Glow plug for diesel engines

• US 4,931,619 A
• Filed: 05/27/1988
• Issued: 06/05/1990
• Est. Priority Date: 05/29/1987
• Status: Expired due to Fees

• Current Assignee: Hitachi Metals (Thailand) Ltd., Jidosha Kiki Co., Ltd.
• Original Assignee: Hitachi Metals (Thailand) Ltd., Jidosha Kiki Co., Ltd.
• Inventors: Kurihara, Koichiro, Masaka, Mitusuke, Hatanaka, Kouji, Ogata, Yasunobu
• Primary Examiner(s): Paschall, M. H.
• Application Number:
  US07/199,629
• Time in Patent Office: 739 Days
• Field of Search: 219/270, 219/552, 219/553, 219/523, 219/544, 423/324, 123/145 A, 123/145 R, 361/264
• US Class Current: 219/270
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3843 Titanium carbides
• CPC Class Codes: C04B 2235/3856 Carbonitrides, e.g. titanium carbonitride, zirconium carbonitride
• CPC Class Codes: C04B 2235/3865 Aluminium nitrides
• CPC Class Codes: C04B 2235/3886 Refractory metal nitrides, e.g. vanadium nitride, tungsten nitride
• CPC Class Codes: C04B 2235/96 Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
• CPC Class Codes: C04B 2237/10 Glass interlayers, e.g. frit or flux
• CPC Class Codes: C04B 2237/123 based on iron group metals, e.g. steel
• CPC Class Codes: C04B 2237/125 based on noble metals, e.g. silver
• CPC Class Codes: C04B 2237/368 Silicon nitride
• CPC Class Codes: C04B 2237/406 Iron, e.g. steel
• CPC Class Codes: C04B 2237/708 of one or more of the interlayers
• CPC Class Codes: C04B 2237/72 Forming laminates or joined articles comprising at least two interlayers directly next to each other
• CPC Class Codes: C04B 2237/765 at least one member being a tube
• CPC Class Codes: C04B 2237/82 Two substrates not completely covering each other, e.g. two plates in a staggered position
• CPC Class Codes: C04B 2237/84 Joining of a first substrate with a second substrate at least partially inside the first substrate, where the bonding area is at the inside of the first substrate, e.g. one tube inside another tube
• CPC Class Codes: C04B 35/5935 obtained by gas pressure sintering
• CPC Class Codes: C04B 35/597 based on silicon oxynitride, e.g. SIALONS
• CPC Class Codes: C04B 37/026 consisting of metals or metal salts
• CPC Class Codes: F02B 3/06 : with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: F23Q 7/001 : Glowing plugs for internal-combustion engines

Abstract

A glow plug for diesel engines in which a ceramic heater is supported, with the one end thereof cantilevered toward the outside, by the tip of a hollow holder; the ceramic heater is composed of a U-shaped heating portion and a pair of leads extending backwards from both ends of the U-shaped heating portion, both being formed integrally by an electrically conductive sintered sialon, which is formed by adding a small amount of Al₂ O₃ to a raw meal containing Si₃ N₄ as a principal ingredient, a small amount of AlN polytype and no greater than 5 wt. % of Y₂ O₃, and mixing the addition product with 23-70 vol. % of at least one type of Ti carbide, nitride and carbide-nitride; an insulating layer is provided on the outer periphery of at least one of the leads and bonded to, and held by, the inside of the holder; and the rear end of the other of the leads is connected by means of a metallic lead wire to an external connection terminal held in an insulated state at the lead end of said holder.

Claims

1. A glow plug for diesel engines comprising a ceramic heater supported, with one end thereof cantilevered toward the outside, by the tip of a hollow holder;

said ceramic heater is composed of a U-shaped heating portion and a pair of leads extending backwards from both ends of said U-shaped heating portion, both being formed integrally by an electrically conductive sintered sialon, which is formed by adding a small amount of Al₂ O₃ to a raw meal containing Si₃ N₄ as a principal ingredient, a small amount of AlN polytype and 5 wt. % or less of Y₂ O₃, and mixing the addition product with 23-70 vol. % of at least one type of Ti carbide, nitride and carbide-nitride;

an electrically insulating layer is provided on the outer periphery of at least one of said leads and bonded to, and held by, the inside of said holder; and

the rear end of at least one of said leads is connected by means of a metallic lead wire to an external connection terminal held in an insulated state at the lead end of said holder.

2. A glow plug for diesel engines as claimed in claim 1 wherein said insulating layer is made of amorphous glass having a softening point of over 700°

C. or crystalline glass and formed into a film thickness of 10-100 μ

m.

3. A glow plug for diesel engines as claimed in claim 1 wherein said electrically insulating layer is made of a mixed glass of amorphous glass and crystalline glass and formed into a film thickness of 10-100 μ

m.

