Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Patent
1990-12-12
1992-08-18
Cuchlinski, Jr., William A.
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
277 27, 277 29, 277177, 277205, F16J 1556
Patent
active
051392747
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to fluid seals for sealing between relatively moveable members such as the piston rod and cylinder of a hydraulic ram.
It is known to prevent leakage beween the piston rod and cylinder of a hydraulic ram using a pressure-energised seal such as a U-ring seal, which responds to hydraulic pressure by expanding radially to apply a sealing force between the rod and cylinder. In order to improve sealing at low pressures, it is also known to provide a second ring seal between the hydraulic pressure source and the first seal so as to control fluid flow to the first seal and help maintain an inter-seal pressure to energise the first seal. The second ring seal conventionally takes the form of a plain rectangular-section ring which has a relatively broad annular sealing face in contact with the piston rod. This type of seal is commonly known as a buffer ring and, besides forming a low pressure seal, it has the additional function of protecting the U-ring seal against damage by limiting the transmission of pressure pulses and particulate impurities in the hydraulic fluid within the ram.
A problem met in the aforesaid type of double seal arrangement is that the inter-seal pressure can, under some circumstances, build-up to excessive levels, increasing the friction forces resisting operation of the ram, possibly damaging the seals and, in the extreme, causing the ram to seize.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a gland seal for a hydraulic ram comprising a double seal arrangement which avoids excessive inter-seal pressures.
According to the invention, a hydraulic seal for sealing between two hydraulic components that move axially one within the other comprises a first pressure-energised ring seal located between the components so as to respond to hydraulic pressure on an axially directed inner face of the seal, and a second ring seal located adjacent said inner face of the first seal so as to control the flow of hydraulic fluid to the first seal, the second ring seal being located in an annular groove in one of said components with an outer annular face that is directed axially towards the first seal and lies opposite an adjacent side wall of the groove to be supported thereby and with a sealing lip that protrudes from said groove and has a radially directed annular sealing face to engage in face-to-face contact with the other of said components, characterised in that an annular inner face of the second ring seal opposite said outer face is angled within said groove away from an adjacent side wall of the groove and towards the sealing lip so that the sealing lip can flex within the groove away from the first seal to release excess pressure between the first and second seals.
In a preferred embodiment of the invention, the second ring seal has a substantially rectangular section except that the corner at the junction of the inner face and sealing lip is bevelled to produce said angled inner face. Thus the second ring seal can be simple in design, being a modified form of a conventional buffer ring.
Further, it will be appreciated that the second ring seal can be readily designed so that the sealing lip flexes to relieve inter-seal pressure at any predetermined level. For example, the angle of the inner face, the overall width of the seal, and the width of the sealing lip can be varied. The materials of which the seal is composed will also determine the relief pressure level at which it will respond.
DESCRIPTION OF THE DRAWING
The invention will now be described by way of example with reference to the accompanying drawing in which:
FIG. 1 is an axial section through part of a hydraulic ram fitted with a gland seal according to the invention, and
FIG. 2 is a section through the second ring seal in FIG. 1.
BEST MODE OF CARRYING OUT THE INVENTION
FIG. 1 shows the rod end of a hydraulic ram comprising a cylinder housing 1 and a piston rod 2. An elastomeric U-ring seal 3 is provided between the housing 1 and piston rod 2 to seal against
REFERENCES:
patent: 2941544 (1960-06-01), Peras
patent: 3195901 (1965-07-01), Mercier
patent: 3351350 (1967-11-01), Shepler
patent: 3771799 (1973-11-01), Sekulich
patent: 4186929 (1980-02-01), Burton et al.
patent: 4189157 (1980-02-01), Mahan et al.
patent: 4262759 (1981-04-01), Young et al.
patent: 4387901 (1983-06-01), Ritsema
patent: 4579041 (1986-04-01), Organ et al.
patent: 4696223 (1987-09-01), Link et al.
patent: 4702482 (1987-10-01), Oseman
patent: 4848778 (1989-07-01), Von Pragenau
patent: 4867460 (1989-09-01), Colo et al.
patent: 4944498 (1990-07-01), Kortgen et al.
Cuchlinski Jr. William A.
Folker James K.
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