Variable Displacement Pump Modulated Regulation
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Solution Overview
Problem
Variable displacement pumps in motor vehicle engines face challenges in regulating oil delivery rate efficiently across different operating conditions, leading to excessive power absorption, fuel consumption, and component stress due to high pressures, with existing solutions experiencing instability and friction-related hysteresis issues.
Innovation Solution
The implementation of modulating members that adjust the regulation pressure on the second stage of the pump based on a control signal and fluid pressure conditions, using a distributor to manage the movement of actuation stages and reduce friction by eliminating the need for guiding components, thereby stabilizing the actuation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed geometry pumps are used to ensure sufficient delivery rate at low speeds, then lubrication is ensured under low speed conditions, but at high rotation speeds the delivery rate exceeds the necessary rate causing high power absorption and higher fuel consumption
Solution Approach 1:
The pump employs variable displacement capability through movable regulation members that dynamically adjust the delivery rate according to operating conditions. The regulation members can change the pump's displacement volume in response to pressure conditions and control signals, allowing the system to adapt between low-speed high-lubrication-demand conditions and high-speed low-lubrication-demand conditions, thereby resolving the contradiction between ensuring lubrication reliability and reducing power absorption.
2Adaptability or versatility
If displacement regulation systems with movable regulation members are implemented, then delivery rate regulation is achieved at different operating conditions, but radial thrusts from spring force and actuation pressures increase causing higher frictions and pressure hysteresis
Solution Approach 1:
The regulation system is divided into two independent actuation stages: a first stage permanently exposed to pumped fluid pressure and a second stage exposed to regulated pressure from a pressure regulator. This segmentation allows the spring force to be balanced by the first stage while the second stage provides fine regulation control, reducing the radial thrusts and frictions compared to single-stage systems while maintaining delivery rate regulation capability.
3Ease of operation
If on-off controlled valves are used for displacement regulation, then simple control is achieved, but regulation stability is not ensured and frictions cause hysteresis in pump reaction
Solution Approach 1:
A pressure regulator acts as an intermediary device between the pumped fluid and the second actuation stage. Instead of using direct on-off valve control that causes instability and hysteresis, the pressure regulator provides continuous pressure modulation, smoothing out the control action and eliminating the friction-related hysteresis while maintaining ease of operation through proportional pressure control.
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 allows for stable and efficient regulation of pump displacement, reducing friction and hysteresis, and optimizing oil delivery rate by modulating the pressure on the second stage, ensuring efficient operation across varying engine conditions without excessive power absorption or fuel consumption.
Implementation Method 1
the rotary piston is configured as a multistage rotary piston for displacement regulation, directly driven by the pressure of the pumped fluid
Implementation Method 2
The rotation of the ring is opposed by a spring
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A variable displacement pump (1) comprises a regulation ring (11) having at least a pair of actuation stages (19, 20), of which a first stage is permanently exposed to pressure conditions of the pumped fluid and is arranged to make the regulation ring (11) move against the action of a spring (23), and a second stage is arranged to act concordantly with the spring (23) in a manner controlled by an electrically-controlled valve (50). A spool valve (40), controlled by the electrically-controlled valve (50) and the pressure conditions of the pumped fluid, is connected between the second stage (20) and the electrically- controlled valve (50) and is arranged to modulate a regulation pressure acting on the second stage (20) depending on a control signal supplied by the electrically-controlled valve (50) and on such pressure conditions. A method for regulating the displacement of such a pump is also provided.