Pressure detecting device

• US 5,181,417 A
• Filed: 12/13/1991
• Issued: 01/26/1993
• Est. Priority Date: 07/10/1989
• Status: Expired due to Fees

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation), Nippon Soken, Inc.
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation), Nippon Soken, Inc.
• Inventors: Uesugi, Hiroshi, Mizuno, Naohito, Ohtsuka, Yoshinori, Nishida, Minoru, Ozaki, Tadashi
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US07/807,629
• Time in Patent Office: 410 Days
• Field of Search: 73/35, 73/115, 73/720, 73/721, 73/723-727, 338/42
• US Class Current: 73/114.18
• CPC Class Codes: G01L 19/0038 being part of the housing other details about the housing G01L19/14
• CPC Class Codes: G01L 19/0084 to the outside of the housing other details about the housing see G01L19/14
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0055 bonded on a diaphragm

Abstract

A device for detecting pressure of a high temperature pressurized fluid. A sensing element having a diaphragm adjacent to one end and a lead wire outlet adjacent to another end in the longitudinal direction of a rectangular parallelopiped configuration of the sensing element including the diaphragm. Thus, the lead wire outlet is a predetermined distance from the diaphragm heated by high temperature fluid. This prevents the lead wire outlet and the other electrical assemblies from suffering deterioration or misoperation caused by high temperature. The reliability of the pressure detecting device can be improved.

Claims

1. A pressure detecting device for measuring combustion pressure in an internal combustion engine which directly faces an inside of a pressure chamber thereof, including a pressurized fluid at a high temperature and high pressure atmosphere, comprising:

a cylindrical housing having a front end thereof which is arranged to be inside said pressure chamber;

an element holder for supporting a sensing element on a surface thereof which is held at the front end of said cylindrical housing, said element holder constituting a pressure passage by which said pressurized fluid is conducted into said housing;

said sensing element comprising semiconductor strain gauge elements for detecting pressures of said pressurized fluid conducted into said pressure passage;

said sensing element being secured on a surface of said element holder and which has a one main surface on which a pressure receiving diaphragm is provided and on which said semiconductor strain gauge elements are formed, said sensing element having a rectangular parallelopiped configuration which extends in a longitudinal direction so that a first end and a second end are opposed at a predetermined interval in the longitudinal direction of said parallelopiped configuration and a longitudinal axis thereof being arranged in parallel with a longitudinal axis of said pressure passage;

an outlet of a lead wire which is arranged adjacent to said second end of said sensing element located spaced from said front end of said pressure passage and at a specific distance from said pressure receiving diaphragm so as to prevent deterioration of said lead wire, bonding wires or connecting portions formed therebetween caused by the temperature of said pressurized fluid; and

wiring means for connecting said semiconductor strain gauge elements disposed in said pressure receiving diaphragm and said lead wire outlet, said wiring means formed on a surface of said element holder.

2. A pressure detecting device as claimed in claim 1, wherein said sensing element is secured by bonding at least at a first end to said element holder so that the longitudinal direction thereof conforms with the pressure conducting direction of said pressure conducting passage formed by said element holder.

3. A pressure detecting device as claimed in claim 2, wherein,

said sensing element is in contact with a surface of said sensing element holder, facing an inside of a space formed between said sensing element holder and said housing by bonding, so that a one main surface of said sensing element opposite to another main surface thereof on which said semiconductor strain gauge element is secured, and wherein

an opening which communicates between said pressure receiving diaphragm and said pressure conducting passage is disposed in said element holder corresponding to a position of said pressure receiving diaphragm in said sensing element.

4. A pressure detecting device as claimed in claim 3, wherein said element holder comprises a metallic substance and said sensing element an oxide monocrystalline substance.

5. A pressure detecting device as claimed in claim 4, wherein a metallic substance such as a Fe-Ni-Co alloy forms said element holder.

6. A pressure detecting device as claimed in claim 4, wherein oxide monocrystalline substance forming said sensing element is sapphire having a heat expansion coefficient approximating that of Fe-Ni-Co alloys.

7. A pressure detecting device as claimed in claim 4, wherein a wiring is formed by a thin metallic layer and wherein a barrier layer of metal with a high melting point is formed at junctions between said wiring and said semiconductor strain gauge elements.

8. A pressure detecting device as claimed in claim 7, wherein said barrier layer includes nickel silicate as metal having a high melting point.

9. A pressure detecting device as claimed in claim 7, wherein said semiconductor strain gauge elements include monocrystalline substances and have a planar orientation (100).

10. A pressure detecting device as claimed in claim 3, wherein said sensing element is bonded through a brazing layer of said element holder and a brazing material.

