Transmission Shift Control Using Slip Reversal to Prevent Stick-Slip
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Solution Overview
Problem
Manual transmissions with multiple shifting devices experience undesired operating behavior, such as the stick-slip effect and torque changes, due to synchronization issues during shifting sequences, leading to reduced shifting quality and increased load on transmission components.
Innovation Solution
A method that defines a slip value based on the rotational speed difference between input and output sides of shifting devices, allowing for controlled switching between load and idle states, and utilizing an active torque source to manage slip reversals, thereby reducing torque direction changes and stick-slip effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sequential actuation of shifting devices is used, then the shifting process can be completed, but stick-slip effect and torque direction changes occur reducing shifting quality
Solution Approach 1:
The patent applies preliminary action by reversing the slip direction of the second shifting device before it is actuated. This is achieved by influencing the rotational speed of either the input side or output side of the second shifting device prior to its engagement, so that when the device closes under slip, the torque acts in the same effective direction throughout the synchronization phase, preventing stick-slip effect and improving shifting quality
2Reliability
If shifting devices close under slip, then synchronization can be achieved, but torque direction changes cause stick-slip effect and load changes on transmission components
Solution Approach 1:
The patent reverses the slip direction of the second shifting device before actuation by influencing the rotational speed of its input or output side. This preliminary speed adjustment ensures that when the shifting device engages, the torque direction remains consistent throughout the synchronization phase, eliminating the stick-slip effect and harmful torque peaks on gear tooth flanks
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces undesirable operating behaviors, enhances shifting quality, and minimizes load and contact changes on gear tooth flanks, torque peaks, and shocks in the transmission components.
Implementation Method 1
a friction element which is used to establish a gear in the automatic transmission
Implementation Method 2
A hydraulic servomotor for the friction element is supplied with hydraulic pressure to control the friction element between engaged, disengaged and slip states
Data Source
Figure 1
Figure 2a~2b
AI summary
The invention relates to a method for operating, in particular shifting, a transmission (1), in particular for motor vehicles, which transmission comprises at least two friction-locking shifting devices (10, 20, 30, 40), which each have an input side (11, 21, 31, 41) and an output side (13, 23, 33, 43), wherein a slip value (S) can be defined on the basis of a difference between a rotational speed of the input side (11, 21, 31, 41) and a rotational speed (11, 21, 31, 41) of the output side, and wherein each of said shifting devices (10, 20, 30, 40) has at least one load shifting state, in which the input side (11, 21, 31, 41) and the output side (13, 23, 33, 43) are connected to each other in order to transmit torque, and an idle shifting state, in which the input side (11, 21, 31, 41) and the output side (11, 21, 31, 41) are substantially not connected to each other, and wherein a first of said shifting devices (10) is shifted from the load shifting state thereof to the idle shifting state thereof or vice versa and a second of said shifting devices (20) is shifted from the idle shifting state thereof to the load shifting state thereof or vice versa in dependence on the slip value (S20) thereof only when said slip value (S20) has a different sign after a zero crossing, in particular in the sense of a slip reversal, than between the shifting of the first shifting device (10) and the zero crossing.