Variable Displacement Charge Pump for Hydraulic Efficiency
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Solution Overview
Problem
Hydraulic systems in agricultural vehicles experience efficiency losses due to the use of fixed displacement pumps, which deliver excess hydraulic fluid as engine speed increases, and variable displacement pumps have limited suction capacity, leading to inefficiencies in fluid distribution across different circuits.
Innovation Solution
A hydraulic system incorporating a variable displacement charge pump that diverts excess fluid to the lubricating circuit and transmission shift control circuit, allowing for demand-driven fluid supply and reducing waste by using a single adjustable pump to serve multiple circuits, with optional use of a separate fixed displacement pump for the transmission shift control circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed displacement pump is used to supply the lubricating hydraulic circuit, then the pump structure is simple and cheap, but efficiency losses occur because the pump delivers excess hydraulic fluid when engine speed increases
Solution Approach 1:
The patent applies a variable displacement pump instead of a fixed displacement pump to supply the lubricating hydraulic circuit. The variable displacement pump dynamically adjusts its delivery volume based on the actual demand of the lubricating circuit, preventing excess fluid delivery and the associated efficiency losses while maintaining structural simplicity through standardized pump design.
Solution Approach 2:
The patent changes the operating parameters of the pump by using a variable displacement pump that can adjust its delivery volume. This allows the pump to match its output to the actual requirements of the lubricating circuit, eliminating the waste of delivering excess hydraulic fluid at high engine speeds while keeping the pump structure relatively simple.
2Loss of energy
If a variable displacement pump is used to supply the main hydraulic circuit, then efficiency losses are avoided, but the pump has limited suction capacity requiring additional charge pumps
Solution Approach 1:
The patent merges the functions of the charge pump and the variable displacement pump by having the variable displacement pump supply both the main hydraulic circuit and the lubricating hydraulic circuit. This integration eliminates the need for a separate charge pump, reducing system complexity while maintaining the efficiency benefits of variable displacement technology.
Solution Approach 2:
The variable displacement pump is designed to perform multiple functions: supplying the main hydraulic circuit with high-pressure fluid and simultaneously supplying the lubricating hydraulic circuit with low-pressure fluid. This multi-functionality eliminates the need for separate pumps, reducing system complexity while avoiding efficiency losses.
3Reliability
If a separate fixed displacement pump is used for the transmission shift control circuit, then the circuit operates independently, but efficiency losses occur from excess fluid delivery
Solution Approach 1:
The patent extracts the transmission shift control circuit from the lubricating hydraulic circuit by providing it with a separate fixed displacement pump. This ensures independent and reliable operation of the shift control circuit while the excess fluid from this pump is utilized to charge the variable displacement pump, converting what would be waste into a useful function.
Solution Approach 2:
The patent converts the harmful effect of excess fluid delivery from the fixed displacement pump into a beneficial function by using it to charge the variable displacement pump. This eliminates the efficiency losses associated with diverting excess fluid to the tank, as the excess fluid now serves a useful purpose in maintaining the charge pressure of the variable displacement pump.
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 efficiency losses by optimizing fluid distribution, enabling speed-independent and demand-driven supply to various hydraulic components, resulting in line savings, cost advantages, and simplified design complexity.
Implementation Method 1
a variable displacement charge pump (22) is provided, which delivers hydraulic fluid to the main hydraulic pump (18)
Implementation Method 2
at least a portion of the hydraulic fluid delivered by the charge pump can be diverted to supply the lubricating hydraulic circuit (12, 14)
Data Source
AI summary
A hydraulic system for an agricultural vehicle is proposed. The hydraulic system comprises a main hydraulic circuit, which is fed with hydraulic fluid by a main hydraulic pump, a variable displacement charge pump which supplies charge pressure to the main hydraulic pump, and a lubricating hydraulic circuits. In order to keep efficiency losses on the vehicle to a minimum, particularly at high engine speeds, part of the hydraulic fluid delivered by the charge pump can be diverted to the lubricating hydraulic circuit.