FR2567983A1 - Packing for plumbing fittings, to be inserted between two parts having channels to be connected in a sealed fashion, comprising a support with at least one opening packed with a seal with small thickness compared to the thickness of the support - Google Patents

Abstract

The packing is a cartridge 1, for a mixer tap mechanism with ceramic plates with circular grinding. The bottom 11 is inserted between a tap body 2 and a stationary ceramic plate 3, and has openings 16, 17 for the connection of the pipes 26, 27 of the tap body with the openings 36, 37 of the plate 3. Flexible tubular seals 12, 13 are inserted in the openings 16, 17 so as to bear on the flat surface 20 of the body 2 and on the plate 3. According to the invention the seals are securely fastened to the bottom 11 along the entire lateral surface 16a, 17a of the openings 16, 17. The seals 12, 13 may be fairly flexible so as to obtain good sealing without excessive strains on the ceramic plate, and without in any way risking being deformed in an unacceptable fashion under axial compression or by depression.

Description

 The invention relates to a fitting for fittings, to be inserted between two parts having channels which must be connected in leaktight manner, of the type comprising a support with two generally parallel faces for the respective support of the two parts, and having at least a communication opening in correspondence with the channels, delimited by a lateral surface between the two faces, and, in association with the support, a tubular joint which fits into the opening to bear respectively on the two parts, and whose l The thickness, normally at the lateral surface of the opening, is several times less than that of the support between the faces.

 The evolution of sanitary tapware, with the wide distribution of so-called mixer taps or mixers in particular, where the metering of cold and hot water, and the adjustment of the flow rate are obtained by a single command, has led to review the design of the seals which ensure the seal between the water inlet and outlet channels, and the progressive and combined sealing members of these channels, in particular because of the multiplication of the seals to be provided, and the reduction in the space available to house these seals.

 The problem is aggravated for taps of this kind, where the shutter members consist of two ceramic plates bearing one on the other by faces with specular polish, and provided with openings and channels suitably arranged so that the displacement of one plate relative to the other along the contact plane determines the desired settings. The arrivals and departures of water are carried out through a fixed plate, the ceramic plates ready neither for machining of complex shape, corresponding to the classic clamping of the joints, nor to mechanical stresses in bending, and the dimensions of the plates must be reduced (a few centimeters in diameter in general), so much to obtain reliable polished contact planes at an acceptable price, only to be housed in a limited space adjustment head.

 Furthermore, for reasons relating to the rationalization of manufacturing, it is desirable that the same adjustment head be used in taps for various uses, or of different styles. It is also not excluded that the same valve bodies may be equipped with different heads.

Finally, the arrangement of the adjustment head in an interchangeable assembly or cartridge facilitates maintenance and repair.

 I1 therefore exist interchangeable cartridges, containing the entire progressive shutter adjustment mechanism, which are mounted on bronze or brass valve bodies fitted with an erected connection plate, using screws or nut rings.

 One could certainly provide seals between the plate of the body and a face of the head, the latter comprising in itself sealed communications with the fixed ceramic plate.

To avoid a multiplication of seals, it is often preferred that the seals are inserted directly between the plate of the valve body and the fixed ceramic plate. For ease of assembly the seals are then included in a gasket comprising a support where openings open in which the seals are inscribed.

 The support can be a free element, or be an integral part of the cartridge.

 Seals that can be used can be classified into two categories: seals, which are elastomer rings whose thickness along the joint plane is of the same order as the thickness along the direction of passage perpendicular to the joint plane, and which will be called O-rings because they exhibit, when tightened and in service, a behavior comparable to that of the O-rings themselves, the cross-section of which is circular.

And the joints, which have a thickness perpendicular to the direction of passage, several times less than the thickness in this direction of passage, and which will be called tubular, the section of tube aspect prevailing over the ring aspect .

 The O-rings deform homogeneously under compression, the deformations practically only affecting the effective cross-section of the seal, the general shape of the ring not being affected. For a true O-ring, the circular section becomes oval, while the neutral fiber which passes through the center of this circular section remains an unchanged circumference. O-rings also resist pressure well in the joint plane.

 However, in return, the O-rings, as soon as the thickness of the support is not very small, occupy a non-negligible surface in the joint plane. We are led to restrict the passage section of the channels, and to misuse the surface of the ceramic plates. In addition, when the seal has multiple passages, the simultaneous sealing of the seals in the same clamping plane involves either an excellent regularity of thickness of the O-rings, or clamping forces which can become excessive.

