Electric vehicle with powertrain having reverse-acting centrifugal clutch

1 . An electric vehicle comprising:

an electric drive motor;

a transmission switchable between a plurality of gear ratios; and

a centrifugal clutch drivingly coupled in a torque transmission path between the electric drive motor and the transmission, the centrifugal clutch including:

a first friction plate rotatable about an axis;

a second friction plate rotatable about the axis and axially movable relative to the first friction plate, the second friction plate being configured to frictionally engage the first friction plate to transmit torque therebetween;

a biasing member that applies a biasing force to the second friction plate that biases the second friction plate in a first axial direction that is toward the first friction plate; and

a base member coupled to the second friction plate for common rotation therewith about the axis, the second friction plate is movable along the axis relative to the base member; and

a counterweight assembly coupled to the second friction plate and configured to apply a counterweight force on the second friction plate in a second axial direction that is away from the first friction plate in response to a rotational speed of the second friction plate exceeding a predetermined rotational speed, the counterweight assembly is coupled to the base member for common rotation therewith.

2 . The electric vehicle according to claim 1 , wherein the biasing member biases the second friction plate axially away from the base member and toward the first friction plate.

3 . The electric vehicle according to claim 1 , wherein the counterweight assembly is coupled to the base member via a first pivot connection and coupled to the second friction plate via a second pivot connection.

4 . The electric vehicle according to claim 3 , wherein the counterweight assembly includes a counterweight, a pivot member, and a transfer member, wherein the counterweight is coupled to the pivot member and the pivot member is coupled to the base member at the first pivot connection, wherein a first end of the transfer member is coupled to the second friction plate and a second end of the transfer member is coupled to the pivot member at the second pivot connection.

5 . The electric vehicle according to claim 1 , wherein the first friction plate is coupled to an input of the transmission for common rotation therewith and the base member is coupled to an output of the electric drive motor for common rotation therewith.

6 . The electric vehicle according to claim 1 , wherein the counterweight force is configured to be less than the biasing force for all operational speeds of the motor.

7 . The electric vehicle according to claim 1 , wherein the centrifugal clutch is configured to have a torque holding capacity that exceeds a torque output of the motor for all operational speeds of the motor but to permit slipping between the first friction plate and the second friction plate in response to a torque disturbance induced by shifting a gear ratio of the transmission.

8 . The electric vehicle according to claim 1 , further comprising a control module configured to shift the transmission between gear ratios.

9 . The electric vehicle according to claim 8 , wherein the control module is configured to receive signals from a plurality of sensors and actively control motor output torque in response to the signals received from the plurality of sensors to actively control an amount of slipping of the centrifugal clutch during a gear shift of the transmission.

10 . The electric vehicle according to claim 1 , wherein the centrifugal clutch is configured to have a torque holding capacity that exceeds a torque output of the motor for all operational speeds of the motor but is within a predetermined torque range of the torque output at a predetermined motor speed, wherein the predetermined motor speed corresponds to a shift point of the transmission and the predetermined torque range is configured such that a torque disturbance due to the shift causes the centrifugal clutch to slip in response to shifting the transmission.

11 . The electric vehicle according to claim 1 , wherein the centrifugal clutch is configured to have a torque holding capacity that permits slipping between the first friction plate and the second friction plate at a predetermined torque output of the motor that corresponds to a shift point of the transmission.

12 . An electric vehicle comprising:

an electric drive motor;

a transmission switchable between a plurality of gear ratios; and

a centrifugal clutch drivingly coupled in a torque transmission path between the electric drive motor and the transmission, the centrifugal clutch including:

a first friction plate rotatable about an axis;

a second friction plate rotatable about the axis and axially movable relative to the first friction plate, the second friction plate being configured to frictionally engage the first friction plate to transmit torque therebetween;

a biasing member that applies a biasing force to the second friction plate that biases the second friction plate in a first axial direction that is toward the first friction plate; and

a counterweight assembly coupled to the second friction plate and configured to apply a counterweight force on the second friction plate in a second axial direction that is away from the first friction plate in response to a rotational speed of the second friction plate exceeding a predetermined rotational speed,

wherein the centrifugal clutch is configured to have a torque holding capacity that exceeds a torque output of the motor for all operational speeds of the motor but to permit slipping between the first friction plate and the second friction plate in response to a torque disturbance induced by shifting a gear ratio of the transmission.

13 . The electric vehicle according to claim 12 , wherein the centrifugal clutch further comprises a base member coupled to the second friction plate for common rotation therewith about the axis, wherein the second friction plate is movable along the axis relative to the base member.

14 . The electric vehicle according to claim 13 , wherein the counterweight assembly includes a counterweight and a pivot member, the counterweight being coupled to the pivot member, the pivot member being coupled to the base member via a first pivot connection and coupled to the second friction plate via a second pivot connection.

15 . The electric vehicle according to claim 14 , wherein the counterweight assembly further comprises a transfer member, wherein a first end of the transfer member is coupled to the second friction plate and a second end of the transfer member is coupled to the pivot member at the second pivot connection.

16 . The electric vehicle according to claim 13 , wherein the second friction plate is axially between the base member and the first friction plate.

17 . The electric vehicle according to claim 12 , further comprising a control module configured to shift the transmission between the plurality of gear ratios, wherein the control module is configured to receive signals from a plurality of sensors and actively control motor output torque in response to the signals received from the plurality of sensors to actively control an amount of slipping of the centrifugal clutch during a gear shift of the transmission.

18 . An electric vehicle comprising:

an electric drive motor;

a transmission switchable between a plurality of gear ratios; and

a centrifugal clutch drivingly coupled in a torque transmission path between the electric drive motor and the transmission, the centrifugal clutch including:

a first friction plate rotatable about an axis;

a second friction plate rotatable about the axis and axially movable relative to the first friction plate, the second friction plate being configured to frictionally engage the first friction plate to transmit torque therebetween;

a biasing member that applies a biasing force to the second friction plate that biases the second friction plate in a first axial direction that is toward the first friction plate; and

a counterweight assembly coupled to the second friction plate and configured to apply a counterweight force on the second friction plate in a second axial direction that is away from the first friction plate in response to a rotational speed of the second friction plate exceeding a predetermined rotational speed,

wherein the centrifugal clutch is configured to have a torque holding capacity that exceeds a torque output of the motor for all operational speeds of the motor but to permit slipping between the first friction plate and the second friction plate in response to a torque disturbance induced by shifting a gear ratio of the transmission,

wherein the centrifugal clutch includes a base member coupled to an output of the electric drive motor for common rotation therewith,

wherein the counterweight assembly includes a counterweight, a pivot member, and a transfer member, wherein the counterweight is coupled to the pivot member,

wherein the pivot member is coupled to the base member via a first pivot connection and coupled to the transfer member via a second pivot connection,

wherein a first end of the transfer member is coupled to the second friction plate and a second end of the transfer member is coupled to the pivot member at the second pivot connection.

19 . The electric vehicle according to claim 18 , further comprising a control module configured to shift the transmission between the plurality of gear ratios, wherein the control module is configured to receive signals from a plurality of sensors and actively control motor output torque in response to the signals received from the plurality of sensors to actively control an amount of slipping of the centrifugal clutch during a gear shift of the transmission.