GAS/AIR MIXING DEVICE FOR A GAS BURNER AND ASSEMBLY COMPRISING A GAS/AIR MIXING DEVICE AND A FAN

Abstract

 Gas/Air mixing device (10) for a gas burner, having a mixer housing (11), a mixing unit (14) and a flow channel (16) for the gas/air mixture. The mixer housing (11) comprises a first inlet opening (12) for air, a second inlet opening for gas and an outlet opening (13) for a gas/air mixture. The mixing unit (14) is positioned within the mixer housing (11), wherein the mixing unit (14) provides the gas/air mixture by mixing the air entering into the mixer housing (11) through said first inlet opening (12) and the gas entering into the mixer housing (11) through said second inlet opening. The flow channel (16) for the gas/air mixture extends between the mixing unit (14) and the outlet opening (13). The flow channel (16) has a flow channel wall (17) being contoured in such a way that - seen in flow direction of the gas/air mixture entering into the flow channel (16) - an angle of inflow (α) is first increasing and thereafter decreasing, said flow channel wall (17) providing a flow deflection of the gas/air mixture flow. Figure 1

Description

[0001] The present patent application relates to a gas/air mixing device for a gas burner. The present patent application relates further to an assembly comprising such a gas/air mixing device and a fan.

[0002] EP 3 015 768 A1 discloses an assembly comprising a gas valve, a fan, a gas/air mixing device and a burner door. The gas/air mixing device comprises a mixer housing providing a first inlet opening for air, a second inlet opening for gas and an outlet opening for gas/air mixture. The fan comprises fan housing with a fan plate housing part and a fan impeller housing part. The fan impeller housing part provides an inlet opening for the gas/air mixture. The inlet opening for the gas/air mixture of the fan housing adjoins the outlet opening for gas/air mixture of the mixer housing.

[0003] JP 2011 185575 A discloses an assembly comprising a fan and a gas/air mixing device. The gas/air mixing comprises a mixer housing providing a first inlet opening for air, a second inlet opening for gas and an outlet opening for gas/air mixture. A mixing unit is positioned within the mixer housing. The mixing unit provides the gas/air mixture by mixing the air entering into the mixer housing through said first inlet opening and the gas entering into the mixer housing through said second inlet opening. The mixing unit comprises a venturi nozzle. A flow channel extends between the mixing unit and the outlet opening of the mixing housing.

[0004] Against this background, a novel gas/air mixing device of a gas burner is provided having a decreased flow restriction between the mixing unit and the outlet opening for gas/air mixture. The novel gas/air mixing device can provide an increased gas/air mixture flow. The novel gas/air mixing device comprises a flow channel extending between the mixing unit and the outlet opening, wherein the flow channel has a flow channel wall being contoured in such a way that - seen in flow direction of the gas/air mixture entering into the flow channel - an angle of inflow is first increasing and thereafter decreasing, said flow channel wall providing a flow deflection of the gas/air mixture flow.

[0005] Preferably, the flow channel wall has a bent contour and has a turning point, wherein - seen in flow direction of the gas/air mixture - upstream of turning point the flow channel wall is concave arched and downstream of turning point the flow channel wall is convex arched. This allows to decrease the flow restriction between the mixing unit and the outlet opening for gas/air mixture and to increase the gas/air mixture flow in a very beneficial way.

[0006] Preferably, a curvature center point of the concave arched section of the bent flow channel wall is positioned on a side of the flow channel wall facing the gas/air mixture flow. A curvature center point of the convex arched section of the bent channel wall is positioned on a side of the flow channel wall turned away from the gas/air mixture flow. This allows to decrease the flow restriction between the mixing unit and the outlet opening for gas/air mixture and to increase the gas/air mixture flow in a very beneficial way.

[0007] Preferably, the outlet opening for the gas/air mixture has an outlet opening central point. The turning point of the bent flow channel wall is positioned on or approximately on an opening axis that runs through the outlet opening central point and perpendicular to the plane in which the outlet opening is lying. This allows to decrease the flow restriction between the mixing unit and the outlet opening for gas/air mixture and to increase the gas/air mixture flow in a very beneficial way.

[0008] The bent flow channel wall may be s shaped or arc tangent shaped or hyperbolic tangent shaped or sinus area shaped.

[0009] The flow channel wall may be provided by by at least three straight flow channel wall sections approximating the bent contour.

[0010] Preferably, the outlet opening for the gas/air mixture has a first outlet opening section turned away from the mixture unit and a second outlet opening section of the facing the mixture unit. Said first opening section is semicircular shaped. Said second opening section is trapezoidal shaped or rectangular shaped. This allows to decrease the flow restriction between the mixing unit and the outlet opening for gas/air mixture and to increase the gas/air mixture flow in a very beneficial way.

