CVT Electric Oil Pump Control for Noise Suppression
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Solution Overview
Problem
In continuously variable transmissions with hydraulic circuits, starting the engine in a no-oil state leads to air entrainment and noise generation due to the lack of oil in the shift oil passage, causing operational issues and potential pump deterioration.
Innovation Solution
The control method involves restricting the operation of the electric oil pump until oil is filled in the secondary pulley oil chamber, ensuring oil pressure is supplied by the source pressure oil pump before allowing the electric oil pump to control oil flow between the primary and secondary pulley oil chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If shift control is started in a no-oil state, then the electric oil pump can immediately perform shift operations, but air entrainment occurs and noise is generated
Solution Approach 1:
The control device checks whether the shift oil passage is filled with oil before allowing the electric oil pump to operate. This preliminary check prevents the pump from running in a no-oil state, eliminating air entrainment and noise generation while maintaining ready-to-shift capability once oil is present
2Productivity
If the electric oil pump operates without oil in the shift oil passage, then shift control can be initiated, but the pump may deteriorate due to lack of lubrication
Solution Approach 1:
The control device performs a preliminary determination to check if the shift oil passage contains oil before permitting electric oil pump operation. This prevents the pump from running without lubrication, ensuring reliability while maintaining shift control readiness
Solution Approach 2:
The control device continuously monitors the oil presence in the shift oil passage and uses this feedback to control the electric oil pump operation. The pump is enabled only when oil is detected, creating a feedback loop that protects pump durability while ensuring shift control availability
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
This approach effectively suppresses noise generation and prevents pump deterioration by ensuring the hydraulic circuit is filled with oil before initiating shift control, maintaining optimal lubrication and reducing operational hazards.
Implementation Method 1
supplying oil pressure to a secondary pulley oil chamber by a source pressure oil pump
Implementation Method 2
controlling an flow of oil into and from a primary pulley oil chamber by an electric oil pump arranged in an oil passage
Data Source
AI summary
A control method of a continuously variable transmission includes supplying oil pressure to a secondary pulley oil chamber by a source pressure oil pump, and controlling a flow of oil into and from a primary pulley oil chamber by an electric oil pump arranged in an oil passage between the primary pulley oil chamber and the secondary pulley oil chamber. After start-up of the source pressure oil pump, an operation of the electric oil pump is restricted until the oil is filled in the oil passage on the secondary pulley oil chamber side of the electric oil pump. The operation of the electric oil pump is permitted when rotation speed of the electric oil pump reaches a predetermined rotation speed.