Variable Displacement Charge Pump Hydraulic System
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Solution Overview
Problem
Existing hydraulic systems in tractors require multiple dedicated pumps for drivetrain lubrication, implement hydraulics, and transmission control, leading to energy wastage due to excess hydraulic oil flow at high engine speeds, as fixed displacement pumps produce unnecessary flow that must be either pumped or bypassed back to the tank without contributing to useful work.
Innovation Solution
A hydraulic system utilizing a single variable displacement charge pump that supplies both charge fluid and lubrication fluid to a main pump and transmission lube circuit, with a pressure responsive displacement control unit to manage flow and pressure, eliminating the need for dedicated fixed displacement pumps by using a fluid restriction to control lube fluid flow passively or actively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fixed displacement pumps are used to supply hydraulic oil to various circuits, then the required flow is provided, but excess flow is produced at high engine speeds which must be bypassed back to tank, wasting energy
Solution Approach 1:
The patent replaces fixed displacement pumps with a variable displacement pump that can dynamically adjust its output flow according to actual circuit demands. The pump's displacement is varied using a control valve that responds to pressure signals from different hydraulic circuits, ensuring the pump only delivers the necessary flow quantity and eliminating excess flow that would otherwise be wasted.
Solution Approach 2:
The invention changes the operating parameters of the pump by implementing variable displacement control. The control valve modifies the pump's displacement parameter based on real-time pressure conditions in different circuits, allowing the system to adapt flow delivery to actual needs and prevent energy waste from bypassing excess flow.
2Reliability
If multiple dedicated pumps are used for different hydraulic circuits, then each circuit receives dedicated flow, but the system complexity increases and energy efficiency decreases
Solution Approach 1:
The patent implements a single variable displacement pump that serves multiple hydraulic circuits simultaneously. This multi-functional pump replaces several dedicated fixed displacement pumps, reducing system complexity while maintaining reliable flow supply to all circuits through pressure-responsive control mechanisms.
Solution Approach 2:
The invention merges the functions of multiple dedicated pumps into a single variable displacement pump. By combining these functions and using a common pump with controlled displacement variation, the system achieves the same operational reliability with fewer components, thereby reducing overall system complexity.
3Duration of action of moving object
If excess hydraulic oil is pumped through the circuit regardless of demand, then flow is continuously supplied, but mechanical efficiency is reduced due to unnecessary work
Solution Approach 1:
The patent incorporates pressure sensing feedback mechanisms in each hydraulic circuit that communicate with the pump's control valve. This feedback allows the pump to sense actual circuit demands and adjust its displacement accordingly, ensuring continuous flow supply only when needed and eliminating unnecessary pumping work that would reduce mechanical efficiency.
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 configuration reduces energy wastage by optimizing hydraulic oil flow, ensuring that only the necessary amount of oil is supplied to each circuit, thereby enhancing mechanical efficiency and reducing energy consumption.
Implementation Method 1
a pressure sensing line communicates the charge fluid line with the displacement control unit
Data Source
Figure 1
AI summary
A hydraulic system (10) for a vehicle comprises a transmission lube circuit (12), a main pump (20), and a variable displacement charge pump (24) for supplying charge fluid to the main pump (20). The variable displacement charge pump (24) has a charge pump outlet (54) and a pressure responsive displacement control unit (46). A charge fluid line (36) communicates the charge pump outlet (54) with an inlet (34) of the main pump (20). A pressure sensing line (48) communicates the charge fluid line (36) with the displacement control unit (46). A lube line (66) communicates the charge pump outlet (54) with the transmission lube circuit (12). A fluid restriction (70) is formed in the lube line (66).