CVT Brake System for Slope Descent Control
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Solution Overview
Problem
Vehicles equipped with continuously variable transmission (CVT) lack a means to prevent unexpected acceleration when descending slopes, as the CVT's clutch-disengagement action isolates the belt and output shaft from the engine's power, leading to repetitive braking and potential brake fade or vapor lock.
Innovation Solution
A brake system that uses a hydraulic pump and circuit to create resistance against the CVT output shaft, controlled by an accelerator manipulator, mimicking an engine brake by reducing the output rotary speed of the prime mover, thereby preventing unexpected acceleration and reducing the need for repetitive braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the CVT functions as a clutch-disengagement action to isolate the belt and output shaft from the engine power, then the engine can idle stably without load, but the vehicle lacks means to prevent unexpected acceleration when descending slopes
Solution Approach 1:
The patent introduces a brake system as an intermediary component between the CVT output shaft and the braking mechanism. This brake system includes a brake device that can apply braking force to the CVT output shaft independently of the engine's clutch-disengagement action, providing reliable slope control without affecting engine idle stability
Solution Approach 2:
The patent segments the braking function from the clutch-disengagement function. The brake system operates independently on the CVT output shaft, separating the engine idle control (clutch-disengagement) from the vehicle speed control (braking), allowing both functions to perform their respective roles without interference
2Ease of operation
If the operator repeats depressing the brake pedal for braking the axle, then the vehicle can be controlled during descent, but brake fade or vapor lock may occur
Solution Approach 1:
The brake system operates automatically based on vehicle speed and throttle position sensors, eliminating the need for repetitive manual brake pedal depression. The control unit automatically activates the brake device when descent conditions are detected, providing self-service braking that prevents brake fade and vapor lock by avoiding excessive manual braking
Solution Approach 2:
The system incorporates feedback mechanisms through sensors that detect vehicle speed, throttle position, and braking force. The control unit processes this feedback information to automatically modulate the brake application, ensuring optimal braking performance during descent without requiring repetitive manual intervention
3Adaptability or versatility
If the CVT functions as clutch-disengagement action, then the belt and driven pulley are isolated from engine rotation, but the vehicle cannot utilize engine brake effect
Solution Approach 1:
The brake system serves as an intermediary that provides engine brake-like functionality without requiring engine power connection. By applying braking force directly to the CVT output shaft, it replicates the energy recovery effect of engine braking while maintaining the clutch-disengagement isolation between engine and transmission
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
The brake system effectively reduces the rotary speed of the CVT output shaft, preventing unexpected acceleration and prolonging the life of the manipulatable brake by providing a stable braking action without repetitive pedal manipulation.
Implementation Method 1
a hydraulic pump and hydraulic circuit which cause resistance against the rotation of the CVT output shaft
Implementation Method 2
The brake system is configured to cause resistance against the rotation of the CVT output shaft... to reduce the output rotary speed of the prime mover
Data Source
AI summary
A brake system is provided for a vehicle equipped with a continuously variable belt transmission (hereafter a “CVT”) having a CVT input shaft and a CVT output shaft. The CVT functions as a clutch-disengagement action for isolating rotation of the CVT output shaft from the CVT input shaft when a rotary speed of the CVT input shaft is reduced to a certain level. The vehicle is equipped with a prime mover driving the CVT input shaft so that an output rotary speed of the prime mover defines the rotary speed of the CVT input shaft. The vehicle includes an accelerator manipulator for controlling the output rotary speed of the prime mover. The brake system can cause a resistance against the rotation of the CVT output shaft using the accelerator manipulator to reduce the output rotary speed of the prime mover to make the CVT function as the clutch-disengagement action.