Engine Drive Reduction with Free Wheel for Smooth Phase Transitions
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Solution Overview
Problem
Conventional drive systems for engine arrangements face challenges in achieving smooth transitions between operating phases, leading to potential damage and inefficiencies, particularly in the transition from starting to running phases due to torque transmission issues.
Innovation Solution
The drive system incorporates a free wheel mechanism that changes its engagement state based on torque direction, allowing for a single-way connection during the starting phase to prevent engine damage and immediate disconnection when combustion torque becomes positive, and a movable third junction element that couples with either the free wheel or accessory pulley depending on the operating phase, enabling efficient power transfer and phase transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional drive system is used to connect the accessory pulley and engine crankshaft, then the system can transmit torque in both directions, but the transition between starting and running phases causes damage to the accessory pulley and electric machine due to uncontrolled torque transmission
Solution Approach 1:
A free wheel mechanism is introduced as an intermediary between the gear reduction mechanism and the engine crankshaft. This free wheel acts as a one-way clutch that allows torque transmission only in the starting phase (when electric machine drives the engine) and automatically disengages during the running phase (when engine drives the electric machine), preventing damage to the accessory pulley and electric machine while maintaining system reliability
Solution Approach 2:
The drive system transitions from a static two-way torque transmission connection to a dynamic one-way connection using the free wheel. The free wheel automatically changes its engagement state based on the direction of torque: engaged during starting phase to transmit torque from electric machine to engine, and disengaged during running phase to prevent reverse torque transmission, enabling smooth phase transitions without mechanical damage
2Reliability
If the gear reduction mechanism maintains continuous torque transmission during phase transitions, then power transfer is efficient, but the accessory pulley and electric machine suffer from torque shocks and potential damage
Solution Approach 1:
The free wheel serves as a protective intermediary that selectively blocks harmful reverse torque while allowing useful forward torque transmission. During the transition from starting to running phase, when the engine begins to generate combustion torque, the free wheel disengages to prevent this torque from being transmitted back to the electric machine and accessory pulley, thereby protecting these components from torque shocks while maintaining efficient power transfer in the intended direction
3Reliability
If a fixed connection is used between the gear reduction mechanism and engine crankshaft, then the structure is simple, but the system cannot respond immediately to combustion torque and protect the electric machine
Solution Approach 1:
The free wheel is designed to automatically respond to combustion torque without external control. When the engine generates positive combustion torque during the transition to running phase, the free wheel self-actuates to disengage from the engine crankshaft, immediately preventing torque transmission to the electric machine. This self-service mechanism provides instant protection response while maintaining relatively simple system architecture
Solution Approach 2:
The connection between the gear reduction mechanism and engine crankshaft transitions from fixed to dynamically controllable through the free wheel. The free wheel's engagement state automatically adjusts based on operating conditions: engaged during starting phase for torque transmission, and disengaged during running phase for protection, enabling immediate response to combustion torque with minimal system complexity
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
This solution enables smoother and more responsive transitions between engine phases, preventing damage to the accessory pulley and electric machine, improving the robustness and reliability of the engine arrangement by allowing automatic and immediate disconnection of the engine and electric machine when combustion torque becomes positive, and optimizing power transfer during running phases.
Implementation Method 1
the free wheel, which receives through the third junction element a first torque oriented in one direction, is in an engaged state. This configuration allows transmission of torque from the electric machine to the engine... When combustion is established, the engine accelerates sharply and the crankshaft provides torque. The free wheel, which receives through the third junction element a second torque oriented in an opposite direction, is in a free state
Data Source
Figure 1~4a
Figure 2b~2c
Figure 3b~3c
AI summary
The invention relates to a drive system (1) for an engine arrangement (2), which comprises a gear reduction mechanism (20) such as an epicyclic gearing including: a first junction element (25) connected to an engine crankshaft (5); a second junction element (21) connected to an accessory pulley (9) which is drivingly connected to an electric machine (6) and at least one accessory (7); a third junction element (22). A free wheel (30) is connected to a non-rotating part (16) of the engine arrangement. In a first operating phase of the drive system, the free wheel is coupled to the third junction element and is configured such that: when the third junction element exerts torque on the free wheel in one direction, the free wheel is in an engaged state and stops the rotation of the third junction element; and when the third junction element exerts torque on the free wheel in the opposite direction, the free wheel is in a free state and allows rotation of the third junction element.