[0011] The assembly according to the present application comprises a gas/air mixing device and a fan according to claim 13.

[0012] Preferred developments of the invention are provided by the dependent claims and the description which follows. Exemplary embodiments are explained in more detail on the basis of the drawing, in which:

Figure 1

shows a perspective cross section through a first gas/air mixing device according to the present application together with a section of a fan;

Figure 2

shows a perspective cross section through a second gas/air mixing device according to the present application together with a section of a fan;

Figure 3

shows a perspective cross section through a third gas/air mixing device according to the present application together with a section of a fan;

Figure 3a

a detail of Fig. 3;

Figure 3b

an alternative for the detail of Fig. 3;

Figure 3c

another alternative for the detail of Fig. 3;

Figure 4

shows a cross section through Figure 1 or 2;

Figure 5

shows a schematic detail of the gas/air mixing device;

Figure 6

shows an alternative schematic detail of the gas/air mixing device.

[0013] The present application relates to a gas/air mixing device of a gas burner. The present application relates further to an assembly comprising a gas/air mixing device and a fan.

[0014] Figures 1, 2 and 3 each show a section through a gas/air mixing device 10 according to the present application.

[0015] The gas/air mixing device 10 has a mixer housing 11.

[0016] The mixer housing 11 of the gas/air mixing device 10 comprises a first inlet opening 12 for air, a second inlet opening (not visible) for gas and an outlet opening 13 for a gas/air mixture.

[0017] The gas/air mixing device 10 has a mixing unit 14 positioned within the mixer housing 11. The mixing unit 14 provides the gas/air mixture by mixing the air entering into the mixer housing 11 through said first inlet opening 12 and the gas entering into the mixer housing 11 through said second inlet opening (not visible.

[0018] The mixing unit 14 may comprise at least one venturi nozzle 15. In the shown embodiment the mixing unit 14 comprises multiple venturi nozzles 15 positioned side by side in a row. The mixing unit 14 may comprise other mixing nozzles than venturi nozzles 15.

[0019] The mixer housing 11 has a flow channel 16 for the gas/air mixture. The flow channel 16 extends between the mixing unit 14 and the outlet opening 13. The gas/air mixture leaving the mixing unit 14 enters into the flow channel 16 in a flow direction FD illustrated in Fig. 3a. The flow direction of the gas/air mixture leaving the mixing unit 14 falls together or is coaxial with the flow direction FD of the gas/air mixture entering into the flow channel 16. The gas/air mixture leaving the mixing unit 14 enters or flows directly into the flow channel 16.

[0020] The flow channel 16 guides the flow of the gas/air mixture leaving the mixing unit 14 towards the outlet opening 13 of the mixer housing 11. The flow channel 16 has a shape such the gas/air mixture flowing through said flow channel 16 is subject to a flow deflection of 90° or approximately 90°.

[0021] The flow channel 16 has a flow channel wall 17 being contoured in such a way that - seen in flow direction FD of the gas/air mixture entering into the flow channel 16 - an angle of inflow α is first increasing and thereafter decreasing.

[0022] In Figures 1, 2, 3 and 3a the flow channel wall 17 has a bent contour and a turning point 18.

[0023] Seen in flow direction FD of the gas/air mixture, upstream of turning point 18 the bent flow channel wall 17 is concave arched and downstream of turning point 18 the bent flow channel wall 17 is convex arched. So, the bent flow channel wall 17 has a flow channel wall section 17a being concave arched and a flow channel wall section 17b being convex arched.

[0024] In the concave arched flow channel wall section 17a the angle of inflow α is - seen in flow direction FD of the gas/air mixture entering into the flow channel 16 - increasing. In the convex arched the angle of inflow α is- seen in flow direction FD of the gas/air mixture entering into the flow channel 16 - decreasing. In the region of the turning point 18 the angle of inflow α has a maximum value.

[0025] A curvature center point C1 of the concave arched flow channel wall section 17a of the bent flow channel wall 17 is positioned on a side of the flow channel wall 17 facing the gas/air mixture flow.

[0026] A curvature center point C2 of the convex arched flow channel wall section 17b of the bent flow channel wall 17 is positioned on a side of the flow channel wall 17 turned away from the gas/air mixture flow.

