Hybrid Vehicle Transmission Mode Control via Hydraulic Brake
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Solution Overview
Problem
Hybrid electric vehicle transmission systems face inefficiencies in high-speed regions and require additional torque multiplication, particularly in single-mode types, limiting their application to larger vehicles, while multi-mode types offer high efficiency but require complex torque delivery apparatuses.
Innovation Solution
A control system that converts the driving mode from a power split mode to an engine coupling mode using a planetary gear set, motor/generators, a brake, and hydraulic pressure control to optimize torque distribution and efficiency, including slip and nonslip control mechanisms to manage brake engagement and reaction forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-mode transmission system is used, then the structure is simpler and does not require torque delivery apparatus, but fuel consumption increases due to deterioration of efficiency at high-speed region
Solution Approach 1:
The transmission system dynamically switches between single-mode and multi-mode operations based on driving conditions. The control apparatus adjusts the engagement state of torque delivery apparatus (clutches and brakes) to transition the planetary gear sets between different connection states, enabling the system to operate in high-efficiency multi-mode at high speeds while maintaining simple single-mode operation at low speeds
2Loss of energy
If a multi-mode transmission system is used, then efficiency at high-speed region is improved and torque multiplication is achieved, but the structure becomes more complex with additional torque delivery apparatus
Solution Approach 1:
The torque delivery apparatus serves multiple functions: it enables mode switching between single-mode and multi-mode operations, provides torque multiplication through planetary gear set configurations, and facilitates transitions between different driving modes (EV mode, power split mode, engine coupling mode). This multi-functionality reduces the need for separate dedicated components for each function
3Loss of energy
If mode conversion from power split mode to engine coupling mode is performed, then driving efficiency is improved, but complex hydraulic pressure control is required
Solution Approach 1:
The control apparatus continuously monitors driving conditions including vehicle speed, engine speed, and motor/generator speeds to determine the optimal operating mode. Based on this feedback, the controller automatically adjusts hydraulic pressure to engage or disengage torque delivery apparatus, transitioning between power split mode and engine coupling mode to maintain optimal efficiency across different operating conditions
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
Improves fuel consumption and drivability by selectively converting between power split and engine coupling modes based on driving conditions, enhancing the efficiency and applicability of hybrid electric vehicle transmission systems.
Implementation Method 1
a hydraulic pump supplying hydraulic pressure required to lock up the brake
Implementation Method 2
a brake selectively connecting the first rotor of the first motor/generator to a transmission housing
Implementation Method 3
a planetary gear set disposed on an input shaft receiving power of an engine
Data Source
AI summary
An apparatus for controlling a transmission system of a hybrid electric vehicle may include: a planetary gear set disposed on an input shaft; two input gears connected to rotation elements of a sun gear, a ring gear and a planet carrier of the planetary gear set; first and second motor/generators disposed on an intermediate shaft and a connecting shaft disposed in parallel with the input shaft; two intermediate gears connected respectively to a rotor of the first and second motor/generators; a brake selectively braking the rotor of the first motor/generator; two output gears; a hydraulic pump; and a controller. The controller performs a hydraulic pressure control for the brake through the hydraulic pump to lock up the brake when a conversion condition is satisfied, and a reaction force control for the sun gear when a driving mode is converted from a power split mode to an engine coupling mode.