Engine Starter Torque Variator for Cold Start Reliability
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Solution Overview
Problem
Existing engine starters face challenges in achieving high speed reduction ratios without reversing the internal gear rotation, leading to potential torque transmission failures and gear breakage during high-speed pinion rotation.
Innovation Solution
Incorporation of a torque variator and one-way clutch in the starter motor system, allowing the planetary carrier and outer gear to lock for initial high-speed engine starting and then release for increased torque transmission, ensuring stable engine start-up, especially in cold conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the movable cam plate is pressed against the stationary cam plate to establish engagement, then the gear reduction ratio is maintained at one for high-speed rotation, but the internal gear may rotate in the opposite direction causing torque transmission failure
Solution Approach 1:
The patent introduces a one-way clutch as an intermediary component between the outer gear and the planetary carrier. This clutch allows the outer gear to rotate in the forward direction (matching sun gear rotation) while preventing reverse rotation. The one-way clutch acts as a mediator that ensures torque is always transmitted in the correct direction, eliminating the reliability issue without affecting the high-speed rotation capability established by the cam plate engagement mechanism.
2Loss of time
If the pinion gear is rotated at high speed to shorten engine starting time, then the engagement depth between pinion and ring gear becomes small, leading to gear breakage
Solution Approach 1:
The patent employs a dynamic speed reduction ratio adjustment mechanism using cam plates and a spring. During engine cranking, the movable cam plate is pressed against the stationary cam plate, establishing a gear reduction ratio of one for high-speed rotation. After engine start, the spring pushes the movable cam plate to disengage, increasing the speed reduction ratio. This dynamic adjustment allows the system to optimize between high-speed rotation (reducing starting time) and adequate engagement depth (preventing gear breakage) at different operational stages.
3Force
If the speed reduction ratio is increased to elevate torque output, then the pinion gear rotation speed decreases, extending the engine starting time
Solution Approach 1:
The patent uses a dynamic speed reduction ratio adjustment mechanism that switches between two states: a reduction ratio of one during engine cranking for high-speed pinion rotation, and a higher reduction ratio after engine start for increased torque output. This dynamic switching resolves the contradiction by allowing the system to prioritize speed during starting and torque after starting, rather than being constrained to a fixed compromise.
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 solution ensures reliable and stable engine starting by maintaining torque transmission in the correct direction, preventing gear breakage and improving startability in cold conditions.
Implementation Method 1
a one-way clutch which permits the outer gear to rotate in a first direction in which the sun gear rotates when the motor rotates to exert the torque on the ring gear for starting the engine and inhibits the outer gear from rotating in a second direction opposite the first direction
Implementation Method 2
a torque variator which works to vary a degree of the torque transmitted from the outer gear to the planetary carrier
Implementation Method 3
a planetary gear train which includes a sun gear installed on an output shaft of the motor, planet gears meshing with the sun gear, an outer gear meshing with the planet gears, and a planetary carrier retaining the planet gears to be rotatable
Data Source
AI summary
A starter for an engine is equipped with a planetary gear train as a torque variator to change torque used to start the engine. The torque variator is capable of changing the degree of torque which is transmitted between a planetary carrier and an outer gear of the planetary gear train, thereby changing a ratio of speed of a sun gear to speed of the planetary carrier of the planetary gear train to increase or decrease the degree of torque required to start the engine. This ensures the stability in starting the engine, for example, in cold conditions and achieves a quick start of the engine as needed.