JPH0416611B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an insert member fixing structure for fitting and fixing an insert member into a cavity formed in a location exposed to combustion gas of an engine.

In general, in engines, for example, an exhaust port liner is fitted and fixed to the exhaust port of a cylinder head, a heat insulating insert is fitted and fixed to an exhaust port provided in the rotor housing of a rotary piston engine, and even a secondary combustion As in the example of fitting and fixing the sub-combustion chamber constituent members to the internal cavity of the cylinder head of a diesel engine, the hollow By fitting and holding the heat-resistant insert member with a slight gap between the inner surface of the cavity and the outer surface of the insert member, the insert member can be inserted while absorbing manufacturing errors and thermal expansion differences between the inner surface of the cavity and the outer surface of the insert member. The combustion gas temperature is maintained at a high temperature through insulation.

As an example of a fixing structure for fixing and holding such an insert member in a cavity with a slight gap, there is a conventional fixing structure for holding an insert member (exhaust An insert member (heat-insulating insert) as disclosed in Japanese Utility Model Publication No. 52-24650, etc. ) is connected and supported to the inner surface of the cavity (exhaust port of the rotor housing) via a pin.

However, in these proposals, the insert member is partially supported elastically by a leaf spring or connected and supported by a pin.
There was a drawback that the insert member could not be firmly fixed.

In addition, because a part of the insert member is pressed against the inner surface of the cavity by the biasing force of the leaf spring, or because the insert member is connected to the inner surface of the cavity with a pin, the airtightness between the insert member and the inner surface of the cavity may be poor. ,
Another disadvantage was that combustion gas leaked.

Furthermore, although a heat insulating space is formed between the outer surface of the insert member and the inner surface of the cavity, they are in contact at the supporting portion, and heat transfer occurs at this contact portion, so that the intended effect is not actually achieved. There was also the problem that the insulation effect could not be expected to be adequate.

Therefore, in view of these points, the present invention fixes the insert member in the cavity by fitting and holding the insert member in the cavity through a porous layer having heat resistance, heat insulation properties, and compressive deformability. Absorbs manufacturing errors and thermal deformation, making it strong and airtight.
Furthermore, the purpose is to make it possible to conduct the process in an adiabatic manner.

In order to achieve this object, the present invention has a structure in which a cavity is formed at a location exposed to combustion gas of an engine, and an insert member is fitted and held in the cavity. A porous sprayed layer is formed by interposing a sprayed layer made of a heat-resistant synthetic resin containing a soft metal and having appropriate pores between the outer surface and the insert member held within the cavity. The compressive deformability of the material absorbs manufacturing errors and thermal deformation, supporting the insert member over a wide area and fixing it firmly and airtightly.The heat-insulating effect of the sprayed layer also increases the amount of combustion gas inside the insert member. It is designed to maintain the temperature.

Embodiments of the present invention will be described in detail below with reference to the drawings.

1 and 2 show a first embodiment applied to a structure for fitting and holding an exhaust port liner in an exhaust port of a reciprocating engine. Reference numeral 1 denotes a cylinder head of the engine, and 2 an exhaust port as a cavity formed through the cylinder head 1. The upstream end of the exhaust port 2 is connected to the combustion chamber 3 of the engine, and the downstream end is connected to the cylinder head. 1 through a gasket 4, and discharge combustion gas (exhaust) in the combustion chamber 3 to the outside of the engine via the exhaust port 2 and the exhaust passage 6. That's what I do. The exhaust port 2 as a whole has a widening taper shape whose diameter increases from the upstream side to the downstream side, and the approximately downstream half portion thereof is formed to have a slightly smaller diameter from the basic position than the other portion, and is provided with a small diameter portion 2a. Further, an annular groove 2b is formed in the peripheral wall (cylinder head 1) at the downstream end. 7 is an exhaust valve seat formed at the opening of the exhaust port 2 to the combustion chamber 3, on which an exhaust valve (not shown) is seated; 8 is a seat for guiding and holding a valve guide (not shown) of the exhaust valve; The valve guide hole 9 is a water jacket through which cooling water flows.

Inside the exhaust port 2, a flange portion 1 is formed in a tapered shape so as to correspond to the shape and dimensions of the exhaust port 2, and can fit into the groove portion 2b at the downstream end.
An exhaust port liner 10 made of a stainless steel pipe or the like having a diameter of 0a is fitted into the exhaust port liner 1.
0 is fixedly held in the exhaust port 2 by fitting the flange portion 10a into the groove portion 2b and bringing the downstream half portion into close contact with the small diameter portion 2a.

A thermally sprayed layer 11 having a thickness of about 300 to 500 μm is separately welded to one or both of the surfaces and is interposed between the surfaces in the close contact portion between the outer surface of the exhaust port liner 10 and the inner surface of the exhaust port 2. ,
The sprayed layer 11 is, as shown in enlarged detail in FIG.
Soft metals 11a, 11a, etc. such as aluminum, copper, and other metals having physical properties similar to aluminum
The heat-resistant synthetic resin 11b, 11b, etc., such as aromatic cyclic polyester resin containing
1c, 11c,...

