Improved by-pass unit

Abstract

Bypass unit (10) comprising a delivery duct (2) and a return duct (3) for a fluid directed to or coming from a fluid-exploiting unit (1), respectively, a first ball valve (11) placed along the delivery duct (2), a second ball valve (12) placed along the return duct (3), and a bypass duct (13) connecting the delivery and return ducts (2, 3) at said valves (11, 12) The valves (11, 12) are two-way spherical shutter and are associated with a first ring-shaped sealing gasket (34, 36) and a second gasket (35, 37) performs its sealing action on the side of the bypass unit (10) connected to the thermal exchange unit (1).

Description

[0001] IMPROVED BY-PASS UNIT

[0002] DESCRIPTION

[0003] The present invention relates to fluid distribution systems, and more particularly to a bypass unit for one such system.

[0004] Preferably, but not exclusively, the invention finds application in thermal air conditioning systems for rooms and the following description will refer to this preferred application.

[0005] Background and scope of the invention

[0006] Thermal air conditioning systems for rooms are based on heat exchange between a heat transfer fluid, in particular a liquid as assumed below, and the environment. Such systems comprise a plurality of thermal exchange units that are each connected to a delivery duct and a return duct for the heat transfer fluid via a bypass unit, whose task is either to allow the liquid to flow from the delivery duct to the thermal exchange unit and from the latter to the return duct during normal operation of the thermal exchange unit, or to interrupt this flow and divert the liquid to a bypass duct which directly connects the delivery and return ducts to each other (bypass condition) when the thermal exchange unit needs to be isolated from the rest of the system, e.g. for maintenance purposes. In this way, there is no need to interrupt the operation of the entire system and no load imbalance is created.

[0007] For its operation, the bypass unit typically comprises a delivery valve and a return valve with an on / off function for liquid flow to or from the thermal exchange unit. Depending on the type of valve used for the delivery and return valves, a bypass valve with an on / off function may also be required for the flow of liquid passing through the bypass duct.

[0008] Since the system has a multiplicity of thermal exchange units, for reasons of space and ease of installation it is common to make the bypass units in the form of an H-shaped element in whose two parallel branches the delivery and return ducts are formed respectively, while in the transverse branch the bypass duct is formed.

[0009] An example of a bypass unit with an H-shaped structure that also has a bypass valve is described in EP 2818776 Bl, where the delivery and return valves are valves with a two-way spherical shutter and the bypass valve is a valve with a linear shutter. Since, as2 RACHELI

[0010] mentioned, thermal air conditioning systems for rooms have a multiplicity of thermal exchange units and require a bypass unit for each of these, systems employing bypass units of this type have the disadvantage of requiring a large number of parts, which makes them expensive and complex. Complexity also makes the need for frequent maintenance more likely, thus making operation more costly. In the specific case of the bypass unit illustrated in the document, the bypass duct is connected to the delivery and return ducts outside the delivery and return valve seats, which increases the axial dimensions of the unit.

[0011] The drawbacks associated with the high number of parts are overcome by bypass units using valves with spherical shutters (hereafter referred to simply as “spheres”) as delivery and return valves, commonly arranged in seats at the intersection of the delivery and return ducts and the bypass duct. These units eliminate the need for a bypass valve and also have the advantage that connecting the bypass duct to the delivery and return ducts at the delivery and return valves reduces the axial dimensions of the unit.

[0012] An example of such a bypass unit using three-way ball valves is described in EP 2990702 Al. The main drawback of these units is the high cost of the valves and their drives, even in the case of valves with a conventional shutter with an internal T-shaped channel, such as those used in the unit described in the mentioned document.

[0013] Another example of a bypass unit using valves with three-way balls arranged in seats at the intersection of the delivery and return ducts and the bypass duct is described in EN 213707 Z2. However, in this unit the cost problem is exacerbated by the fact that valves with specially designed shutters are used, in which the third way consists of a duct made on the outer surface of the shutter.

[0014] The purpose of the present invention is to provide a bypass unit that overcomes the above-mentioned drawbacks.

[0015] In particular, the aim of the present invention is to provide a bypass unit with as few components as possible, of limited cost and easy and economical operation.

