CVT Input Torque Calculation Using Accumulator State Feedback
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Solution Overview
Problem
The existing control apparatuses for vehicles with continuously-variable transmission mechanisms face challenges in accurately calculating input torque during the releasing process state of the second engagement device, particularly due to the influence of hydraulic pressure storage in accumulators on controllability.
Innovation Solution
A control apparatus that includes a transmission shifting control portion to calculate input torque based on the storage state of hydraulic pressure in the accumulator, considering the operation states of the second engagement device, and adjusts torque capacity values accordingly to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the input torque is calculated based on the torque capacity of the second engagement device during the releasing process state, then the calculation can be performed without additional sensors, but the accuracy is degraded due to the influence of hydraulic pressure storage in the accumulator
Solution Approach 1:
The control apparatus monitors the operation state of the second engagement device and the storage state of the accumulator, and uses this feedback information to select the appropriate torque calculation method. When the accumulator is in a charged state, the system switches to using the torque capacity of the second engagement device for calculation, while when the accumulator is discharged, it uses the actual input torque sensor data, thereby maintaining high accuracy throughout the releasing process state.
Solution Approach 2:
The system changes the calculation parameters dynamically based on the accumulator's storage state. By detecting whether the accumulator is charged or discharged, the control apparatus switches between different torque calculation approaches (torque capacity-based vs. sensor-based), adapting the calculation method to the current hydraulic system state to ensure accuracy.
2Measurement precision
If hydraulic sensors are added to detect the storage state of the accumulator, then the input torque calculation accuracy can be improved, but the device complexity and cost increase
Solution Approach 1:
The control apparatus utilizes existing system components (the second engagement device and accumulator) and their operational states to determine the appropriate torque calculation method. The system serves itself by using the natural state information of the hydraulic components without requiring additional sensors, thereby maintaining accuracy while avoiding increased complexity.
Solution Approach 2:
The second engagement device serves multiple functions: it not only controls the clutch engagement but also provides torque capacity information that can be used for input torque calculation. The accumulator's charge state serves as an indicator for selecting the calculation method, making existing components multi-functional and eliminating the need for dedicated sensors.
3Ease of operation
If the torque capacity value of the second engagement device is used for input torque calculation during the releasing process state, then the calculation can be performed without additional sensors, but slippage control of the continuously-variable transmission mechanism may be compromised
Solution Approach 1:
The control apparatus continuously monitors the accumulator's storage state and uses this feedback to dynamically adjust the torque calculation method. During the releasing process state, when the accumulator is charged, the system uses the torque capacity value with appropriate safety margins to maintain both operational simplicity and slippage prevention reliability.
Solution Approach 2:
The system applies a conservative approach by using the torque capacity value of the second engagement device, which represents an upper bound or excessive estimate of the actual torque. This partial action ensures that even if the calculation is not perfectly accurate, the control system maintains sufficient clamping force to prevent slippage, prioritizing reliability over precise torque matching.
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 enhances the accuracy of input torque calculation during the releasing process state, enabling better control of the continuously-variable transmission mechanism and preventing slippage, even without hydraulic sensors to detect storage states.
Implementation Method 1
an accumulator that is connected to the hydraulic passage so as to store the first hydraulic pressure that flows through the hydraulic passage
Implementation Method 2
an electromagnetic valve configured to regulate a first hydraulic pressure supplied to the electromagnetic valve via a hydraulic passage
Data Source
AI summary
A control apparatus for a vehicle that including a drive-force transmitting apparatus and a hydraulic control unit. The drive-force transmitting apparatus defines a drive-force transmitting path through which a drive force is to be transmitted by a continuously-variable transmission mechanism when the drive-force transmitting path is established by engagement of an engagement device. An electromagnetic valve of the hydraulic control unit regulates a hydraulic pressure supplied to the electromagnetic valve via a hydraulic passage, such that the regulated hydraulic pressure is supplied toward the engagement device. An accumulator of the hydraulic control unit is connected to the hydraulic passage, so as to store the hydraulic pressure that flows through the hydraulic passage. The control apparatus calculates, based on a storage state of the hydraulic pressure in the accumulator, an input torque inputted to the continuously-variable transmission mechanism when the engagement device is in a releasing process state.