Silencing conduit for reducing noise in an air duct for a gas storage heater

Abstract

A silencing conduit (6) for reducing noise propagation from a fuel-fired heating apparatus (1) having an air inlet (4). The silencing conduit (6) comprises an inlet (8) configured to be coupled to an air duct (7); an outlet (9) configured to be coupled to the air inlet (4) of the heating apparatus (1), so that comburent air (10) can flow from the air duct (7) through the silencing conduit (6) into the air inlet (4); a damping chamber (11) in communication with the inlet (8) and the outlet (9), a damper block (13) of sound absorbing material received inside the damping chamber (11); a passage aperture (14) formed between the inlet (8) and the damping chamber (11), a shutter plate (15) mounted at the passage aperture (14) and configured to partially obstruct the passage aperture (14) thereby defining a locally restricted flow cross-section (16); the shutter plate (15) defining a shutter aperture (17) and being movable with respect to the passage aperture (14) in multiple different adjustment positions in which the shutter aperture (17) and the passage aperture (14) overlap with different areas of obstruction of the passage aperture (14), thereby allowing adjustment of the locally restricted flow cross-section (16).

Description

SILENCING CONDUIT FOR REDUCING NOISE IN AN AIR DUCT FOR A GAS STORAGE HEATER

[0001] TECHNICAL FIELD

[0002] The present disclosure and invention relate to the field of fuel fired storage water heaters and more particularly to a silencing box or silencing conduit section for damping vibrations and noise in an air duct for a fuel fired storage heater, particularly in an air duct for feeding comburent air to a pre-mixing box that mixes the comburent air with a combustion fuel prior to entering a premix burner of the storage water heater.

[0003] BACKGROUND

[0004] Many residential and commercial heating and hot water systems include a furnace, boiler, or domestic water heater having a fuel burner, e.g. gas burner of the premix burner type. For this purpose the heating or hot water system has a premixing box or premixing space upstream of the fuel burner, an air duct connected to the premixing space for feeding comburent air into the premixing space, a fuel duct connected to the premixing space or to the air duct at an entrance region of the premixing space for feeding combustion fuel into the premixing space. Depending on the heating power of the heating and hot water system, adequate air fans must be provided to convey large amounts of comburent air through the air duct. Both the air fan operation and the air flow itself (during operation), but also the burner operation (especially during a starting phase with increase combustion noise) generate undesired noise and vibrations which are propagated along the air duct. In addition, duct cross-section restrictions may lead to undesired whistling noise.

[0005] In order to reduce the noise, it is known to connect noise damping conduit sections in the air duct which have specifically selected flow section variations and contain noise absorbing material, e.g. foam material the purpose of reducing the occurrence of noise and vibrations in the air duct.

[0006] There are however still disadvantages with current designs of silencing conduit sections. One disadvantage is due to the fact that there is no universal noise damping structure which could be applied with equally good results to air duct systems in heating systems having different air duct lay-out and dimension, different burner properties and different operational conditions, e.g. different required thermal power.

[0007] To obviate this disadvantage and to obtain at least a certain degree of product standardization it is known to manufacture a reduced number of differently dimensioned silencing conduit sections and to mount a specifically shaped diaphragm plate onto the silencing conduit section in order to be able to adapt a cross-section restriction or a cross-section variation of the silencing conduit section to the specific noise- and vibrational behavior of the heatingsystem. It also known to sell the silencing conduit section together with a number of different diaphragm plates so that the silencing conduit section can be adapted to future modifications of the heating system by unmounting the previously mounted diaphragm plate and replacing it with a different new diaphragm plate.

[0008] However, frequently the set of different diaphragm plates gets lost over time or the installer is reluctant to unmount and mount diaphragm plates to adapt the silencing conduit section to heating system modifications, because this unmounting and mounting operation is not always carried out easily.

[0009] Moreover, the known diaphragm plates allow only for an approximate adaptation and any desirable fine adjustment is impossible.

[0010] OBJECTIVE OF THE INVENTION

[0011] It would be desirable to provide a silencing conduit section for air ducts in heating and hot water systems, particularly for air ducts for fuel fired water storage heaters, with improved capabilities of installing, adjustment and adaptation to system modifications.

