Powertrain Directional Shift Control Without Output Speed Sensor
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Solution Overview
Problem
Current construction machines experience a significant reduction in engine power when shifting from reverse to forward gear, leading to inadequate performance and operator complaints due to the absence of a torque converter output speed sensor, which results in excessive torque transmission and insufficient engine speed during gear shifts.
Innovation Solution
A method and system where a control module determines a desired engine speed value by comparing first and second desired engine speed values based on the detection of direction changes and gear settings, bypassing the default zero output speed of the torque converter, to ensure smooth operation and prevent excess torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the output speed of the torque converter is set to zero by default during direction change, then the control algorithm can operate without a torque converter output speed sensor, but the machine experiences significant reduction in engine power and inadequate performance
Solution Approach 1:
The patent introduces an intermediary calculation method that uses the relationship between transmission input speed, transmission output speed, and gear ratio to estimate torque converter output speed during direction changes. Instead of directly measuring it with a sensor, the system calculates it as an intermediate value using available sensor data and transmission characteristics, thereby avoiding the need for an additional sensor while maintaining accurate power control.
2Ease of operation
If the desired engine speed is determined using lookup tables from PTS and CTS algorithms, then the engine speed control is simplified, but the machine delivers inadequate power for an extended period during direction change
Solution Approach 1:
The patent implements a dynamic engine speed determination method that transitions from static lookup table values to a dynamic calculation based on real-time operating conditions. During direction changes, the system dynamically adjusts the desired engine speed by considering the torque converter's actual output speed (calculated through the intermediary method) and the current transmission state, rather than relying on predetermined lookup table values. This dynamic approach ensures adequate power delivery while maintaining ease of control through automated algorithmic adjustment.
3Device complexity
If the torque converter output speed is not known during direction change, then the control system can operate without additional sensors, but excess torque is transmitted to powertrain components
Solution Approach 1:
The patent implements a feedback mechanism where the calculated torque converter output speed (derived from transmission input speed, output speed, and gear ratio) is continuously fed back to the control algorithm. This feedback loop enables the system to monitor and adjust the engine speed and torque output in real-time during direction changes, preventing excess torque transmission to powertrain components while maintaining a relatively simple control system configuration that uses existing sensors.
Data Source
AI summary
A method for controlling powertrain of a machine not having a torque converter output speed sensor during a direction change of the machine is provided. The method includes retrieving a first desired engine speed value and a second desired engine speed value based on a detection of the direction change by a control module. The second desired engine speed value is determined based on a current gear setting of a gear shift lever and a desired gear setting of the gear shift lever. The method further includes determining the desired engine speed value based on a comparison between the first desired engine speed value and the second desired engine speed value by the control module. The control module is configured to identify a lower value of the first desired engine speed value and the second desired engine speed value as the desired engine speed value.