[0016] According to the invention a bypass unit is provided comprising a delivery duct and a return duct for a fluid directed to a fluid-exploiting unit (in the preferred application a thermal exchange unit) or, respectively, or coming from the latter, a first ball valve placed along the delivery duct, a second ball valve placed along the return duct, and a bypass duct connecting the delivery and return ducts at said valves. In such bypass unit the valves are valves with3 RACHELI

[0017] a two-way spherical shutter and are associated with a first ring-shaped sealing gasket dimensioned and arranged so that, in a closed condition of the valves a first gap exists between the shutter of each valve and the gasket, which gap establishes communication between the delivery and return ducts and the inside of the seat, and hence the bypass duct, on the side of the bypass unit connected to an installation the fluid-exploiting unit is part of, whereas a second gasket performs its sealing action on the side of the thermal exchange unit cutting off the communication between the seat and the delivery and return ducts on that side.

[0018] According to an advantageous feature of the invention, the first ring-shaped sealing gasket is dimensioned and arranged to maintain communication between the delivery duct and the thermal exchange unit and between this and the return duct through the internal shutter channel until the closed condition is reached.

[0019] According to another advantageous feature of the invention, the second gasket is dimensioned and arranged so as to make a seal on the surface of the spherical shutter in both open and closed conditions of the valve and to create on the side of the thermal exchange unit, during the rotation of the shutter to pass from one to the other condition, a second gap, symmetrical to the first one, which puts the delivery and return ducts in communication with the inside of the seat and therefore with the bypass duct.

[0020] Other advantageous features of the invention will result from the dependent claims.

[0021] Brief description of the drawings

[0022] Further features of the invention will become clearer from the detailed description that follows, referring to a purely illustrative and therefore non-limiting embodiment thereof, illustrated in the accompanying drawings, wherein:

[0023] Figures 1 A and IB show the hydraulic connections between a bypass unit and a thermal exchange unit in a room air-conditioning system in the normal operating condition and the bypass condition, respectively;

[0024] Figures 2 - 4 are perspective views of some possible embodiments of the bypass unit according to the invention;

[0025] Figures 5 A - 5D are cross-sectional views of the bypass unit according to the invention, taken in a plane passing through line A - A of Fig. 3, showing the unit in different working conditions;

[0026] Figures 6A - 6D are enlarged scale views of one of the parallel branches of the4 RACHELI

[0027] unit illustrated in Figures 5 A - 5D,

[0028] Figures 7A - 7C are sectional views in enlarged scales of some examples of a sealing gasket used on the side of the thermal exchange unit in the valves of the bypass unit according to the invention;

[0029] Fig. 8A is a view similar to Figures 7A - 7C showing a sealing gasket with a double seat;

[0030] Fig. 8B is a diagram of the arrangement of the two gasket seats in Fig. 8A; Figures 8C and 8D are cross-sectional views of a valve using the gasket in Fig.

[0031] 8A in the closed and open condition, respectively;

[0032] Figures 9A and 9B are analogous views of Figures 8C and 8D for a valve using a two-part sealing gasket on the thermal exchange unit side;

[0033] Fig. lOAis a hydraulic connection diagram similar to Figures lAand IB, relating to two different flush and direct drain modes;

[0034] Fig. 1 OB is a sectional view, similar to Figures 5 A - 5D, showing the bypass unit according to the invention in the condition corresponding to Fig. 10A;

[0035] Figures 11 A, 11B and 12A, 12B are hydraulic connection diagrams and cross- sectional views similar to those in Figures 10A, 10B, relating to two different counterflow flush and drain modes.

[0036] Detailed description of the invention

[0037] An improved by-pass unit according to the present invention will now be described in detail with reference to the accompanying figures.

