Sealing in an Adapter for Available Sealing Grooves

The present invention relates to a sealing in an adaptor for such available sealing grooves which have previously been used for more conventional types of sealing devices. The invention is mainly directed to a sealing for reciprocating pistons as for instance used in hydraulic or pneumatic motors, in which it is intended to seal the reciprocating piston rod between a chamber under pressure and a chamber having no pressure. In the following the invention will mainly be described with reference to hydraulic piston-cylinder motors, but it is obvious to the expert that the invention is not restricted to such field of use and that it can be used for all kinds of different purposes.

In reciprocating hydraulic motors like hydraulic piston-cylinder units, the piston rod is generally sealed close to the outer end of the cylinder, and for this purpose the cylinder is formed with a radial groove in which a sealing is mounted. The sealed is secured by a cylinder end. The said sealing groove can only be used for conventional sealings for which the groove is designed. In such applications it is therefore not possible to use certain types of modern sealing which need a specially designed sealing groove. One such modern type sealing comprises a sealing ring of uniform thickness and provided in a sealing groove which at the end thereof facing the pressurized chamber has a raised portion providing a stronger pressure by the part of the sealing ring located adjacent the pressurized chamber then the remaining part of the sealing ring. Such sealings are previously known and have proved to be advantageous. In order to make use of such sealings and other advantageous sealings in available sealing grooves the present invention relates to an adaptor which both contains a sealing of the above mentioned type or of another type for providing a sealed connection between the adaptor and the reciprocating piston rod and another sealing for providing a seal between the adaptor and the available sealing groove in which the adaptor is mounted.

The characterizing features of the invention are evident from the appended claims.

The invention will now be described more in detail with reference to the accompanied drawings which illustrate some embodiments of the invention.

FIG. 1 is an axial cross section through a portion of a piston-cylinder motor having a reciprocating piston and in which a sealing in an adaptor according to the invention is mounted in the available sealing groove of the cylinder part.

FIG. 2 separately shows a part of the adaptor together with the sealing rings belonging thereto before being mounted, and

FIG. 3 in a corresponding way shows an alternative embodiment of an adaptor with the sealing rings in its mounted and pressurized state.

FIG. 4 shows an axial cross section through a modified embodiment of the invention.

FIGS. 5 and 6 illustrate in the same way as in FIG. 2 two further alternative embodiments of the sealing.

In FIG. 1 is shown a hydraulic motor having a reciprocating piston rod 1 and a cylinder 2 which adjacent the outer end is formed with a sealing groove 3 designed for mounting of a conventional sealing which is secured by means of a cylinder end 4 which is mounted at the end of the cylinder 2 by means of screws 5.

According to the invention an adapter 6 is provided for the purpose of adapting the illustrated hydraulic motor to a modern type of sealing. The adapter 6 comprises an adapter body 7 of a suitable hard material like metal, plastic or similar material, a first sealing 8 providing a seal between the reciprocating piston rod 1 and the adaptor body 7 and a second sealing 9 providing the seal between the cylinder 2 and the adapter body 7. As most clearly illustrated in FIG. 2 the adapter body 7 is formed with two different grooves for the sealings 8 and 9, of which the groove 10 for the sealing 8 is provided open radially inwards and in the illustrated case also open axially outwards from the pressurized chamber P. At the axial end of the groove 10 facing the pressurized chamber P the groove 10 is formed with a radially inwards widened portion 11 having less diameter than the remaining part of the groove. In the sealing groove 10 a sealing ring 12 of rubber-elastic materiel is provided. The sealing ring 12 preferably has a rectangular cross section form. As usual a lubricating ring 13 and a support ring 14 are provided in the sealing groove 10 axially outside the sealing ring 12.

At the end of the sealing facing the pressurized chamber P the adaptor body 7 is formed with a radially outwards directed groove 15 in which a sealing ring 16 of rubber-elastic materiel like an O-ring is provided. In order to prevent the sealing ring 16 from being forced into the space between the adaptor body 7 and the cylinder groove 3 there is provided a support ring 17. The adaptor body preferably has such dimensions as to nearly completely fill the cylinder sealing groove 3 and has to be secured in the axial direction by the cylinder end 4.

The widened portion 11 of the sealing groove 10 for the piston road sealing 8 provides a harder pressure on the part of the sealing 12 facing the pressurized chamber P than the remaining part of the sealing ring. Thereby the said widened portion 11 provides a more effective sealing than conventional sealing rings, and at the same time the risk is reduced that the sealing is pressed out into the space between the piston rod 1 and the lubricating ring 13 and the support ring 14 respectively and the cylinder end 4.

The second sealing 9 provides a seal between the adaptor body 7 and the cylinder groove 3 against the pressure medium which may tend to moove radially outwards between the adaptor body 7 and the cylinder groove 3.

As shown the sealings 8 and 9 are provided in grooves which are axially open, but it is to be understood that the sealings may also be provided in closed grooves. Consequently FIG. 3 shows a sealing between the adaptor body 7 and the cylinder 2 mounted in a closed groove provided some distance spaced from the end of the adaptor body facing the pressurized chamber P. Likewise the sealing 8 for the piston rod may be slightly spaced from the end of the adaptor body 7 which is opposite to the end facing the pressurized chamber P. Preferably, however, the sealing 9 is provided closer to the pressurized chamber P than the sealing 8.

FIG. 4 shows an embodiment of the sealing according to the invention comprising two piston rod sealings 8', 8" provided axially spaced and two cylinder sealings 9' and 9" likewise provided axially spaced. As evident the piston rod sealing 8' and the cylinder sealing 9" are provided in grooves which are open in the axial direction, whereas the piston rod sealing 8" and the cylinder sealing 9' are provided in grooves which are closed in the axial direction. The sealings 8' and 8" may be of the same or different kind, and also the sealings 9' and 9" may be of the same or different kind. Preferably the sealings 8" and 9" are formed for a higher sealing pressure than the sealings 8' and 9' respectively, since the first mentioned sealing takes a larger part of the sealing pressure than the latter sealings.

In FIGS. 5 and 6 two further embodiments of the invention are shown in the same way as in FIG. 2. The latter embodiments of the invention comprises an adapter body 7 intended to be mounted in the available sealing groove in the cylinder or a similar means of a cylinder-piston apparatus. At the end facing the pressurized chamber the adaptor body 7 is formed with a sealing ring 16 and a belonging support ring 17 and at the opposite end a sealing between the adaptor body 7 and the reciprocating piston rod (not shown) is mounted. In FIG. 5 the last mentioned sealing ring 18 is formed as a so called compact sealing ring which is known per se and which has a belonging support ring 19. In FIG. 6 the said last mentioned sealing is formed as a lip sealing ring 20 of a type which is known per se.

It is to be understood that the above described embodiments of the invention which are illustrated in the drawings do not restrict the invention and that all kinds of different modifications may be presented within the scope of the appended claims.