Charge Pump Capacity Adjustment via Main Pump Inlet Pressure
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Solution Overview
Problem
In existing hydraulic systems with serially connected pumps, the pump capacity of the first pump is not regulated based on the pressure at the inlet side of the second pump, leading to indirect control of the system's operating conditions, which can result in pressure spikes and cavitation issues affecting the service life of the main pump.
Innovation Solution
A pump unit with a main pump and a charge pump featuring a variable pump capacity, where the charge pump's capacity is adjusted using an adjusting means dependent on the inlet pressure of the main pump, utilizing a stroke ring and pressure chamber to generate an adjusting force directly from the inlet pressure, ensuring rapid and precise adjustment to prevent pressure spikes and cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pump capacity of the charge pump is adjusted using a complex control device with electronic control units, then the adjustment precision can be improved, but the device complexity increases
Solution Approach 1:
The charge pump's adjusting mechanism uses its own delivery pressure to automatically adjust its pump capacity. The adjusting force is generated internally by the pressure differential between the delivery side and intake side, eliminating the need for external electronic control units and complex control devices while maintaining precise adjustment capability
Solution Approach 2:
The system implements automatic feedback control where the delivery pressure of the charge pump directly influences the adjusting mechanism. When delivery pressure changes, it automatically adjusts the pump capacity to maintain optimal operating conditions, creating a self-regulating system without complex electronics
2Reliability
If the pump capacity of the charge pump is adjusted rapidly in response to main pump inlet pressure changes, then the reliability improves by preventing pressure spikes and cavitation, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The charge pump automatically adjusts its capacity in response to main pump inlet pressure changes by using the pressure differential across its own components. The adjusting mechanism responds directly to pressure changes without requiring additional sensors, control units, or complex control mechanisms, thereby maintaining high reliability while avoiding increased device complexity
Solution Approach 2:
The system uses hydraulic pressure from the charge pump's own delivery side to actuate the adjusting mechanism. The pressure differential between delivery and intake sides creates the adjusting force needed to modify pump capacity, eliminating the need for separate control systems while ensuring rapid response to maintain reliability
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 solution ensures immediate and precise adjustment of the charge pump's capacity in response to changes in the main pump's inlet pressure, preventing pressure spikes and undersupply, thereby enhancing the service life of the main pump and improving the system's response behavior and control precision.
Implementation Method 1
a pressure chamber is formed between the recess in the housing part and the stroke ring; the pressure chamber is acted upon with an adjustment pressure to produce the adjusting force
Data Source
AI summary
A pump unit includes a main pump (4) and a charge pump (5), the pump capacity of which is adjustable via an adjusting element. To adjust the pump capacity of the charge pump (5), an adjusting element of the charge pump (5) is acted upon by an adjusting force which is dependent on the inlet pressure of the main pump (4).