Otto's engine is patented in 1877, but…

Otto's engine is patented in 1877, but the patent will soon be challenged and overturned.

The Otto engine is designed as a stationary engine and in the action of the engine, the stroke is an upward or downward movement of a piston in a cylinder.

Used later in an adapted form as an automobile engine, four strokes are involved: (1) downward intake stroke—coal-gas and air enter the piston chamber, (2) upward compression stroke—the piston compresses the mixture, (3) downward power stroke—ignites the fuel mixture by electric spark, and (4) upward exhaust stroke—releases exhaust gas from the piston chamber.

Otto only sells his engine as a stationary motor.

Otto intends his invention to replace the steam engines predominant in these years, even though his engine is still primitive and inefficient.