Electric drive axle with mode adjustment mechanism and method for operation of said axle and mode adjustment mechanism
View Patent ↗Systems and methods for an electric drive axle are provided. In one example, the electric drive axle may include an electric motor-generator rotationally coupled to a gearbox having a one-way clutch mounted on an output shaft and operable in an engaged configuration and a disengaged configuration, where in the engaged configuration, the one-way clutch transfers rotational energy from the output shaft to an output gear rotationally coupled to a plurality of drive wheels. The gearbox further includes a mode adjustment mechanism including a lock ring rotationally coupled to the output shaft and configured to selectively engage an input gear and the one-way clutch in a plurality of operating modes.
1. An electric drive axle, comprising:
an electric motor-generator rotationally coupled to a gearbox comprising:
a one-way clutch mounted on an output shaft and operable in an engaged configuration and a disengaged configuration, where in the engaged configuration, the one-way clutch transfers rotational energy from the output shaft to an output gear rotationally coupled to a plurality of drive wheels; and
a mode adjustment mechanism including a lock ring rotationally coupled to the output shaft and configured to selectively engage an input gear and the one-way clutch in a plurality of operating modes;
where the lock ring is splined to the output shaft.
2. The electric drive axle of claim 1 , where the mode adjustment mechanism selectively engages the input gear and the one-way clutch via axial translation of the lock ring.
3. The electric drive axle of claim 1 , where the mode adjustment mechanism is configured to operate in a disconnect mode where the lock ring is rotationally disconnected from the input gear and the one-way clutch.
4. The electric drive axle of claim 3 , where in the disconnect mode,
a first lock ring spline in the lock ring is decoupled from a gear spline in the input gear; and
a second lock ring spline in the lock ring is decoupled from a first clutch spline in a housing of the one-way clutch.
5. The electric drive axle of claim 3 , where the mode adjustment mechanism is configured to operate in a first gearing mode in which:
the lock ring is rotationally coupled to the input gear; and
a housing of the one-way clutch is rotationally engaged with the lock ring; and
where in the first gearing mode:
a first lock ring spline in the lock ring is in meshed engagement with a gear spline in the input gear; and
a second lock ring spline in the lock ring is in meshed engagement with a second clutch spline in the housing of the one-way clutch.
6. The electric drive axle of claim 1 , where the mode adjustment mechanism is configured to operate in a lock mode where a spline in the lock ring is engaged with a ground spline.
7. The electric drive axle of claim 1 , where in a second gearing mode,
a first lock ring spline in the lock ring is in meshed engagement with a gear spline in the input gear; and
a second lock ring spline in the lock ring is decoupled from a first clutch spline in a housing of the one-way clutch.
8. The electric drive axle of claim 1 , where the gearbox further comprises a differential configured to transfer rotational energy to the plurality of drive wheels from the output gear.
9. The electric drive axle of claim 1 , where the one-way clutch is a sprag clutch including a plurality of sprag mechanisms positioned between a housing of the one-way clutch and a surface of the output shaft.
10. A method for operating an electric drive axle in a vehicle, comprising:
shifting a mode adjustment mechanism into a disconnect mode, in the disconnect mode a lock ring is rotationally disconnected from an input gear; and
shifting the mode adjustment mechanism into a lock mode;
where in the lock mode the lock ring is rotationally engaged with a stationary ground spline;
where the input gear is rotationally coupled to an electric motor-generator;
where a one-way clutch is mounted on an output shaft;
where the mode adjustment mechanism includes the lock ring rotationally coupled to the output shaft; and
where the output shaft is coupled to an output gear rotationally coupled to a plurality of drive wheels.
11. The method of claim 10 , further comprising:
shifting the mode adjustment mechanism into a first gearing-bypass mode, in the first gearing-bypass mode:
rotational energy is transferred from the input gear to the lock ring; and
rotational energy is transferred from the lock ring directly to a housing of the one-way clutch; and
shifting the mode adjustment mechanism into a second gearing mode, in the second gearing mode:
rotational energy is transferred from the input gear to the lock ring; and
rotational energy is transferred from the lock ring to the output shaft.
12. The method of claim 10 , where the mode adjustment mechanism is shifted into the disconnect mode responsive to determining a state of charge of an energy storage device electrically coupled to the electric motor-generator has surpassed a threshold value.
13. The method of claim 10 , where shifting the mode adjustment mechanism into the disconnect mode includes axially translating the lock ring away from the one-way clutch.
14. The method of claim 10 , where the electric drive axle includes a differential configured to transfer rotational energy to the plurality of drive wheels from the output gear.
15. An electric drive axle, comprising:
an electric motor-generator rotationally coupled to a gearbox comprising:
a one-way clutch mounted on an output shaft and operable in an engaged configuration and a disengaged configuration, where in the engaged configuration, the one-way clutch transfers rotational energy from the output shaft to an output gear rotationally coupled to a plurality of drive wheels; and
a mode adjustment mechanism including a lock ring rotationally coupled to the output shaft;
where in a disconnect mode the lock ring in the mode adjustment mechanism is rotationally decoupled from the one-way clutch and the input gear; and
a controller including instructions stored in non-transitory memory that when executed cause the controller to:
shift the mode adjustment mechanism into a first gearing mode, where:
the lock ring is rotationally coupled to the input gear; and
a housing of the one-way clutch is rotationally engaged with the lock ring.
16. The electric drive axle of claim 15 , further comprising a controller including instructions stored in non-transitory memory that when executed cause the controller to:
shift the mode adjustment mechanism into the disconnect mode.
17. The electric drive axle of claim 16 , where the mode adjustment mechanism is shifted into the disconnect mode responsive to determining an occurrence of a vehicle tow condition in a vehicle including the electric drive axle and where the vehicle tow condition is a condition where the vehicle is being towed or anticipated to be towed via a towing vehicle configured to pull the vehicle.
18. The electric drive axle of claim 15 , wherein the controller includes instructions stored in the non-transitory memory that when executed cause the controller to:
shift the mode adjustment mechanism into a second gearing mode where:
a first lock ring spline in the lock ring is in meshed engagement with a gear spline in the input gear; and
a second lock ring spline in the lock ring is decoupled from a spline in a housing of the one-way clutch.