Here, to explain the method for producing the thermal sprayed layer 11, for example, the surface of the workpiece (the inner surface of the exhaust port 2 or the outer surface of the exhaust port liner 10) is subjected to a blast treatment in advance, and then cleaned to make it uneven.
By plasma spraying a mixture of soft metal powder and heat-resistant synthetic resin powder onto this uneven surface at a plasma temperature of approximately 3000°C, voids 11c, 11c, etc. are automatically generated at the same time as the spraying. A porous sprayed layer 11 is formed.

After forming the porous sprayed layer 11, the exhaust port liner 10 is press-fitted into the exhaust port 2 from its downstream end side (outside the cylinder head 1) toward the upstream side (combustion chamber 3 side). At this time, since the exhaust port 2 is tapered toward the back side in the press-fitting direction, the porous sprayed layer 11 is compressively deformed as the press-fitting occurs.

In that case, the distance between the above thermal spray nozzle and the work surface should be 300 mm to obtain an appropriate porosity (40 to 50%).
~500mm is suitable.

Further, the particle size of each of the metal and synthetic resin powders is preferably about 10 to 50 μm. This is because if the particle size is outside this range, the two powder components will not be mixed uniformly, and the distribution of each component in the sprayed layer 11 will become non-uniform, making it impossible to obtain the necessary characteristics.

Furthermore, if the synthetic resin component is less than 10% by weight or exceeds 90% by weight, the desired properties cannot be obtained, so the mixing ratio of the soft metal and heat-resistant synthetic resin should be 10 to 90% by weight. A range is available, of which 40-60% by weight is optimal. Therefore, the mixing ratio of the soft metal is set at 90 to 10% by weight, preferably 60 to 40% by weight. Note that as the mixing ratio of the synthetic resin increases, the porosity tends to increase.

The porous sprayed layer 11 thus formed has, for example, a synthetic resin component of 60% by weight (a metal component of 40% by weight) and a porosity of about 50%.
It has a characteristic (compressive deformability) that when pressurized with a pressure of 400 Kg/cm ² , 30 to 40% of the layer thickness is crushed and deformed without protruding in a direction perpendicular to the pressurizing direction (compressive deformability).

Therefore, in the above embodiment, the exhaust port liner 10 has a soft metal 11 inside the exhaust port 2.
Heat-resistant synthetic resin 11b containing a, 11a,...
11b, ... with moderate pores 11c, 11c,
Because they are fitted and held together via the thermal sprayed layer 11 having ..., there may be a manufacturing error of, for example, about 50 to 100 μ between the inner diameter of the exhaust port 2 and the outer diameter of the exhaust port liner 10, or the exhaust port 2 Even if a thermal expansion difference between the wall portion (cylinder head 1) and the exhaust port liner 10 causes a thermal deformation of, for example, about 10 to 15 μm between the two, the manufacturing error and thermal deformation will be avoided by the thermal sprayed layer 11. is easily absorbed by compressive deformation. This allows exhaust port 2
The exhaust port liner 10 can be used over a wide area without providing any space between the inner surface and the inner surface of the exhaust port liner 10.
Therefore, the exhaust port liner 10 can be firmly and reliably fixed.

Further, the thermal sprayed layer 11 has pores 11 inside it.
c, 11c, . . . have a heat insulating effect, so that the heat retention of the exhaust port liner 10 can be improved. As a result, the exhaust gas temperature can be maintained at a high temperature, so that the oxidation reaction of the incompletely combusted gas in the exhaust gas in the exhaust passage 6 and the catalyst device disposed in the exhaust passage 6 can be promoted. Exhaust purification efficiency can be increased.

Furthermore, since the sprayed layer 11 is interposed between the inner surface of the exhaust port 2 and the outer surface of the exhaust port liner 10 while being compressed and deformed, the airtightness between both surfaces is increased, the burden on the gasket 4 is reduced, and the exhaust gas to the outside 1 is Leakage can be prevented.

Further, FIG. 3 shows a second embodiment in which the present invention is applied to a structure in which an auxiliary chamber constituent member constituting an auxiliary combustion chamber (overflow chamber) is fitted and fixed in a cavity of a cylinder head of an overflow chamber type diesel engine. In the figure, 12 is cylinder 1
A cylinder block 14 forming the cylinder block 3 is reciprocatably fitted into the cylinder 13 and has a recess 1 on the top surface.
A piston 15 having a piston 4a is a cylinder head closely fixed to the upper surface of the cylinder block 12 via a gasket 16.
A main combustion chamber 17 is formed by the portion surrounded by the three walls.