[0038] With reference to Figures 1A and IB, in thermal air conditioning systems for rooms, each thermal exchange unit 1 is connected to the delivery and return ducts 2, 3 for the heat carrier liquid in such a way as to define a circuit which presents, upstream and downstream of the unit 1 with reference to the direction of circulation of the liquid (indicated in the two figures respectively by the broken line arrows fl, f2), an assembly of components for the management and regulation of said circulation comprising, as an essential component, a bypass unit, depicted as a whole by the broken line block 10, which constitutes the object of the invention. This assembly may possibly also include a filter (broken line block 4) downstream of bypass unit 10 in the flow direction and a regulating / balancing valve (broken line block 5) upstream of the bypass unit 10 in the return direction. These diagrams are entirely conventional, but their description is useful for an easier understanding of the invention.5 RACHELI

[0039] The bypass unit 10 comprises, again in conventional manner:

[0040] a first valve (delivery valve) 11, associated with the delivery duct 2 and having an on / off function for the flow of liquid to the thermal exchange unit 1;

[0041] a second valve (return valve) 12 associated with the return duct 3 and having an on / off function for the flow of liquid leaving the thermal exchange unit 1 and directed to the rest of the system;

[0042] a bypass duct 13, which establishes a connection between the delivery and return ducts 2, 3 in the closed condition of the two valves 11, 12. This duct connects to the delivery and return ducts 2, 3 at the valves 11, 12.

[0043] In the diagrams, the open condition of a passage for the liquid circulating in the system is shown in black and the closed condition in white.

[0044] The valves 11, 12 are both open during normal operation of the thermal exchange unit 1 (Fig.

[0045] 1A) and closed (Fig. IB) in the bypass condition. In addition, during a flush and drain step, the valves 11, 12 can independently assume the open or closed condition, or an intermediate position between them, to achieve the liquid flow paths required by the particular flush and drain mode, as will be seen below. For the sake of clarity, please note that in the description of the valves 11, 12 and their operation, the terms “open” and “closed” and the like refer to the flow of liquid to or from the thermal exchange unit 1.

[0046] As illustrated in Figures 2 - 4, the bypass unit 10 can be made, again in a conventional manner, in the form of an H-shaped body 20, in whose two parallel branches 21, 22 the delivery and return ducts 2, 3 are formed, while in the transverse branch 23 the bypass duct 13 is formed. The numbers 24, 25 indicate the manoeuvre levers of the valves 11, 12. The body 20 can have a one-piece structure (Fig. 2) or a two- or multi-piece structure (Figures 3, 4). In the case of a structure in two or more pieces, these are joined at the transverse branch 23. Regardless of the type of structure, the manoeuvre levers 24, 25 can be mounted in-plane and rotate about a common axis coplanar to the plane of the duct axes 2, 3, as depicted in Figures 2 and 4, or they can be mounted out-of-plane and rotate about axes perpendicular to the plane of the duct axes 2, 3, as depicted in Fig. 3. Whether the invention is made as a one-piece structure or as a structure in two or more pieces has no influence on the invention and therefore, for simplicity’s sake, the invention will be illustrated in the following in connection with the two-piece solution alone.

[0047] Reference will now be made to Figures 5 A - 5D and 6A - 6D. With regard to Figures 6A -6 RACHELI

[0048] 6D, for the sake of simplicity and clarity of description, it is assumed that the branch of the body 20 depicted therein is the branch 21 in which the delivery duct 2 is formed.

[0049] According to the invention, the two valves 11, 12 are valves with a two-way spherical shutter 30 and respectively 31, arranged in a seat 32 and respectively 33 with the interposition of a pair of ring-shaped sealing gaskets 34, 35 and respectively 36, 37, placed the first on the system side and the other on the thermal exchange unit side 1. The numbers 38, 39 indicate the internal channels of the two shutters connecting the respective inlet and outlet ports. In the drawings it has been assumed that the closing rotation of the shutters is clockwise for the shutter 30 and anticlockwise for the shutter 31; obviously, opening will require a reverse rotation. The transition from the open valve condition to the closed valve condition can be achieved by a 90° rotation either clockwise or anticlockwise.

[0050] The gaskets 34 - 37 are dimensioned and arranged in such a way as to always maintain points of support on the surface of the spherical shutter 30, 31, so as to support it and keep its axis of rotation perfectly aligned with that of the pivot of the manoeuvre levers 24, 25 and thus allow perfect functionality under all conditions of the respective valve.

