The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 03, 1976
Filed:
Sep. 11, 1973
Torazo Nishimiya, Mito, JA;
Yasunori Mori, Hitachi, JA;
Hitachi, Ltd., , JA;
Abstract
A dilute air-fuel mixture operation as a method for purifying exhaust gas is effective for reducing simultaneously carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) contained in the engine exhaust. However, such operation reduces engine power remarkably. Though a reciprocating internal combustion engine having first and second spark plugs has been introduced to compensate this disadvantage, it has in turn brought about the problem that there is a tendency of increasing quantities of nitrogen oxides. While an increase of the interval between the firing of the two plugs may control an increase of nitrogen oxides, this results in a reduction of engine power. A most effective method of exhaust purification is to control an ignition system such that the interval between the firing of two plugs is made short only when high engine power is required, and the firing interval is made comparatively long in the normal operation of the engine.