Starting aids for combustion engines

In an ignition aid for internal combustion engines comprising a first metallic electrode, a second metallic electrode and a resistive heating means in circuit with and responsive to electric current passing through the first and second electrodes, for igniting a combustive mixture in said engine, the improvement wherein:

• said second electrode comprises an electrically conductive hollow body, removably insertable in an aperture in said engine, said body including a sleeve member and an electrically conductive bridge portion bridging one end of said sleeve member;
• said heating means comprising a sintered, refractory, ceramic composite having a central portion interposed between a pair of terminal-defining end portions, said central portion having a higher electrical resistance than said end portions;
• said first electrode extending into the sleeve member of said body but being spaced therefrom, said first electrode comprising two parts which are relatively movable, said heating means disposed between one part of said first electrode and said bridge portion with said terminal end portions in a non-point contact relationship with said first electrode and said bridge portion;
• spring means associated with said relatively movable parts of said first electrode for establishing electrical contact between said one part of first electrode and the bridge portion of said second electrode and said end portions of said heating means;
• means for electrically connecting said relatively movable parts of said first electrode while permitting relative movement between said parts;
• and
• sealing means for blocking said space between the other part of said first electrode and said sleeve member of said body, preventing the passage of combustion gases therebetween, insulating and fixably positioning the other part of said first electrode with respect to said second electrode.