 Tubular joints, on the other hand, occupy a minimum of section in the joint plane. They are susceptible to notable deformations in the direction of passage (axial) under reduced compression forces, which allows the multiplication of the passages and of the corresponding seals in the joint plane, without particular difficulties of individual sealing. By pressure gauges, the pressure of the liquid, of the water in the material, on the interior surface of the seal, squeezes this seal against the lateral surface of the opening where it is inserted, this pressure being transmitted to the terminal edges of the seal which bear on the parts between which sealing is to be ensured, due to the fluid behavior of the elastomer which constitutes the joint. In the case of the valves mentioned above, the surfaces where the end sections of the joints bear are the plate of the body and fixed ceramic.

 However, the flexibility of the joint in axial compression can cause the joint to fold during assembly, the axial compression resulting in warping of the joint along localized generatrices, comparable to the buckling of a long rod under axial load. The end edges of the joint then cease to carry their entire surface on the support piece.

 Similar deformation of the seal can occur when the liquid inside the seal is in depression relative to the environment. The seal is then "swallowed". Such a depression can occur, either when a water column is created downstream of the joint, opening to the atmosphere at a lower level, or when the speed of the water passing through the joint is greater than its speed at outlet into the atmosphere, by dynamic pressure effect.

 However, in the case of tubular joints with circular section, swallowing the joint requires considerable depressions, the joint resisting by arching effect, with perfect symmetry of forces. It is not the same when the radius of curvature of the periphery in cross section of the joint varies along this periphery, the regions where the radius of curvature is the greatest having the least resistance to depression. In practice, the resistance of the joint to depression becomes critical when, at least at one point on the periphery of the joint, the corresponding center of curvature is situated outside the section of the joint delimited by this periphery.

 The invention relates to a fitting for fittings of the kind mentioned above, with tubular seals which do not have the drawbacks which are specific to this type of seal, while retaining the corresponding advantages.

 To this end, the invention proposes a fitting for fittings, to be inserted between two parts having channels which must be connected in leaktight manner, of the type comprising a support with two generally parallel faces for the respective support of the two parts, and having less a communication opening, in correspondence with the channels, delimited by a lateral surface between the two faces, and, in association with the support, a tubular joint which fits into the opening to bear respectively on the two parts, and the thickness of which, taken normally at the lateral surface of the opening, is several times less than that of the support between its faces, characterized in that the joint is secured to the support at least along the entire lateral surface of the 'opening.

 It is clear that the weaknesses of the tubular joints lie in deformations where the joint deviates locally from the side wall of the opening where it is inserted. The joining of the joint with this side wall prohibits this type of deformation.

 The joints can be secured to the side wall of the opening of the support by gluing. In a preferred variant, the seal is formed in place by overmolding, the support having been made adherent beforehand by a conventional adhesion operation, for example by immersion in a solution called "primary".

The characteristics and advantages of the invention will become apparent from the description which follows, by way of example, with reference to the accompanying drawings in which
Figure 1 is an axial section along the plane II of Figure 2, of a mixer valve cartridge whose bottom forms a packing according to the invention
Figure 2 is a top view of the cartridge shown in Figure 1
Figure 3 is an enlarged schematic view of a tubular gasket for packing according to the invention
Figures 4 to 6 show the modes of deformation of the seals of the prior art, which avoids the present invention; among these figures
Figures 4A and 4B relate to an O-ring
FIGS. 5A and 5B to a tubular joint in axial compression
FIGS. 6A and 6B to a tubular joint having a section with variable curvature.

 According to the embodiment shown in Figures 1 and 2, a cartridge 1, comprising a cylindrical skirt 10 and a generally planar bottom 11, is designed to enclose the shutter and distribution mechanism of mixing valves, this mechanism comprising in known manner two ceramic plates superimposed with surfaces in contact with specular polish.

In Figure 1, only the lower plate 3, fixed, is shown. This plate 3, the upper face 30 of which is flat and of specular polish, has three openings 36, 37 and 38, respectively assigned to the outlet of the mixed water, to the inlet of hot water and the inlet of Cold water. The opening 38 is not visible in FIG. 1, but corresponds to the opening 18 in the bottom 11, visible in FIG. 2.

 It will be recalled that the second ceramic plate, not shown, has recesses such that the inlet openings 37 and 38 are partially masked in a complementary manner, while the outlet opening 36 is progressively masked. Thus a first movement of the second plate allows the additional metering in hot and cold water, and a second movement adjusts the overall flow independently.

