Method for synchronizing a gear on a gearbox shaft
A method for synchronizing a gear on a parallel-shafts vehicle gearbox shaft including at least one primary shaft connected to a power source, one secondary shaft driven by the primary shaft to transmit driving torque to wheels over plural transmission ratios, and at least one mechanism coupling a gear to its shaft to engage a transmission ratio without mechanical synchromesh members. The power source is made to operate to produce a signal commanding the reference torque (T 1 ref ), equal to minimum torque that can be transmitted to minimize a discrepancy (ω 2 K−ω 1 ) between a primary speed (ω 1 ) and a secondary speed (ω 2 ) multiplied by a reduction ratio (K), when the relevant gear is coupled to its shaft, wherein the control signal is given by the sum (K w Kω 2 −K s ω 1 +T 1 int ), in which (T 1 int ) is a term derived by integrating the primary speed (ω 1 ).
1. A method of synchronizing a gear on a parallel-shaft vehicle gearbox including at least one primary shaft connected to a power source, a secondary shaft driven by the primary shaft to transmit motive torque to wheels over plural transmission ratios, and at least one means of coupling a gear to its shaft to engage a transmission ratio without mechanical synchronizing members, the method comprising:
making the power source operate to produce a reference torque control signal T 1 ref , which reference torque is equal to a minimum transmittable torque to minimize a discrepancy ω 2 K−ω 1 between a primary speed ω 1 and a secondary speed ω 2 multiplied by a reduction ratio K as a relevant gear is being coupled to its shaft,
wherein the control signal is given by sum
K w Kω 2 −K s ω 1 +T 1 int ,
in which T 1 int is an integration term of the primary speed ω 1 .
2. The synchronizing method as claimed in claim 1 , wherein the reference torque control signal T 1 ref is controlled by feeding back a correction term into the discrepancy between the primary and secondary speeds ω 2 K−ω 1 .
3. The synchronizing method as claimed in claim 2 , wherein the control signal is based on the sum K w Kω 2 −K s ω 1 +T 1 int , in which K w and K s are constants.
4. The synchronizing method as claimed in claim 3 , wherein the constants K w and K s are fixed to ensure stability of the reference torque signal K 1 ref .
5. The synchronizing method as claimed in claim 2 , wherein the correction term for correcting the speeds discrepancy ω 2 K−ω 1 is proportional to T 1 int .