Variable Displacement Lubricant Pump Pressure Relief Valve
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Solution Overview
Problem
Variable displacement lubricant pumps experience high local pressure peaks and flow rate inaccuracies at high rotating speeds due to disturbed equilibrium forces between control chambers and pretensioning elements, leading to inadequate lubricant flow adaptation to engine demand.
Innovation Solution
Incorporation of a pressure relief valve, such as a radial groove, directly connecting the discharge zone to the second control chamber, which allows calibrated leakage and maintains differential pressures, ensuring equilibrium forces remain undisturbed and lubricant flow is adapted to engine demand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the control ring is positioned at a high pumping volume position to increase lubricant flow rate, then the pumping volume is improved, but high local pressure peaks occur in the discharge zone which disturb the equilibrium forces and cause flow rate inaccuracies
Solution Approach 1:
A pressure relief valve is introduced as an intermediary element between the discharge zone and the second control chamber. This valve provides a controlled pressure relief path that prevents excessive pressure buildup in the discharge zone while maintaining the high pumping volume position of the control ring, thereby preserving flow rate accuracy without sacrificing productivity
Solution Approach 2:
The pressure relief valve modifies the pressure parameter in the discharge zone by providing a controlled leakage path. This changes the pressure distribution characteristics, allowing the system to operate at high pumping volumes without generating the harmful pressure peaks that would otherwise disturb the equilibrium forces and compromise flow rate accuracy
2Productivity
If the pump operates at high rotating speeds to increase productivity, then the lubricant flow rate is improved, but high local pressure peaks occur which disturb the equilibrium forces between control chambers and pretensioning element
Solution Approach 1:
The pressure relief valve serves as a mediator that decouples the relationship between high rotating speed and pressure peak generation. By providing an alternative pressure relief path, it allows the pump to operate at high speeds for increased productivity without transferring the full mechanical energy into harmful pressure peaks in the discharge zone
Solution Approach 2:
The pressure relief valve converts the potentially harmful effect of high rotating speeds (which generate pressure peaks) into a beneficial controlled pressure relief mechanism. The valve transforms the excess pressure energy into a controlled leakage flow, allowing the pump to exploit high-speed operation for increased productivity while neutralizing the harmful pressure effects
3Power
If the pump allows high pressure in the discharge zone to maintain pumping efficiency, then the pumping performance is improved, but the equilibrium forces between control chambers and pretensioning element are disturbed causing flow rate inaccuracies
Solution Approach 1:
The pressure relief valve acts as an intermediary that separates the discharge zone pressure from the control chamber pressures. It allows the discharge zone to maintain high pressure for pumping performance while preventing this pressure from being transmitted to the second control chamber, thereby preserving the equilibrium forces and ensuring accurate flow rate adaptation
Solution Approach 2:
The pressure relief valve creates a segmentation or decoupling between the discharge zone pressure system and the control chamber pressure system. This segmentation allows independent optimization of pumping performance (high discharge pressure) and flow rate control accuracy (stable control chamber pressures), resolving the contradiction between these two requirements
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
The pressure relief valve effectively prevents high differential pressure peaks, ensuring consistent lubricant flow rate adaptation to engine demand, even at high speeds, by allowing minimal calibrated leakage from the discharge zone to the second control chamber.
Implementation Method 1
The pressure relief valve allows only a calibrated leakage of the lubricant from the discharge zone to the second control chamber so that the pressures between the second control chamber and the discharge zone remain still different but without high differential pressure peaks
Data Source
Figure 1
AI summary
The present invention refers to a variable displacement lubricant pump (10) for providing pressurized lubricant for an interna! combustion engine. The mechanical pump (10) comprises a pump rotor (20) with radially siidable vanes (22) rotating in a shiftable control ring (14), whereby the control ring (14) envelopes numerous pump chambers (24). The pump chambers (24) rotate through a charge and a discharge zone (32, 34) inside the control ring (14). Further, the pump (10) comprises a pretensioning element (42) which is pushing the control ring (14) to a high pumping volume direction. A first control chamber (28) is pushing the control ring (14) to a low pumping volume direction, and a second control chamber (30) is pushing the control ring (14) to a high pumping volume direction if the lubricant is pressurized. The pump (10) also comprises a pump outlet (48) which is connected to the first control chamber (28). Both control chambers, i.e. the first and the second control chamber (28, 30), are connected to each other via a throttle valve (52). Both control chambers (28, 30) can have a different circumferential extend around the control ring (14), so that the effective surfaces of the two control chambers (28, 30) and the respective moment arms are different. Both control chambers (28, 30) act against each other, i.e. act in different pumping volume directions. The control ring (14) of the pump (10) is provided with a pressure relief valve (54) which connects the discharge zone (34) to the second control chamber (30).