CVT Ratio Control Clamp for Corrupted Input Filtering
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Solution Overview
Problem
Current continuously variable transmission (CVT) ratio control systems are vulnerable to unintended deceleration or acceleration due to corrupted inputs from engine control module (ECM) or transmission control module (TCM) algorithms, software, or calibrations, leading to hazardous conditions and undesirable shutdowns.
Innovation Solution
The proposed apparatus includes a driver commanded ratio unit, a ratio selection and control clamp control portion with a ratio limits and override ring, a ratio control execution ring, and a transmission solenoid control ring, which calculates and applies pressure ranges for pulleys to maintain safe operation, using vehicle speed and acceleration data to prevent unintended deceleration or acceleration by filtering out corrupted inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ratio control system defaults to safe mode when corrupted inputs are detected, then safety is improved, but system availability and power transmission are reduced
Solution Approach 1:
The patent implements preliminary validation checks on input signals from the ECM before they are processed by the ratio control algorithm. The TCM screen module proactively detects corrupted inputs such as invalid accelerator pedal position signals or erroneous vehicle speed data before they can cause unintended acceleration or deceleration, allowing the system to maintain normal operation while filtering out hazardous inputs.
Solution Approach 2:
The patent introduces a TCM screen module as an intermediary between the ECM and the ratio control system. This intermediary layer validates incoming signals and blocks corrupted inputs from reaching the ratio control algorithm, thereby preventing safety hazards while allowing legitimate commands to pass through unchanged, maintaining both safety and system availability.
2Reliability
If the ratio control system continuously monitors and validates inputs, then reliability is improved, but computational load and system complexity increase
Solution Approach 1:
The patent implements selective validation where the TCM screen module focuses computational resources on validating only the most critical input signals that could lead to unintended acceleration or deceleration, such as accelerator pedal position and vehicle speed signals. This partial validation approach provides sufficient safety assurance without requiring exhaustive checking of all possible inputs, thereby limiting the increase in system complexity.
3Speed
If the system accepts all commanded ratios from the ECM, then responsiveness to driver input is improved, but vulnerability to corrupted inputs increases
Solution Approach 1:
The patent implements preliminary validation checks on input signals from the ECM before they are processed by the ratio control algorithm. The TCM screen module proactively detects corrupted inputs such as invalid accelerator pedal position signals or erroneous vehicle speed data before they can cause unintended acceleration or deceleration, allowing the system to maintain normal operation while filtering out hazardous inputs.
Solution Approach 2:
The patent employs feedback mechanisms where the TCM screen module continuously monitors the validity of input signals and adjusts its filtering behavior accordingly. When valid inputs are detected, the system responds quickly by passing commands through to the ratio control algorithm. When corrupted inputs are detected, the module activates filtering to block hazardous commands, thereby dynamically balancing responsiveness with input security based on real-time signal validation.
Data Source
AI summary
An apparatus for ratio control of a continuously variable transmission includes a driver commanded ratio unit outputting a signal defining a commanded ratio. A clamp control portion is in communication with the driver commanded ratio unit. The clamp control portion includes: a ratio limits and override ring selecting a ratio matching the commanded ratio from an executable functions having stored ratio code data; a screening monitor continuously receiving output from the executable functions and using an input from a vehicle speed signal to compute minimum and maximum ratio limits for the ratio selected by the ratio limits and override ring; and a ratio control execution ring in communication with the screening monitor. The ratio control execution ring calculates a range of pressures allowed for operation of both primary and secondary pulleys of the continuously variable transmission.