4. A glow plug for diesel engines as claimed in claim 1 wherein said insulating layer is formed by a plurality of laminated layers.

5. A glow plug for diesel engines as claimed in claim 1 wherein said insulating layer is formed, keeping dimensional difference in the thickness of said insulating film to 100 μ

m or less.

6. A glow plug for diesel engines as claimed in claim 1 wherein the wall thickness of said U-shaped heating portion comprising said ceramic heater is made smaller than the wall thickness of said leads.

7. A glow plug for diesel engines as claimed in claim 1 wherein an insulating layer is provided on the outer periphery of said leads and bonded to, and held by said holder;

the rear ends of said leads are connected to said external connection terminals supported in an insulated state at the rear end of said holder via metallic lead wires.

8. A glow plug for diesel engines as claimed in claim 1 wherein an insulating layer is provided on the outer periphery of said leads and bonded to, and held by, said holder;

one of the rear ends of said leads is connected to the rear end of said holder, and the other thereof to an external connection terminal held in an insulated state at the rear end of said holder.

9. A glow plug for diesel engines as claimed in claim 1 wherein said insulating layer is formed with screen printing.

10. A glow plug as claimed in claim 1 wherein the amount of Y₂ O₃ is 1-4 wt. %.

11. A glow plug for diesel engines comprising a ceramic heater supported, with one end thereof cantilevered toward the outside, by the tip of a hollow holder;

said ceramic heater is composed of a U-shaped heating portion and a pair of leads extending backwards from both ends of said U-shaped heating portion, both being formed integrally by an electrically conductive sintered sialon, which is formed by adding a small amount of Al₂ O₃ to a raw meal containing Si₃ N₄ as a principal ingredient, a small amount of AlN polytype and 5 wt. % or less of Y₂ O₃, and mixing the addition product with 23-70 vol. % of at least one type of Ti carbide, nitride and carbide-nitride;

an electrically insulating layer and a metallized layer are provided on the outer periphery of at least one of said leads and bonded to, and held by, the inside of said holder via a bonding material; and

the rear end of at least one of said leads is connected by means of a metallic lead wire to an external connection terminal held in an insulated state at the lead end of said holder.

12. A glow plug for diesel engines as claimed in claim 11 wherein said insulating layer is made of amorphous glass having a softening point of more than 700°

C. or crystalline glass and formed into a film thickness of 10-100 μ

m.

13. A glow plug for diesel engines as claimed in claim 11 wherein said insulating layer is formed with screen printing.

14. A glow plug for diesel engines as claimed in claim 11 wherein said metallized layer is formed by baking one of Ag-Pd paste and Ni paste.

15. A glow plug as claimed in claim 11 wherein the amount of Y₂ O₃ is 1-4 wt.%.

16. A glow plug for diesel engines comprising a ceramic heater supported, with one end thereof cantilevered toward the outside, by the tip of a hollow holder;

said ceramic heater is composed of a U-shaped heating portion and a pair of leads extending backwards from both ends of said U-shaped heating portion, both being formed integrally by an electrically conductive sintered sialon, which is formed by adding a small amount of Al₂ O₃ to a raw meal containing Si₃ N₄ as a principal ingredient, a small amount of AlN polytype and 5 wt. % or less of Y₂ O₃, and mixing the addition product with 23-70 vol. % of at least one type of Ti carbide, nitride and carbide-nitride;

an insulating sheet is integrally interposed between said leads of said ceramic heater at least at a location corresponding to the tip of said holder. and an electrically insulating layer is provided on the outer periphery of at least one of said leads and bonded to, and held by, the inside of said holder; and

the rear end of at least one of said leads is connected by means of a metallic lead wire to an external connection terminal held in an insulated state at the lead end of said holder.

17. A glow plug for diesel engines as claimed in claim 16 wherein said insulating layer is made of amorphous glass having a softening point of more than 700°

C. or crystalline glass and formed into a film thickness of 10-100 μ

m.

18. A glow plug for diesel engines as claimed in claim 16 wherein said insulating layer is formed with screen printing.

19. A glow plug as claimed in claim 16 wherein the amount of Y₂ O₃ is 1-4 wt. %.

20. A glow plug for diesel engines characterized in that a ceramic heater supported, with one end thereof cantilevered toward the outside, by the tip of a hollow holder;

said ceramic heater is composed of a U-shaped heating portion and a pair of leads extending backwards from both ends of said U-shaped heating portion, both being formed integrally by an electrically conductive sintered sialon;

an electrically insulating layer is provided on the outer periphery of at least one of said leads and bonded to, and held by, the inside of said holder;

said insulating layer being made of amorphous glass having a softening point of more than 700°

C. or crystalline glass and formed into a film thickness of 10-100 μ

m; and

the rear end of at least one of said leads is connected by means of a metallic lead wire to an external connection terminal held in an insulated state at the rear end of said holder.