[0051] In particular, considering for simplicity’s sake only the valve 11, the gasket 34 which makes the seal between the shutter 30 and the walls of the seat 32 on the system side has a substantially rectangular cross-section and is arranged and dimensioned in such a way that the outer surface of the shutter 30 is in contact with the inner surface of the gasket 34 only at the inner edge of the latter which faces the seat 32 and that contact takes place along the entire circumference of the inner surface of the gasket 34 only in the open condition of the valve (Figures 5A, 6A). As soon as the shutter 30 begins to rotate to bring the valve to a closed condition, the contact between the shutter 30 and the gasket 34 occurs only along an arc of said circumference, creating a first gap 40 which puts in communication the inlet section 2’ of the delivery duct entering the valve 11 with the inside of the seat 32 (Figures 5B, 5C, 6B, 6C), allowing communication between the duct 2 and the bypass duct 13 through said seat while still maintaining the connection between the inlet section 2’ and the outlet section 2” of the duct 2 through the internal channel 38 of the shutter.

[0052] In the embodiment illustrated in Figures 5A to 6D, the gasket 35 which forms the seal between the shutter 30 and the walls of the seat 32 on the side of the thermal exchange unit 1 consists of one or more pieces and has a section substantially in the shape of a rectangular trapezoid with the oblique side placed on the inner side of the gasket. The gasket 35 is7 RACHELI

[0053] arranged and dimensioned so that contact between the outer surface of the shutter 30 and the inner surface of the gasket occurs over the entire circumference of the gasket 35 in the open and closed conditions of the valve 11 (Figures 5 A, 5D, 6A, 6D). As soon as the shutter 30 begins to rotate to bring the valve from the open condition to the closed condition and vice versa, the contact only occurs further along an arc of that circumference (Figures 5B, 5C, 6B, 6C), symmetrical to the arc of contact with the gasket 34 with respect to the axis of the duct, creating a second gap 41, symmetrical to the gap 40, which maintains communication between the sections of duct 2’ and 2” through the internal channel 38 and the seat 32 despite the opening of communication with the bypass duct 13.

[0054] Similarly to what has been described for the valve 11, in the valve 12 the rotation of the shutter 31 will create corresponding gaps 42, 43 to the gaps 40, 41, which place in communication the inside of the seat 33, and therefore the bypass duct 13, with the section 3” of return duct exiting the valve while still maintaining the connection between the incoming section 3’ and the outgoing section 3” of the duct 3 through the internal channel 39 of the shutter 31.

[0055] Figures 5A and 5D also show the path of the liquid to and from the thermal exchange unit 1 inside the valves 11, 12. In the normal operating condition, with the valves 11, 12 open (Fig. 5A), the path is the same as in conventional bypass valves, through the internal channels 38 and 39 of the shutters 30, 31. On the other hand, in the bypass condition, with the valves 11, 12 closed (Fig. 5D), the liquid passes from the inlet section 2’ of the delivery duct 2 to the seat 32 and from the latter to the bypass duct 13 via the gap 40, passing externally to the shutter 30, and from the bypass duct 13 to the chamber 33 of the valve 12 and from the latter to the outlet section 3” of the return duct 3 via the gap 42 in the valve 12, passing externally to the shutter 31.

[0056] With reference to Figures 7A - 7C, the gasket 35 can have different configurations to optimise the values of the operating torques of the shutter. For example, the oblique side can be formed by an arc of a circle (Fig. 7A), or by a line segment (Fig. 7B), or even by a pair of line segments having a different inclination with respect to the axis of the gasket (as illustrated in Figures 5, 6 and as best shown in Fig. 7C).

[0057] In addition, as illustrated in Figures 8A - 8D for the case of the gasket 35, it is possible to make the oblique side of the gasket into two distinct parts 350 (larger or outer diameter part) and 351 (smaller or inner diameter part), which are also approximately rectangular trapezoid in shape. With this configuration, the inner surface of the gasket 35 is in contact8 RACHELI

[0058] with the shutter 30 at one of the two parts of the seat, e.g. the outer part 350, in the open condition of the valve 11 (Fig. 8D) and at the other part 351 in the closed condition (Fig.

