Four-Wheel Drive Torque Control for Drivetrain Noise Suppression
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Solution Overview
Problem
Four-wheel drive vehicles experience noise generation due to torsional vibration resonance between bevel gears, leading to teeth rattling, especially when switching between all-cylinder and reduced-cylinder operating modes, which also results in drive loss and fuel economy degradation.
Innovation Solution
A four-wheel drive vehicle configuration with a torque transmission assembly and a controller that adjusts the torque ratio to the auxiliary drive wheels using a torque ratio adjusting device and noise suppression module, increasing the torque ratio in specific engine operating ranges to suppress noise generation in both all-cylinder and reduced-cylinder modes, while minimizing fuel economy degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coupling is fully fastened to transmit power to rear wheels, then four-wheel drive capability is improved, but drive loss increases and fuel economy degrades
Solution Approach 1:
The coupling degree between the transfer case and rear wheels is made dynamically adjustable rather than fixed. The coupling 28 can vary its engagement state between fully fastened, partially fastened, and fully released, allowing the torque transmission system to adapt its configuration based on driving conditions, thus optimizing the balance between four-wheel drive capability and fuel economy.
Solution Approach 2:
The torque distribution ratio to rear wheels is changed as a control parameter. By adjusting the coupling 28's engagement state, the torque ratio applied to rear wheels varies continuously, enabling the system to operate in different drive modes (two-wheel drive, four-wheel drive with partial torque, full four-wheel drive) to minimize energy loss while maintaining necessary traction.
2Object-affected harmful factors
If torque is increased to suppress noise from drivetrain resonance, then noise generation is reduced, but drive loss increases and fuel economy degrades
Solution Approach 1:
The patent addresses drivetrain resonance by applying controlled vibration countermeasures. The noise suppression module 34 detects resonance conditions in the drivetrain (including bevel gears, propeller shaft, and rear-wheel differential device) and adjusts torque distribution to counteract the resonant vibrations, thereby suppressing noise while minimizing additional energy consumption through precise control.
Solution Approach 2:
The noise suppression module 34 implements a feedback control mechanism that monitors drivetrain operating conditions and torque variations, identifies resonance states, and automatically adjusts the coupling 28's torque distribution accordingly. This closed-loop control ensures noise suppression is activated only when resonance is detected, avoiding unnecessary energy loss during normal operation.
3Loss of energy
If the coupling is partially fastened to reduce drive loss, then fuel economy is improved, but noise suppression capability deteriorates during resonance
Solution Approach 1:
The coupling 28 maintains dynamic adjustability that allows it to transition from a partially fastened state (for fuel economy) to a state that provides sufficient torque transmission for noise suppression when resonance is detected. The noise suppression module 34 controls this dynamic adjustment in real-time based on drivetrain conditions.
Solution Approach 2:
The noise suppression module 34 detects early signs of drivetrain resonance and preemptively adjusts the coupling 28's torque distribution before full resonance occurs. This preliminary anti-action prevents noise generation while minimizing the duration and magnitude of torque increases, thereby reducing associated energy losses.
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
Effectively reduces noise generation and maintains fuel economy by dynamically adjusting torque distribution to match engine operating modes, preventing resonance-induced noise and drive loss.
Implementation Method 1
a coupling capable of varying a transmission torque may be disposed on the propeller shaft. When the coupling is fully fastened (i.e., engaged), an output torque of the engine is evenly applied to the front and rear wheels
Implementation Method 2
a pair of bevel gears meshed with each other, specifically, a bevel gear provided on an extended line of a central axis of the front-wheel differential device and a bevel gear provided on an extended line of a central axis of the propeller shaft, are used to transmit power
Implementation Method 3
the drivetrain having a predetermined characteristic frequency of vibration with respect to torsional vibration co-resonates with the frequency of the torque variation of the engine and causes a large vibration in the drivetrain
Implementation Method 4
Depending on the oscillation frequency of the torque variation of the engine, the drivetrain having a predetermined characteristic frequency of vibration with respect to torsional vibration co-resonates with the frequency of the torque variation of the engine
Data Source
AI summary
A four-wheel drive vehicle is provided, including an engine with an operating mode that is switchable between all-cylinder and reduced-cylinder operating modes, a torque transmission assembly for transmitting an output torque of an engine to main drive wheels and auxiliary drive wheels, a torque ratio adjusting device included in the torque transmission assembly and configured to adjust a ratio of the output torque distributed to the auxiliary drive wheels, and controller that executes a noise suppression module for increasing the torque ratio provided to the auxiliary drive wheels by the torque ratio adjusting device so as to suppress noise generation at the torque transmission assembly, in the all-cylinder and reduced-cylinder operating modes. The noise suppression device changes the torque ratio provided to the auxiliary drive wheels according to engine operating ranges where the torque transmission assembly is in a noise generating state in the all-cylinder and reduced-cylinder operating modes, respectively.