Power-Shift Transmission Control Unit Torque Management
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Solution Overview
Problem
Existing methods for operating power shiftable transmissions in vehicles face challenges in reducing drive torque during upshifts, particularly when moments of inertia are high, leading to excessive torque increase, which affects comfort and can necessitate the internal combustion engine to switch to coasting, but this is not always permissible due to conditions like excessive unburned oxygen supply or electric machine temperature.
Innovation Solution
A method where a control unit in the transmission system adjusts the torque transmission rate of shift elements based on the availability of drive torque reduction, using open-loop or closed-loop systems, to ensure comfortable shifting by influencing the torque transmission rate depending on the available drive torque reduction, and prolonging the upshift duration if necessary to limit thermal load on shift elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If drive torque is reduced during upshift to avoid excessive torque increase, then shifting comfort is improved, but vehicle acceleration performance deteriorates
Solution Approach 1:
The patent dynamically adjusts the torque transmission rate of shift elements based on real-time operating conditions. The control unit modulates the torque transmission rate during upshift according to the rotational speed of the moment of inertia and the requested drive torque reduction, allowing optimal balance between comfort and acceleration performance under varying conditions.
Solution Approach 2:
The control method changes the torque transmission rate parameter during the upshift process based on detected operating parameters (rotational speed, requested torque reduction). By dynamically adjusting this parameter, the system achieves comfortable shifting while maintaining acceleration performance when conditions permit.
2Productivity
If gear shift is completed quickly to improve responsiveness, then productivity is improved, but drive torque reduction must be increased which worsens engine operation
Solution Approach 1:
The system dynamically determines the appropriate torque transmission rate based on current rotational speed and engine operating conditions. This allows fast shifting when engine conditions permit, while preventing harmful engine operation when torque reduction would be excessive.
Solution Approach 2:
The control unit receives information about the requested drive torque reduction and uses this feedback to adjust the torque transmission rate accordingly. This closed-loop control ensures that rapid shifting does not compromise engine operation by providing real-time adjustment based on actual operating conditions.
3Reliability
If drive torque is reduced to maintain engine operation, then engine reliability is improved, but shifting comfort deteriorates due to excessive torque increase
Solution Approach 1:
The control method adjusts the torque transmission rate parameter based on the requested drive torque reduction, allowing the system to maintain engine operation while minimizing torque increase during upshift, thereby preserving shifting comfort.
4Power
If torque transmission rate is increased to maintain acceleration, then vehicle power is improved, but thermal load on shift elements increases
Solution Approach 1:
The system dynamically adjusts the torque transmission rate based on real-time conditions, increasing it only when necessary for acceleration while considering thermal constraints. The control unit balances power transmission needs with thermal load management.
Data Source
AI summary
A method for operating a power shiftable transmission of a motor vehicle, the transmission including a control unit, an input shaft, an output shaft, a gear set, and multiple shift elements, the method including transmitting, with the control unit, a request for a reduction of a drive torque acting on the input shaft for carrying out an upshift, and determining, with the control unit, whether the reduction is completely possible, partially possible, or impossible based on a signal. When the reduction is completely possible, the method includes controlling, with the control unit, a torque transmission rate of a shift element of the multiple shift elements to be engaged during the upshift according to a first way. When the reduction is partially possible or impossible, the method includes controlling, with the control unit, the torque transmission rate according to a second way, the second way differing from the first way.