[0012] SUMMARY OF THE INVENTION

[0013] In carrying out principles of the present invention, in accordance with representative embodiments thereof, a silencing conduit is provided for reducing the noise and vibration propagation in an air duct of a fuel-fired heating apparatus which is representatively a storage water heater but could alternatively be a variety of other types of fuel-fired heating devices without departing from principles of the present invention.

[0014] According to a general aspect of the invention, a silencing conduit is provided for reducing the noise and vibration propagation in an air duct of a fuel-fired heating apparatus, in particular a gas storage water heater having an air inlet,

[0015] the silencing conduit comprising:

[0016] an inlet configured to be coupled to an air duct;

[0017] an outlet configured to be coupled to the air inlet of the fuel fired heating apparatus, so the comburent air can flow from the air duct through the silencing conduit) into the air inlet;

[0018] a damping chamber having an interior in fluidic communication with the inlet and the outlet, the damping chamber forming a damper seat;

[0019] a damper block or sound absorbing material or sound absorbing structure received in the damper seat inside the damping chamber;

[0020] a passage aperture formed between the inlet and the damping chamber,

[0021] a shutter plate mounted at the passage aperture and configured to partially obstruct the passage aperture defining a locally restricted flow cross-section;

[0022] the shutter plate defining a shutter aperture and being slidable with respect to the passage aperture in multiple different adjustment positions in which the shutter aperture and thepassage aperture overlap with different areas of obstruction of the passage aperture, thereby allowing adjustment of the locally restricted flow cross-section.

[0023] Thanks to the slidable arrangement of the shutter plate the restricted flow cross-section can be adjusted without unmounting and replacing shutter plates, no multiple different shutter plates need to be provided, no shutter plates can get lost, different adjustment positions can be easily achieved and tested for the adaptation of the silencing conduit to the specific conditions of the storage heater or heating system.

[0024] BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIGURE 1 schematically illustrates part of a fuel-fired water heater with a silencing conduit,

[0026] FIGURE 2 is a perspective view from an inlet side of a silencing conduit according to an embodiment,

[0027] FIGURE 3 is a perspective view from an outlet side of the silencing conduit in figure 2,

[0028] FIGURE 4 is an inlet side view of the silencing conduit in figure 2, showing locally restricted flow cross-section in an adjustment position of a shutter plate, according to an embodiment,

[0029] FIGURE 5 is a lateral cross-section view of the silencing conduit in figure 2,

[0030] FIGURE 6 is a perspective cross-section view of the silencing conduit in figure 2,

[0031] FIGURE 7 is a perspective exploded view of a silencer conduit according to an embodiment,

[0032] FIGURE 8 is a perspective view of an inlet side cover portion of a silencer conduit according to an embodiment,

[0033] FIGURE 9 is a frontal view of the inlet side cover portion in figure 8,

[0034] FIGURE 10 is a side view of the inlet side cover portion in figure 8,

[0035] FIGURE 11 is a lateral cross-section view of the inlet side cover portion in figure 8,

[0036] FIGURE 12 is a rear view of the inlet side cover portion in figure 8,

[0037] FIGURE 13 is a cross-section view of the inlet side cover portion in figure 8 according to the sectional plane XIII-XII in figure 10,

[0038] FIGURE 14 is a side view of a hollow body portion of a silencer conduit according to an embodiment,

[0039] FIGURE 15 is a rear view of the hollow body portion in figure 14,

[0040] FIGURE 16 is a front view of the hollow body portion in figure 14,

[0041] FIGURE 17 is a cross-section view of the hollow body portion according to the sectional plane XVII-XVII in figure 16,

[0042] FIGURE 18 is a perspective sectional view of a silencing conduit according to a further embodiment.

[0043] DETAILED DESCRIPTION

[0044] Schematically illustrated in FIG. 1 is a fuel-fired fluid heating apparatus 1, representatively a commercial gas-fired storage water heater. The heating apparatus 1 comprises a storage tank for holding a fluid, e.g. domestic sanitary water, to be heated, a heat exchanger e.g. of a condensing type, arranged in an interior of the storage tank, a fuel burner 2, an air fan 3, an air inlet 4 and an exhaust outlet for flue gas. During operation of apparatus 1, comburent air is sucked by the air fan 3 through the air inlet 4 to the fuel burner 2 and flue gases flow from the fuel burner 2 through the heat exchanger and the exhaust outlet.