11. A pressure detecting device as claimed in claim 10, wherein said sensing element is bonded through a metallized layer and said brazing layer to said element holder.

12. A pressure detecting device as claimed in claim 10, wherein,

a flow hold layer is provided for preventing said brazing material from flowing into a main surface of said sensing element including said pressure receiving diaphragm,

said flow hold layer having a low cowetting property to said brazing material,

said flow hold layer is formed on a surface of said sensing element and in contact with said element holder, and

said main surface opposes said opening of said element holder.

13. A pressure detecting device as claimed in claim 12, wherein said brazing material is Ag and said flow hold layer is made from silicon nitride.

14. A pressure detecting device as claim in claim 2, said sensing element has a rectangular parallelopiped configuration and is secured on the inside wall of said pressure passage so that said first end of said sensing element is disposed adjacent to an inlet of said pressure passage and so that said second end of said sensing element is disposed at an inner part of said pressure passage;

said pressure passage of said element holder having a sectional area sequentially narrower from said inlet toward said inner part;

an opening which is disposed on said side wall of said pressure passage so as to communicate a lead wire outlet arranged at a second end of said sensing element to an inside space enclosed by said element holder and said housing.

15. A pressure detecting device as claimed in claim 1, wherein said pressure detecting device comprises:

a hollow cover which covers said semiconductor strain gauge elements, wiring, and said outlet of the lead wire, each arranged on one main surface of said sensing element;

said semiconductor strain gauge element being covered by said hollow cover with a space therebetween.

16. A pressure detecting device as claimed in claim 15, wherein an opening is disposed in a part of said hollow cover and said lead wire outlet is connected by said wiring passing through said opening.

17. A pressure detecting device as claimed in claim 15, wherein

said sensing element has a rectangular parallelepiped configuration and said sensing element is bonded to the inside wall of said pressure conducting passage through said hollow cover having said rectangular parallelepiped configuration.

18. A pressure detecting device as claimed in claim 17, wherein:

said pressure receiving diaphragm is produced by attenuating thickness of a part of a bottom wall of said rectangular parallelepiped sensing element and adjacet to said first end of said sensing element and;

said semiconductor strain gauge elements is formed on a surface thereof facing to an inside space of said sensing element opposite to the surface on which a pressure receiving surface of said pressure receiving diaphragm is provided and a wiring is extendedly formed from said semiconductor strain guage element to said lead wire outlet provided at said second end of said sensing element and arranged on the surface thereof facing an inside space formed by said hollow cover.

19. A pressure detecting device as claimed in claim 17, wherein said element holder is made of metallic substance and said sensing element is made of silicon while said sensing element being bonded to said element holder by glass bonding procedure.

20. A pressure detecting device as claimed in claim 17, wherein

said semiconductor strain gauge elements and a wiring are formed on a sensing element made of silicon,

an insulative layer exists between said semiconductor strain gauge elements and said sensing element.

21. A pressure detecting device for measuring pressure of a high temperature fluid according to claim 1, wherein a pressure receiving aperture is provided inside a surface of said pressure passage of said element holder, and a pressure receiving diaphragm provided on said sensing element is disposed at a portion of said element holder opposite said pressure receiving aperture.

22. A pressure detecting device for measuring a combustion pressure in an internal combustion engine which directly faces an inside of a pressure chamber thereof, including a pressurized fluid in a high temperature and pressure atmosphere, comprising:

a cylindrical housing wherein a front end thereof is arranged to be inside said pressure chamber;

an element holder made of metal for supporting a sensing element on a surface thereof which is held at the front end of said cylindrical housing, said element holder constituting a pressure passage by which said pressurized fluid is conducted into said housing;

said sensing element comprising semiconductor strain gauge elements for detecting pressures of said pressurized fluid conducted into said pressure passage;

said sensing element made of an oxide-monocrystalline substrate and which is secured on a surface of said element holder and which has one main surface on which a pressure receiving diaphragm is provided, in which said semiconductor strain gauge elements, made of monocrystalline silicon, are formed, said sensing element having a rectangular parallelopiped configuration which extends in a longitudinal direction so that a first end and a second end are opposed at a predetermined interval in the longitudinal direction of said parallelopiped configuration and a longitudinal axis thereof being arranged in parallel with a longitudinal axis of said pressure passage;

an outlet of a lead wire which is arranged adjacent to said second end of said sensing element at a specific distance from said pressure receiving diaphragm so as to prevent deterioration of said lead wire, bonding wires or connecting portions formed therebetween caused by the temperature of said pressurized fluids; and

wiring means for connecting said semiconductor strain gauge elements disposed in said pressure receiving diaphragm and said lead wire outlet.