GB2094419A

GB2094419A - Multi-function annular sealing element

Info

Publication number: GB2094419A
Application number: GB8205468A
Authority: GB
Original assignee: ALSACE MINES POTASSE
Current assignee: ALSACE MINES POTASSE
Priority date: 1981-03-05
Filing date: 1982-02-24
Publication date: 1982-09-15
Also published as: IT8247906A0; IT1148102B; DE3207999A1; GB2094419B; FR2501322B1; FR2501322A1; DE3207999C2

Abstract

There is provided a multi-function annular sealing element 7 particularly adapted to be used in apparatus comprising a smooth shaft 2 and a concentric cylinder 1, the relative movements of which are sliding movements, rotary movements, or nil, such as for example guiding, pivotable connection, or fixed connection arrangements. The annular sealing element 7 comprises a single piece made of elastic material and having a cross- section in the shape of an L, an element constituting a scraper 74 being situated outside of the angle formed by the two legs 71, 72 of the L, and a tongue 75 provided with a projection fittable into a groove in the cylinder bore being situated internally of the angle formed by the two legs of the L in such a way as to leave spaces between these legs. The sealing element 7 also bears against a multi- part annular key 6 which holds in place an end abutment 4. The abutment 4 carries two guide rings 3 and a sealing element 10. <IMAGE>

Description

SPECIFICATION Multi-function annular sealing element The present invention relates to an annular sealing element performing a plurality of functions. The device is usable in apparatus which comprises a smooth rod or shaft and a concentric cylinder and wherein the relative movements are sliding or rotary or nil, such as for example guiding, pivotable connection, or fixed assembly arrangements.

The present invention concerns more particularly mechanical, pneumatic and hydraulic jacks.

It is known that in apparatus having a piston and a cylinder, concentric with one another, a guide block for the piston rod is fitted on one of the cylinder ends and, if appropriate, serves as a mechanical abutment stopping the piston at the end of its travel. This guide block is often fixed by means of an annular key made up of a plurality of elements. It may also be secured by an elastic retaining ring comprising one or more pieces.

Up to the present time, to immobilise the key or retaining ring a holding ring has been used, comprising externally a machined groove wherein a ring of elastic material is mounted (toroidal ring).

The function of this ring has been to ensure a tight seal at the holding ring relatively to external contaminants or pollutants. The holding ring is fixed by a steel retaining ring inserted in a groove internally of the cylinder. Moreover it has been customary to fix in the holding ring a sealing element having a scraping action and intended to protect the piston rod and the sealing device against dirt when the jack is operating in dirty conditions, for example in mining apparatus or earth moving machinery.

This known sealing and fixing assembly has a certain number of disadvantages: corrosion occurs at the steel retaining ring, causing it to swell and in the end to fracture, or issue from its housing, thus releasing the assembly. The scraped-off products collect in the cavity situated above the holding ring, this cavity being required for positioning the steel retaining ring. Also, when the piston ring is deformed the scraping action is impaired and possibly is not done at all. It may even happen that the scraper is ejected from its seating. The assembly is complicated because of the many parts required. Hence it is expensive and takes a long time to position; disassembly is often difficult because of corrosion.

The present invention aims to provide an annular sealing element which by itself performs all the functions of holding the annular retaining ring or key, sealing against external pollutants and dirt, scraping, and self-locking, thus obviating the disadvantages described hereinbefore.

A first aspect of the present invention provides an annular sealing element usable in apparatus comprising a concentric cylinder and smooth piston shaft, a guide block serving as a mechanical abutment or end-of-travel stop for the piston, the sealing element ensuring a tight seal between the piston and the end of the cylinder and retaining in position an annular retaining ring or key which serves as a mechanical abutment for the guide block, said annular sealing element being characterised in that it comprises a single piece of resilient or elastic material having an L-shaped cross-section, a first leg of which is parallel to the piston rod and is constituted at its end by a portion so shaped and dimensioned that it bears on the one hand on the mechanical abutment and on the other hand on the annular retaining ring, and whereof a second leg is substantially perpendicular to the first and has a sufficient length to bear against the end face of the cylinder, an element acting as a scraper being situated externally of the angle formed by the two legs of the L, and a tongue provided with a projection engageable in a groove formed within the cylinder being situated in the angle formed by the two legs of the L in such a manner as to leave spaces between these two legs.

A second aspect of the invention provides an annular sealing element having a cylindrical portion, an annular flange projecting radially outwardly from an end of the cylindrical portion, a locating member for locating the element in position in use, and a generally inwardly directed annular flange adapted to seal resiliently against a shaft member located within the element in use.

A third aspect of the invention provides a jack incorporating a sealing device of the type defined above.

A fourth aspect of the invention provides a device comprising a cylinder, a shaft located within a stop member held within the cylinder proximal of an end thereof, locating means holding the stop member in position in the cylinder, and an annular sealing element at an end of the cylinder and comprising a first portion abutting against the stop member and the locating means, a second portion bearing on said end of the cylinder, a flange portion bearing against the shaft to form a seal there against, and a tongue portion locating said element in position, the arrangement being such that said sealing element forms a generally dust tight seal between the shaft and the cylinder and retains the locating means in position, said sealing element being at least partially resilient to allow ready removal from the device.

