WO2007060699A1

WO2007060699A1 - System for sealed connection of an air/gas mixer device to a valve unit

Info

Publication number: WO2007060699A1
Application number: PCT/IT2005/000695
Authority: WO
Inventors: Armando Previato; Davide De Iulio
Original assignee: Sit La Precisa S.P.A.
Priority date: 2005-11-28
Filing date: 2005-11-28
Publication date: 2007-05-31

Abstract

A system for sealed connection of an air/gas mixer device (1) to a valve unit (2) is described, wherein a gas delivery section of the valve unit (2) is connected, in fluid communication, with a gas supply section of the mixer (1), comprising means for interlocking coupling, respectively provided on the mixer device (1) and on the valve unit (2), coaxially engageable with each other, gas-tight sealing means between the sections for passage of the gas from the valve unit (2) to the mixer device (1), means for axial retention between the interlocking coupling means for holding the mixer relative to the valve unit in the direction of mutual axial coupling.

Description

SYSTEM FOR SEALED CONNECTION OP AN AIR/GAS MIXER DEVICE TO A VALVE UNIT

Technical field

The present invention concerns a system for sealed connection of an air/gas mixer device to a valve unit, according to the characteristics mentioned in the preamble of main claim 1. Technological background

In the specific technical field of the present invention, in particular in boilers and similar apparatus, principally for domestic use, comprising a system for pre-mixing the combustible mixture to be fed to the burner, there is the requirement to connect the gas inlet section of the air/gas mixer device to the delivery section of the valve unit associated therewith and intended to deliver the flow of gas to the burner in a controlled manner. In the known applications, the air/gas mixer is provided with a tubular portion (defining the gas supply section) protruding radially from the body of the mixer itself, and intended to be connected to the delivery section of the valve body via a flanged attachment connection with corresponding clamping screws. That solution, although guaranteeing mutual locking, renders the assembly (and the corresponding disassembly) of the mixer on the valve body rather complex. In particular, the known system does not prove to be particularly rapid and flexible, does not permit any orientability in the mutual positioning of the mixer on the valve body, therefore rendering assembly on site by the installer rather difficult. It further requires the use of flanges and/or flanged connectors with corresponding fixing screws, components which also entail overall dimensions which conflict with the requirement for a desired compactness of the whole.

Description of the invention The problem underlying the present invention is that of providing a system for sealed connection, structurally and functionally designed so as to enable the limitations mentioned with reference to tine prior art cited to be remedied. This problem is solved by the invention by means of a sealed connection system produced according to the claims which follow. Brief description of the drawings

Further characteristics and advantages of the invention will become clearer from the following detailed description of a preferred exemplary embodiment thereof, illustrated by way of non-limiting example with reference to the appended drawings, in which:

Figure 1 is a diagrammatic view of a connection system according to the invention, between a mixer device and a valve unit, - Figure 2 is a view on an enlarged scale and in partial section of the connection system of Figure 1 in the uncoupled state, Figure 3 is a view corresponding to that of Figure 2 in which the connection system is in the coupled state,

Figure 4 is a partial view in front elevation of a member of the connection system according to the invention.

Preferred way of implementing the invention

With reference to the drawings mentioned, the reference 1 indicates an air/gas mixer device, shown only diagrammatically, arranged to be connected to a valve unit 2, also shown only partially, according to a system for sealed connection produced according to the present invention. The invention finds particular, but not exclusive, application in the connection of air/gas mixers to valve units in gas equipment such as, for example, boilers with a gas burner for domestic use. The connection system provides for a tubular portion 3 defined in the mixer 1 and capable of being coupled by axial insertion in a seat 4 provided in a wall 2a of the valve unit.

More particularly, the tubular portion 3 protrudes radially from the main body Ia of the mixer device and is axially pierced by a through hole 5, said hole constituting the inlet section for the flow of gas into the mixer delivered via the valve unit 2.