[0045] An exemplary water heating system 5 includes the fuel-fired fluid heating apparatus 1 having the air inlet 4 coupled to a silencing conduit 6 (for reducing the propagation of noise and vibrations) which in turn is coupled to an air duct 7 for conveying the comburent air.

[0046] As described above, heating apparatus 1 generates noise and vibrations which should be properly damped and the propagation of which along the air duct 7 should be reduced. Accordingly, silencing conduit 6 forms a locally restricted flow cross-section and a damping chamber for holding a damper block or sound absorbing material or sound absorbing structure therein, such that the air flow is forced to flow through the locally restricted flow cross-section and through the damping chamber and acoustic waves are at least partly absorbed or damped by the combined effect of the locally restricted flow cross-section and the sound absorbing material. For example, the damper block or sound absorbing material may include a foam material, e.g. a melamine foam.

[0047] Referring now to FIGS. 2 to 7, an exemplary silencing conduit 6 comprises:

[0048] an inlet 8 configured to be coupled to an air duct 7;

[0049] an outlet 9 configured to be coupled to the air inlet 4 of the fuel fired heating apparatus 1 , so the comburent air 10 can flow from the air duct 7 through the silencing conduit 6) into the air inlet 4;

[0050] a damping chamber 11 having an interior in fluidic communication with the inlet 8 and the outlet 9, the damping chamber 11 forming a damper seat 12;

[0051] a damper block 13 of sound absorbing material is received in the damper seat 12 inside the damping chamber 11;

[0052] a passage aperture 14 formed between the inlet 8 and the damping chamber 11,

[0053] a shutter plate 15 mounted at the passage aperture and configured to partially obstruct the passage aperture defining a locally restricted flow cross-section 16;

[0054] the shutter plate 15 defining a shutter aperture 17 and being slidable or movable with respect to the passage aperture 14 in multiple different adjustment positions in which the shutter aperture 17 and the passage aperture 14 overlap with different areas of obstruction of the passage aperture 14, thereby allowing adjustment of the locally restricted flow cross-section 16.

[0055] Thanks to the slidable arrangement of the shutter plate 15, the restricted flow crosssection 16 can be adjusted without unmounting and replacing shutter plates, no multiple different shutter plates need to be provided, no shutter plates can get lost, different adjustment positions can be easily achieved and tested for the adaptation of the silencing conduit 6 to the specific conditions of the heating apparatus 1 or heating system 5.

[0056] In an advantageous embodiment, the shutter plate 15 is continuously positionable with respect to the passage aperture 14 to allow setting the adjustment positions in a continuous manner, thereby allowing continuous (or fine-) adjustment of the locally restricted flow crosssection 16.

[0057] In accordance with an embodiment, the silencing conduit 6 comprises a hollow body 18 defining internally the damping chamber 11 and forming the inlet 8, the outlet 9 and the passage aperture 14. The shutter plate 15 is mounted in or on the body 18 and forms a first guide portion 19, e.g. a circular or circular arch shaped protrusion or groove, which engages a corresponding second guide portion 20 of the body 18, e.g. a circular or circular arch shaped groove or projection, and determines a rotational support of the shutter plate 15 with respect to body 18 about a shutter rotation axis 21. At least the shutter aperture 17, preferably both the shutter aperture 17 and the passage aperture 14, is / are eccentric to the shutter rotation axis 21 so that a relative position between the shutter aperture 17 and the passage aperture 14 con be adjusted along an arch shaped path, which allows for a great variety of settable shapes and areas of the locally restricted flow cross-section 16.

[0058] In accordance with an embodiment, the silencing conduit 6 includes a locking device 22 interacting with the body 18 and with the shutter plate 15 and operable to fix the shutter plate 15 with respect to the body 18 in said adjustment positions.

[0059] The locking device 22 comprises a first locking portion 23 formed by the shutter plate 15 and a second locking portion 24 formed by the body 18 which first and second locking portions 23, 24 are eccentric to the shutter rotation axis 21 and configured to always face each other in said adjustment positions and to be fixedly connectable to each other, e.g. by a locking screw 25.

[0060] In accordance with an embodiment, the silencing conduit 6 includes a setting indicator 26 configured to visually indicate a current adjustment position of the shutter plate 15 and to automatically change the indication of the current adjustment position in response to moving the shutter plate 15 with respect to the passage aperture 14.

