Dual-Differential Freewheel Mechanism for Unbraked Coasting
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Solution Overview
Problem
Existing vehicle transmission systems with integrated freewheels suffer from engine braking during coasting, leading to increased fuel consumption and limited flexibility in speed adjustment between wheels, especially during extreme cornering, where one wheel may slide due to predetermined speed ratios.
Innovation Solution
A transmission system with a second differential that reunites the power flows from the first differential, allowing for a flexible output shaft speed greater than or equal to the input shaft speed, and featuring asymmetrical coupling between differentials to enable freewheeling without engine braking, where the output shaft can accelerate unbraked even when the input shaft slows down.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a freewheel mechanism with predetermined speed ratios is used to limit output shaft speed, then the output shaft speed can be controlled within a narrow range, but the wheels cannot achieve true freewheeling during coasting and engine braking occurs
Solution Approach 1:
The transmission system is segmented into two independent differential units (first differential 4 and second differential 5) that can operate semi-independently. The first differential handles power transmission during driving, while the second differential enables freewheeling during coasting by allowing the output shaft to rotate faster than the input shaft without engaging the freewheel mechanism.
Solution Approach 2:
The coupling between the first and second differentials is designed asymmetrically, where one rotary connection of the first differential couples to a rotary connection of the second differential rotating at the same speed and direction, while another couples to one rotating at the same speed but opposite direction. This asymmetry enables the system to differentiate between driving and coasting conditions.
2Speed
If the output shaft speed is predetermined by the gear ratio, then the transmission maintains a fixed relationship between input and output speeds, but the output shaft cannot accelerate independently during coasting
Solution Approach 1:
The system dynamically switches between two operational modes: during driving, the freewheel is engaged and the output shaft speed is predetermined by the gear ratio; during coasting, the freewheel disengages and the output shaft can rotate at speeds exceeding the input shaft speed through the second differential, allowing independent acceleration.
3Speed
If the differential force distribution is predetermined by a locked freewheel, then the rotational speeds are completely determined, but the wheels cannot adjust to different distance requirements during extreme cornering
Solution Approach 1:
The power flow is segmented into two separate differential paths, allowing each differential to independently adjust its force distribution. This segmentation enables the system to accommodate different speed requirements at the wheels during extreme cornering without being constrained by a single predetermined ratio.
4Power
If the engine speed is continuously coupled to the driven wheels, then power transmission is maintained, but fuel consumption increases during coasting due to engine braking
Solution Approach 1:
The system periodically engages and disengages the freewheel mechanism based on operating conditions. During coasting, the freewheel disengages, allowing the output shaft to rotate independently of the engine, eliminating engine braking and reducing fuel consumption. During acceleration, the freewheel re-engages to restore power transmission.
Data Source
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AI summary
The invention relates to a transmission with a freewheel and an integrated, first differential, comprising at least one toothed planetary gear rotatably mounted in a first planetary gear carrier, which meshes with two internal ring gears on two further rotary connections of the first differential, the speeds of which exceed the rotational speed of the first planetary gear carrier in determine the first differential, further with a second differential, comprising at least one in a second planetary gear carrier rotatably mounted, toothed planetary gear, which meshes with two internal ring gears on two further rotary connections of the second differential, the speeds of which determine the speed of the second planetary gear carrier in the second differential , wherein a rotating connection of the first differential, whose internal ring gear meshes with at least one planet wheel of the first differential, is coupled to one of the three rotating connections of the second differential in such a way that these two rotating connections coupled to one another ues rotate at the same speed, and wherein another rotary connection of the first differential, whose internal ring gear meshes with at least one planet wheel of the first differential, is coupled to another of the three rotary connections of the second differential in such a way that these two rotary connections coupled to one another have oppositely equal rotations Speeds rotate, and finally at least one of the two rotary connections of the first differential coupled to the second differential remains unaffected from the outside, so that its speed can adjust freely when a pulling torque is applied to an output shaft of the transmission coupled to the second differential, so that the output speed can increase under the influence of the pulling torque without affecting the input speed.