[0027] The concave arched flow channel wall section 17b of the bent flow channel wall 17 is defined by a radius of curvature r1. The convex arched flow channel wall section 17b of the bent flow channel wall 17 is defined by a radius of curvature r2. A ratio r1/r2 defined by the radius of curvature r1 of the concave arched section 17a and the radius of curvature r2 of the convex arched section 17b is the following range: 0,8 ≤ r1/r2 ≤ 1,2.

[0028] Preferably, the ratio r1/r2 is the following range: 0,9 ≤ r1/r2 ≤ 1,1.

[0029] Most preferred, the ratio r1/r2 is the following range: 0,95 ≤ r1/r2 ≤ 1,05.

[0030] In the shown embodiment the ratio r1/r2=1.

[0031] The outlet opening 13 for the gas/air mixture of the mixer housing 11 is at least partially circular shaped and has an outlet opening central point P1.

[0032] The turning point 18 of the bent flow channel wall 17 is positioned on or approximately on an axis 19 that runs through the outlet opening central point P1 and perpendicular to the plane in which the outlet opening 13 is lying.

[0033] If the turning point 18 is positioned on said axis 19, the distance Δx between the turning point 18 of the bent flow channel wall 17 and said axis 19 is 0.

[0034] If the turning point 18 is positioned offset from said axis 19, the distance Δx between the turning point 18 of the bent flow channel wall 17 and said axis 19 is greater than 0.

[0035] If the turning point 18 is positioned approximately on said axis 19, a ratio Δx/d defined by a distance Δx between the turning point 18 of the bent flow channel wall 17 and the axis 19 and an opening diameter d of the outlet opening 13 is the following range: 0 < Δx/d ≤ 0,1.

[0036] Preferably, the ratio Δx/d is the following range: 0 < Δx/d ≤ 0,07.

[0037] Most preferred, the ratio Δx/d is the following range: 0 < Δx/d ≤ 0,05.

[0038] In the shown embodiment the ratio Δx/d=0.

[0039] The bent flow channel wall 17 may be - seen in a cross section in the flow direction FD of the gas/air mixture entering into the flow channel 16 - s shaped or arc tangent shaped or hyperbolic tangent shaped or sinus area shaped.

[0040] The flow channel wall 17 may be provided by at least three straight flow channel wall sections 17s approximating the bent contour. Figure 3b shows a flow channel wall 17 in which the bent contour of Fig. 3a is approximated by three straight flow channel wall sections 17s. Figure 3c shows a flow channel wall 17 in which the bent contour of Fig. 3a is approximated by five straight flow channel wall sections 17s. The middle one of the straight flow channel wall sections 17s runs through the turning point 18 and defines the maximum value of the angle of inflow α. The straight flow channel wall sections 17s positioned upstream of the middle flow channel wall sections 17s as well as the straight flow channel wall sections 17s positioned downstream of the middle flow channel wall sections 17s define all an angle of inflow α being smaller than the maximum value defined by the middle one of the straight flow channel wall sections 17s.

[0041] The flow channel wall 17 is preferably an integral element of the mixer housing 11 (see Figures 3).

[0042] Alternatively, the flow channel wall 17 is provided by an insert 25 (see Figures 1, 2 and 4) positioned within the mixer housing 11.

[0043] The novel gas/air mixing device 10 of a gas burner has a decreased flow restriction between the mixing unit 14 and the outlet opening 13 for gas/air mixture. The novel gas/air mixing device 19 can provide an increased gas/air mixture flow.

[0044] The outlet opening 13 for the gas/air mixture has a first outlet opening section 13a turned away from the mixture unit 14 and a second outlet opening section 13b turned away from the mixture unit 14. Said first outlet opening section 13a is semicircular shaped. Said second opening section 13b is trapezoidal shaped (see Figure 4, 5) or rectangular shaped (see Figure 6).

[0045] The trapezoidal shaped or rectangular shaped second opening section 13b of the outlet opening 13 increases the opening area of the outlet opening 13 by the sections A1 shown in Figures 5 and 6. This provides a further decreased flow restriction between the mixing unit 14 and the outlet opening 13 for gas/air mixture and a further increased gas/air mixture flow.

[0046] Then present application also provides an assembly comprising a gas/air mixing device 10 as described above and a fan 20 (see Figures 1, 2 and 3). The fan 20 comprises a fan housing 21 and a fan impeller 22 positioned with the fan housing 20.

[0047] Fan housing 21 and mixer housing 11 may be provided by separate elements or by an integral element.

[0048] The fan housing 21 has an inlet opening 23 for the gas/air mixture. The plane in which the inlet opening 23 of the fan housing 21 is lying runs parallel to the plane in which the outlet opening 13 of the mixer housing 13 is lying. If the fan housing 21 and mixer housing 11 are provided by an integral element, the inlet opening 23 of the fan housing 21 and the outlet opening 13 of the mixer housing 11 are lying in the same plane.

