Glow plug and spark plug, and manufacturing method therefor
AssigneeNgk Spark Plug Co., Ltd.
InventorsHiroaki Nasu, Wataru Matsutani, Chiaki Kumada, Katsunari Ninomiya
Life of this patent
Estimating the term…
Abstract
In a glow plug and a spark plug, the surface of a main metal shell is coated with a chromate film in which the quantity of trivalent chrome is 95 wt % or more of the contained chrome components and which has a thickness of 0.2 μm to 0.5 μm.
Claims24
A glow plug comprising:
- a main metal shell;
- a resistance heater disposed in the main metal shell such that the leading end of said resistance heater projects over either end surface of said main metal shell, wherein
- the surface of said main metal shell is coated with a chromate film containing trivalent chrome by 95 wt % or more of contained chrome components and having a thickness of 0.2 μm to 0.5 μm.
A method of manufacturing a glow plug incorporating a resistance heater disposed in a main metal shell such that the leading end of said resistance heater projects over either end surface of said main metal shell, said method of manufacturing a glow plug comprising the step of:
- immersing said main metal shell in a chromate processing bath containing trivalent chrome salt and a complexing agent for said trivalent chrome mixed therein so that a chromate film containing trivalent chrome by 95 wt % or more of contained chrome components and having a thickness of 0.2 μm to 0.5 μm is formed on the surface of said main metal shell.
A spark plug comprising:
- a central electrode;
- an insulating member disposed on the outside of said central electrode;
- a main metal shell disposed on the outside of said insulating member;
- and
- a ground electrode disposed opposite to said central electrode such that a spark discharge gap is formed;
- wherein the surface of said main metal shell is coated with a chromate film containing trivalent chrome by 95 wt % or more of contained chrome components and having a thickness of 0.2 μm to 0.5 μm.
A method of manufacturing a spark plug incorporating a central electrode, an insulating member disposed on the outside of said central electrode, a main metal shell disposed on the outside of said insulating member and a ground electrode disposed opposite to said central electrode to form a spark discharge gap, said method of manufacturing a spark plug comprising the step of:
- immersing said main metal shell in a chromate processing bath containing trivalent chrome salt and a complexing agent for said trivalent chrome mixed therein so that a chromate film containing trivalent chrome by 95 wt % or more of contained chrome components and having a thickness of 0.2 μm to 0.5 μm is formed on the surface of said main metal shell.
Dependencies are inferred from the claim text.