Method for anticipating downshifting and for monitoring an automatic transmission
AssigneeRENAULT s.a.s.
InventorRemi Vandekerkhove
Life of this patent
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Abstract
A method for anticipating downshifting upon uphill driving on a vehicle including an automatic transmission and including change laws imposing a change to a lower gear based on pre-established downshifting curves. The method imposes a change to the lower gear to the transmission independently from the gear set point established by the change laws when the acceleration that can be reached at the maximum torque on the current gear is lower than an acceleration threshold necessary for maintaining the vehicle speed.
Claims10
A method for performing downshifts when driving uphill on a vehicle including an automatic transmission that includes change laws to impose changes to a lower gear based on preestablished downshift curves of the change laws, the method comprising:
- comparing by an automatic transmission control computer an acceleration aest (Cm-max) that can be reached at a maximum torque on a current gear to an acceleration threshold needed to maintain a current speed of the vehicle;
- and
- changing a gear ratio of the transmission to the lower gear by the automatic transmission control computer independently of a gear set point established by the change laws, when the acceleration aest (Cm-max) that can be reached at the maximum torque on the current gear is less than the acceleration threshold needed to maintain the current speed of the vehicle,
- wherein the acceleration aest(Cm—max) that can be reached at the maximum torque is estimated by a relationship of:
- a
- est
-
- (
- C
- m_max
- )
- =
- a
- mes
- +
- 1
- M
-
- C
- r
-
- (
- C
- m_max
- )
- -
- C
- r
-
- (
- C
- m
- )
- r
- ,
- in which
- ames is measured acceleration of the vehicle, M is weight of the vehicle, Cr(Cm—max) is torque on the wheel corresponding to maximum engine torque, Cr(Cm) is torque applied to a wheel corresponding to current engine torque, and r is radius of tires of the vehicle.
Dependencies are inferred from the claim text.