Shuttling Spool Grease Injector for Precise Bearing Lubrication
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Solution Overview
Problem
Existing lubricant injection systems are complex and expensive, with metering valves not designed to inject lubricant directly into each bearing, leading to inconsistent lubrication, with some bearings being over- or under-lubricated.
Innovation Solution
A grease injector design featuring a shuttling spool and dual springs, where the primary spring is 3 times stiffer than the reload spring, allowing for precise grease delivery and high reload pressures, independent of injector opening, and efficient air pocket bleeding, resulting in improved lubricant distribution and reduced return flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex metering valves are used to regulate lubricant supply, then lubrication control is achieved, but manufacturing cost increases and device complexity increases
Solution Approach 1:
The injector is divided into functionally independent segments: a shuttling spool mechanism for precise metering, a plunger system for grease delivery, and spring-based actuation. Each segment performs a specific function, allowing simplified individual components to work together for precise overall control without requiring a complex integrated valve design.
Solution Approach 2:
The injector uses dynamic elements including a movable shuttling spool that responds to pressure differentials, a reciprocating plunger driven by spring forces, and timed operational cycles. These dynamic mechanisms enable precise lubrication metering through motion-based control rather than complex static valve geometry.
2Extent of automation
If centralized lubrication system is used, then automatic lubrication is achieved, but inconsistent lubrication distribution occurs among multiple bearings
Solution Approach 1:
The system divides the centralized lubrication into independent injector units, each with its own shuttling spool and plunger mechanism. Each injector independently meters and delivers grease to its specific bearing, ensuring consistent lubrication distribution across multiple bearings while maintaining automatic operation through unified pressure-driven actuation.
Solution Approach 2:
The injector incorporates inherent feedback mechanisms where grease pressure actuates the shuttling spool, which automatically regulates the metering process. The system responds to pressure differentials and flow conditions, self-adjusting to deliver consistent lubrication quantities without external control inputs.
3Stress or pressure
If high grease delivery pressure is used, then thick grease delivery is improved, but return flow increases
Solution Approach 1:
The injector pre-charges the plunger with the exact required grease quantity during the refill phase before delivery begins. The shuttling spool closes the refill port at the precise moment when the plunger is fully charged, preventing overfilling and ensuring that only the necessary amount of grease is delivered at high pressure, minimizing return flow.
Solution Approach 2:
The system uses dynamic pressure management where the shuttling spool responds to pressure differentials to control timing. During delivery, high pressure is maintained for effective grease injection, while during refill, pressure is automatically reduced and controlled through the spool's port closure, optimizing the balance between delivery pressure and return flow minimization.
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 design ensures accurate and efficient grease delivery at higher pressures, minimizing return flow and maintaining consistent lubrication across all bearings, with a compact and reliable injector package that can handle thick greases even in cold conditions.
Implementation Method 1
In the rest position both the main spring (also referred to as primary spring) and reload spring are preloaded
Implementation Method 2
The main spring (also referred to as primary spring) and reload spring are configured to bias against each other
Implementation Method 3
the application of pressurized grease at the inlet (134) urges the shuttling spool (112) axially upwardly
Implementation Method 4
the application of pressurized grease raises the plunger (126) a preselected amount
Data Source
Figure 1
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Figure 3
AI summary
A lubricant injector used for dispensing a preselected amount of grease when the grease is delivered to the injector in a pressurized condition, the lubricant injector includes a generally cylindrical body which includes an upper grease reservoir adapted to selectively receive grease from a lower grease reservoir, wherein both reservoirs are filled with grease, the body includes a lower grease inlet and an upper grease outlet, the body also includes an inlet and an outlet. It further includes a shuttling spool slid-ably housed axially within the body wherein the shuttling spool is adapted to move axially upwardly upon application of pressurized grease at the inlet, and axially downwardly when the grease is not pressurized at the inlet such that upon application of pressurized grease at the inlet the shuttling spool is urged axially upwardly toward the outlet and configured to close off grease communication between the upper and lower grease reservoirs and substantially simultaneously open the inlet for communication of a preselected amount of grease into the lower grease reservoir. The lubricant injector is configured such that upon the preselected amount of grease entering the lower grease reservoir, simultaneously an equivalent amount of grease is dispensed from the outlet of the upper grease reservoir, and during this operation the upper and lower grease reservoirs are isolated.