Planetary Gear Hub Motor for Dual-Speed Heavy Equipment
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Solution Overview
Problem
Heavy equipment with wheel-specific hub motors are limited by space constraints, typically available only in single-speed versions, leading to slow site-to-site driving speeds and inefficient torque characteristics.
Innovation Solution
An electric motor construction with a planetary gear system, featuring an annular stator, torque takeoff shaft, sun gear, ring gear, planet gears, and a coupling arrangement allowing for direct high-speed, low-torque transmission or low-speed, high-torque transmission through the planetary gear system, enabling separate slow and fast driving modes without additional brake components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single-speed hub motor is used due to space constraints, then the motor can be mounted on the wheel hub, but the site-to-site driving speed becomes unnecessarily slow
Solution Approach 1:
The patent applies a planetary gear system with variable gear ratios that can dynamically switch between low-range and high-range modes. The gear system includes a sun gear, planet gears, and a ring gear that can engage different gear ratios based on operating conditions, enabling the hub motor to adapt between slow working speeds and fast traveling speeds.
Solution Approach 2:
The hub motor construction integrates multiple functions into a single device by combining the electric motor with a planetary gear system. This universal design allows the same motor unit to provide both low-speed high-torque operation for working and high-speed operation for site-to-site travel, eliminating the need for separate mechanical drive trains.
2Force
If motors are selected for low-speed working requirements, then low-speed performance is improved, but site-to-site driving proceeds at unnecessarily slow speed
Solution Approach 1:
The planetary gear system changes the transmission ratio parameter to match different operating requirements. In low-range mode, a lower gear ratio provides high torque multiplication for working operations. In high-range mode, a higher gear ratio reduces torque multiplication but increases output speed for site-to-site travel, thus resolving the contradiction between torque and speed requirements.
3Adaptability or versatility
If a mechanical drive train with low-range and high-range gear systems is used, then speed adaptability is improved, but the device complexity increases
Solution Approach 1:
The planetary gear system employs a nested structure where planet gears are arranged around a sun gear and contained within a ring gear. This compact nested arrangement allows multiple gear ratios to be integrated within the limited space of the wheel hub, providing both low-range and high-range capabilities without requiring separate external gear systems.
Solution Approach 2:
The patent merges the electric motor and planetary gear system into a single integrated hub motor unit. This combination consolidates what would traditionally be separate components (motor, transmission, differential) into one compact assembly, reducing overall system complexity while maintaining the capability for both low-speed working and high-speed travel.
4Volume of moving object
If the space in wheel hub is limited, then the motor can be mounted on hub, but the motor must come in single-speed version
Solution Approach 1:
The planetary gear system is nested within the motor housing and wheel hub structure, utilizing the limited radial and axial space efficiently. The compact epicyclic gear train fits within the annular space between the motor rotor and the wheel hub, enabling multi-speed functionality without increasing the overall wheel hub dimensions.
Data Source
AI summary
An electric motor construction is provided with a planetary gear system, including an annular thin-rimmed stator (1) as well as a torque takeoff shaft (2) concentric relative thereto. The construction includes inside the stator (1) an annular thin-rimmed rotor (3); a sun gear (4) fixedly coupled to the rotor and concentric with the takeoff shaft (2); an intra-rotor immovably coupled ring gear (5) with a toothed inner surface; planet gears (6) meshing with the ring gear and the sun gear; a planet carrier (7) that the planet gears are supported on; as well as a coupling arrangement (8) for transmitting torque of the rotor optionally directly or by way of the planet carrier to the torque takeoff shaft.