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Combustion-chamber structure of engine

a combustion chamber and engine technology, applied in the direction of engine cooling apparatus, liquid cooling, valve arrangement, etc., can solve the problems of increasing the temperature of the valve, improper valve temperature, and increasing the temperature of the cylinder

Inactive Publication Date: 2021-10-07
MAZDA MOTOR CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This invention aims to design a structure for an engine's combustion chamber that can handle high temperatures and reduce the amount of heat lost during the process. As a result, the likelihood of preignition, a condition that causes damage to engine valves, is minimized.

Problems solved by technology

There is a problem, however, that the heat may be excessively stored at the heat-insulation layer, thereby making the temperature of the valves improperly high.
This heating may cause a temperature increase of the valve itself, thereby increasing the cylinder temperature.
Thereby, the air taken in an intake stroke of the engine may be heated excessively, so that improper preignition may occur in a compression stroke of the engine.

Method used

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  • Combustion-chamber structure of engine
  • Combustion-chamber structure of engine
  • Combustion-chamber structure of engine

Examples

Experimental program
Comparison scheme
Effect test

embodiment 1

[0061]FIG. 6 is a partially-sectional side view showing the intake valve 11 according to a first embodiment. FIG. 7 is an enlarged view of a sectional portion of the intake valve 11 of FIG. 6, which shows a positional relationship of the intake valve 11 with the vale seat 4S (cylinder head 4). The structure of the intake valve 11 which is shown here is applicable to the exhaust valve 12. The intake valve 11 comprises the intake valve body 110 which includes the umbrella part 111 and the stem part 112, the heat-insulation layer 71 and the heat-barrier layer 72 which are shown in the comparative example 2 as well, and the heat-diffusion layer 73 which is not provided in the comparative example 2.

[0062]The heat-insulation layer 71 is provided at the valve seat 113 of the umbrella part 111. The heat-insulation layer 71 has a specified thickness in a valve shaft (axial) direction and is of a circular shape which is similar to the valve head 113 in a plan view of the valve shaft direction...

embodiment 2

[0078]In a second embodiment, a preferable example as the intake valve will be shown. FIG. 9 is a partially-sectional side view showing an intake valve 11A according to the second embodiment. The intake valve 11A comprises the intake valve body 110 including the umbrella part 111 and the stem part 112, the heat-insulation layer 71, the heat-barrier layer 72, and the heat-diffusion layer 73. What is different from the above-described first embodiment is that there is provided a valve-face heat-barrier layer 721 which covers over the valve face 114 of the umbrella part 111.

[0079]The valve-face heat-barrier layer 721 covers the valve face 14 over an area from a base end section 111A (a portion connected to the tip section 112A of the stem part 112) of the umbrella part 111 to a position of the umbrella part 111 which partially overlaps with the contact portion 731. That is, the structure in which the contact portion 731 is exposed to the contact face CP of the umbrella part 111 is the ...

embodiment 3

[0083]A preferable example of the intake valve will be shown as a third embodiment as well. FIG. 10 is a partially-sectional side view showing an intake valve 11B according to the third embodiment. The intake valve 11B comprises the intake valve body 110 including the umbrella part 111 and the stem part 112, the heat-insulation layer 71, the heat-barrier layer 72, and the heat-diffusion layer 73. What is different from the above-described second embodiment is that there is provided a stem-part heat-barrier layer 722 which is provided to cover over the stem part 112 in addition to the valve-face heat-barrier layer 721, and the heat-diffusion layer 73 extends from the valve face 114 to the stem part 112.

[0084]Similarly to the second embodiment, the valve-face heat-barrier layer 721 is provided on the valve face 114 in an area from an end edge of the contact portion 731 to the base end section 111A. The stem-part heat-barrier layer 722 is provided on the stem part 112 such that it is c...

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Abstract

A combustion-chamber structure of an engine comprises a combustion chamber which is partitioned by a cylinder block, a cylinder head, a piston, an intake valve, and an exhaust valve. The intake valve (exhaust valve) comprises an intake valve body including an umbrella part having a valve head and a valve face, a heat-insulation layer provided at the valve head and having smaller heat conductivity than the valve body, a heat-barrier layer provided to cover the valve head with the heat-insulation layer and having smaller heat conductivity than the valve body and the heat-insulation layer, and a heat-diffusion layer provided between the heat-insulation layer and the heat-barrier layer and having larger heat conductivity than the heat-insulation layer and the heat-barrier layer. The heat-diffusion layer comprises a contact portion which contacts with the cylinder head when the intake valve is closed.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to a combustion-chamber structure of an engine which comprises a heat-barrier layer to suppress heat loss.[0002]A combustion chamber of a gasoline engine or the like for a vehicle is required to reduce heat dissipation (heat loss) through a wall surface of the combustion chamber. A technology that a heat-barrier layer made of a small heat-conductivity material is coated on the combustion-chamber wall surface, such as a crown surface of a piston, for heat-loss reduction is known. A temperature difference between combustion gas generated in the combustion chamber and the combustion-chamber wall surface is made so small by providing the heat-barrier layer that the heat loss can be reduced.[0003]Japanese Patent Laid-Open Publication No. 2018-172997 discloses a combustion-chamber structure in which a heat-insulation layer is provided at a piston crown surface in addition to the heat-barrier layer. The heat-barrier layer cover...

Claims

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Application Information

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IPC IPC(8): F01P3/14F01L3/02F01L3/18
CPCF01P3/14F01P2003/006F01L3/18F01L3/02F01L3/04F01L3/12F01L3/20F01L2303/00
Inventor NOU, YOSHIHISAAOKI, OSAMUHARADA, YUJIUCHIDA, KENJIGE, XIYAO
Owner MAZDA MOTOR CORP