Step-Change Transmission Dual Pump Segmentation
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Solution Overview
Problem
Existing step-change transmissions face inefficiencies due to single pumps that either waste power by maintaining high fluid line pressure when demand is low or cavitate under high-pressure demands, leading to energy loss and operational instability.
Innovation Solution
A transmission system incorporating a first fluid pump for high-pressure fluid pressurization and a second variable displacement pump, with a charge pump providing low-pressure fluid to assist the high-pressure pump, ensuring only necessary fluid is pressurized and minimizing cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a single fixed displacement pump is used to satisfy maximum pressure and flow demand, then the transmission can meet high-pressure demands, but the pump is inefficient during low-pressure and low-flow demand periods and wastes energy
Solution Approach 1:
The single pump system is segmented into two separate pumps: a first fixed displacement pump for high-pressure fluid delivery and a second variable displacement pump for low-pressure continuous flow. This segmentation allows each pump to operate in its optimal efficiency range for different pressure demands, resolving the contradiction between meeting maximum pressure requirements and avoiding energy waste during low-demand periods.
Solution Approach 2:
The second variable displacement pump dynamically adjusts its displacement based on real-time fluid demand conditions. When high-pressure demand exists, it operates at higher displacement; when demand is low, it reduces displacement or shuts off, preventing energy waste while ensuring the first pump only operates when truly needed for high-pressure functions.
2Use of energy by moving object
If a single variable displacement pump is used to adjust to varying demand, then energy efficiency improves, but the pump becomes expensive and difficult to control and may still cavitate under high-pressure demands
Solution Approach 1:
The system segments the pumping functions by assigning the first fixed displacement pump to handle high-pressure demands where reliability is critical, and the second variable displacement pump to handle low-pressure continuous flow where energy efficiency is prioritized. This segmentation avoids placing excessive control demands on a single variable displacement pump while preventing cavitation issues in the high-pressure pump.
Solution Approach 2:
The second variable displacement pump acts as an intermediary that provides continuous low-pressure flow to the system, reducing the burden on the first high-pressure pump. This intermediary pump handles the baseline fluid delivery, allowing the first pump to operate only when high-pressure conditions require it, thereby improving overall system reliability.
3Ease of operation
If high pressure is maintained continuously to ensure availability for shifting operations, then shifting performance is ensured, but unnecessary power is wasted during periods when high pressure is not demanded
Solution Approach 1:
The first fixed displacement pump operates periodically rather than continuously, activating only when high-pressure fluid is demanded for shifting operations. The second variable displacement pump provides continuous low-pressure flow to maintain basic system operation and lubrication. This periodic activation of the high-pressure pump ensures shifting performance is available when needed while eliminating continuous power waste.
Solution Approach 2:
The system employs pressure sensors and control logic that monitor real-time fluid pressure conditions. When pressure drops below a threshold indicating high-pressure demand (such as during clutch engagement or brake application), the first pump is activated. When pressure remains stable and high-pressure demand is absent, the first pump shuts off, preventing energy waste while ensuring rapid response when shifting operations are required.
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 system achieves efficient and stable operation by matching fluid pressurization to demand, reducing energy waste and minimizing cavitation, thus enhancing transmission efficiency and reliability.
Implementation Method 1
The first fluid pump may be configured to pressurize a first flow of fluid
Implementation Method 2
The second fluid pump may have variable displacement to pressurize a second flow of fluid
Implementation Method 3
ensuring only necessary fluid is pressurized and minimizing cavitation
Data Source
AI summary
A transmission is provided for a mobile machine. The transmission may have a plurality of available gear combinations selectively engaged to produce multiple stepped output ratios. The transmission may also have a first fluid pump and a second fluid pump. The first fluid pump may be configured to pressurize a first flow of fluid. The second fluid pump may have variable displacement to pressurize a second flow of fluid. At least one of the first and second flows of fluid may be directed to cause selective engagement of the plurality of available gear combinations.