WO2013178912A1

WO2013178912A1 - Membrane valve

Info

Publication number: WO2013178912A1
Application number: PCT/FR2013/051105
Authority: WO
Inventors: Marco Martino SPANEVELLO
Original assignee: Mgi Coutier
Priority date: 2012-05-30
Filing date: 2013-05-21
Publication date: 2013-12-05
Also published as: CN104350317B; FR2991423B1; FR2991423A1; CN104350317A

Abstract

The invention relates to a valve (1) comprising a body (3) including a recess, a seat (4) arranged transversely inside the body and provided with through-openings (8) through which the fluid is to pass, and a flexible membrane (2) capable of sealing said through-openings, the membrane being retained at the centre thereof, in a deformed and prestressed position, on a central pin (12). The seat (4) comprises, on the periphery thereof, bearing means (13) engaging with complementary bearing means (14) formed in the recess (7) of the body (3), said means being in permanent contact with one another after the valve has been assembled. The resulting limit stop guarantees that the membrane (2) is prestressed. Said limit stop is advantageously completed by a sealing O-ring (17). The invention can be used in the automotive field, for example in an assisted-braking circuit.

Description

Diaphragm type valve

The present invention relates generally to the technical field of non-return valves and the like, such as valves for regulating pressure, maintaining a vacuum, purging, venting, etc. to be inserted in circuits and pipes traversed by gaseous or liquid fluids. This invention relates more particularly to such a valve of the membrane type, applicable to the field of the automobile.

Motor vehicles are equipped with several circuits and pipes, which serve to transport various fluids such as air, oil vapor, fuel ..., to the various devices of the engine, or from these devices. To guarantee the proper direction of the flow, these circuits and pipelines are usually equipped with valves, structurally similar to each other but can have quite various functions: anti-return, pressure regulation, vacuum maintenance, bleeding, set-up air.

The valves of this type often fulfill a very important function from the point of view of the safety of the occupants of the vehicle or the respect of the environmental standards: braking, fight against the pollution and / or improvement of the efficiency of the engine. This is the case, for example, with valves inserted in brake assist circuits, vacuum-based control circuits and circuits for the transfer of oil and fuel vapors.

For all these applications, and particularly in the case of brake assist, a good maintenance of the vacuum and a very short vacuum setting time are fundamental requirements. Another requirement becoming more and more important is the maintenance of the cleanliness of the components of the valves, to avoid any pollution and the possible degradation of their own function and / or that of downstream organs, such as turbocharger or vacuum pump. . Efforts must therefore be made to improve in this sense the design and manufacture of check valves and the like, intended for the automotive field.

A particular type of check valve or vacuum retainer is the diaphragm valve, which comprises a recessed body, a seat disposed within the body transverse thereto, the seat being provided with passage orifices for the fluid, and a flexible circular membrane that can be applied against the seat by closing its orifices, or be separated from said orifices. The membrane is most often maintained by its center, for example on a central pin carried by the seat. It covers or disengages a series of orifices in the seat, which usually are circular orifices distributed at constant angular intervals all around the central pin on which the membrane is maintained.

As examples of check valves or the like having such a constitution, reference is made here to CN patent documents 201705473 U, GB 2452139 A and US 5413599.

The main functional requirements of a check valve or vacuum retainer of this type are, on the one hand, a good seal of the contact of the membrane on the seat in the "non-passing" direction and, on the other hand , the opening pressure as low as possible in the "running" direction of the valve.

To satisfy these two contradictory requirements, difficult to reconcile, certain solutions consist in exerting on the membrane a sufficient prestressing to guarantee a frank contact of this membrane with the seat, in the zone to be sealed, for example against a circular edge projecting in the peripheral area of the seat. Conventionally, the prestressing of the membrane is obtained either by means of a compression spring urging a flat and rigid membrane, or by giving said membrane a specific shape, in particular an arched "umbrella" shape, causing a deformation of the membrane.

