Ngk Spark Plug Company, Limited

Kabushiki Kaisha Tokai Rika Denki Seisakusho

Yusuke Nomura

Kuniharu Tanaka

Haruki Yoshida

Yutaka Yokoyama

Nobuyoshi Araki

Michitaka Yamada

Hirokazu Kurono

Hironori Uegaki

Toshimasa Saji

Jumpei Isasa

Akito Ishihara

Shun Kondo

Toshiki Kon

Yuki Sakai

Katsuya Takaoka

Hideto Yamada

Toshinori Takeichi

A panel device includes a panel unit, a light-blocking layer, and an indicator light projector. The light-blocking layer is located between the panel unit and the indicator light projector, specifically, on a rear surface of the panel unit. The indicator light projector is located relatively close to the light-blocking layer. When indicators displayed on the panel unit are viewed from the outer side, representations provided by the indicator light projector are visually recognizable even when viewed from an angled position.

Panel device

A panel device includes a panel unit, a light source, and a light-blocking layer. The panel device includes a light attenuation layer, or a tinted layer, to blacken the panel unit. The light attenuation layer is located between the light source and the light-blocking layer, specifically, on the rear surface of the light-blocking layer.

A spark plug according to one embodiment of the present invention includes an insulator formed of an alumina-based sintered body, wherein the insulator contains 90 wt % or more of an aluminum component in terms of oxide, and wherein crystal grains of the insulator has an average grain size of 1.5 mm or smaller and a grain size standard deviation of 1.2 &#x3bc;m or smaller.

Spark plug

The spark plug includes an insulator made from an alumina-based sintered body, and the insulator contains 90 to 98 wt % of an Al component in oxide equivalent. The insulator contains 1 to 5 wt % of an Si component, 0.1 to 1 wt % of an Mg component, 2 wt % or less of a Ca component, 0.3 to 6 wt % of a Ba component, and 0.11 to 5 wt % of a rare earth component, in oxide equivalent. In analysis using a scanning transmission electron microscope with a probe diameter of an electron beam set at 1 nm, Si and a rare earth element are detected at a crystal grain boundary having a thickness of 15 nm or less, and an alkaline earth metal at the crystal grain boundary is less than a detection limit.

The spark plug includes an insulator formed of an alumina-based sintered body, and the insulator contains Si, Ba, and a rare earth element. In an analysis of the insulator by using a scanning transmission electron microscope having an electron-probe diameter of 1 nm, Si and a rare earth element are detected at a crystal grain boundary having a thickness of 15 nm or less, a content of an alkaline earth metal is less than a detection limit at the crystal grain boundary, and a diffraction spot is present in an electron diffraction pattern of a portion where Ba is detected.

Disclosed is a spark plug including: an insulator having an axial hole formed along an axis of the spark plug; a center electrode disposed in a front end side of the axial hole; and a metal shell fixed around an outer circumference of the insulator, with a front end portion of the insulator protruding frontward from a front end of the metal shell. The front end portion of the insulator consists only of a first section and a second section located adjacent to and frontward of the first section and having an inner diameter larger than that of the first section. The second section has a chamfered area formed on an inner circumferential surface thereof so as to continue to a front end of the insulator.

Spark plug including an insulator with a front end portion having first and second sections

An alumina-based sintered body includes 92 mass % to 96 mass % of Al in terms of an oxide, and at least three elements selected from Group II elements, one of the at least three elements being 1.90 mass % or more of Ba in terms of an oxide. The alumina-based sintered body includes the following phases in a grain boundary phase present between alumina crystal grains: a first crystal phase containing Si and at least one of the Group II elements, and a second crystal phase containing Al and at least one of the Group II elements. In X-ray diffraction of the alumina-based sintered body, the maximum relative intensity of the first crystal phase and the maximum relative intensity of the second crystal phase are both 2 or above relative to the maximum diffraction intensity of the alumina crystal.

A spark plug including an insulator containing not less than 92 mass % and not greater than 96 mass % of Al component in terms of oxide, wherein the insulator is formed from an alumina sintered body comprising alumina crystal and a grain boundary phase present between crystal grains of the alumina crystal. Assuming that mass contents of an Si component, an Mg component, a Ba component, and a Ca component in terms of oxide are represented by M, M, M, and M, respectively, and a sum of M, M, M, and Mis represented by Mt, the grain boundary phase contains these components so as to satisfy conditions (1) to (4) as follows: (1) 0.17&#x2266;M/Mt&#x2266;0.47; (2) 0.005&#x2266;M/Mt&#x2266;0.07; (3) 0.29&#x2266;M/Mt&#x2266;0.77; (4) 0.03&#x2266;M/Mt&#x2266;0.19.

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Aichi, Japan

Yusuke Nomura