In the tubular portion 3 are identified, starting from the end connected to the body Ia of the mixer, a first portion 3a and a second portion 3b of casing with cylindrical profile, contiguous with each other, the second portion having a smaller diameter than the first. In the outer casing of the first portion 3a a circumferential groove 6 is provided. Starting from said groove 6, the first portion 3a is further tapered, with the diameter decreasing in the direction of the second portion 3b, and the surface thereof extends in a substantially conical manner. The conical tapering, the function of which will be clearly apparent hereinafter, involves the first portion 3a as far as a shoulder surface 7 from which the second cylindrical portion 3b extends axially. In the second portion a circumferential slot 8 is further provided, constituting a seat for receiving a sealing ring 9, conveniently of the "O- ring" type, provided to produce the gas-tight seal in the axial coupling between the tubular portion 3 and the seat 4.

Said seat 4 is preferably defined by a through hole of circular cross- section provided in the wall 2a of the valve unit 2, the hole constituting the terminal part of the delivery pipe (not shown) for delivery of the gas from the valve unit. In the hole 4 are correspondingly identified a first and a second cylindrical surface 4a, 4b, contiguous, and having different diameters with a radial shoulder 4c being defined between same. The surfaces 4a, 4b have dimensions such as to be respectively engaged coaxially by the portions 3a, 3b of the tubular portion 3 once the axial insertion of the portion in the seat has taken place, with coupling tolerances such as to permit freedom of relative rotation between the tubular portion and the seat about the axial insertion direction. The gas- tight seal is guaranteed by the engagement of the ring 9 with the cylindrical surface 4b.

The connection system also comprises a retaining member, indicated as a whole by 10, held axially on the body of the valve unit 2 and also capable of engaging the groove 6 as will be explained hereinafter. More particularly, the retaining member comprises a clip of harmonic steel wire, which has a preferred substantially V-shaped configuration with two arms 10a, 10b extending for at least a portion into the seat 4, in a mirror- image arrangement with respect to a diametral median plane of the seat, as is clearly illustrated in Figure 4. The arrangement of the portions 10a, 10b is such that they can engage the groove 6 when the tubular portion 3 is axially coupled to the seat 4 and consequently lock the mixer 1 and the valve unit 2 axially to each other. Said arms 10a, 10b are further resiliency deformable between a first position in which each of said portions protrudes into the seat (Fig. 4) and a second position in which each of said portions is outside the seat in order to disengage the groove. In the preferred configuration of Figure 4, the free ends of the arms 10a, 10b of the clip, and also the bent region at the vertex 10c of the clip are secured to the wall 2a of the valve unit via screw means 11 conveniently fixed in threaded holes 12 provided in the valve body. In this regard, the ends of the arms may conveniently be bent into an eyelet in order to be held in a stable manner by the head of the respective fixing screw 11. Alternatively, provision may be made for the free ends of the arms 10a, 10b and also the bent region of the vertex 10c to be secured round appendages (in the shape, for example, of nipples or other similar protuberances) protruding from the valve body, preferably provided in one piece with said valve body. It should be noted that the spreading apart of the portions of the retaining member 10, in the step of axial insertion of the tubular portion 3 into the seat 4, is facilitated by the tapering with conical surface, behind the shoulder 7, which tapering further permits control of the force of insertion during the axial coupling. The connection system provides that, starting from the position of Figure 2, with parts disengaged, and mutually distanced axially, the tubular portion 3 of the mixer 1 is pushed axially into the seat 4 of the valve unit 2. The insertion effects the spreading apart of the arms 10a, 10b of the retaining member 10 (by means of interference with the conical tapered surface) and the subsequent engagement of the arms in the groove 6 with a snap coupling which ensures the axial retention of the tubular portion relative to the seat. In this state, however, angular relative rotation is permitted, between the coupled parts, about the coupling axial direction, and the gas-tight seal is guaranteed by the contact of the O-ring 9 with the cylindrical surface 4b.

For the uncoupling of the valve unit from the mixer device it is sufficient to disengage the tubular portion 3 axially from the seat 4 with a withdrawal stress such as to bring about the resilient spreading apart of the arms 10a, 10b in order to disengage the groove 6 and allow the withdrawal of the portion 3 from the seat until the valve unit 2 is completely uncoupled from the mixer device 1. The invention thus solves the problem posed, obtaining numerous advantages with respect to the known solutions.