The description given hereinafter by way of non-limitative example will enable the invention to be better understood.

Fig. 1 is a longitudinal sectional view through part of an hydraulic jack comprising a sealing element according to the invention.

Fig. 2 shows a detailed view of Fig. 1.

The jack shown in Fig. 1 comprises a concentric cylinder (1 ) and piston and shaft (2). It comprises two guide rings (3) and a mechanical end abutment (4) for the piston. Sealing-tightness between the mechanical abutment and the piston shaft is obtained by means of a sealing element (10), and sealing-tightness between the mechanical abutment (4) and the cylinder by a toroidal ring (5). In the constructional form illustrated in Figs. 1 and 2, the mechanical abutment (4) is held in place by an annular key consisting of a plurality of parts (6) which is introduced into a groove of the bore of the cylinder (1). According to another constructional form the rectangular-section key is replaced by a steel retaining ring in one or more pieces.The cylinder (1 ) is closed in sealing-tight manner at the piston rod region by means of the annular sealing element (7) according to the invention.

This sealing element (7) is substantially L-shaped in cross-section, one leg (71) being parallel to the piston shaft or jack rod and the other leg (72) substantially perpendicular. The end of the leg (71) bears on the one hand on the mechanical abutment (4) and on the other hand on the key (6). It thus holds the key (6) in its groove. The leg (72) has a shape and a length such that it bears on the end face (11) of the cylinder (1), or in another constructional form it caps it as illustrated in part in Fig. 1 (13), thus providing a seal against external pollutants.

Outside of the angle of the L the sealing element (7) comprises a scraper lip (74) which bears against the rod (2) of the jack. This lip wipes the jack rod (2) and thus prevents the jack from becoming contaminated internally. The scrapedoff products pass on to the flat external surface of the leg (72) of the sealing element (7), on which they cannot accumulate. Within the angle formed by the legs (71 ) and (72) of the sealing element (7) there is provided a tongue (73) provided with a relief or projection (75) which engages in a groove (12) of the bore of the cylinder (1).

The sealing element is preferably made of an elastics or resiliant material such as rubber, polyethylene, polyamide, polyurethane. It is possible to use materials of different hardness or quality for certain portions of the sealing element, depending on requirements of actual use. More particularly the scraper lip (74) or the projection (75) may be made of a material of different hardness relatively to the remainder of the sealing element (7).

As the foregoing description shows, the sealing element (7) according to the invention can scrape the jack rod (2), hold the key (6) in position and provide a seal against external pollutants.

Moreover, its assembly and disassembly are easy to carry our manually without tools for the assembly operation, with a simple screwdriver for disassembly, since the spaces ensure the necessary flexibility. The sealing element is also not affected by elastic deformation of the rod.

Claims

1. An annular sealing element adapted to be used in an apparatus comprising a smooth piston shaft and a concentric cylinder, a guide block serving as a mechanical end-of-travel abutment, and an annular retaining ring or key serving as mechanical abutment means for the guide block, said annular sealing element being characterised in that it comprises a piece of elastics or resilient material with an L-shaped cross-section whereof a first leg is parallel to the piston rod and is constituted at its end by a portion having a form and dimensions that it bears on the one hand on the mechanical abutment and on the other hand on the annular retaining ring or key, and whereof a second leg is substantially perpendicular to the first and is of sufficient length to bear against the end face of the cylinder, an element constituting a scraper being situated externally of the angle formed by the two legs of the L, and a tongue provided with a projection engageable into a groove within the cylinder bore being situated in the angle formed by the two legs of the L in such manner as to leave spaces between these two legs.

2. An annular sealing element having a cylindrical portion, an annular flange projecting radialiy outwardly from an end of the cylindrical portion, a locating member for locating the element in position in use, and a generally inwardly directed annular flange adapted to seal resiliently against a shaft member located within the element in use.

3. An element as claimed in claim 2, wherein said element is integrally formed of resilient material.

4. An element as claimed in claim 3, wherein said element is of rubber, polyethylene, polyamide or polyurethane.

5. An element as claimed in claim 2, 3 or 4, wherein portions of said element have different degrees of resiliency.

6. An annular sealing element substantially as hereinbefore described with reference to the accompanying drawings.

7. A device comprising a cylinder, a shaft located within a stop member held within the cylinder proximal of an end thereof, locating means holding the stop member in position in the cylinder, and an annular sealing element at an end of the cylinder and comprising a first portion abutting against the stop member and the locating means, a second portion bearing on said end of the cylinder, a flange portion bearing against the shaft to form a seal there against, and a tongue portion locating said element in position, the arrangement being such that said sealing element forms a generally dust tight seal between the shaft and the cylinder and retains the locating means in position, said sealing element being at least partially resilient to allow ready removal from the device.

8. A device as claimed in claim 7, wherein the device is a jack or prop.

9. A device as claimed in claim 7 or 8, wherein said second portion forms a cap over the end of the cylinder.

10. A jack or prop including an annular sealing element as defined in any one of claims 1 to 6.

11. The features hereinbefore disclosed or their equivalents in any novel combination;