Power Split Continuously Variable Transmission Using Electric Machine
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Solution Overview
Problem
Existing continuously variable transmission devices with hydrostatic variators require large construction space, are costly, and operate with reduced efficiency due to cooling and lubricant needs, leading to increased drag losses and mechanical vibrations, which affect lifespan and require time-consuming warm-up phases.
Innovation Solution
A continuously variable transmission device with power split using an electric machine instead of a hydrostatic variator, allowing for smaller construction space, lower manufacturing costs, and improved efficiency by eliminating hydrostatic unit losses, with the electric machine capable of operating as a generator for enhanced drive train efficiency and recuperation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a hydrostatic variator is used for continuous variation of gear ratios, then the transmission device can provide continuous gear ratio adjustment, but it requires large construction space and has high manufacturing cost
Solution Approach 1:
The patent replaces the hydrostatic variator (mechanical-hydraulic system) with an electric machine coupled to a planetary transmission (mechanical system). This substitution eliminates the need for hydrostatic components while achieving continuous gear ratio variation through electrical control of the electric machine, thereby reducing construction space and manufacturing cost.
2Adaptability or versatility
If a hydrostatic variator is used for continuous variation of gear ratios, then the transmission device can provide continuous gear ratio adjustment, but it operates with reduced efficiency due to cooling and lubricant needs
Solution Approach 1:
The patent replaces the hydrostatic variator with an electric machine and planetary transmission system. This substitution eliminates the hydraulic fluid circulation system (pumps, motors, coolers, lubricant pathways) that causes drag losses, thereby improving efficiency while maintaining continuous gear ratio adjustment capability.
3Adaptability or versatility
If a hydrostatic variator is used for continuous variation of gear ratios, then the transmission device can provide continuous gear ratio adjustment, but it generates mechanical vibrations that affect lifespan
Solution Approach 1:
The patent replaces the hydrostatic variator with an electric machine coupled to a planetary transmission. This substitution eliminates the mechanical vibrations inherent in hydrostatic systems (from fluid dynamics, piston motion, and hydraulic connections) while maintaining continuous variability, thereby improving reliability and lifespan.
4Adaptability or versatility
If a hydrostatic variator is used for continuous variation of gear ratios, then the transmission device can provide continuous gear ratio adjustment, but it requires time-consuming warm-up phases
Solution Approach 1:
The patent replaces the hydrostatic variator with an electric machine and planetary transmission system. This substitution eliminates the thermal fluid system that requires warm-up to reach operating temperature and viscosity specifications. The electric machine can be immediately activated without warm-up, reducing time loss while maintaining continuous gear ratio adjustment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces construction space and manufacturing costs, enhances efficiency by minimizing drag losses, lowers mechanical loads, and eliminates the need for warm-up phases, enabling higher spontaneity and efficient operation across the vehicle's operating range, with the electric machine facilitating reverse direction operation without additional mechanical units.
Implementation Method 1
an electric machine (36) for continuous variation of the gear ratio of the transmission device (1), wherein the electric machine (36) is coupled to an electric energy source (38)
Implementation Method 2
the electric machine (36) capable of operating as a generator for enhanced drive train efficiency and recuperation
Data Source
AI summary
A continuously variable transmission device (1) has a power split which takes place in the area of a sum planetary transmission (9). A first shaft (8) of the sum planetary transmission (9) can be brought into operational connection with a drive engine or machine (3). A second shaft (12) of the sum planetary transmission (9) can be connected, for continuous variation of the gear ratio, with an electric machine (36) which itself can be coupled with an electric energy source (38).