Four-Wheel Drive Planetary Gear Neutral Mode
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Solution Overview
Problem
Existing four-wheel driving systems for vehicles fail to prevent excessive load on the transmission and torsion phenomena caused by rotation differences between front and rear wheels, especially when driving on rough roads or getting stuck, leading to potential damage and inability to escape slough conditions.
Innovation Solution
A four-wheel driving apparatus featuring a planetary gear set, counter shaft, sleeve, center differential, and transfer gear device that allows selective coupling between the sun gear and carrier, enabling neutral mode operation to prevent excessive rotational force transfer and torsion, using a no-slip differential to maintain power distribution between front and rear wheels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a differential gearing is used to allow wheels to rotate smoothly during turns, then the vehicle can navigate curve roads without slipping, but when one wheel falls into a slough, all power passes through the slough wheel and cannot be transferred to grounded wheels
Solution Approach 1:
The differential mechanism is segmented into multiple independent power transfer paths through the planetary gear set, allowing power to be distributed to both slough and grounded wheels simultaneously. The carrier and planet gears create separate torque transmission routes that prevent complete power loss to the slough wheel.
Solution Approach 2:
The system changes the torque distribution parameter dynamically by using the planetary gear mechanism to provide different gear ratios to front and rear wheels. This allows the system to adapt power distribution based on wheel load conditions, maintaining traction when one wheel is in slough.
2Reliability
If a limited slip differential gear is used to distribute power to both low and high resistance wheels, then the vehicle can drive on rough roads, but excessive load and torsion occur in the transmission when the vehicle is towed
Solution Approach 1:
The planetary gear set provides dynamic torque distribution that automatically adjusts based on load conditions. During normal driving, it limits slip by distributing power to both wheels. During towing, the mechanism dynamically adapts to prevent excessive torque from being transmitted to the transmission.
Solution Approach 2:
The planetary gear mechanism acts as an intermediary between the transmission and the wheel differentials. It mediates torque transmission by providing gear reduction and torque distribution, preventing excessive load from reaching the transmission while still enabling power distribution to both wheels during rough road driving.
3Power
If a planetary gear set is used to transfer power to front and rear wheels, then power distribution is maintained, but rotation difference between front and rear wheels causes torsion phenomenon
Solution Approach 1:
The power transfer system is segmented into independent front and rear wheel differential units, each capable of handling rotation differences locally. This segmentation allows each wheel pair to rotate at different speeds without creating torsion in the main transmission shaft.
Solution Approach 2:
The planetary gear set serves as an intermediary that decouples the rotation speeds of front and rear wheels. By providing gear reduction and independent differential action at each wheel pair, it mediates the rotation difference and prevents torsion from being transmitted back to the power source.
Data Source
AI summary
A four-wheel driving apparatus for a vehicle may include a planetary gear set including a sun gear, a carrier, and a ring gear, and provided so that the sun gear is coupled to a transmission output shaft; a counter shaft provided in parallel to the transmission output shaft; a sleeve included in the counter shaft, receiving operating force of a shift fork to slide along a longitudinal direction of the counter shaft, and provided to be selectively coupled to any one of the sun gear and the carrier of the planetary gear set according to a sliding position; a center differential connected to a front differential through a front output shaft and connected to a rear differential through a rear output shaft; and a transfer gear device disposed to connect between the counter shaft and any one of the front output shaft and the rear output shaft.