PTO Transmission Gear Ratio Determination via Shaft Speed Estimation
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Solution Overview
Problem
In vehicles equipped with a single shaft speed sensor, the rotational speed of shafts upstream or downstream of the clutch and/or transmission is unknown during PTO clutch engagement, making precise control challenging.
Innovation Solution
A method and system that utilize measured PTO shaft speed and known gear ratio options to determine the selected gear of the PTO transmission, employing a controller with estimators to calculate normalized clutch gear ratios and select the appropriate gear ratio based on shaft acceleration, allowing for accurate control of the PTO clutch engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single shaft speed sensor is used, then device complexity is reduced, but measurement precision of shaft speeds upstream or downstream of clutch and transmission deteriorates
Solution Approach 1:
The patent introduces an intermediary computational system (controller with estimators) that indirectly determines shaft speeds upstream and downstream of the clutch/transmission by processing data from the single PTO shaft speed sensor. Instead of directly measuring all shaft speeds with multiple sensors, the system uses algorithms to estimate the unknown speeds based on the known gear ratios and the single measured PTO shaft speed, thus resolving the contradiction between using fewer sensors and maintaining measurement precision.
2Measurement precision
If multiple shaft speed sensors are installed, then measurement precision of all shaft speeds is improved, but device complexity increases
Solution Approach 1:
The system enables self-service by allowing the single PTO shaft speed sensor to serve multiple measurement needs through computational estimation. The controller uses the PTO shaft speed data along with known transmission gear ratios to self-determine the speeds of other shafts in the system, eliminating the need for additional sensors and reducing device complexity while maintaining the ability to monitor all critical shaft speeds.
3Ease of operation
If PTO clutch engagement is controlled without accurate gear ratio information, then ease of operation is improved, but reliability of clutch engagement control deteriorates
Solution Approach 1:
The patent implements feedback control by continuously monitoring the PTO shaft speed and using this information to determine the current transmission gear ratio through multiple estimators. This feedback loop provides the controller with accurate, real-time gear ratio information, enabling reliable clutch engagement control. The system adapts to the current gear state and adjusts clutch control accordingly, ensuring reliable operation while maintaining ease of use through automated determination of gear ratios.
Data Source
AI summary
A method includes receiving a first shaft speed, measuring a parameter indicative of a PTO shaft speed, determining a PTO shaft acceleration by monitoring the parameter indicative of the PTO shaft speed over time, determining, via a plurality of estimators, a plurality of normalized PTO clutch gear ratios, wherein each of the plurality of estimators determines one of the plurality of normalized PTO clutch gear ratios based, at least in part, on the first shaft speed, the PTO shaft speed, and one of a plurality of known PTO transmission gear ratio options, and selecting one of the plurality of estimators, when the PTO shaft acceleration drops below a threshold value, wherein the normalized PTO clutch gear ratio determined by the selected estimator is about 1.