[0061] Advantageously, the setting indicator 26 includes a pointer 26’ formed by one of the body 18 and the shutter plate 15 and an indicator scale 26” formed by the other of the body 18 and the shutter plate 15.

[0062] In accordance with embodiments, the damper seat 12 is ring shaped and the damperblock 13 has a closed ring shape or an open arch shape and is placed with interference fit or fixed in the damper seat 12 so to avoid undesired movement or rattle of the damper block 13 inside the damping chamber 11. The open arch shape of the damper block 13 allows an excentric positioning of the passage aperture 14 while avoiding space interference or overlap of the damper block 13 with the passage aperture 14.

[0063] In accordance with an embodiment, the damping chamber 11 forms a tubular cylindrical side wall 27 extending about a central cylinder axis 28, and a tubular tapering side wall 29 extending between the cylindrical side wall 27 and the outlet 9 and having a major first end 29’ with circular cross-section connected to the cylindrical side wall 27 and coaxial with the cylinder axis 28, and a minor second end 29” with circular cross-section eccentrical with respect to the cylinder axis 28 and having a second end diameter d29 smaller than a first end diameter D29 of the major first end 29’. The minor second end 29” forms the outlet 9 or is connected to a cylindrical outlet side wall 30 forming the outlet 9. The outlet 9 is coaxial with the minor second end 29” and / or eccentrical with respect to the cylinder axis 28.

[0064] The tapering side wall 29 defines an eccentric, stepless (in the sense of edge-less), i.e. smooth continuous, cross-section reduction or diameter reduction from the major first end 28’ to the minor second end 28”.

[0065] Preferably, the tapering side wall 29 defines an eccentric taper such that in only and exactly one cross-section plane 30 radial to the cylinder axis 28 the cylinder side wall 27 and the tapering side wall 29 are unilaterally (at a bottom side only) aligned and rectilinear (see Figs.5, 6, 17, 18).

[0066] Preferably, the tapering side wall 29 defines an unilateral rounded S-shape taper (Fig.19).

[0067] The eccentric cross-section variation and taper of the damping chamber 11 towards the outlet 9 reduce noise propagation (e.g. fan noise, burner noise) from the outlet 9 towards the inlet 8.

[0068] According to an embodiment, the passage aperture 14 and the inlet 8 (which may be both circular and coaxial) are eccentric to the cylinder axis 28 of the cylindrical side wall 27. Advantageously, the passage aperture 14 and the inlet 8 are radially offset with respect to cylinder axis 28 in an opposite direction than the outlet 9 (Fig. 5). This creates an offset 31 of the conduit structure transversal to an undesired noise propagation direction so that noise propagation through the silencing conduit 6 is reduced.

[0069] In an embodiment, the body 18 forms a tubular inlet side wall 32 extending from the inlet 8 to the passage aperture 14, preferably parallel to the cylinder axis 28, and having one or more circumferential steps 33 that reduce a flow section defined by the inlet side wall 32 from the inlet 8 toward the passage aperture 14. The stepwise reduction of flow section reduces the risk ofoccurrence of whistle noises originated by the air flow into the silencing conduit 6 and stiffens the silencing conduit 6 locally which influences its vibrational modes.

[0070] In accordance with an embodiment, the body 18 comprises a body portion 18’ forming at least part of the damping chamber 11, the outlet 9 and a first mounting flange 34, and an inlet portion 18” forming at least the inlet 8 and the passage aperture 14 and a second mounting flange 35. The body portion 18’ and the inlet portion 18” are connected together along the first mounting flange 34 and the second mounting flange 35, e.g. by mounting screws 36.

[0071] The body portion 18’ forms a first shutter seat cavity 37’ and the inlet portion 18” forms a second shutter seat cavity 37” facing the first shutter seat cavity 37’ and defining together a shutter seat 37 which houses a disc shaped portion of the shutter plate 15. This allows to easily interpose the shutter plate 15 between the body portion 18’ and the inlet portion 18” during assembly of the silencing conduit 6.

[0072] In accordance with an embodiment, the passage aperture 14 and the shutter aperture 17 are both circular, preferably of identical diameter, and can be preferably fully overlap in a fully open adjustment position.