Such solutions guarantee a good seal at rest, that is to say in the absence of pressure difference between upstream and downstream of the valve, but in return they increase the opening pressure and the losses of load of the valve. But current applications are increasingly demanding the reduction of the opening pressure and pressure drops, because of unstable and often low sources of depression. These current classic solutions thus find their limits.

Also known are diaphragm valves in the form of a simple flexible disk, of flat shape in the free state, which can be perforated at its center, the membrane being only deformed and prestressed by its support against a slightly concave seat. The deformation of the membrane remains in this case a critical characteristic, which is the result of a compromise between the behavior of the membrane to obtain the seal, on the one hand, and the deformability of this membrane under a weak opening pressure and with low pressure drops, on the other hand. Obtaining a good compromise here requires a good mastery of all the parameters related to both the structure of the valve and its manufacturing process. This objective is often difficult to achieve, with commonly used joining techniques, such as rotational friction welding or ultrasonic welding used for assembling plastic components. This lack of control leads in particular to sometimes high rejection rates, in the industrial production of the valves in question.

More particularly, as illustrated in Figure 1 of the accompanying schematic drawing, which is a partial sectional view of a valve according to the state of the art, obtaining the desired preload for the membrane 2, mounted between a half upper body 3a and a seat 4, is a function of the initial dimensions of several components or parts of components, as well as the relative depression dimension between these components during the welding assembly process. All these dimensions, measured here in the axial direction, have an effect on the final relative position of the two components which are the upper half-body 3a and the seat 4. In particular, the depression dimension has significant tolerances, related to the welding machine and the positioning means of the components to be assembled, which is the cause of a great variability of the prestressing of the membrane 2.

In the example illustrated in FIG. 1, the tolerances on the four dimensions indicated j 1, j 2, j 3 and j 4 have a uniform impact on the deformation of the membrane 2 of a valve assembled by rotational friction welding. according to the relationship:

JG = j3 - j1 - j2 - j4 in which

- JG represents the deformation of the membrane relative to its rest position, that is to say the difference in height between the two following planes, perpendicular to the axis of the valve:

• plane passing through the line of contact between the rear surface of the membrane and the sealing edge of the seat,

• plane tangential to the same rear surface of the membrane, in the center of it towards the picot,

- j1 is the thickness of the membrane,

- j2 is the axial distance between the central support of the membrane and a reference surface of the valve body, - j4 is the axial distance between the sealing edge of the seat and a reference surface of the seat of the valve,

- j3 is the axial distance between the two aforementioned reference surfaces, which distance is dependent on recess during assembly.

The present invention aims to limit the "chain" of dimensions and tolerances involved in the prestressing of the diaphragm of a valve of the kind in question, in particular by eliminating the depression dimension related to the welding assembly process, so as to to obtain for the membrane prestressing better controlled, providing a more reliable operation of the valve itself in both the closed position and the open position, while maintaining a simple and economical manufacturing.

For this purpose, the invention relates to a valve comprising a hollow body, a seat disposed within the body transversely thereto, the seat being provided with passage openings for the fluid, and a circular flexible membrane. can be applied against the seat by closing its orifices, or be spaced from said orifices, the membrane being held by its center, in deformed position and prestressed, for example on a central pin carried by the seat, this valve being essentially characterized by the fact that the seat comprises, in its peripheral zone, bearing means cooperating with complementary bearing means formed in the recess of the body of the valve, and sol idaires of the body or a part thereof, these bearing means coming into permanent mutual contact after assembly of the valve.

In a preferred embodiment of the valve, object of the invention, the bearing means carried by the seat are constituted by an annular flat bearing surface located at the periphery of said seat, while the complementary bearing means carried by the body of the valve are constituted by support fins, projecting radially into the recess of said body, from the peripheral wall of this recess.

Advantageously, the body still bears, in the central region of its recess, other means of support, in particular in the form of radial fins coming into contact with the face of the membrane opposite the seat, in the central region of this membrane. .

