Wheel Loader Brake-Gear Layout for Compact Electric Drivetrains
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Solution Overview
Problem
Existing mobile work machines, such as wheel loaders and excavators, face challenges with bulky and costly drive and brake systems, inefficiencies in electric drives, and the need for separate brake systems due to limited recuperation capabilities, leading to space and cost inefficiencies.
Innovation Solution
A compact brake system where the gearbox unit is integrated between the drive wheel and brake element, allowing for the transfer of braking force through the gear unit, eliminating the need for a central joint shaft and enabling a strong braking system with a small, inexpensive brake unit, and utilizing electric motors with a hydraulic pump for hybrid operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate braking system is provided for each wheel hub, then sufficient braking performance is achieved, but space requirements and cost increase significantly
Solution Approach 1:
The brake unit is merged with the transmission unit to form an integrated braking system. The transmission unit's gear mechanism is used to amplify the braking force generated by a single brake unit, eliminating the need for separate brake systems at each wheel hub while maintaining sufficient braking performance and reducing overall space requirements.
Solution Approach 2:
The transmission unit serves dual functions: power transmission from the electric motor and force amplification for the braking system. This multi-functionality allows the same mechanical components to serve both drive and brake functions, reducing the need for dedicated braking components at each wheel.
2Power
If a cardan shaft is used to transmit power from the central engine, then power transmission is achieved, but the overall height and weight of the machine increase
Solution Approach 1:
The power transmission system is segmented into distributed electric motors located at or near each transmission unit, eliminating the need for a central engine and cardan shafts. This segmentation allows for a lower overall machine height while maintaining effective power transmission to the drive wheels.
3Force
If a minimum gear ratio is used between the electric motor and impeller, then high torque is achieved, but the size and cost of the electric motor increase
Solution Approach 1:
The transmission unit is merged into the braking system, allowing the same gear mechanism to serve both power transmission and braking force amplification functions. This integration enables the use of a smaller, more cost-effective electric motor while maintaining the required torque output through the transmission's gear ratio.
4Reliability
If brakes are assigned directly to each wheel hub, then braking performance is ensured, but the system becomes cost-intensive and space-consuming
Solution Approach 1:
The brake unit is combined with the transmission unit to form an integrated braking system. This merger reduces the number of independent braking components from four (one per wheel hub) to a single centralized brake unit, simplifying the overall system while maintaining effective braking performance through the transmission's force amplification capability.
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 configuration results in a more compact, cost-effective, and efficient drive and brake system, reducing space requirements and operational costs while enhancing braking performance, allowing for a more efficient and flexible implementation of electric drives in mobile work machines.
Implementation Method 1
the gear unit is arranged in/within the brake row at least between the at least one drive wheel and the brake element, so that a braking force of the brake unit and/or the brake element can be transmitted via the gear unit to the at least one drive wheel
Data Source
Figure 1~2
AI summary
A mobile working machine (1), in particular a wheel loader (1) or the like, with a vehicle frame (2) and with an electric motor (4) and at least one electrical energy storage device for storing drive energy for the electric motor (4), wherein at least one transmission unit (5) is provided, wherein at least one brake unit (7, 16) separate from the electric motor (4) and having at least one brake element (22) is provided for braking the at least one drive wheel (20), is proposed which at least partially improves the disadvantages of the prior art.According to the invention, this is achieved by providing a brake series in operative connection, consisting of the brake element (22) of the brake unit (7, 16) and the gear unit (5) as well as the at least one drive wheel (20), wherein the gear unit (5) is arranged at least between the at least one drive wheel (20) and the brake element (22), so that a braking force of the brake unit (7, 16) and/or the brake element (22) can be transmitted via the gear unit (5) to the at least one drive wheel (20).