[0073] In an embodiment, pointer 26’ of the setting indicator 26 is formed by the second locking portion 24 of the locking device 22, and the indicator scale 26” of the setting indicator 26 is provided on the first locking portion 23 of the locking device 22.

[0074] In a preferred embodiment, the indicator scale 26” and the first locking portion 23 are formed by a protruding peripheral section of the shutter plate 15 protruding visibly outward of the silencing conduit 6 or body 18 and defining a circumferentially extending slot 38.

[0075] The second locking portion 24 comprises a locking protrusion and receiving a locking screw 26 that can be tightened against the protruding peripheral section of the shutter plate 15.

[0076] In accordance with an embodiment, the silencing conduit 6, e.g. a wall of the damping chamber 11 can form a pressure detection port 39 for receiving a pressure sensor or pressure responsive switch for the purpose of diagnosing conduit clogging.

[0077] The body 18 and / or the shutter plate 15 may be formed of any suitable material, such as a polymer material, e.g., polypropylene.Reference numeralsfuel-fired fluid heating apparatus 1fuel burner 2air fan 3air inlet 4water heating system 5silencing conduit 6air duct 7inlet 8outlet 9comburent air 10damping chamber 11damper seat 12damper block 13passage aperture 14shutter plate 15locally restricted flow cross-section 16 shutter aperture 17hollow body 18a body portion 18’inlet portion 18”first guide portion 19second guide portion 20shutter rotation axis 21locking device 22first locking portion 23second locking portion 24locking screw 25setting indicator 26pointer 26’scale 26”cylindrical side wall 27cylinder axis 28tapering side wall 29major first end 29’minor second end 29”second end diameter d29first end diameter D29cross-section plane 30radial offset 31inlet side wall 32circumferential steps 33 first mounting flange 34 second mounting flange 35 mounting screws 36first shutter seat cavity 37’ second shutter seat cavity 37” shutter seat 37slot 38pressure detection port 39

Claims

CLAIMS1. Silencing conduit (6) for reducing noise propagation from a fuel-fired heating apparatus (1) having an air inlet (4),the silencing conduit (6) comprising:an inlet (8) configured to be coupled to an air duct (7);an outlet (9) configured to be coupled to the air inlet (4) of the heating apparatus (1), so that comburent air (10) can flow from the air duct (7) through the silencing conduit (6) into the air inlet (4);a damping chamber (11) having an interior in fluidic communication with the inlet (8) and the outlet (9), the damping chamber (11) forming a damper seat (12);a damper block (13) of sound absorbing material received in the damper seat (12) inside the damping chamber (11);a passage aperture (14) formed between the inlet (8) and the damping chamber (11), a shutter plate (15) mounted at the passage aperture (14) and configured to partially obstruct the passage aperture (14) thereby defining a locally restricted flow cross-section (16);the shutter plate (15) defining a shutter aperture (17) and being movable with respect to the passage aperture (14) in multiple different adjustment positions in which the shutter aperture (17) and the passage aperture (14) overlap with different areas of obstruction of the passage aperture (14), thereby allowing adjustment of the locally restricted flow cross-section (16).

2. Silencing conduit (6) according to claim 1, wherein the shutter plate (15) is continuously positionable with respect to the passage aperture (14) to allow setting the adjustment positions in a continuous manner, thereby allowing fine-adjustment of the locally restricted flow crosssection (16).

3. Silencing conduit (6) according to claim 1 or 2, wherein the silencing conduit (6) comprises a hollow body (18) defining internally the damping chamber (11) and forming the inlet (8), the outlet (9) and the passage aperture (14),wherein the shutter plate (15) is mounted on the body (18) and forms a first guide portion (19) which engages a corresponding second guide portion (20) of the body (18) and determines a rotational support of the shutter plate (15) with respect to body (18) about a shutter rotation axis (21).

4. Silencing conduit (6) according to claim 3, wherein the shutter aperture 17 and the passage aperture (14) are eccentric to the shutter rotation axis (21) and a relative position between theshutter aperture (17) and the passage aperture (14) can be adjusted along an arch shaped path.

5. Silencing conduit (6) according to claim 3, comprising a locking device (22) interacting with the body (18) and with the shutter plate (15) and operable to fix the shutter plate (15) with respect to the body (18) in said adjustment positions.

