Patent attributes
A rotation-speed-calculation-apparatus includes: a detector configured to detect a rotation-angle of an engine; and a CPU and a memory coupled to the CPU. The CPU is configured to perform: calculating an engine-speed each time the detector detects a predetermined-angle based on a time-period required for the engine to rotate the predetermined-angle; and determining whether the engine-speed calculated is in a low-rotation range equal to or lower than a threshold-value or in a high-rotation range over the threshold-value. The CPU is configured to perform: the calculating including: calculating the engine-speed based on a time-period required for the engine to rotate a first-predetermined-angle when it is determined that the engine-speed is in the low-rotation range; and calculating the engine-speed based on a time-period required for the engine to rotate a second-predetermined-angle smaller than the first-predetermined-angle when it is determined that the engine-speed is in the high-rotation range.