A hollow portion 18 having a hemispherical upper portion and a stepped cylindrical lower portion is bored in the lower surface of the cylinder head 15 over portions corresponding to the cylinder block 12 and the cylinder 13, respectively.
A cylindrical sub-chamber is provided in the lower part (cylindrical part) of the cavity 18, which forms a sub-combustion chamber 19 with the upper part of the cavity 18, and also forms a communication passage 20 that communicates the sub-combustion chamber 19 with the main combustion chamber 17. The component 21 is prevented from rotating by a rotation prevention pin 22 and is tightly fitted and fixed.

There is a space between the outer surface of the auxiliary chamber constituent member 21 and the inner surface (lower inner surface) of the cavity 18 corresponding to the outer surface.
Thermal sprayed layer 11 similar to the first embodiment, ie soft metal 11a, 11, having a layer thickness of 300 to 500μ
Heat-resistant synthetic resin 11b, 11b, containing a,...
A sprayed layer 11 having appropriate pores 11c, 11c, . . . is interposed therebetween. In this case as well, the auxiliary chamber forming member 21 is press-fitted into the cavity 18. Since the cavity 18 is not tapered, the sprayed layer 1
1 becomes compressed while being pulled in the shear direction, and although the amount of compression deformation is small, it is compressed and deformed. At this time, as is usually done, for example, by chamfering the outer peripheral corner of the upper end, which is the press-fitting tip of the auxiliary chamber constituent member 21, to have an arcuate cross-section, the press-fitting can be performed while compressing the sprayed layer 11 smoothly. It can be carried out. Reference numeral 23 denotes a fuel injection nozzle which is screwed and fixed to the cylinder head 15 so that the jet nozzle 23a faces the sub-combustion chamber 19, and injects fuel into the sub-combustion chamber 19. Reference numeral 24 indicates a fuel injection nozzle whose tip heat generating portion 24a is connected to the sub-combustion chamber 19. This glow plug is screwed and fixed to the cylinder head 15 so as to protrude from the cylinder head 15, and heats the intake air in the auxiliary combustion chamber 19 when the engine is started.

Therefore, in this embodiment, the subchamber component 21 is fitted and fixed in the cavity 18 with the porous sprayed layer 11 interposed between the outer surface of the subchamber component 21 and the inner surface of the cavity 18. Therefore, the porous sprayed layer 11 connects the cavity 18 and the sub-material component 21.
For example, manufacturing errors of about 30 to 50μ and thermal deformation of about 10μ between the subchamber component 21 and
can be supported and firmly fixed over a wide area without creating a gap between the inner surface of the cavity 18 and the combustion gas in the sub-combustion chamber 19 at a high temperature due to the heat insulating effect of the porous sprayed layer 11. It is possible to improve the combustion performance of the engine by keeping it at a constant temperature.

Further, since the space between the inner surface of the cavity 18 and the outer surface of the sub-chamber component 21 can be airtightly filled by the sprayed layer 11, the quench zone for combustion gas is reduced, and the initial HC can be reduced.

Note that the present invention is not limited to the first and second embodiments described above, and can also include forming a cavity in a location exposed to combustion gas in various engines, and inserting an insert member into the cavity. Of course, it can also be applied to the case of fitting and holding.

As explained above, according to the present invention, in a structure in which an insert member is fitted and held in a cavity formed in a location exposed to combustion gas of an engine,
The above-mentioned insert member is fitted and fixed by interposing a thermally sprayed layer made of a heat-resistant synthetic resin containing a soft metal and having appropriate pores between the outer surface and the inner surface of the cavity. Due to its compressive deformability, manufacturing errors and thermal deformation between the cavity and the insert member can be absorbed, and the insert member can be firmly fixed. In addition, the heat-insulating properties and ventilation-insulating properties of the sprayed layer make it possible to maintain the combustion gas inside the insert at a high temperature and prevent gas leakage, which has an excellent practical effect of improving engine performance. It is something.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIGS. 1 and 2 show the first embodiment, with FIG. 1 being a longitudinal sectional view and FIG. 2 being an enlarged sectional view of the main part. FIG. 3 is a longitudinal sectional view showing the second embodiment. 1... Cylinder head, 2... Exhaust port (cavity), 3... Combustion chamber, 6... Exhaust passage, 10...
...Exhaust port liner, 11...Thermal spray layer, 11a...
...Soft metal, 11b...Heat-resistant synthetic resin, 11c...
...Vacancy, 12...Cylinder block, 13...Cylinder, 14...Viston, 15...Cylinder head, 17...Main combustion chamber, 18...Cavity part, 10
... Sub-combustion chamber, 21... Sub-chamber constituent member.

Claims (1)

[Claims] 1 In a structure in which a cavity is formed in a place exposed to engine combustion gas and an insert member is fitted and held in the cavity, a heat-resistant material containing a soft metal is placed between the inner surface of the cavity and the outer surface of the insert member. 1. A structure for fixing an insert member for an engine, characterized in that the insert member is held within a cavity by interposing a thermally sprayed layer made of synthetic resin and having appropriate pores.