These other fins in particular take place, after assembly of the valve, around the central pin holding the membrane. Thus, on the whole, complementary support means ensure a relative "fixed" position of the two components of the valve that are on the one hand the seat, whether it is an independent part or integrated into a lower half-body, and secondly the complementary part of this seat, which can be designated as upper half-body. Thanks to such a "free stop" and also to the other support means which immobilize the membrane axially in its central zone, the prestressing of this membrane is guaranteed, this prestressing resulting from a "chain" of dimensions depending solely on the dimensional characteristics components, any variation of said preload related to the assembly process including welding is excluded.

According to a complementary aspect of the invention, the valve further comprises an annular elastically deformable member, such as a sealing O-ring, interposed and compressed between the peripheral zone of the seat and at least one peripheral portion of the valve body, said annular member urging the seat towards the abutment position of its bearing means against the complementary bearing means carried by the body.

Thus, the seat is biased towards its stop open position, so that this stop is guaranteed, during the assembly of the valve and throughout its life, by an elastic member which allows to "catch up" the tolerances of im nension and the games and which also "absorbs" the variability of the assembly process, while guaranteeing the tightness between the components.

In the case where the seat is constituted by an independent piece, housed in the recess of a body itself composed of an upper half-body and a lower half-body, the annular member such as O-ring seal is advantageously interposed and compressed between the peripheral area of the seat, the base of the upper half-body and a peripheral portion, preferably cone-conic surface of the lower half-body, surrounded by the base of the half upper body.

Thus, in the case of a seat constituted by an independent part, the O-ring ensures, by its compression, the free stop of this seat against the upper half-body, while achieving alone the seal between three zones belonging to respectively to said seat, to the upper half-body and the lower half-body, these three zones being able to be at different pressure values at the same time. In any case, the invention will be better understood from the description which follows, with reference to the attached schematic drawing showing, for example, an embodiment of this valve.

Figure 1 (already mentioned) is a partial sectional view of a valve according to the state of the art,

Figger 2 is a view in the neck passing through the axis of a valve according to the present invention,

3 shows, in section and on an enlarged scale, a detail of the region of the O-ring of the valve of FIG. 2,

Figure 4 is a front view of the seat only of this valve.

Referring to Figure 2, a valve, generally designated by the reference numeral 1, comprises a body 3 having a recess 7, composed of two half-bodies 3a and 3b together, arranged along the same central axis A. The flap 1 is adapted to fulfill the function of check valve.

The two half-bodies are respectively designated as upper half-body 3a and lower half-body 3b, with reference to the drawing, without this implying a particular orientation of the valve 1 in its use. The upper half-body 3a is extended along the axis A by an outlet nozzle 5 for the fluid flowing through the valve 1. The lower half-body 3b comprises a fluid inlet nozzle, not visible, also located in the axis A.

The outer body 3a has a base 6 of circular shape, which caps the lower half-body 3b, so that the union of the two demi-body 3a and 3b delimits a recess 7 of shape general cylindrical, centered on the axis A.

A seat 4, here constituted by an independent piece, is placed inside the recess 7 of the body 3, transversely to the axis A. The seat 4 is pierced with a plurality of passage orifices 8, for the passage of fluid, arranged all around the axis A. The passage holes 8 communicate with an internal channel 9 formed by the dem i-lower body 3b. These passage orifices also open into the upper face 10 of the seat 4, which is a concave face delimited externally by a projecting circular edge January 1.

A flexible membrane 2, circular and flat in the free state, is mounted in the recess 7 of the body 3. The membrane 2 is held at its center on a central pin 12, integral with the seat 4.

In the closed position of the valve 1, as shown in Figure 2, the membrane 2 is applied against the upper face of the seat 4 and on the edge 1 1 protruding from this seat 4, so as to close the outlet of all the through openings 8 and thereby stop any reflux of the fluid. In the open position (not shown), the membrane 2 is deformed upwards so as to deviate from the seat 4 and to clear the opening of the through openings 8, while allowing the circulation of the fluid in the "passing" direction. Of the valve 1, that is to say from the inlet nozzle and the internal channel 9 to the outlet nozzle 5.

