Multi-Speed Transmission Modal Splitter for Shift Quality
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current heavy machinery transmissions face issues with shift quality, shift time, and durability due to double transition shifts in multi-speed transmissions, particularly in the center shifts of high/medium/low ratio 'splitter' sections.
Innovation Solution
A transmission design featuring two rear planetary gear sets with modal operation, utilizing three modal torque-transmitting mechanisms and an input torque-transmitting mechanism to achieve up to eleven speed ratios with single transition shifts, including overdrive ratios, by selectively engaging different gear members to manage power flow and torque ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multi-speed input section with splitter section is used, then number of speed ratios is increased, but double transition shifts occur compromising shift quality and durability
Solution Approach 1:
The transmission is divided into a multi-speed input section and a two-speed splitter section, with the splitter section providing modal operation in three distinct modes. This segmentation allows the center shifts to be eliminated by operating the splitter in high, medium, or low ratio modes without requiring double transition shifts, thereby maintaining reliability while achieving multiple speed ratios.
Solution Approach 2:
The splitter section dynamically switches between three operational modes (high ratio mode, medium ratio mode, low ratio mode) by selectively engaging different torque-transmitting mechanisms. This dynamic modal operation allows the transmission to adapt the splitter's behavior to different operating conditions, eliminating the need for problematic double transition shifts while providing versatile speed ratio options.
2Speed
If center shifts (CL to AM, CM to AH) are implemented, then speed ratio transitions are achieved, but shift time increases and internal gear durability is compromised
Solution Approach 1:
The transmission pre-configures the splitter section with three ready-to-engauge torque-transmitting mechanisms (high ratio, medium ratio, low ratio). When a shift is required, the appropriate mechanism is already positioned and can be engaged immediately without requiring intermediate transition steps, thereby reducing shift time and avoiding prolonged engagement of internal gears.
Solution Approach 2:
The problematic double transition shift sequence is extracted and replaced by directly engaging the appropriate torque-transmitting mechanism in the splitter section. Instead of forcing sequential transitions through center shifts, the system selectively engages the needed mechanism (high, medium, or low ratio) directly, eliminating unnecessary intermediate steps and reducing shift time.
3Adaptability or versatility
If high number of speed ratios is provided, then versatility is improved, but internal speeds increase reducing efficiency
Solution Approach 1:
The modal planetary gear sets in the splitter section are designed with different local characteristics for each mode. The high ratio mode, medium ratio mode, and low ratio mode each have optimized gear configurations that maintain appropriate internal speeds for their specific function. This local optimization allows multiple speed ratios to be achieved without uniformly increasing internal speeds across all operations.
Solution Approach 2:
The transmission changes operational parameters by selectively engaging different torque-transmitting mechanisms in the splitter section. Each mode (high, medium, low ratio) operates with different engagement parameters that optimize the internal speeds for that specific mode, allowing the system to achieve multiple speed ratios while maintaining energy efficiency by avoiding consistently high internal speeds.
Data Source
AI summary
An automatic transmission providing modal speed ratios, single transition gear shifting, low internal speeds, and an output lock feature is provided. First, second and third modal torque-transmitting mechanisms are selectively engagable along with first and second input torque-transmitting mechanisms to effect power flow to first and second planetary gear set to cause the speed of a member of one of the gear sets to increase in the first mode (when the first and second input torque-transmitting mechanisms are engaged in successive order while the first modal torque-transmitting mechanism is engaged), decrease in the second mode (when the first and second input torque-transmitting mechanisms are engaged in reverse order while the second modal torque-transmitting mechanism is engaged) and increase in the third mode (when the first and second input torque-transmitting mechanisms are engaged in successive order while the third modal torque-transmitting mechanism is engaged).