9-Speed Transmission Form-Locking Shift Element Sensor Control
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Solution Overview
Problem
Transmission devices, particularly 9-speed transmissions, face inefficiencies due to drag torques from friction-locking shift elements in disengaged states and potential mechanical or hydraulic malfunctions that prevent form-locking shift elements from disengaging correctly, leading to undefined operating states like overdetermined gear sets or unwanted power flow interruptions.
Innovation Solution
A method for operating a transmission device that includes a sensor device associated with form-locking shift elements to detect their operating state and generate disengagement control signals, ensuring reliable distinction between engaged and disengaged states, and transitioning to a safe operating state if disengagement is not successful, thereby preventing undefined operating states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If friction-locking shift elements are used to implement transmission ratios, then the transmission device can achieve multiple transmission ratios, but drag torques occur in the disengaged state which lower the overall efficiency of the transmission
Solution Approach 1:
The shift element is divided into two distinct components: a form-locking shift element for torque transfer and a friction-locking shift element for synchronization and engagement control. This segmentation allows the form-locking element to be disengaged completely (eliminating drag torque) while the friction-locking element handles the engagement process smoothly.
Solution Approach 2:
The friction-locking shift element acts as an intermediary between the form-locking shift element and the power flow. It provides a smooth transition during engagement by allowing slip and gradual torque transfer, protecting the form-locking element from shock loads during the engagement process.
2Loss of energy
If form-locking shift elements are used to eliminate drag torques, then overall efficiency of the transmission is improved, but mechanical or hydraulic malfunctions may prevent correct disengagement leading to undefined operating states
Solution Approach 1:
A sensor device is integrated to detect the operating state of the form-locking shift element and provide feedback signals to the control device. This feedback mechanism allows the control system to verify whether the shift element has successfully disengaged or engaged, and to detect malfunctions by comparing the actual state with the requested state.
Solution Approach 2:
The control device is programmed with predetermined responses to detected malfunctions, such as activating warning signals or initiating corrective procedures. This beforehand cushioning ensures that undefined operating states are prevented and the transmission is protected from damage due to malfunctioning shift elements.
3Loss of energy
If form-locking shift elements are used, then no drag torques occur in the disengaged state, but the shift element must be close to the synchronization point to be switched, increasing the complexity of control
Solution Approach 1:
The friction-locking shift element serves as a mediator that handles the synchronization requirement. It allows the transmission speeds of the connected shafts to equalize through controlled slip, preparing the system for the form-locking element's engagement without requiring precise synchronization control of the form-locking element itself.
Solution Approach 2:
The control of the friction-locking shift element is achieved through hydraulic actuation with controlled pressure buildup, replacing complex mechanical synchronization mechanisms. The hydraulic system naturally provides smooth, controlled engagement by regulating fluid pressure, simplifying the control architecture.
4Loss of energy
If form-locking shift elements are used, then efficiency is improved, but excessively rapid torque buildup may prevent disengagement during upshifts
Solution Approach 1:
The friction-locking shift element acts as a buffer or intermediary that absorbs and moderates rapid torque changes. During upshifts, it allows controlled torque transfer and slip, preventing excessively rapid torque buildup that would otherwise lock the form-locking shift element in its engaged state and prevent proper disengagement.
Data Source
AI summary
A method for operating a 9-speed transmission which changes operating states by actuating shift elements. At least one of the shift elements is a form-locking shift element, which disengages to implement a defined transmission operating state during which the power flow, between transmission input and output shafts, is present or interrupted. A sensor is associated with the locking shift element. An operating state of the locking shift element can be determined by the sensor. Upon a request to disengage the locking shift element, a disengagement control signal is generated and the locking shift element is actuated in the disengagement direction, depending on the disengagement control signal. The transmission is shifted to a safe operating state, in which at least the transmission output shaft can rotate, when an engaged operating state of the locking shift element is determined by the sensor even though a disengagement control signal was generated.