Rear Clutch Mechanism for Electric 4WD Speed Range Control
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Solution Overview
Problem
Skid-steer loaders with electric motors face challenges in achieving multiple speed ranges and efficient power transmission due to the faster spinning speed of electric motors compared to hydrostatic motors, leading to the need for improved drive mechanisms.
Innovation Solution
A rear clutch mechanism is introduced, comprising first and second clutch packs, spring housings, and hydraulic fluid management to control engagement and disengagement of the clutch packs with the rear axle shaft, allowing for multiple modes of operation including parked, front wheel drive, and four wheel drive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If electric motors are used to replace hydrostatic motors, then oil usage is eliminated and environmental performance is improved, but the faster spinning speed of electric motors requires greater speed reduction, increasing device complexity
Solution Approach 1:
The drive mechanism is segmented into multiple clutch packs (first and second clutch packs) that can independently engage and disengage, allowing selective power transmission to front and rear axles. This segmentation enables the system to manage the high-speed electric motor output through staged speed reduction and selective engagement, reducing the complexity burden on any single component.
Solution Approach 2:
The clutch mechanism employs dynamic engagement and disengagement of clutch packs based on operational requirements. The spring housings and hydraulic fluid system enable dynamic adjustment of clutch engagement states, allowing the drive mechanism to adapt to varying speed and torque requirements, thereby managing the speed reduction demand dynamically rather than through fixed rigid gearing.
2Adaptability or versatility
If a rear clutch mechanism with spring housings and hydraulic fluid is added to control clutch engagement, then multiple speed ranges and improved traction are achieved, but device complexity increases
Solution Approach 1:
The clutch mechanism is designed with multi-functionality to achieve multiple speed ranges and drive modes (front wheel drive, four wheel drive, parked) through a single integrated system. The first and second clutch packs, along with the spring housings and hydraulic fluid, work together to provide versatile operational modes without requiring separate mechanisms for each function, thereby managing complexity through consolidation.
Solution Approach 2:
Hydraulic fluid serves as an intermediary medium to control the engagement and disengagement of clutch packs. The fluid transmits force to the spring housings, which in turn control the clutch packs' engagement with the rear axle shaft. This intermediary hydraulic system provides smooth, controlled engagement and disengagement, enabling multiple speed ranges without requiring complex mechanical linkages.
3Ease of operation
If hydraulic fluid is used to move spring housings away from clutch packs for disengagement, then precise control of clutch engagement is achieved, but the system requires additional hydraulic components and fluid management
Solution Approach 1:
The spring housings are designed to automatically engage and disengage clutch packs through the action of springs and hydraulic fluid pressure. When hydraulic fluid is introduced, it naturally pushes the spring housings away from the clutch packs, utilizing the fluid's pressure to perform the disengagement action without requiring additional actuators or complex control mechanisms. The system leverages the inherent properties of hydraulic fluid and spring force to achieve self-service operation.
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 rear clutch mechanism enables multiple speed ranges and improved traction by allowing for precise control of clutch engagement, eliminating free-wheeling, and providing better stability and room under the cab, while adapting to the faster spinning electric motors.
Implementation Method 1
a first cavity defined between the assembled first and second spring housings, the first cavity fluidly connected to a hydraulic hose to receive hydraulic fluid to increase hydraulic pressure therein; and when the first cavity contains hydraulic fluid, the first spring housing moves away from the first clutch pack and the second spring housing moves away from the second clutch pack
Implementation Method 2
the first and the second spring housings together form a first spring recess configured to receive a first spring; when the first cavity does not contain hydraulic fluid, the first spring is in an active state to push the first and second spring housings, respectively, against the first and second clutch packs, respectively
Data Source
AI summary
A rear mechanism for a work machine includes first and second spring housings operably engaged by one or more springs. The first and second spring housings are assembled with an endcap housing between first and second clutch packs that engage a rear axle of the work machine. A first cavity is formed between the first and second spring housing, and a second cavity is formed between the first housing and the endcap housing. Pressurizing the first cavity compresses the springs and releases a park brake of the work machine to enable front wheel drive of the work machine. While pressurizing the first cavity, the second cavity is pressurized such that the first spring housing compresses the first clutch pack to enable four wheel drive of the work machine.