GB2180599A

GB2180599A - Seal device for pneumatic or hydraulic circuit

Info

Publication number: GB2180599A
Application number: GB08617302A
Authority: GB
Inventors: Vincenzo Masserdotti
Original assignee: Metal Work SpA
Current assignee: Metal Work SpA
Priority date: 1985-08-02
Filing date: 1986-07-16
Publication date: 1987-04-01
Also published as: GB8617302D0; GB2180599B; DE8615796U1; FR2585780A3; ES1000567Y; IT206299Z2; FR2585780B3; ES1000567U; IT8522707V0

Abstract

In a pneumatic or hydraulic circuit component comprising a threaded tang and an annular projection forming a radially protruding abutment surface, an annular seat (14, 15) is formed proximal to the area of union between the said tang (11) and said projection (12). The seat (14, 15) has a substantially triangular section, one side of the seat being an extension of the profile of the tang and the opposite side of the seat being inclined by between 30 DEG and 60 DEG ; the depth of the seat is such as to receive the toroidal washer in a non-deformed condition so that it protrudes for a greater height than half the diameter of its section from said abutment surface. The component can ensure a perfect leak-free seal even at relatively high service pressures, without the surfaces involved having to be machined to narrow tolerances. <IMAGE>

Description

SPECIFICATION Pneumatic on hydraulic circuit component with improved seal device The present invention relates to a pneumatic or hydraulic circuit component, such as a cap screw or a connection, featuring a seal device so as to ensure a perfect leak-free seal even at relatively high service pressures, without the surfaces involved in the said seal having to be machined to narrow tolerances.

Various types of seal washers are known that are intended to be inserted between two elements, in particular a threaded body to be screwed into a matching seat, and this latter.

One of such washers is known by the name of "O"-ring, in that it is toroidal in shape, and is very widely used on account of its excellent performance from many standpoints, as is well-known to persons skilled in the art.

However, a correct use of this type of washer on threaded bodies such as tangs, cap screws, etc. requires the narrow tolerance ma chining of a seat for partial housing of the "O"-ring seal so as to ensure that it does not move out of its correct position and is not expelled by the surfaces, which are translated and rotated one in relation to the other; for such relative movement sets up shear stresses in the washer, the movement of which is facilitated by its circular cross section.

Moreover, this type of washer demands a correct locking of the parts between which it is inserted so as to avoid deformations that fail to assure the seal or that damage the elastomeric material of which the washer is made.

In particular, the parts between which the "O"-ring is inserted require to have direct reciprocal abutment surfaces so that the said parts can be brought together only to a certain extent even when they are forcefully locked. To this position of locking there should correspond a correct deformation of the washer, neither too slight-which would place the seal at risk-not too great, which would damage it.

As well as representing a cost, the incidence of which on components of the type in question is not low, the narrow tolerance machine-tooling of a suitable seat for the "0"ring can cause serious problems if the configu ration of the seat and that of the opposed surface, between which the washer is locked, are not such as to assure that the washer undergoes a deformation that provides an adequate seal.

The object of the present invention is to embody a component provided with an im proved seal-device such as will obviate the drawbacks of the known art and thus assure a satisfactory seal with an "O"-ring housed in a seat shaped so that it assures a deformation of the washer able to provide a satisfactory seal in respect of variously configurated surfaces, horizontal or inclined in particular, in the latter case as the result of more or less pronounced bevels.

To achieve this object, the present invention embodies a pneumatic or hydraulic circuit component comprising a threaded tang and an annular projection which forms a radially protruding abutment surface, characterized in that proximal to the area of union between the said tang and the said projection a substantially triangular section annular seat is formed; and in that one side of the said seat is an extension of the profile of the tang and the opposite side of the said seat is inclined by between 30 and 60 , the depth of the seat being such as to receive the toroidal washer in a non-deformed condition so that it protrudes for a height greater than half the diameter of its section from the said abutment surface.

The structural and functional characteristics of the invention, and its advantages over the known art, will become apparent from an examination of the following description, referred to the appended drawings.

In the drawings: Figure 1 is a sectional view of a component embodied according to he innovative principles of the invention, in which the "O"-ring washer is locked against a flat surface; and Figure 2 shows the same component as in Fig. 1, but with the "O"-ring locked against an inclined surface.

A cap screw, per se of conventioned type, is indicated in the drawings by the numeral 10, and is intended as a typifying general example of a threaded body for screwing into a seat, with a washer inserted between body and seat; for any other type of connection, as far as the presence of a threaded tang as indicated by 11 cutted proximally to an abutment surface 12 is concerned, has a similar configuration.

An annular seat for an "O"-ring washer 13 is formed in said surface 12 adjacent to the root of the tang 11.

According to the present invention, the said seat is formed of the vertical inner wall 14 of the tang 11 and of an opposed inclined outer wall 15, which is joined to the wall 14 by a relatively broad loop 16.

The angle formed by the walls 14 and 15 can be of between 30 and 60 , and preferably in the region of 45". The width of this angle and the depth of the seat 14, 15, 16 will in any case be such as to ensure that there is within the said seat an empty space that will guarantee that the washer will deform when subjected to crushing stress, the said washer-when unstressed-protruding from the seat by a dimension H which is preferably greater than half the diameter D.

In this manner a perfect leak-free seal is assured both when the washer 13 is locked against an opposed horizontal surface 17 (Fig.

1) and when it is locked against an inclind surface 18 (Fig. 2), this latter being the case when the tang is received in a seat having a wide- angle bevel.

In the case of the horizontal surface 17, the deformation of the washer 13 will be such as to wholly occupy the seat 14, 15, 16. In the case of the inclined surface 18, on the other hand, although the deformation of the washer 13 will suffice to guarantee an adequate seal, it will leave an empty space proximal to the loop 16.

As a consequence of the seat being of the kind proposed in the present invention, the washer can to great extend be housed within it; however, for its progressive insertion into the seat the washer has to undergo a pronounced deformation because of the tapered shape of the said seat, with the result that the sealing effect of the washer is good even when the crushing stress is relatively low.

In practical use the seat is satisfactory, with no rupture or extrusion of the washer over a wide range of deformation thereof, and this because of the specific configuration of the surface on which it rests when the tang is tightened.

An essential advantage of the present invention is that, as it is without undercuts, and indeed has a surface 15 outwards at a relatively wide angle, the seat can be readily produced using a machine tool, which fact positively affects the cost of the final products.

Claims

1. A pneumatic or hydraulic circuit component comprising a threaded tang and an annular projection forming a radially protruding abutment surface, characterized in that proximal to the area of union between the said tang (11) and said projection (12) a substantially triangular section annular seat (14, 15) is formed, one side of the seat being an extension of the profile of the tang and the opposite side of the seat being inclined by between 30 and 60 , the depth of the seat being such as to receive the toroidal washer in a non-deformed condition so that it protrudes for a greater height than half the diameter of its section from said abutment surface.

2. A component as described in claim 1, characterized in that the said seat is formed of the vertical inner wall (14) of the tang (11) and of an opposed inclined outer wall (15) joined to the wall (14) by a relatively broad loop (16).

3. A pneumatic or hydraulic circuit component, substantially as herein described with reference to, and as shown in, the accompanying drawings.