Among these may be numbered the rapidity and ease of coupling (and uncoupling) between the mixer and the valve unit, particularly appreciable in the step of assembly (disassembly) on site by the installer of the entire equipment on which the mixer and the valve unit are fitted.

Another advantage lies in the relative orientability between the mixer and the valve unit (while guaranteeing axial retention with a gas-tight seal), which facilitates the installation of the equipment by increasing the layout flexibility of same. Another advantage lies in the compactness of the overall dimensions obtainable with the system of the invention, without the need for connecting flanges and corresponding fixing screws. The system of the invention also makes it possible to maintain control of the forces for axial insertion and withdrawal of the parts being coupled. A further advantage lies in the fact that the system according to the invention may easily be adapted also to conventional structures of valve units and mixers, in particular taking advantage of the threaded holes provided in the valve body (for the fixing of conventional flanges/connectors) for the clamping of the screws for securing the metal wire retaining member as described above.

Yet other advantages lie in the ease of maintenance obtainable with such a system, and in the structural simplicity of the coupling members, in any case such as to ensure stability in the mutual retention, and resultant adequate gas-tight seal.

Claims

C L A I IW S

1. A system for sealed connection of an air/gas mixer device (1) to a valve unit (2), wherein a gas delivery section of said valve unit (2) is connected, in fluid communication, with a gas supply section of the mixer (1), comprising: interlocking coupling means, respectively provided on the mixer device (1) and on the valve unit (2), coaxially engageable with each other, gas-tight sealing means between said sections for passage of the gas from the valve unit (2) to the mixer device (1), means for axial retention between said interlocking coupling means for holding the mixer relative to the valve unit in the direction of mutual axial coupling, characterized in that said coupling means comprise a tubular portion (3) protruding from one of said mixer and valve unit and also bearing on its outer casing a transverse groove (6), the portion (3) being capable of being received in a seat (4) defined in the other of said mixer and valve unit, and in that said retaining means comprise at least one retaining member (10) held axially with respect to the seat (4) and extending with at least one portion into said seat in an arrangement such as to engage the groove (6) when the tubular portion (3) is received in the seat (4) so as to lock the mixer (1) and the valve unit (2) axially to each other, said retaining member (10) being resiliency deformable between a first position in which said portion protrudes into the seat (4) and a second position in which said portion is outside the seat in order to disengage the groove (6).

2. A connection system according to claim 1, wherein said retaining member (10) is made of metal wire.

3. A connection system according to claim 2, wherein said retaining member (10) is made of harmonic steel.

4. A connection system according to claim 2 or 3, wherein said coupling seat (4) is provided in the body of said valve unit (2) and said wire retaining member (10) is secured on said body via screw means (11) or by the bending of parts of said wire round respective appendages protruding from said valve body.

5. A connection system according to claim 4, wherein said wire retaining member (10) comprises at least two contiguous arms (10a, 10b) angled to each other and arranged in mirror-image in said seat (4) with respect to a diametral median plane of said seat.

6. A connection system according to any one of the preceding claims, wherein said seat (4) is provided in a wall (2a) of the valve unit (2) with circular transverse section and is defined by a first and a second cylindrical surface (4a, 4b), extending axially in mutual prolongation and also having a different diameter, such as to define a radial shoulder (4c) between said surfaces, the gas-tight seal of the interlocking coupling being produced along the second surface (4b) of smaller diameter, the axial retention by means of said retaining member (10) being produced at the first surface (4a) of larger diameter, such that in the axial interlocking coupling there is no interference between the sealing means and the axial retention means.

7. A connection system according to claim 6, wherein said tubular portion (3) protrudes from said mixer device (1) and comprises a first and a second portion (3a, 3b) of outer casing having different diameters such as to engage by axial coupling the respective surfaces (4a, 4b) of said seat (4), the portion (3a) of larger diameter of the tubular portion (3) being tapered, starting from the groove (6), in the direction of the corresponding shoulder (7) defined between said portions (3a, 3b) with different diameter.

8. A connection system according to claim 7, wherein the tapered part is configured with a conical surface.