[0059] 8C). The part of the gasket corresponding to the intermediate seat part 352 between the two parts 350, 351 is never in contact with the shutter 30. This configuration can be adopted for all proposed gasket 35 geometries.

[0060] Figures 9A, 9B show a gasket 35’ comprising two axially separate ring-shaped elements 353 (smaller or inner diameter element) and 354 (larger or outer diameter element). One of these, e.g. the inner element 353, is in contact with the shutter 30 in the closed condition of the valve 11 while the other 354 is in contact with the shutter in the open condition of the valve. The gasket 35’ therefore acts similarly to the double-seated gasket 35’ in Figures 8 A - 8D.

[0061] The invention clearly obviates the problems of the prior art. In fact, the creation of gaps 40, 41 in the valve 11 and corresponding gaps 42, 43 in the valve 12, which allow the liquid to flow around the shutters 30, 31, allows the use of two-way balls, which are simpler and less costly to make than three-way balls. Furthermore, despite the use of two-way balls, the arrangement of the delivery and return valves can be maintained at the intersection of the bypass duct 13 and the delivery and return ducts 2, 3, so that it is not necessary to connect the bypass duct 13 to these ducts externally to the valves themselves and thus eliminates the need to have a valve also in the duct 13, also reducing the axial dimensions of the unit, as in the solution known from EP 2990702 Al.

[0062] Figures 10A, 11A, 12A show, for the sake of completeness, diagrams of the hydraulic connections in different flush and drain modes of the system, and Figures 10B, 11B, 12B show the corresponding conditions of the valves 11, 12 according to the invention.

[0063] Figures 10A, 10B illustrate two direct flush and drain modes, in which the configuration of the valves 11, 12 is the same. Precisely, in both modes the delivery valve 11 is open, preventing the passage of a flushing liquid from the delivery duct 2 to the bypass duct 13, and the return valve 12 is closed. The flushing liquid entering through the delivery duct 2 passes through the valve 11 to the filter 4, as in normal operation. In the first direct flush and drain mode, the liquid is immediately discharged through the drain valve 4a of the filter 4, as indicated by arrow 13. In the second mode, the liquid continues from the filter 4 and arrives at the thermal exchange unit 1, passes through it and, as indicated by arrow f4, is then discharged through a discharge device 6 located upstream of the actual regulating / balancing valve 5a in the block 5.9 RACHELI

[0064] Figures 11 A, 1 IB, 12A and 12B illustrate two counterflow flush and drain modes, whereby the flushing liquid arrives at the bypass unit 10 via the return duct 3. In both modes, the flushing liquid is discharged through the drain valve 4a associated with the filter 4. In the first mode (Figures 11A, I IB), the bypass duct 13 is not required: the valve 11 is closed and the valve 12 is open, and the liquid can flow through it to the regulating / bal anting valve 5, pass through it, pass through the thermal exchange unit 1 and flow out of it to the drain 4a, as indicated by arrow f5. In the second mode (Figures 12A, 12B), the thermal exchange unit 1 is not involved and, to reach the drain valve 4a, the liquid must flow from the return duct 3 to the delivery duct 2. For this purpose, the valve 12 is closed and the liquid can pass from the section 3” of the return duct 3 to the bypass duct 13 and reach the filter 4, and then the drain valve 4a through the valve 11, which is partially open, i.e. it is rotated 45° from the fully open condition. The situation of the valve 11 is therefore similar to that depicted in Figures 5B, 5C. To prevent the flushing liquid from flowing back through the delivery duct 2 this is closed, outside the unit 10, by a special valve, not shown. The liquid path in this second mode is indicated by the arrow f6.

[0065] Naturally, the present invention is not limited to the particular embodiment previously described and illustrated in the accompanying drawings, but numerous modifications can be made to it in detail, within the reach of the person skilled in the art, without thereby departing from the scope of the invention itself, as defined in the appended claims.

