Vehicular Oil Pump Discharge Segmentation for Torque Reduction
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Solution Overview
Problem
The existing oil pump systems in vehicular power transmitting systems face challenges in maintaining a low pressure in the low-pressure discharge passage over a broad range of input shaft speeds, leading to increased drive torque and limited speed range of the continuously variable transmission.
Innovation Solution
The system adjusts the amount of discharge from the high-pressure discharge passage to ensure that the working oil of relatively high pressure can be consumed by the amount discharged, maintaining the low-pressure discharge pressure at a predetermined level, even at varying input shaft speeds, by determining the high-pressure discharge amount to be larger than half of the total discharge amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the pressure of working oil in the low-pressure discharge passage is held at a low level to reduce drive torque, then fuel economy is improved, but the pressure difference between pressure chambers causes leakage from high-pressure to low-pressure chambers through gear clearances, reducing discharge amount from high-pressure passage
Solution Approach 1:
The discharge passages are segmented into high-pressure and low-pressure passages, with specific pressure chambers assigned to each. The oil relief groove selectively connects only the specific pressure chamber (located between discharge passages) to the low-pressure discharge passage, while other pressure chambers remain connected only to the high-pressure discharge passage. This segmentation prevents leakage from high-pressure chambers while allowing pressure control in the specific chamber to reduce drive torque.
Solution Approach 2:
The oil relief groove acts as an intermediary pathway that selectively connects the specific pressure chamber to the low-pressure discharge passage. This intermediary structure enables controlled pressure equalization in the specific chamber without affecting other pressure chambers, thereby reducing drive torque while maintaining high-pressure discharge integrity.
2Force
If the oil relief groove is provided to prevent abrupt pressure increase in the specific pressure chamber, then drive torque is reduced, but the leakage from high-pressure discharge passage increases due to increased pressure difference
Solution Approach 1:
The oil relief groove is provided only in the specific pressure chamber located between the high-pressure and low-pressure discharge passages, while other pressure chambers do not have this relief groove. This local differentiation allows the specific chamber to have reduced pressure (lowering drive torque) while other chambers maintain high pressure (preventing leakage).
Solution Approach 2:
The pump chamber is segmented into multiple pressure chambers with different pressure control strategies. The specific pressure chamber is separated from other chambers through the selective provision of the oil relief groove, enabling independent pressure management. This segmentation allows the specific chamber to serve as a pressure relief zone without compromising the pressure integrity of other chambers.
3Quantity of substance
If the high-pressure discharge amount is increased to afford the consumption of high-pressure working oil, then the leakage issue is mitigated, but the drive torque increases due to higher pressure requirements
Solution Approach 1:
The oil relief groove extracts or removes the pressure buildup issue from the specific pressure chamber by providing a dedicated relief pathway to the low-pressure discharge passage. This extraction of the pressure problem from the specific chamber allows the high-pressure discharge system to maintain its integrity and discharge amount without requiring increased drive torque across all chambers.
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 adjustment allows for a broader range of input shaft speed operation with reduced drive torque, ensuring efficient operation of the continuously variable transmission and maintaining the low-pressure discharge pressure, thereby effectively reducing the required drive torque of the oil pump.
Implementation Method 1
a driving gear rotated about its axis by an engine, an annular driven gear having internal teeth meshing with external teeth of the driving gear
Implementation Method 2
a pressure difference between the pressure of the working oil in the specific pressure chamber and the pressure of the working oil in the pressure chamber which is adjacent to the specific pressure chamber and which communicates with the high-pressure discharge passage increases, causing a leakage of the working oil
Data Source
AI summary
A vehicular power transmitting system including an oil pump constructed to sufficiently reduce a required drive torque. A high-pressure-port discharge amount of first and second high-pressure passages of the oil pump is determined such that an amount of consumption of working oil of relatively high pressure can be afforded only by the high-pressure-port discharge amount, during steady-state running of a vehicle in which engine speed is not lower than a predetermined threshold value corresponding to a predetermined lowest target input shaft speed of a continuously variable transmission for its shifting control. The pressure of the working oil discharged from first and second low-pressure discharge passages is kept at a predetermined low level, and the required drive torque of the oil pump is sufficiently reduced.