 The tightness between the two wafers, obtained by specular polishing of the facing faces, and the movement of the second wafer, precise and gentle, with respect to the first 3, requires that the second wafer be urged to bear on the first, by spring means, well flat. Furthermore, the plates should not be subjected to excessive bending, due to the relatively low flexural strength of rigid ceramics, not to mention that a deflection of a plate would compromise the seal between the plates.

Also the fixed plate is not clamped tightly on the bottom of the cartridge, but immobilized with a small clearance along the plane of the face 30, and stopped with a significant clearance in the direction perpendicular to the plane of the face 30, in order to allow the intimate contact of the plates under the stress of the spring means applied to the second, mobile plate.

 The bottom 11 of the cartridge 1 is pierced with three openings 16, 17 and 18, assigned respectively to the outlet of the mixed water, to the inlet of hot water and to the inlet of cold water. The cartridge 1 being molded, the openings 16, 17 and 18 flare upward, to ensure a clearance for the mold cores.

 The valve body 2 in bronze or brass ends with a plate 20 where channels 26, 27 and 28 open. The channel 26 is connected to the outlet member of the taps, drawing spout, shower hose or hand shower , or shower drain diverter, or any other desired arrangement. Channels 27 and 28 are connected respectively to the hot and cold water inlets.

 So that a tight connection is made between the valve body 2 and the mechanism for distributing and adjusting the flow rates inside the cartridge 1, that is to say between the channels 26, 27 and 28 of the valve body 2 and the openings of the channels 36, 37, 38 in the ceramic plate 3, the openings 16, 17 and 18 in the bottom 11 of the cartridge 1 are lined with tubular seals 12, 13 and 14 respectively, which fit into the openings 16, 17 and 18 in contact with the side walls 16a, 17a and 18a of these openings between the parallel faces of the bottom 11, upper lla and lower llb. These tubular joints 12, 13 and 14 protrude slightly beyond the faces 11a and 11b, so as to bear on one side on the underside of the ceramic plate 30, and on the other on the plate 20. note that the upper end of the seals 13 and 14 has a peripheral ring at mid-thickness of the seal, which enters a corresponding recess of the periphery of the openings 37 and 38 in the plate 3, in order to ensure correct alignment of the openings 37 and 38 with openings 17 and 18.

 It was understood that during assembly, the cartridge 1 is tightened on the plate 20 of the body 2, by means of nut rings and suitable threads. In addition, the spring means of the mechanism, which bear on a cover of the cartridge 1, urge the plate 3 against the face 11a of the bottom 11, by means of the movable plate. I1 follows that the tubular joints 12, 13 and 14 are compressed by the bearing of their terminal ends on the wafer 3 and the plate 20, the bottom li then acting as a support for the joints, without participating in sealing.

 It will be noted that all that has just been described is known.

 But, according to the invention, and to avoid certain drawbacks of the known arrangement on which we will extend further, the seals 12, 13, 14 are secured to the bottom 11 along all the lateral surfaces 16a, 17a and 18a of the openings 16, 17 and 18 respectively.

 Two processes are planned to ensure this joining.

When it comes to applying the invention to an existing gasket, with seals whose execution tool exists, the bonding of the seals 12, 13, 14 against the side walls 16a, 17a, 18a coated with a suitable layer of glue is a relatively economical solution.

 On the other hand, especially in cases where the damping of an existing tool is not to be taken into account, it will be advantageous to produce all of the seals in a single overmolding operation of the seals in place in the openings 16, 17, 18 of the support 11. According to the usual process in adherent overmolding, the support piece is coated with a compound, called "primary", at least at the locations where the adhesion of the overmolded material to the support is sought. The "primer" ensures the formation of an adhesion interface between the support and the overmolded material.

 Figure 3 schematically illustrates the result of overmolding. In the support 11 is made a cylindrical opening 19. On the lateral su-rface 19th of the opening 1-9 was overmolded a seal 15 made of elastomer, made adherent to the support 11 by a primary interface 15a, of negligible thickness . During overmolding, the edges 15c and 15b are formed on the joint 15 which protrude beyond the faces 11a and 11b of the support 11, and spread over these faces by forming bevels. This form results from the wetting of the support by the elastomer due to the action of the "primary".

