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Pressure sensor unit having a ring-like pressure sensing element

  • US 7,107,819 B2
  • Filed: 11/27/2001
  • Issued: 09/19/2006
  • Est. Priority Date: 11/30/2000
  • Status: Expired due to Fees
First Claim
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1. A pressure sensor unit (1, 200, 210, 220, 230) in which a ring-like pressure sensing element (3) is incorporated in a cylindrical unit body portion (2) having a spark plug insertion hole (4) formed in a bottom surface thereof, the pressure sensing element (3) surrounding the spark plug insertion hole (4);

  • when a side where the pressure sensing element (3) is located in a direction of an axis (O) is set as a front end side, the unit body portion (2) is inserted into and fixed to a plug hole (PH) from the front end side in the direction of the axis (O); and

    in that state, a spark plug (100) is inserted into the spark plug insertion hole (4) to be thereby attached to an attachment hole (PF) at a bottom of the plug hole (PH), so that the pressure sensing element (3) is nipped and retained between a sensor support portion (102) projecting like a collar from an outer circumferential surface of a metal shell (101) of the spark plug (100), and an opening circumferential edge portion (GS) of the attachment hole (PF);

    whereinthe pressure sensing element (3) is disposed in a clearance (7) formed between an outer cylinder member (5) forming an outer circumferential surface portion of the unit body portion (2) and an inner cylinder member (6) forming an inner circumferential surface portion likewise, and an output from the pressure sensing element (3) is extracted by a sensor output lead wire (9) via a sensor output terminal (8) led out into the clearance (7); and

    in a state where the spark plug (100) has been attached, a rear end of at least one of the inner cylinder member (6) and the outer cylinder member (5) in the direction of the axis (O) is located between a rear end of the pressure sensing element (3) and a rear end of an insulator (110) of the spark plug (100) (hereinafter, referred to as “

    in a standard section (SS)”

    ), while at a rear of the standard section (SS), no component of the pressure sensor unit (1) exists in an area inside an inner circumferential surface (5b) of the outer cylinder member (5) or an extended plane (EP) thereof.

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