Variable Displacement Pump Spool Valve Control
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Solution Overview
Problem
Conventional variable displacement pumps face limitations in energy conservation due to a restricted range of variation in the opening area of the variable metering orifice, which is influenced by the minute movement of the cam ring, resulting in insufficient energy savings.
Innovation Solution
The implementation of a variable displacement pump design that includes a first control valve to manage pressure between the upstream and downstream sides of the variable metering orifice and a second control valve to variably control the opening area, utilizing a spool valve body that can move significantly to enhance the range of variation, thereby improving energy conservation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the opening area of the variable metering orifice is controlled based on the cam ring movement, then the pump structure remains simple, but the range of variation in opening area is limited due to minute cam ring movement
Solution Approach 1:
The control system is divided into two independent control valves: a first control valve that controls pressure introduction to the fluid pressure chamber based on upstream and downstream pressures, and a second control valve that independently controls the opening area of the variable metering orifice based on fluid chamber pressure and suction passage pressure. This segmentation allows each valve to perform its specific function optimally without being constrained by the other, thereby achieving both structural simplicity and wide adaptability in opening area variation.
Solution Approach 2:
The invention introduces a second control valve as an intermediary component between the fluid pressure chamber and the variable metering orifice. This intermediary valve enables independent control of the opening area based on pressure differential, decoupling the orifice control from the cam ring movement and allowing for a significantly larger range of opening area variation while maintaining overall system simplicity.
2Device complexity
If the opening area variation range is limited by cam ring movement, then the control system remains simple, but sufficient energy conservation cannot be achieved
Solution Approach 1:
The second control valve is designed with a spool valve body that can move dynamically over a significant range within the valve body bore. This dynamic movement allows the opening area of the variable metering orifice to be adjusted over a wide range, enabling the pump to adapt to varying energy requirements and achieve sufficient energy conservation, while the overall control system remains relatively simple in structure.
3Device complexity
If a single control valve is used for pressure control, then the control system is simple, but the opening area control range is insufficient for energy conservation
Solution Approach 1:
The control system is segmented into two independent control valves with distinct functions: the first control valve manages pressure introduction to the fluid pressure chamber, while the second control valve independently manages the opening area of the variable metering orifice. This functional segmentation enables precise control over energy consumption by allowing independent optimization of pressure control and flow control, thereby achieving sufficient energy efficiency without excessive system complexity.
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 design achieves sufficient energy conservation by allowing for a larger range of variation in the opening area of the variable metering orifice, enhancing the pump's efficiency and enabling better energy management, particularly in applications like power steering systems.
Implementation Method 1
a first control valve configured to control the pressure to be introduced into a first fluid pressure chamber by being controlled based on the pressure on the upstream side and the pressure on the downstream side of a variable metering orifice
Implementation Method 2
a second control valve configured to variably control the opening area of the variable metering orifice, which includes a valve body controlled based on the pressure of a second fluid pressure chamber or suction passage and the pressure of the first fluid pressure chamber
Data Source
AI summary
A variable displacement pump according to the present invention is notably configured such that the opening area of a variable metering orifice (MO) is variably controlled by a second control valve (6) as a spool valve having a second spool valve body (61). According to this type of the second control valve (6), a larger amount of movement (stroke movement) of the second spool valve body (61) can be ensured. Consequently, the opening area of the variable metering orifice (MO) can be controlled without being restricted by a range of variation in a proper discharge amount based on an amount of movement of a cam ring (2), thereby achieving sufficient energy conservation of the pump.