Device for reducing the drop in tractive force

• US 8,266,985 B2
• Filed: 01/26/2009
• Issued: 09/18/2012
• Est. Priority Date: 02/18/2008
• Status: Expired due to Fees

• Current Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: ZF Friedrichshafen AG (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Dobele, Bernd, Wiencek, Norbert
• Primary Examiner(s): Wright, Dirk
• Application Number:
  US12/864,887
• Publication Number:
  US 20100331141A1
• Time in Patent Office: 1,331 Days
• Field of Search: 475/2, 477/2, 746/61
• US Class Current: 74/661
• CPC Class Codes: B60K 6/105 the accumulator being a flywheel
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 10/24 including control of energy storage means
• CPC Class Codes: B60W 30/19 Improvement of gear change, e.g. by synchronisation or smoothing gear shift
• CPC Class Codes: F16H 2061/0425 Bridging torque interruption
• CPC Class Codes: F16H 61/04 Smoothing ratio shift
• CPC Class Codes: F16H 61/682 with interruption of drive
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y10T 74/19014 Plural prime movers selectively coupled to common output

Abstract

A device for reducing the drop in tractive force during the gear shifting phase of an automatic transmission comprising an automatically actuated drive clutch. The device comprises a rotary storage device that can be coupled, if necessary via two transmission ratio steps (4, 5) that are each assigned a friction clutch (6, 7), to the output shaft of the transmission or, if the transmission has a downstream range group, to the output shaft of the main friction transmission. Only one of the two friction clutches (6, 7) can be activated at any time, and a step up ratio can be achieved and the rotary storage device can be loaded with one of the transmission ratio steps (5). A step down ratio can be achieved and energy can be released from the rotary storage device to the output shaft using the other transmission ratio step (4).

Claims

1. A device for reducing a drop in tractive force during a gear shifting phase of an automatic transmission (1) with an automatically actuated drive clutch, the device comprising:

a rotary storage device (8) being connectable with a friction lock by two transmission ratio steps (4, 5) that are each assigned a friction clutch (6, 7) to either an output shaft (3) of the transmission (1) or, if the transmission has a downstream range group, to the output shaft of a main friction transmission, and only one of the two friction clutches (6, 7) being activated at any time, and a step up ratio being achieved, and

the rotary storage device being loaded with one of the transmission ratio steps (5) in situations outside of the gear shifting phase, and

a step down ratio being achieved and energy being released from the rotary storage device (8) to the output shaft (3) with the other transmission ratio step (4) during a gear shifting phase.

2. The device for reducing the drop in tractive force according to claim 1, wherein the two friction clutches (6, 7) are constructively joined to form a power-shiftable double clutch.

3. The device for reducing the drop in tractive force according to claim 1, wherein the device for reducing the drop in tractive force is controlled by an electronic control unit (ECU) of the automatic transmission (1).

4. A method of operating a device for reducing a drop in tractive force during a gear shifting phase of an automatic transmission (1) having an automatically actuated drive clutch, the device comprising a rotary storage device (8) being connectable with a friction lock by two transmission ratio steps (4, 5) that are each assigned a friction clutch (6, 7) to one of an output shaft (3) of the transmission (1) or, if the transmission has a downstream range group, to an output shaft of a main friction transmission, only one of the two friction clutches (6, 7) being activated at any time, and a step up ratio being achieved and the rotary storage device being loaded with one of the transmission ratio steps (5) in situations outside of the gear shifting phase, a step down ratio being achieved and energy being released from the rotary storage device (8) to the output shaft (3) with the other transmission ratio step (4) during a gear shifting phase, the method comprising the steps of:

loading the rotary storage device (8) in situations outside of the gear shifting phase by engaging the friction clutch (7) assigned to the step up ratio (5), such that a speed level of the rotary mass of the rotary storage device (8) is elevated by a predetermined factor corresponding to the achievable ratio above a level of rotational speed of the output shaft;

deactivating the step up ratio (5) between either the output shaft or the output shaft (3) of the main transmission and the rotary storage device (8), during a gear shifting phase, if the clutch (7) assigned to the transmission ratio step (5) is engaged by disengaging the clutch (7) assigned to this transmission ratio step (5); and

engaging the clutch (6) assigned to the step down ratio (4) to overlap with the torque of the drive clutch such that energy of the rotary storage device (8) is transferred to one of the output shaft (3) or the output shaft of the main transmission to one of prevent and reduce the drop in tractive force during the gear shifting phase.

5. The method of operating the device for reducing the drop in tractive force during the gear shifting phase of an automatic transmission (1) according to claim 4, further comprising the step of engaging the clutch (6) assigned to the step down ratio (4) when the torque of the drive clutch of the automatic transmission (1) falls below a predetermined threshold value.

6. The method of operating the device for reducing the drop in tractive force during the gear shifting phase of an automatic transmission (1) according to claim 4, further comprising the step of disengaging the clutch (6) assigned to the step down ratio (4) when the torque transferred from the drive clutch exceeds a predetermined threshold value after the gear shifting phase.

7. The method of operating the device for reducing the drop in tractive force during the gear shifting phase of an automatic transmission (1) according to claim 4, further comprising the step of loading the rotary storage device (8) outside of a gear shifting phase in situations in which either the vehicle is either accelerated or braked, or in which shifting is anticipated.