 As we have already observed, the simultaneous sealing of the joints 12, 13 and 14 assumes that the entire periphery of each of the joints comes to bear on its bearing surface. The compensation for flatness defects, both of the end edges of the seals and of the bearing surfaces, involves variable crushing of the seals. It is necessary that the joints be very flexible so that the differences in deformation in crushing do not translate into high local differential forces, in particular when the bearing surface is a ceramic plate which is not clamped on its support, but pressed on the joints through a second plate by springs which allow the sliding of the second plate on the first.

 The flexibility of the joints has as a corollary a lower resistance specific to deformations. The O-rings (in the sense which has been given here to this expression), as represented in FIGS. 4A (free joint) and 48 (compressed joint), respond to compression by an ovalization of the joint in its section, the general shape of ring being preserved. It is apparent, without the need for a detailed study, that the O-ring requires a relatively high force to crush, and that its shape gives it very good resistance to perpendicular deformations. to the axis of the ring.

 Referring to FIGS. 5A and 5B, which correspond, for a tubular joint, to FIGS. 4A and 4B relating to the O-rings, it will be understood that, at the same absolute crushing value, the tubular joint opposes a much weaker force, due both to its length, which reduces relative crushing, and to the form of deformation it undergoes, with a restriction of the passage section at mid-height. In fact the deformation represented in FIG. 5B is unstable, due to the reaction of the tube to a reduction in diameter of passage in the central part. Irregular folds are formed, with flattening of the tube towards the central part. These irregular deformations often lead to defects in bearing capacity of the end sections of the tubular joint.

 The arrangement according to the invention of course eliminates this type of deformation. It is possible to use very flexible elastomers and to reconcile great flexibility in crushing with the absence of risks of uncontrolled deformations.

 Another type of deformation is possible with tubular joints which have, in cross section, profiles with variable curvature, like the joints 12, 13, 14 of FIGS. 1 and 2. FIGS. 6A and 68 schematize these deformations, for a joint which roughly has the shape of the joint 12, that is to say in plan, three rectilinear sides at right angles, and a fourth curvilinear side, the connections between sides being effected by rounding with a small radius.

 These deformations are likely to occur when the interior passage of the tubular joint is in depression relative to the exterior. It should be remembered that this situation may be due to static causes (presence of a column of water opening to the atmosphere below the joint) or to dynamic causes (speed of passage of water through the joint greater than the outlet speed of the same stream of water to the atmosphere).

 As seen in Figure 68, the joint faces which have a radius of curvature, in the plane of a very large cross section, are swallowed by the internal depression.

The representation of FIG. 6B is schematic, and is unstable, like that of FIG. 5B. Indeed the orientation of the pressure forces, which controls the deformation, is modified by the deformations in the direction which accentuates the deformation. While the convex part with a small radius of curvature resists depression as an arch, the straight parts become concave and swallow and turn.

 In absolute terms, for perfectly flexible joints, any deviation from perfect circularity is likely to induce the swallowing of the joint under vacuum. In practice, it can be assumed that for the areas of the joint whose center of curvature of the periphery of a straight section is inside this periphery, the risks of swallowing can be neglected, which means that they should be considered otherwise.

 Anyway, moreover, this risk disappears by application of the present invention.

 The foregoing considerations show that the present invention cannot be limited to the examples described, but embraces all variants of execution or application.

Claims (5)

 1. Fitting for fittings (1), to be inserted between two parts (2, 3) having channels (26, 27, 36, 37) which must connect in a leaktight manner, of the type comprising a support (20) with two faces (lla, llb) generally parallel for the respective support of the two parts (2, 3) and having at least one opening (16) for communication, in correspondence with the channels, delimited by a lateral surface (16a) between the two faces , and, in association with the support (11), a tubular joint (12) -which fits in the opening (16) to bear respectively on the two parts (2, 3), and whose thickness taken normally the lateral surface of the opening is several times smaller than that of the support between its faces, characterized in that the seal (12) is secured to the support (11) at least along the entire lateral surface (16a) of the opening (16).  2. A fitting according to claim 1, characterized in that the seal (12) is secured to the support by gluing.  3. A packing according to claim 1, characterized in that the seal (12) is formed in place Dar overmolding, the support (11) having been made adherent by a conventional operation beforehand.  4. A fitting according to any one of claims 1 to 3, characterized in that the support (11) comprises a plurality of openings (16, 17, 18) occupying, in a plane parallel to the plane of the faces of the support, together at least one third of the total surface of the support.  5. A fitting according to any one of claims 1 to 4, characterized in that the curve, which forms the periphery of the opening (16) in a plane parallel to the faces of the support, locally has at least one center of curvature located at the outside of this periphery.