As shown more particularly in FIG. 4, the passage orifices 8 of the seat 4 are arranged in several concentric circles, for example three concentric circles C1, C2 and C3, surrounding the central pin 1 2. The passageways of a circular row have an angular offset of half a step from the axes of the adjacent through-holes belonging to the preceding or following circular row. Thus, the passage holes 8 are numerous and close to each other, which provides:

in the open position: a larger total passage section for the fluid, the flow being balanced and the deformation of the membrane 2 being homogeneous, which contributes to a reduction of the pressure drops,

in the closed position: an improved support of the membrane 2 against the seat 4, with a more homogeneous distribution of the mechanical stresses exerted on the membrane, which limits the risks of damage of this membrane by tearing, formation of slits or deformation persistent.

All around its circular zone including the through-holes 8, and thus in its peripheral zone, the seat 4 has an annular flat bearing surface 13, which is situated in a plane perpendicular to the axis A and which forms means of rotation. 'support. The upper half-body 3a has support fins 14, which project radially in the recess 7, from the peripheral wall 1 5 of this recess 7. The upper half-body 3a further comprises other fins 1 6 located in its central region. The support fins 14 form complementary support means to the support means formed by the annular flat bearing surface 13. The other fins 16 are distinct from the support fins 14 and form other means of support. support from support means and complementary support means.

When the valve 1 is assembled, that is to say when the upper half-body 3a and the lower half-body 3b are joined by imprisoning between 4, the support fins 14 of the upper half-body 3a come into contact with the annular flat bearing surface 13 of the seat 4, by producing a free stop which fixes the relative position of the seat 4 and dud upper em-body 3a.

Simultaneously, the other fins 1 6 of the upper half-body 3a, which here constitute the other support means, take place around the central pivot 12 and come into contact with the face of the membrane 2 opposite the seat 4, thus realizing the preload of this membrane 2. The frank stop made as indicated above, combined with the support of the vanes 16 on the central region of the membrane 2, ensures the prestressing of said membrane 2, in the sense of a controlled pressure of the membrane 2. against the seat 4 and in particular on the projecting edge 11 of this seat 4. In practice, these means contribute to controlling the axial dimension indicated in H (amplified) in FIG. 2.

As shown in detail in FIG. 3, an o-ring seal 17 is interposed and compressed between the three components which are the upper half-body 3a, the lower half-body 3b and the seat 4. The O-ring 17 takes support simultaneously:

against the base 6 of the upper half-body 3a,

against a conical surface 18 formed on the periphery of the lower body 3b, and

under an annular flange 19 formed on the periphery of the seat 4. At the same time as the assembly of the flap 1, with axial displacement of the lower half-body 3b along the arrow F, the O-ring 17 is deformed by the conical surface 1 8 of the lower half-body 3b. Then sliding along the axis A, the O-ring 1 7 distributes the compression force in the radial direction, that is to say towards the base 6 of the upper half-body 3a, and in the axial direction it is ie between the conical surface 18 of the bottom half-body 3b and the annular flange 19 of the seat 4. The seal between the three components is thus guaranteed, at the same time as the O-ring 17 requests the seat 4 in the axial direction towards the stop position.

The slope of the conical surface 18 is optimized so as to axi mate the neck of the inner body 3b, while guaranteeing the internal tightness of the valve 1 by pressing the O-ring 17 against the flange 19 of the seat 4, this in order to absorb the dimensional tolerances related to the components and the assembly operation. In the case of a valve 1 assembled by welding, the O-ring 17 seal acts as a "barrier" vis-à-vis unwanted particles of melt, which would emerge during the welding operation of the half upper body 3a on the lower half-body 3b, making unnecessary any washing or blowing / suction operations to remove these particles.

It will be noted that the assembly of the half-body 3a on the half-body 3b is also possible, by other means, in particular by snapping as indicated at 20 in FIG.

