192 clutches and power-stop control – Transmission control and clutch control – Common control
Reexamination Certificate
2001-12-07
2003-01-28
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Transmission control and clutch control
Common control
C192S003630, C701S067000
Reexamination Certificate
active
06510931
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of operating a torque transfer system in a motor vehicle, and it also relates to a torque transfer system that is capable of operating according to the inventive method.
A torque transfer system in the sense of the present invention is an arrangement with the capability to convert a characteristic rotary quantity of an input shaft into an either identical or different rotary quantity of an output shaft and/or with the capability to couple and uncouple the input shaft and the output shaft. As the term is used in the present context, a torque transfer system can include a clutch device and/or transmission device and/or a torque converter device or any other mechanism in the same general category.
A characteristic rotary quantity is used to characterize the dynamic situation of a rotating part, particularly a shaft. Specific examples of characteristic rotary quantities are a torque or an rpm rate.
A transmission device in the sense of the present invention is a mechanism that can be shifted in steps or in a continuous, step-less range, into different shift positions corresponding to different transmission ratios between two shafts of the transmission device. The transmission device can be shifted automatically or manually, or in a partially automatic or automated mode with the possibility of manual intervention.
A transmission device in the sense of the present invention encompasses in particular manually operated step-shifting transmissions, or cone-pulley transmissions, or automatic transmissions. An automatic transmission is a transmission device in which the shifts are controlled automatically and occur without interruption in the tractive force, specifically with a planetary gear mechanism. The transmission in the present context is configured in particular as an automated shift transmission. The term “automated shift transmission” relates to a transmission device in which the shift movements are automated, but are accompanied by an interruption in vehicle traction.
A clutch device in the sense of the present invention may be configured with or without power branching and can include a start-up clutch, a friction clutch, a reverse-gear clutch, a laminar disc clutch, a magnet-powder clutch, a converter bypass clutch, or another device of the same general category.
With special preference, the clutch is configured as an electronically controlled clutch device in which the movement between different positions of the clutch can be performed under electronic control. An electronically controlled clutch device has been described by and is available from the assignee of the present invention under the name “Electronic Clutch Management (ECM)”.
In particular, an electronically controlled clutch device of the foregoing description has the capability of operating in a crawl mode.
A crawl mode in the sense of the present invention is an operating mode where the clutch is held in a position to transmit a predetermined amount of crawl torque. A crawl torque in the present context means in essence a small amount of torque that is transmitted through the clutch, e.g., while the engine is running, the brake is not applied, and the gas pedal or other fuel-metering device is being actuated. The crawl torque is transmitted also when a gear is set in the transmission of the motor vehicle. In particular, a crawl mode is controlled by a control device in accordance with a predetermined characteristic which can include mathematical functions, curve fields, or other functional relationships.
A transmission device in the sense of the present invention includes in particular a control device, an actuating device, and a shifting device. The shifting device has at least two movable elements, in particular a shifter finger as a first shifter element, and a shifter shaft or shifter fork as a second shifter element.
The first shifter element can be moved in a shift gate arrangement with at least one selector track and at least one shift track. The selector track and the shift tracks in the sense of the present invention may be real or virtual tracks. A virtual track means that the movement of the first shifter element is not constrained by physical guide barriers, but is nevertheless limited within certain track-like paths. The limitations or constraints on the movement may be realized by elements that are coupled to the first shifter element. The arrangement may include travel-delimiting devices which can be part of a control device or an actuating device.
The shift gate arrangement can have a configuration where the shift tracks join the selector track at right angles. In particular, the shift gate arrangement may be configured with three or four parallel shift tracks that meet the selector track at different selector positions.
A shift track in the sense of the present invention consists either of one branch that runs in one direction from a selector position on the selector track, or two branches that run in opposite directions from a selector position on the selector track.
Torque transfer systems with transmission devices, including automated shift transmissions, belong to the known state of the art and are commercially available.
However, experience has shown that automated shift transmissions in particular are more prone to wear, which often causes components to fail prematurely. Also, in known devices the shift movements into certain positions are not performed with the degree of precision given by a control device.
OBJECT OF THE INVENTION
It is therefore the object of the present invention to provide a method of operating a torque transfer system in a motor vehicle, and to provide a torque transfer system that is capable of operating in accordance with the inventive method, so that the precision of the shift movements is improved and the amount of wear is reduced in a cost-effective and technically non-complicated manner.
SUMMARY OF THE INVENTION
To meet the foregoing objective, the invention proposes a method of operating a torque transfer system in a motor vehicle. The torque transfer system includes a shifter device with a movable element that is movable into a plurality of shift positions, an actuator device to apply an actuating force to the movable element, a control device to control the actuator device, and a position-detecting device to detect a position of the movable element. The movable element is subject to a position-dependent force, and the shift positions coincide with minima of the potential energy of the position-dependent force. As a result, the movable element has a tendency to fall into the nearest one of the shift positions.
In a first step of the inventive method, an output signal is issued by the control device to the actuator device with the end purpose of moving the movable element to a targeted shift position or more specifically, to a position within a given first tolerance band of the target position. When the movable shifter element has arrived within a second tolerance band that is wider than the first tolerance band and contains the latter, the movement of the shifter element stops at least for a short time interval. The stop can be the result of two or more forces canceling each other at a specific point. Specifically, one of the forces is a position-dependent field force of a force potential, while at least one other of the forces is a holding force of the movable element that counterbalances the field force. Under the inventive method, the targeted shift position is located essentially at a point where the force potential has a local maximum or minimum, i.e., where the field force reverses its direction.
In a second step of the inventive method, a stall-releasing signal is generated by the control device in accordance with a predetermined characteristic, to overcome the holding force on the movable shifter element at least partially to allow the shifter element to move and to ensure that the shifter element settles at a final position within the first tolerance band of the targeted position.
Berger Reinhard
Vornehm Martin
Winkelmann Stefan
Bonck Rodney H.
Darby & Darby
LuK Lamellen und Kupplungsbau Beteiligungs KG
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