Claims

CLAIMS1. A bypass unit (10) comprising a delivery duct (2) and a return duct (3) for a fluid directed to or coming from a fluid-exploiting unit (1), respectively, a first valve (11) placed along the delivery duct (2), a second valve (12) placed along the return duct (3), and a bypass duct (13) connecting the delivery and return ducts (2, 3) at said valves (11, 12), characterised in that the valves (11, 12) are valves with a two-way spherical shutter (30, 31) and such spherical shutters (30, 31) are associated with a first ring-shaped sealing gasket (34, 36) dimensioned and arranged so that, in an off condition of the valves (11, 12) in respect of the fluid-exploiting unit (1), a first gap (40, 42) exists between the shutter (30, 31) of each valve (11, 12) and the gasket (34, 36), which gap establishes communication between the delivery (2) and return (3) ducts and the inside of the seat (32, 33) of the valve (11, 12), and hence the bypass duct (13), on the side of the bypass unit (10) connected to an installation the fluid-exploiting unit (1) is part of, whereas a second ring-shaped sealing gasket (35, 37; 35’) performs its sealing action on the side of the bypass unit (10) connected to the fluid-exploiting unit (1), thereby cutting off the communication between the seat (32, 33) and the delivery and return ducts (2, 3) on that side.

2. The bypass unit (10) according to claim 1, characterised in that the gaskets (34, 35, 36, 37; 35’) are dimensioned and arranged so that an internal surface thereof has abutment points on the surface of the respective spherical shutter (30, 31) in any operating condition of the valves (11, 12), so as to support the shutter (30, 31) and to keep its axis of rotation always in perfect alignment with the axis of rotation of a respective manoeuvre lever (24, 25).

3. The bypass unit (10) according to claims 1 and 2, characterised in that the first ringshaped gasket (34, 36) is dimensioned and arranged so as to maintain the communication between the delivery duct (2) and the fluid-exploiting unit (1) and between the latter and the return duct (3) through an internal channel (38, 39) of the shutter (30, 31) until the off condition is attained.4 The bypass unit (10) according to claim 3, characterised in that the first ring-shaped gasket (34, 36) has a substantially rectangular cross-sectional shape and is dimensioned and arranged so that the contact between the shutter (30, 31) and the gasket (34, 36) occurs only at the internal comer of the latter facing the seat (32, 33).11 RACHELI5 The bypass unit (10) according to any one of the preceding claims, characterised in that the second ring-shaped gasket (35, 37; 35’) is dimensioned and arranged so as to perform its sealing action on the surface of the spherical shutter (30, 31) in both the on and the off conditions of the valve (11, 12) and to create on the side of the fluid-exploiting unit (1), during the rotation of the shutter (30, 31) for moving from one condition to the other, a second gap (41, 43), symmetrical to the first one (40, 42), which also establishes communication between the delivery and return ducts (2, 3) and the inside of the seat (32, 33) of the valve (11, 12), and hence the bypass duct (13).

6. The bypass unit (10) according to claim 5, characterised in that the second gasket (35, 37) is made as an integral piece whose cross-sectional shape is substantially a right trapezium the oblique side of which is located on the inner side of the gasket (35, 37) and consists of an arc of circumference or a straight-line segment or yet a pair of straight-line segments with different inclinations relative to the axis of the gasket (35, 37).

7. The bypass unit (10) according to claim 6, characterised in that the second gasket (35, 37) is located in a seat comprising two separate portions (350, 351) such that the gasket is in contact with the surface of the spherical shutter (30, 31) at one of the seat portions (350) in the on condition of the valve (11, 12) and at the other seat portion (351) in the off condition of the valve (11, 12), whereas it is not in contact with the surface of the spherical shutter (30, 31) at an area intermediate zone between said seat portions (350, 351).

8. The bypass unit (10) according to claim 5, characterised in that the second gasket (35’) comprises two separate ring-shaped elements (353, 354) housed in respective seats in the body of the valve (11, 12), one of which elements (353) is in contact with the surface of the spherical shutter (30, 31) in the off condition of the valve (11, 12) whereas the other (354) is in contact with the surface of the spherical shutter (30, 31) in the on condition of the valve (11, 12).

9. The bypass unit (10) according to any preceding claim, characterised in that the installation the fluid-exploiting unit (1) is part of is an installation for thermal conditioning of spaces, and the fluid-exploiting unit (1) is a thermal exchange unit.

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