The valve 1, previously described, is particularly applicable in the automotive field, for circuits and pipes traversed by a liquid or gaseous fluid: braking assistance circuit, pure air ducts or air laden with oil vapors or fuel or other, fuel transfer lines, etc.

As is obvious, and as is apparent from the foregoing, the invention is not limited to the sole embodiment of this valve which has been described above, by way of example; it embraces the contrary, all variants of implementation and application respecting the same principle.

It is thus, in particular, that one would not move away from the scope of the invention:

- by integrating the seat to the lower half-body of the valve, instead of making this seat as an independent piece,

- by providing on the seat passage openings in number and other provisions,

by performing the assembly of the components of the valve, regardless of the number and shape, by any method or technique, such as a "bayonet" system,

- by using any equivalent means of those described, and in particular:

- by replacing the circular bearing surface of the seat and the support fins of the upper half-body by any surfaces or other shapes forming a stop,

replacing the O-ring with any elastically deformable and compressible member, such as a spring washer or spring, or with an elastic form directly molded with the upper or lower half-body or with the seat, - using the valve not as a check valve, but in a similar function such as pressure regulating valve, vacuum or vacuum check valve, purge valve, vent valve, etc. as long as the structure of this valve is preserved,

- By realizing on the same principle a double valve or other industrial product more or less complex, for example a device incorporating two opposing check valves and performing, as a whole, a function "switch" fluid flow.

Claims

1. Valve (1) of the membrane type, the valve (1) comprising a body (3) having a recess (7), a seat (4) disposed inside the body (3) transversely thereto, the seat (4) being provided with passage orifices (8) for the passage of fluid, and a flexible circular membrane (2) that can be applied against the seat (4) by closing off the passage orifices (8) or being separated from said orifices passage (8), the membrane (2) being held by its center, in deformed and prestressed position,

the valve (1) being characterized in that the seat (4) comprises, in its peripheral zone, support means (13) arranged to cooperate with complementary support means (14) which are formed in the recess (7) of the body (3) and which are integral with the body (3) or a portion (3a) of the body (3), the support means (13) and the complementary support means (14) being arranged to come into permanent mutual contact after assembly of the valve (1).

2. Valve (1) according to claim 1, characterized in that the support means (13) are formed by an annular flat bearing surface located on the periphery dud it seat (4), while the means of complementary supports (14) are constituted by support fins projecting radially into the recess (7) from the peripheral wall (15) of this recess (7).

3. Valve (1) according to claim 1 or 2, characterized in that the body (3) carries, in the central region of its recess (7), other bearing means which comprise fins (16) and which are arranged to come into contact with a central region of the face of the membrane (2) opposite the seat (4).

4. Valve (1) according to any one of the preceding claims, characterized in that the membrane (2) is held by its center, in deformed position and prestressing, on a central pin (12) carried by the seat (4) .

5. Valve (1) according to claims 3 and 4, characterized in that the fins (16) belonging to said other support means take place, after assembly of the valve (1) around the central pin (12).

6. Valve (1) according to any one of the preceding claims, characterized in that it further comprises an annular elastically deformable member, such as an O-ring (17) sealing, interposed and compressed between the peripheral zone (19) of the seat (4) and at least one peripheral portion (6, 1 8) of the body (3), so that said elastically deformable annular member urges the seat (3) to the stop position of its means of support (13) against the complementary support means (14).

7. Valve (1) according to claim 6, characterized in that, its seat (4) being formed by an independent piece, housed in the recess (7) of the body (3), the body (3) being composed of an upper half-body (3a) and a lower half-body (3b), the elastically-deformable annular member, such as an O-ring (1 7) for sealing, is interposed and compressed between the peripheral zone (19) of the seat (4), the base (6) of the upper half-body (3a) and a peripheral portion (18), preferably cone-shaped surface, of the lower half-body (3b), surrounded by the base (6) the upper half-body (3a).