Automated synchronization
View Patent ↗A method for making the synchronization process in automatic transmissions more robust and shortening the same, while at the same time taking the noise comfort into consideration.
1. A method of controlling a synchronizing device during a shifting operation in an auto shift gearbox in a motor vehicle, wherein:
a synchronization duration is determined using a formula including a friction force and, if the target synchronizing force is below a predetermined threshold (F Min ) at the moment of impact on the synchronization unit, the target synchronizing force is increased from the moment of impact on the synchronization unit in accordance with a predetermined gradient (g) until the predetermined threshold (F Min ) is reached;
at the moment of impact on the synchronization unit, the target synchronizing force equals an applied synchronizing force (F synch1 ); and,
at the moment of impact, the applied synchronizing force (F synch1 ) is greater than zero.
2. The method as set forth in claim 1 , wherein the predetermined threshold exceeds the maximum expected friction force but is below a value for which losses of comfort due to a synchronizing jolt are expected.
3. The method as set forth in claim 1 , wherein the target synchronizing force is kept constant if at the moment of impact on the synchronization unit the target synchronizing force is higher than a predetermined threshold.
4. The method as set forth in claim 1 , wherein the moment of impact on the synchronization unit is the moment of impact of two friction surfaces to be synchronized upon each other.
5. The method as set forth in claim 1 , wherein the moment of impact on the synchronization unit is the moment of impact of the friction surface of the synchro ring on the friction surface of the shift gear.
6. The method as set forth in claim 1 , wherein emergency measures are initiated when the synchronization is not completed after the synchronization duration starting at the moment of impact on the synchronization unit has elapsed.
7. The method as set forth in claim 6 , wherein the emergency measures include a further increase of the target synchronization force.
8. The method as set forth in claim 1 , wherein the synchronization duration is calculated in accordance with the equation
Δ
t
=
c
Gang
·
Δ
n
(
F
Min
-
F
Reib
)
+
(
F
Min
-
F
Sync
)
2
2
·
g
·
(
F
Min
-
F
Reib
)
if the applied synchronizing force (F Sync ) is below the predetermined threshold (F Min ), with Δn the rotational speed difference to be synchronized, F Sync the applied synchronizing force, C Gang a gear-dependent coefficient, and g a time gradient.
9. The method as set forth in claim 1 , wherein the synchronization duration is calculated in accordance with the equation
Δ
t
=
c
Gang
·
Δ
n
(
F
Sync
-
F
Reib
)
if the applied synchronizing force is higher than the predetermined threshold (F Min ), with Δn the rotational speed difference to be synchronized, F Sync the applied synchronizing force, and C Gang a gear-dependent coefficient.
10. The method as set forth in claim 3 , wherein the synchronization duration is calculated in accordance with the equation
Δ
t
=
c
Gang
·
Δ
n
(
F
Sync
-
F
Reib
)
if the applied synchronizing force is higher than the predetermined threshold (F Min ), with Δn the rotational speed difference to be synchronized, F sync the applied synchronizing force, and C Gang a gear-dependent coefficient.
11. The method as set forth in claim 4 , wherein the moment of impact on the synchronization unit is the moment of impact of the friction surface of the synchro ring on the friction surface of the shift gear.
12. A device including a control apparatus for controlling a synchronizing device during a shifting operation in an auto shift gearbox in a motor vehicle, wherein:
the control apparatus is provided to determine a synchronization duration using a formula including a friction force and to ensure that, if at the moment of impact on the synchronization unit, the target synchronizing force is below a predetermined threshold (F Min ), beginning at the moment of impact on the synchronization unit, the target synchronizing force is increased in accordance with a predetermined gradient (g) until the predetermined threshold (F Min ) is reached;
at the moment of impact on the synchronization unit, the target synchronizing force equals an applied synchronizing force (F synch1 ); and,
at the moment of impact, the applied synchronizing force (F synch1 ) is greater than zero.