Torque Distribution Control for Four-Wheel Drive Vehicles
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Solution Overview
Problem
Existing torque distribution systems in four-wheel drive vehicles face challenges in balancing traction between front and rear wheels, leading to reduced starting performance and potential durability issues in the rear differential gear when excessive torque is distributed to the rear wheels.
Innovation Solution
A torque distribution control apparatus that includes a vehicle-speed detector, wheel-speed detector, sub-driving-wheel distribution-torque calculator, and torque limiter, which calculates and limits the sub-driving-wheel distribution torque based on predetermined conditions to prevent excessive torque transmission to the rear wheels, ensuring balanced traction and protecting the rear differential gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine speed or engine output torque is limited to protect the rear differential gear, then the durability of the rear differential gear is improved, but the total traction of the front wheels and rear wheels decreases, reducing starting performance
Solution Approach 1:
The patent changes the control parameter from limiting engine output torque to directly limiting the sub-driving-wheel distribution torque. This allows the engine to operate at full power while the torque distribution to rear wheels is controlled, resolving the contradiction between protecting the differential gear and maintaining starting performance
Solution Approach 2:
The patent introduces a torque limiter as an intermediary component between the engine and the rear differential gear. This torque limiter directly controls the torque transmitted to rear wheels, acting as a mediator that protects the differential gear without requiring reduction of engine output, thus maintaining starting performance
2Force
If the sub-driving-wheel distribution torque is increased to suppress front wheel slip, then the traction in rear wheels is improved, but the load on the rear differential gear increases excessively, reducing durability
Solution Approach 1:
The patent changes the control approach by directly limiting the sub-driving-wheel distribution torque parameter rather than controlling it through engine output limitation. This enables precise control of torque magnitude to ensure adequate traction while preventing excessive load on the differential gear
Solution Approach 2:
The patent implements a feedback control mechanism where the torque limiter monitors the sub-driving-wheel distribution torque and adjusts it to remain within safe limits. This feedback loop ensures that traction requirements are met while preventing durability-damaging excessive loads on the rear differential gear
Data Source
AI summary
A torque distribution control apparatus for a four-wheel drive vehicle includes a vehicle-speed detector configured to detect a vehicle speed of the vehicle. A wheel-speed detector is configured to detect wheel speeds of main driving wheels and sub-driving wheels of the vehicle. A sub-driving-wheel distribution-torque calculator is configured to calculate a sub-driving-wheel distribution torque in accordance with a rotation speed difference between the main driving wheels and the sub-driving wheels calculated based on an output from the wheel-speed detector. A torque limiter is configured to limit an upper limit of the sub-driving-wheel distribution torque. A controller is configured to control the sub-driving-wheel distribution torque to be transmitted to the right and left sub-driving wheels by right and left torque distribution clutches in accordance with a driving state of the vehicle.