Variable Vane Pump Relief Valve for Cold-Start Eccentricity Control
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Solution Overview
Problem
Variable displacement vane pumps face challenges in reducing eccentricity and ensuring fail-safe operation, particularly at cold start conditions where lubricant viscosity is high, leading to delayed normal operation and potential pressure imbalances.
Innovation Solution
Incorporating a pressure-controlled relief valve that moves from a first to a second valve position based on predetermined lubricant pressure, allowing fluid communication from the outlet path to the control chamber, thereby reducing eccentricity and ensuring displacement control independently of the main control valve, and a feedback channel connected to a main control valve for pressure regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single control chamber is used for moving lubricant, then the pump structure is simplified, but the ability to reduce eccentricity and ensure fail-safe operation is compromised
Solution Approach 1:
The single control chamber is segmented into two separate control chambers (first control chamber and second control chamber) that can independently control the control slide. This segmentation allows the pump to maintain simplified structure while improving reliability through redundant control paths and fail-safe operation capability.
2Reliability
If the relief valve blocks fluid communication at low pressure, then normal operation is maintained, but cold start conditions with high viscosity lubricant cause delayed operation and pressure imbalances
Solution Approach 1:
The relief valve's pressure threshold parameter is adjusted or designed to allow fluid communication during cold start conditions when lubricant viscosity is high, and then blocks communication when pressure reaches normal operating levels. This parameter change enables the system to adapt to different operating conditions and eliminate cold start delays.
3Ease of operation
If the main control valve controls pressure in the control chamber, then displacement control is achieved, but independent fail-safe displacement control is not available
Solution Approach 1:
The control system is segmented into a main control valve for normal displacement control and a relief valve for independent fail-safe control. The relief valve can independently control fluid communication to the control chamber, providing adaptability and versatility for different operational scenarios including fail-safe conditions.
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 solution effectively reduces eccentricity and ensures reliable operation by allowing pressurized lubricant to displace the control slide in the displacement decreasing direction, even at cold start conditions, thereby improving pump efficiency and preventing pressure imbalances.
Implementation Method 1
A resilient structure biases the control slide in the displacement increasing direction
Implementation Method 2
the relief valve having an activation surface being in fluid communication with the outlet path and being movable from a first valve position to a second valve position based on a predetermined pressure of the lubricant acting on the activation surface
Implementation Method 3
In its second valve position, the relief valve permits fluid communication of the lubricant from the outlet path to the control chamber through the relief port, thereby pressurizing the control chamber and displacing the control slide in the displacement decreasing direction
Data Source
AI summary
A variable displacement vane pump is described. The pump includes a control chamber provided between a housing and a control slide. A pressure-controlled relief valve is in fluid communication with the outlet path and moves to block or unblock a relief port based on output pressure of the lubricant. A feedback channel fluidly connects the control chamber to an inlet path of the pump. The feedback channel further connects to a control port that is connected to a main control valve. The relief valve and control valve are distinct and not fluidly connected. The relief valve moves once the pressure in the outlet path exceeds a predetermined amount, opening the relief port, and thus delivers a portion of the output lubricant to the control chamber via the relief port, thereby pressurizing the control chamber and reducing eccentricity of the pump by displacing the control slide.