Four-Wheel Drive Vehicle Propeller Shaft Speed Synchronization
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Solution Overview
Problem
Existing four-wheel drive vehicles experience noise and vibration issues during mode switching from two-wheel drive to four-wheel drive due to sharp changes in propeller shaft rotational speed, which can discomfort drivers and passengers.
Innovation Solution
A four-wheel drive vehicle system with a dog clutch, multi-plate clutches, and a hydraulic circuit controlled by a control device that synchronizes the rotational speed of the propeller shaft using torque from one auxiliary drive wheel while preventing torque transmission from the other clutch to manage the switching process, thereby minimizing noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If torque is transmitted from both hydraulic clutches simultaneously to increase propeller shaft speed during mode switching, then the switching speed from two-wheel drive to four-wheel drive is improved, but noise and vibration increase due to sharp rotational speed changes
Solution Approach 1:
The patent divides the torque transmission process into two separate phases: first, torque is transmitted from only one hydraulic clutch (first hydraulic clutch) to gradually increase the propeller shaft speed and synchronize the meshable members of the dog clutch; second, after synchronization is achieved, torque transmission from the other hydraulic clutch (second hydraulic clutch) is engaged. This segmentation prevents simultaneous torque application that would cause sharp speed changes, thereby reducing noise and vibration while maintaining quick switching performance.
2Device complexity
If the same amount of hydraulic oil is supplied to both hydraulic clutches at the same time, then the system operation is simplified, but the switching time from two-wheel drive to four-wheel drive mode increases
Solution Approach 1:
The patent applies preliminary action by first supplying hydraulic oil to the first hydraulic clutch before supplying oil to the second hydraulic clutch. This sequential engagement ensures that the propeller shaft speed is gradually increased through controlled torque transmission from the first clutch, achieving synchronization of the dog clutch meshable members. Only after this preliminary synchronization is achieved is the second clutch engaged, preventing sharp speed changes and noise while maintaining efficient switching timing.
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
Enables quick switching between two-wheel and four-wheel drive modes while suppressing noise and vibration, improving the driving experience by controlling the rotational speed synchronization and torque distribution.
Implementation Method 1
a hydraulic circuit that supplies hydraulic oil to the pair of hydraulic clutches to bring multiple clutch plates into frictional contact with each other
Implementation Method 2
bring multiple clutch plates into frictional contact with each other
Implementation Method 3
increases the speed of the rotation of the propeller shaft by using torque transmitted from the auxiliary drive wheels through the hydraulic clutches
Data Source
AI summary
A four-wheel drive vehicle includes a dog clutch that selectively interrupts transmission of a drive force to a propeller shaft, first and second multi-plate clutches that selectively interrupt transmission of the drive force from the propeller shaft to left and right rear wheels, first and second pistons that press the first and second multi-plate clutches, and a hydraulic circuit that supplies hydraulic oil to first and second cylinder chambers. During a transition to a four-wheel drive mode, torque transmitted through the first multi-plate clutch increases the speed of rotation of the propeller shaft so as to engage the dog clutch, and the second multi-plate clutch is kept from transmitting torque to the propeller shaft.