Dual Planetary Gear Braking for Energy-Efficient Ratio Control
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Solution Overview
Problem
Existing transmission arrangements for electrically propelled working machines, such as haulers and excavators, face energy inefficiency due to the need for constant fluid pressure to lock brake discs, which consumes energy and affects gear ratio control.
Innovation Solution
A transmission arrangement featuring two planetary gear sets with a combined brake mechanism using both a normally disengaged and a normally engaged brake, allowing for controlled friction and energy-efficient locking, enabling improved gear ratio control without continuous hydraulic pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a normally disengaged brake is used to lock the brake disc during gear ratio control, then the gear ratio can be controlled, but constant fluid pressure is required which consumes energy
Solution Approach 1:
The brake mechanism is segmented into two distinct brakes: a first normally disengaged brake for controllable friction during gear ratio changes, and a second normally engaged brake for locking the brake disc in parked positions. This segmentation allows each brake to be optimized for its specific function, eliminating the need for continuous fluid pressure.
Solution Approach 2:
The first brake is engaged only periodically during gear ratio transitions rather than continuously. The brake disc rotates freely during normal operation and is braked only when gear ratio changes are required, converting continuous energy consumption into periodic action.
2Use of energy by moving object
If a normally engaged brake is used to lock the brake disc, then the brake disc can be locked without constant fluid pressure, but controlled friction during gear shifting becomes difficult
Solution Approach 1:
The brake system is divided into two functional segments: the second normally engaged brake provides reliable locking without continuous pressure, while the first normally disengaged brake provides controlled friction during gear ratio transitions. This segmentation resolves the contradiction between locking capability and friction control.
Solution Approach 2:
The first normally disengaged brake acts as an intermediary mechanism that provides the controlled friction needed during gear ratio changes, while the second normally engaged brake serves as the primary locking mechanism. The intermediary first brake enables smooth transitions without requiring the second brake to provide continuous pressure.
3Reliability
If constant fluid pressure is applied to the brake, then the brake disc remains locked, but energy is continuously consumed
Solution Approach 1:
The second normally engaged brake is pre-configured to lock the brake disc in parked positions without requiring continuous fluid pressure. The spring force or mechanical engagement is prepared in advance to maintain the locked state passively, eliminating continuous energy consumption while ensuring reliability.
Solution Approach 2:
The second normally engaged brake is designed to maintain its locking function through self-sustaining mechanical means rather than continuous external energy input. The brake disc remains locked through the inherent mechanical properties of the normally engaged brake system.
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 enhances energy efficiency by reducing energy consumption during braking and gear shifting, allowing for better control of friction and preventing wheel rotation when parked, thus optimizing the transmission for electric machines.
Implementation Method 1
a first normally disengaged brake and a second normally disengaged brake, which are configured to act on the first brake disc and the second brake disc, respectively, to control friction between the brake discs and the first and second normally disengaged brakes
Implementation Method 2
a first normally engaged brake and a second normally engaged brake, which are configured to act on the first brake disc and the second brake disc, respectively
Data Source
AI summary
The present disclosure relates to a transmission arrangement. The transmission arrangement comprises at least a first and a second planetary gear set and a first and a second brake mechanism respectively configured to optionally apply a braking torque to a respective member of the respective planetary gear set. Each one of the first and second brake mechanisms comprises a respective brake disc, a normally disengaged brake for acting on the brake disc, and a normally engaged brake for acting on the brake disc.