Bellows-Sealed Adhesive Dispenser With Tangential Flow Channels
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Solution Overview
Problem
Devices for outputting flowable media, such as hot glue or hot melt adhesives, face issues with dynamic seals wearing out over time, leading to leakage and potential failure of safety functions, while static seals like bellows seals can create 'dead spaces' where the medium oxidizes or ages, altering its properties.
Innovation Solution
The design incorporates channels with tangential openings to the cavity, promoting rotational flow and preventing dead spaces, using a bellows seal with axially spaced balancing sections and a thermoplastic material for enhanced sealing and chemical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a dynamic seal is used to seal the bearing portion against the cavity, then the seal can accommodate rod movement, but the seal wears out over time leading to leakage and loss of sealing effect
Solution Approach 1:
The patent employs a bellows seal, which is a flexible membrane structure that accommodates rod movement through elastic deformation rather than sliding contact. The bellows seal comprises a membrane wall with axial folds that expand and contract to follow rod displacement, eliminating wear between moving surfaces while maintaining sealing integrity over time.
2Reliability
If a bellows seal with a compensating portion is used to seal the bearing portion, then sealing tightness is maintained, but dead spaces form in the cavity where the medium oxidizes or ages
Solution Approach 1:
The patent introduces radial channels that extend from the cavity through the bellows seal into the bearing portion, creating a new flow dimension that bypasses the dead space problem. These channels allow continuous medium circulation from all regions of the cavity, including areas behind the compensating portion, preventing oxidation and aging by ensuring constant medium replacement.
3Ease of operation
If the rod moves between first and second end positions to control medium output, then portionwise application is achieved, but flowable medium can enter the actuator area compromising safety functions
Solution Approach 1:
The bellows seal acts as a flexible barrier that separates the cavity containing the flowable medium from the bearing portion containing the actuator. The seal maintains this separation throughout the full range of rod motion, preventing medium leakage into the actuator area while still allowing rod displacement to control medium output through the dispensing opening.
Data Source
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AI summary
The present invention relates to a device (1) for dispensing a flowable medium, wherein the flowable medium is preferably an adhesive, in particular a hot melt adhesive or a hot melt adhesive, comprising a housing with a cavity (2) for receiving the flowable medium, a rod (5) mounted in a bearing section of the housing, wherein the rod (5) is movable in an axial direction and vice versa by means of an actuator between a first end position and a second end position, a dispensing opening opening into the cavity (2) for dispensing the flowable medium, wherein the rod (5) has a sealing section, wherein the sealing section closes the dispensing opening in the first end position and is spaced apart from the dispensing opening in the second end position, a bellows seal (7) for sealing the bearing section against the cavity (2), wherein the rod passes through the bellows seal (7),wherein the bellows seal (7) is mounted in a sealed manner on the rod (5) and in a sealed manner on the housing, wherein a first section of the bellows seal (7) is fixedly connected to the rod (5) with respect to the rod (5) and a second section of the bellows seal (7) is fixedly connected to the housing with respect to the housing, wherein the bellows seal (7) has at least one compensating section (8) for compensating for axial compression or stretching of the bellows seal (7), wherein the compensating section (8) projects radially towards adjacent areas of the bellows seal (7), and comprising at least one channel opening into the cavity (2) through which the flowable medium can flow into the cavity (2), wherein a projection of a central axis (10, 10a) of a channel section (9) opening into the cavity (2)9a) of at least one channel forms a circle tangent to a circle (3, 3a) concentric to the rod (5) on a projection plane perpendicular to the axial direction.