Transmission Shift Schedule Selection Using Net Tractive Effort
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Solution Overview
Problem
Conventional vehicle transmissions face limitations in switching between economy and performance shift schedules due to compatibility issues with engine data communication, leading to restricted vehicle installations and negatively affecting fuel economy and performance.
Innovation Solution
A system that includes a transmission control circuit with an economy mode shift schedule, capable of calculating vehicle acceleration, accelerator pedal position, and net tractive effort force to select and control gear shifts based on these parameters, independent of the current shift schedule, ensuring seamless transitions without impacting vehicle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmission control module waits to receive engine data from the engine control module before selecting a shift schedule, then the transmission can operate with accurate engine torque information, but the transmission cannot quickly switch between shift schedules when driving conditions change
Solution Approach 1:
The transmission control module calculates vehicle acceleration, determines torque converter mode, computes net tractive effort force, and determines the economy mode shift schedule in advance based on current operating conditions, before receiving engine torque data from the engine control module. This preliminary calculation allows the transmission to immediately implement the appropriate shift schedule once the data is received, eliminating the waiting delay.
2Ease of manufacture
If the transmission is mounted behind an engine with which it is not compatible, then the transmission cannot receive engine data from the engine control module, but this limits the number of vehicles in which the transmission can be installed
Solution Approach 1:
The transmission control module independently calculates vehicle acceleration, determines torque converter mode, computes net tractive effort force, and selects the economy mode shift schedule using its own processing capabilities and available data, rather than relying on the engine control module to provide all necessary information. This self-sufficiency allows the transmission to function with any engine, greatly increasing versatility.
3Productivity
If the transmission operates in a performance-based shift schedule, then vehicle performance is maintained, but fuel economy is negatively affected
Solution Approach 1:
The transmission control module dynamically switches between performance-based and economy mode shift schedules based on real-time calculation of vehicle acceleration, torque converter mode, and net tractive effort force. The system transitions to economy mode when conditions permit (low acceleration, adequate tractive effort margin) to improve fuel economy, and switches back to performance mode when needed, optimizing the balance between performance and fuel efficiency.
Data Source
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AI summary
The present invention discloses a system for selecting an economy mode shift schedule for a motor vehicle. The system includes a transmission having a torque converter and a plurality of selectable gear ranges. The system also includes a transmission control circuit that includes a control module which has the economy mode shift schedule stored therein. The transmission control circuit is configured to operably control the transmission. Also included in the system is an engine control circuit configured to control the operation of an engine which is operably coupled to the transmission. A communication link is configured to transfer information between the transmission control circuit and the engine control circuit. The control module further includes instructions stored therein for executably controlling the transmission control circuit to: calculate vehicle acceleration; determine a change in accelerator pedal position; compute a net tractive effort force of the vehicle for a current gear range of the transmission; compare the net tractive effort force to a maximum tractive effort for a desired gear range; select the economy mode shift schedule for the transmission based on the comparison; and control shifting between gear ranges of the transmission according to the economy mode shift schedule.