Patent ID: 11870221
Assignee: FEDERAL-MOGUL IGNITION GMBH
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A spark plug, comprising:
a shell having a thread area and an axial bore;
an insulator having a ceramic body and an axial bore, the insulator disposed at least partially within the axial bore of the shell, the ceramic body being made from a ceramic material;
a gasket disposed at least partially within the axial bore of the insulator;
an internal seal disposed at least partially within the axial bore of the insulator;
a center electrode disposed at least partially within the axial bore of the insulator; and
a ground electrode configured to create a spark gap with the center electrode,
wherein

 
  
   
    (
    
     
      T
      IS
     
     
      D
      
       C
       ⁢
       E
      
     
    
    )
   
   ⁢
   
    (
    
     
      D
      S
     
     
      D
      M
     
    
    )
   
   ⁢
   
    
     (
     
      
       ρ
       
        T
        ⁢
        H
       
      
      
       
        ρ
        
         T
         ⁢
         H
        
       
       -
       ρ
      
     
     )
    
    
     0
     .
     5
    
   
  
  >
  2
 

or, (
    
     
      T
      G
     
     
      D
      
       C
       ⁢
       E
      
     
    
    )
   
   ⁢
   
    (
    
     
      D
      S
     
     
      D
      M
     
    
    )
   
   ⁢
   
    
     (
     
      
       ρ
       
        T
        ⁢
        H
       
      
      
       
        ρ
        
         T
         ⁢
         H
        
       
       -
       ρ
      
     
     )
    
    
     0
     .
     5
    
   
  
  >
  2
 

where TIS is a radial thickness of the insulator at the internal seal, DCE is a diameter of the center electrode, Ds is a diameter of the internal seal, DM is a major diameter at the thread area of the shell, ρTH is a density of the ceramic material that is fully dense and pore-free, ρ is a density of the ceramic material, and TG is a radial thickness of the insulator at the gasket.