6. Silencing conduit (6) according to claim 5, wherein the locking device (22) comprises a first locking portion (23) formed by the shutter plate (15) and a second locking portion (24) formed by the body (18), the first and second locking portions (23, 24) being eccentric to the shutter rotation axis (21) and configured to always face each other in said adjustment positions and to be fixedly connectable to each other.

7. Silencing conduit (6) according to any one of the preceding claims, comprising a setting indicator (26) configured to visually indicate a current adjustment position of the shutter plate (15) and to automatically change the indication of the current adjustment position in response to moving the shutter plate (15) with respect to the passage aperture (14).

8. Silencing conduit (6) according to claims 3 and 7, wherein the setting indicator (26) includes a pointer (26’) formed by one of the body (18) and the shutter plate (15) and an indicator scale (26”) formed by the other of the body (18) and the shutter plate (15).

9. Silencing conduit (6) according to any one of the preceding claims, wherein the damper seat (12) is ring shaped and the damper block (13) has an open arch shape and is placed with interference fit or fixed in the damper seat (12).

10. Silencing conduit (6) according to any one of the preceding claims, wherein the damping chamber (11) is delimited by:- a tubular cylindrical side wall (27) extending about a central cylinder axis (28), and- a tubular tapering side wall (29) extending between the cylindrical side wall (27) and the outlet (9),the tapering side wall (29) having a major first end (29’) with circular cross-section and a first end diameter (D29), the first end (29’) being connected to the cylindrical side wall (27) and coaxial with the cylinder axis (28),the tapering side wall (29) having a minor second end (29”) with circular cross-section and eccentrical with respect to the cylinder axis (28) and having a second end diameter (d29) smaller than the first end diameter (D29),the minor second end (29”) forming the outlet (9).

11. Silencing conduit (6) according to claim 10, wherein the tapering side wall (29) defines an eccentric cross-section reduction from the major first end (28’) to the minor second end (28”).

12. Silencing conduit (6) according to claim 10, wherein the tapering side wall (29) defines an eccentric taper such that in a only and exactly one cross-section plane (30) radial to the cylinder axis (28) the cylinder side wall (27) and the tapering side wall (29) are unilaterally aligned and rectilinear on a first side and the tapering side wall (29) defines an unilateral rounded S-shape taper on a second side opposite the first side.

13. Silencing conduit (6) according to claim 10, wherein the passage aperture (14) and the inlet (8) are both circular and coaxial and eccentric to the cylinder axis (28) of the cylindrical side wall (27).

14. Silencing conduit (6) according to claim 10, wherein:- the outlet (9) is radially offset with respect to cylinder axis (28), and- the passage aperture (14) and the inlet (8) are radially offset with respect to cylinder axis (28) in an opposite direction than the radial offset of the outlet (9).

15. Silencing conduit (6) according to claim 3, wherein the body (18) forms a tubular inlet side wall (32) extending from the inlet (8) to the passage aperture (14) and having a plurality of circumferential steps (33) that reduce an inlet flow section defined by the inlet side wall (32) from the inlet (8) toward the passage aperture (14).

16. Silencing conduit (6) according to claim 3, wherein the body (18) comprises:- a body portion (18’) forming part of the damping chamber (11), the outlet (9) and a first mounting flange (34), and- an inlet portion (18”) forming at least the inlet (8) and the passage aperture (14) and a second mounting flange (35),the body portion (18’) and the inlet portion (18”) being connected together along the first mounting flange (34) and the second mounting flange (35),the body portion (18’) forming a first shutter seat cavity (37’) and the inlet portion (18”) forming a second shutter seat cavity (37”) facing the first shutter seat cavity (37’) and defining together with the first shutter seat cavity (37’) a shutter seat (37) which houses a disc shaped portion of the shutter plate (15).

17. Silencing conduit (6) according to claims 6 and 8, wherein the pointer (26’) of the setting indicator (26) is formed by the second locking portion (24) of the locking device (22), and the indicator scale (26”) of the setting indicator (26) is provided on the first locking portion (23) of the locking device (22).

18. Silencing conduit (6) according to claim 1, wherein the silencing conduit (6) forms a pressure detection port (39) for receiving a pressure sensor or pressure responsive switch for of diagnosing conduit clogging.

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