Switched Reluctance Motor Planetary Gear Speed Multiplication
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Solution Overview
Problem
Current parallel hybrid systems for vehicles are inefficient in recovering and storing braking energy at low speeds due to motor inefficiency, which decreases significantly as motor speed decreases, particularly in applications like mass transit and refuse collection.
Innovation Solution
Incorporating a switched reluctance motor with a planetary gear assembly into the vehicle driveline, allowing the motor to operate at a higher speed range by gearing the rotor to rotate at least three times faster than the through-shaft, thereby maintaining high efficiency even at low speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a motor is used to recover braking energy in a parallel hybrid system, then energy storage capability is improved, but motor efficiency deteriorates at low speeds
Solution Approach 1:
A planetary gear assembly is introduced as an intermediary mechanism between the motor and the driveline. The gear assembly includes a sun gear connected to the motor shaft, planet gears, and a ring gear connected to the driveline. This intermediary allows the motor to operate at higher speeds independently of the driveline speed, maintaining motor efficiency while still enabling energy recovery at low vehicle speeds.
Solution Approach 2:
The invention changes the speed parameter relationship between the motor and the driveline through the planetary gear system. The gear ratio allows the motor speed to be several times higher than the driveline speed, so the motor operates in its high-efficiency high-speed range even when the vehicle is moving at low speeds during braking events.
2Loss of energy
If motor speed is increased to maintain high efficiency, then motor efficiency is improved, but device complexity increases
Solution Approach 1:
The planetary gear assembly serves multiple functions: it acts as a speed multiplier to maintain motor efficiency, functions as a clutch to disconnect the motor from the driveline when not needed, and provides a compact structure that integrates seamlessly into the existing driveline. This multi-functionality reduces the need for additional separate components.
Solution Approach 2:
The planetary gear assembly is nested within the motor housing, with the sun gear connected to the motor shaft and the ring gear connected to the driveline. This nested configuration minimizes space requirements and integrates the speed-multiplying function directly into the motor assembly without requiring separate external gearboxes.
Data Source
Figure 1~4
Figure 5~6
AI summary
A switched reluctance motor includes a stator (36), a rotor (40), and a planetary gear assembly (48). The rotor (40) defines an internal cavity that houses the planetary gear assembly (48). The switched reluctance motor receives input and provides output through a common single shaft (22). The shaft (22) is part of a vehicle driveline and can be positioned to provide driving input to a transmission or drive axle, for example. The planetary gear assembly (48) includes a planet carrier (56a,56b) that is fixed for rotation with the shaft (22) and a sun gear (50a,50b) that is coupled to the rotor (40). The planetary gear assembly (48) allows the rotor (40) to rotate at a higher speed than the shaft (22) such that the switched reluctance motor can operate more efficiently for low speed vehicle applications.