Axle Drive Motor Assemblies for Industrial Trucks
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Solution Overview
Problem
Industrial trucks with high lifting capacities require powerful axle drives that are costly, space-intensive, and experience delayed reactions to acceleration and braking due to large electric motors and rotating masses, leading to inefficiencies and maintenance challenges.
Innovation Solution
Mechanically coupling multiple small electric motors to form motor assemblies, with connecting gears between the motors and wheel hubs, allowing for individual control of drive torque and speed, and optimizing the arrangement to minimize space and weight while ensuring efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If larger electric motors are used to increase power output, then the power and lifting capacity are improved, but the installation space requirement increases significantly
Solution Approach 1:
The patent divides a single large electric motor into multiple smaller electric motors (at least two per wheel hub). These smaller motors are arranged in a distributed configuration around the axle center line, providing the same total power output while occupying less overall space. The segmentation allows for more efficient space utilization in the axle drive assembly.
2Power
If larger electric motors are used to increase power output, then the desired power increase is achieved, but the cost increases disproportionately
Solution Approach 1:
The patent uses multiple smaller standard electric motors instead of one large custom motor. These smaller motors can be selected from existing standard catalogs, avoiding the need for expensive custom manufacturing. The modular approach allows for more economical procurement and assembly.
3Power
If larger electric motors are used to increase power output, then the power requirement is met, but the installation and assembly effort increases greatly
Solution Approach 1:
The smaller electric motors have reduced dimensions and weight compared to a single large motor, making them easier to handle, position, and install. The modular design allows for simpler assembly procedures and reduced installation effort overall.
4Power
If larger electric motors with greater rotating masses are used, then the power output increases, but the reaction time to acceleration and braking commands increases significantly
Solution Approach 1:
The patent reduces the rotating mass by using multiple smaller motors with smaller rotors instead of one large motor with a large rotor. The total moment of inertia is reduced, allowing the axle drive to respond more quickly to acceleration and braking commands while maintaining the required power output.
5Power
If larger electric motors are used to increase power output, then the power requirement is satisfied, but the heat losses increase
Solution Approach 1:
The patent arranges multiple smaller electric motors to operate within their optimal efficiency ranges. Each motor operates at a more favorable load point compared to a single large motor operating at high power demand, reducing overall energy losses and heat generation.
Data Source
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AI summary
The invention relates to an axle drive of a mobile working machine, in particular a forklift truck, with electric motors (E1, E2, E3, E4) for driving two individually driven wheel hubs (2, 3) arranged on an axle centerline (A). In order to optimize the axle drive with increased performance, particularly with regard to relatively low construction and assembly costs and minimal space requirements, it is proposed that the wheel hubs (2, 3) are each connected to at least two electric motors (E1, E2 or E3, E4) mechanically coupled to each other to form a motor assembly (M1 or M2).