Low-friction shaft seal composed of bio-inspired materials covering low-speed range under water environment

Abstract

Shaft seals with a seal lip are used in various applications to separate gases and fluids, but their sealing function and durability are affected by the extent of lubrication at the dynamic seal faces between a rotating shaft and the seal lip. A new sealing system consisting of two hydrated seal rings and non-Newtonian lubricants was designed by a biomimetic approach to minimise frictional loss and provide high waterproof function when separating air and water. This system demonstrates significant superiority in low-speed rotation, conditions under which the lubrication mechanism of an oil seal or mechanical seal does not generally work well. Fibre reinforcement of the seal ring material was performed to prevent the deformation of the soft seal rings because of the frictional force in the tangential direction of the shaft and water pressure. This reinforcement enabled the new sealing system to obtain both high waterproof performance and low frictional characteristics in the speed range of 20–100 r/min.

Experimental testing on the influence of shaft rotary lip seal misalignment for a marine hydro-kinetic turbine

“…Nakanishi et al [14] introduced a new type of shaft seal with two hydrated lips to separate water and atmosphere with low fictional torque. Honda et al [15] examined the application of bio-inspired material for a shaft seal covering a low range under water environment. De Cal [16] examined the vibration response due to the misalignment of a tidal turbine shaft.…”

Hydrated Seal Lip for Live Center in Machine Tools

“…A contact-type rotary shaft seal made of the hydrophilic material polyvinyl formal (PVF) was devised because such a seal using a hydrophilic material could show good performance just as an oil seal using a hydrophobic material shows an excellent function (Nakanishi et al, 2009). In a previous study, a shaft seal used an aqueous solution of polyethylene glycol (PEG), which is a non-Newtonian fluid; this solution was injected between the PVF seal rings to support the lubrication and sealing action at the sliding surface (Honda et al, 2018a). In another study, a new PVF seal with a simplified configuration that did not use a PEG solution was proposed (Honda et al, 2018b).…”

“…In another study, a new PVF seal with a simplified configuration that did not use a PEG solution was proposed (Honda et al, 2018b). While an oil seal demonstrates fluid lubrication on the sliding surface, a rotary shaft seal made of PVF is designed to provide boundary lubrication because oil films do not form easily in water-based environments (Bhate et al, 2004;Nakanishi et al, 2016Nakanishi et al, , 2018Honda et al, 2018a).…”