Toroidal CVT for Motor Vehicle Power Take-Off
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power take off (PTO) systems in motor vehicles face issues such as sudden engine stall during launch due to speed mismatches, wheel slip and power recirculation in trailers, inefficient energy use, and overload problems when handling varying loads, particularly in agricultural and military applications.
Innovation Solution
A torque-controlled continuously variable transmission system with a toroidal-race rolling-traction type variator that regulates reaction torque and automatically adjusts drive ratio to accommodate changes in speed and load, allowing for controlled launch, reduced wheel slip, and efficient engine operation by maintaining constant speed and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional fixed ratio gearbox is used to provide fixed PTO speed, then the PTO can operate at a constant required speed, but the engine must run at fixed high speed even when low power is needed, resulting in unnecessary fuel consumption
Solution Approach 1:
The patent applies a continuously variable transmission (CVT) instead of a fixed ratio gearbox, allowing the drive ratio to be dynamically adjusted. This enables the engine speed to vary according to actual power demands while maintaining the required PTO speed, thereby reducing fuel consumption when high power is not needed.
Solution Approach 2:
The invention changes the fixed parameter (drive ratio) to a variable parameter through the use of CVT. The drive ratio can be continuously adjusted to match the power requirements of the implement, allowing the engine to operate at lower speeds when less power is required, thus improving energy efficiency.
2Speed
If a clutch is engaged to accelerate the PTO from standstill to operating speed, then the PTO can be launched, but the speed mismatch between engine and PTO shaft causes sudden shock and may stall the engine
Solution Approach 1:
The CVT allows the drive ratio to be dynamically adjusted during launch. As the PTO accelerates from standstill, the transmission can continuously vary the ratio to match the engine speed with the PTO shaft speed, preventing sudden shocks and engine stalling while achieving smooth acceleration.
Solution Approach 2:
The system performs preliminary speed matching through continuous ratio adjustment before full power engagement. The CVT prepares the speed relationship between engine and PTO shaft in advance, ensuring smooth acceleration without shock loads that could cause engine stall.
3Power
If fixed drive ratios are used to provide high engine speed for peak power, then high power can be provided to the implement, but the engine cannot slow down when the load decreases, leading to inefficient energy use
Solution Approach 1:
The continuously variable transmission enables dynamic adjustment of the drive ratio based on actual power demands. When the implement requires less power, the transmission ratio is adjusted to allow the engine to operate at lower speeds, maintaining energy efficiency while still providing the necessary power when needed.
Solution Approach 2:
The invention transforms the fixed drive ratio parameter into a variable one, allowing continuous adjustment of the relationship between engine speed and PTO speed. This enables the engine to match its operating speed to the actual power requirements, improving energy efficiency across varying load conditions.
4Power
If the PTO is allowed to slow down to handle varying loads, then the engine can maintain high speed for high power, but conventional fixed ratio transmissions cannot accommodate speed changes
Solution Approach 1:
The CVT provides dynamic adaptability by continuously adjusting the drive ratio in response to varying loads. When the load increases and the PTO tends to slow down, the transmission adjusts the ratio to maintain engine speed for high power availability while accommodating the PTO speed changes.
Solution Approach 2:
The invention changes the fixed transmission ratio parameter to a variable parameter that can adapt to different operating conditions. This allows the system to maintain engine speed for high power output while permitting PTO speed to vary according to load requirements, achieving both power availability and adaptability.
Data Source
AI summary
A drive arrangement is disclosed for a motor vehicle power take off (PTO). The arrangement comprises a PTO shaft 104,158,207 of a known type intended for coupling to a power driven implement. An input shaft is arranged to be coupled to a rotary driver such as an engine. A continuously variable transmission such as 10 is coupled between the input and PTO shafts to transfer drive between them at a continuously variable ratio. In accordance with the invention, the continuously variable transmission is constructed and arranged such as to regulate torque and to automatically accommodate changes in speed at the PTO Shaft by virtue of changes in its drive ratio.