TWO-STAGE TRANSMISSION FOR ELECTRICALLY DRIVEN VEHICLE

The present invention relates to a two-stage transmission for an electrically driven vehicle including a dog clutch and a friction clutch, and an object of the present invention is to prevent a torque drop when shifting gears. The two-stage transmission for the electrically driven vehicle includes a planetary gear mechanism (12), a dog clutch (28), a friction clutch (30), an armature (26) to switch between the dog clutch (28) and the friction clutch (30), and an electromagnetic coil (31) to drive the armature (26). In the dog clutch (28) and the friction clutch (30), the coupling relationship among the rotational elements of the planetary gear mechanism (12) is set such that the dog clutch (28) is fastened and the friction clutch (30) is not fastened in speed reduction (the first speed), and the dog clutch (28) is not fastened and the friction clutch (30) is fastened in speed increase (the second speed). To prevent the torque drop when shifting the gears, a ratchet-type one-way clutch (50) is disposed such that a rotational phase position of the ratchet-type one-way clutch (50) is coincident with that of the dog clutch (28). When shifting from the second speed to the first speed, since the rotational phase of the dog clutch (28) is adjusted by the ratchet-type one-way clutch (50), the shifting is instantaneously completed without waiting operation for the phase adjustment, resulting in preventing a transmission shock.