Washer-type pressure sensor
First Claim
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1. A washer-type pressure sensor comprising:
- a ring-shaped electrode having an output terminal extending therefrom;
a pair of piezoelectric elements provided on both sides of said electrode;
first and second pressure plates provided outside of respective piezoelectric elements;
an electrically insulating retainer holding said ring-shaped electrode, said piezoelectric elements and at least said first pressure plate in an assembled condition; and
an electrically conductive cover member having a first section extending along the outer circumferential periphery of said insulating retainer for covering the same, said cover member being electrically insulated from said first pressure plate by said insulating retainer.
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Abstract
A washer-type pressure sensor employs a cross-sectionally channel-shaped pressure plate which defines a space in which an assembly of a center electrode, piezoelectric elements, the other pressure plate and insulating members can be housed. With such construction, the insulating member surrounding the assembly of the center electrode, the piezoelectric elements, the outer pressure plate is not subject to corrosive liquid leaking from the inside of the engine. Therefore, life of the pressure sensor can be significantly expended.
81 Citations
15 Claims
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1. A washer-type pressure sensor comprising:
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a ring-shaped electrode having an output terminal extending therefrom; a pair of piezoelectric elements provided on both sides of said electrode; first and second pressure plates provided outside of respective piezoelectric elements; an electrically insulating retainer holding said ring-shaped electrode, said piezoelectric elements and at least said first pressure plate in an assembled condition; and an electrically conductive cover member having a first section extending along the outer circumferential periphery of said insulating retainer for covering the same, said cover member being electrically insulated from said first pressure plate by said insulating retainer. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A washer-type pressure sensor for monitoring internal pressure in an engine cylinder of an internal combustion engine, the pressure sensor being mounted on an engine block and secured thereon by means of a spark plug, comprising:
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a ring-shaped electrode having an output terminal extending therefrom; a pair of piezoelectric elements provided on both sides of said electrode; first and second pressure plates provided outside of respective piezoelectric elements, said second pressure plate being disposed in a position close to said engine block and said first pressure plate being disposed in a position remote from said engine block; an electrically insulating retainer holding said ring-shaped electrode, said piezoelectric elements and at least said first pressure plate in an assembled condition; and an electrically conductive cover member having a first section extending along the outer circumferential periphery of said insulating retainer for covering the same, said cover member being electrically insulated from said first pressure plate by said insulating retainer. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A washer-type pressure sensor comprising:
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a ring-shaped electrode having first and second sides and an output terminal extending therefrom; first and second piezoelectric elements provided on the first and second sides, respectively, of said electrode; first and second pressure plates adjoining said first and second piezoelectric elements; an electrically insulating retainer holding said electrode, said piezoelectric elements, and at least said first pressure plate in an assembled state; and an electrically conducting cover integrally formed with said second pressure plate and having a first section extending along the outer circumferential periphery of said insulating retainer, said cover being electrically insulated from said first pressure plate by said insulating retainer.
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Specification