine that is simple in construction, prevents cracking at the corners, and is highly reliable in terms of strength.

In particular, by arranging the annular gasket concentrically with the head liner, a compressive load that is almost uniform in the circumferential direction is applied to the corners of the head liner, which also increases the substantial strength of the ceramic cylinder liner and prevents damage. can be avoided.

[Brief explanation of drawings]

Fig. 1 is a plan view showing a head liner of an adiabatic engine according to the present invention, Fig. 2 is a front sectional view of the head liner taken along the line - in Fig. 1, and Fig. 3 a shows an exaggerated view of the deformation of the head liner due to an explosive load. 3b is a stress distribution diagram, FIG. 4 is a front sectional view showing a general adiabatic engine, FIG. 5 is a front sectional view showing a simplified load support point of the head liner, and FIG. Figure a is a front sectional view exaggerating the deformation of the head liner due to the explosive load, and Figure 6 b.
7A is a front sectional view exaggerating the deformation of the head liner due to an explosive load when a gasket is placed in the center of the head liner, and FIG. 7B is a stress distribution diagram of the same. a...corner part, 1...head liner, 1b...
...Top wall, 1c...Peripheral wall part, 2...Cylinder head, 3...Cylinder body, 11...Cylindrical part, 1
9...Cylinder liner, 24...Gasket.

Claims (1)

[Scope of utility model registration request] An annular gasket with a smaller diameter than the inner diameter of the head liner is installed between the top wall of the cylindrical part provided on the lower wall of the cylinder head and the upper wall of the inverted cup-shaped ceramic head liner fitted into the cylinder head. A structure of an adiabatic engine characterized in that the lower end surface of the head liner is superimposed on the cylinder body and the upper end surface of the cylinder liner by the tightening force of head bolts that are concentrically sandwiched and fasten the cylinder head to the cylinder body.