Staggered configuration for wankel engine spark plugs

In a rotary internal combustion engine having housing walls defining a trochoidally shaped chamber, an eccentrically mounted rotor for planetary movement in said chamber and cooperating with said housing walls to define a plurality of variable volume chambers into which is introduced a combustible mixture, said engine having spark plugs interposed in said housings walls and having spark terminals for igniting said mixture at a predetermined sequence, the combination comprising:

• a. housing means defining a cooling passage along at least one of said housing walls and containing a flowing coolant, that portion of said one housing wall separating said variable volume chambers from said passage having a predetermined section thickness to promote an improved heat transfer rate, said one wall having a gas side and a coolant side, said cooling passage and coolant therein being effective to extract heat from said one wall portion to prevent detrimental housing distortion, and
• b. a plurality of bosses extending into said passage for containing said spark plugs and each boss having an axis transverse to the direction of coolant flow, each boss having an upstream side and a downstream side taken with respect to the direction of said coolant flow, the axes of said bosses being non-aligned with respect to a centerline of coolant flow through said passage and non-aligned with respect to any transverse section of said flow adjacent said bosses, said bosses positioning said terminals in a staggered pattern or approaching an aligned pattern with respect to a centerline of the gas side of said one wall.