[0049] The fan impeller 22 has a fan impeller rotation axis 24. The fan impeller rotation axis 24 runs perpendicular the plane in which the inlet opening 23 of the fan housing 21 is lying and perpendicular to the plane in which the outlet opening 13 of the mixer housing 13 is lying.

[0050] The turning point 18 of the bent flow channel wall 17 of the gas/air mixing device 10 is lying on or approximately on the fan impeller rotation axis 24 and on or approximately on the axis 19.

List of reference signs

[0051] 

10

gas/air mixing device

11

mixer housing

12

inlet opening for air

13

outlet opening for a gas/air mixture

14

mixing unit

15

venturi nozzle

16

flow channel

17

flow channel wall

17a

flow channel wall section

17b

flow channel wall section

17s

straight flow channel wall section

18

turning point

19

axis

20

fan

21

fan housing

22

fan impeller

23

inlet opening

24

fan impeller rotation axis

25

insert

Claims

1. Gas/Air mixing device (10) for a gas burner, having

a mixer housing (11),

wherein the mixer housing (11) comprises a first inlet opening (12) for air,

wherein the mixer housing (11) comprises a second inlet opening for gas,

wherein the mixer housing (11) comprises an outlet opening (13) for a gas/air mixture,

a mixing unit (14) positioned within the mixer housing (11),

wherein the mixing unit (14) provides the gas/air mixture by mixing the air entering into the mixer housing (11) through said first inlet opening (12) and the gas entering into the mixer housing (11) through said second inlet opening,

a flow channel (16) for the gas/air mixture,

wherein the flow channel (16) extends between the mixing

unit (14) and the outlet opening (13),

characterized in that

the flow channel (16) has a flow channel wall (17) being contoured in such a way that - seen in flow direction of the gas/air mixture entering into the flow channel (16) - an angle of inflow (α) is first increasing and thereafter decreasing, said flow channel wall (17) providing a flow deflection of the gas/air mixture flow.

2. Gas/Air mixing device as claimed in claim 1, characterized in that

the flow channel wall (17) has a bent contour and has a turning point (18), wherein - seen in flow direction of the gas/air mixture - upstream of the turning point (18) the flow channel wall (17, 17a) is concave arched and downstream of the turning point (18) the flow channel wall (17, 17b) is convex arched.

3. Gas/Air mixing device as claimed in claim 2, characterized in that

a curvature center point (C1) of the concave arched section (17a) of the bent flow channel wall (17) is positioned on a side of the flow channel wall (17) facing the gas/air mixture flow.

a curvature center point (C2) of the convex arched section (17b) of the bent flow channel wall (17) is positioned on a side of the flow channel wall (17) turned away from the gas/air mixture flow.

4. Gas/Air mixing device as claimed in claim 2 or 3, characterized in that

a ratio r1/r2 defined by a radius of curvature r1 of the concave arched section (17a) a radius of curvature r2 of the convex arched section (17b) is the following range 0,8 ≤ r1/r2 ≤ 1,2, preferably 0,9 ≤ r1/r2 ≤ 1,1.

5. Gas/Air mixing device as claimed in claim 4, characterized in that the ratio r1/r2=1.

6. Gas/Air mixing device as claimed in one of claims 2 to 5, characterized in that

the outlet opening (13) for the gas/air mixture has an outlet opening central point (P1),

the turning point (18) of the bent flow channel wall (17) is positioned on or approximately on an axis (19) that runs through the outlet opening central point (P1) and perpendicular to the plane in which the outlet opening (13) is lying.

7. Gas/Air mixing device as claimed in claim 6, characterized in that

a ratio Δx/d defined by a distance Δx between the turning point (18) of the bent flow channel wall (17) and the axis (19) and an opening diameter d of the outlet opening (13) is the following range:

0 ≤ Δx/d ≤ 0,10, preferably 0 ≤ Δx/d ≤ 0,07.

8. Gas/Air mixing device as claimed in one of claims 1-7, characterized in that the bent flow channel wall (17) is s shaped or arc tangent shaped or hyperbolic tangent shaped or sinus area shaped.

9. Gas/Air mixing device as claimed in one of claims 2-8, characterized in that the flow channel wall (17) is provided by at least three straight flow channel wall sections (17s) approximating the bent contour.

10. Gas/Air mixing device as claimed in one of claims 1 to 9, characterized in that the flow channel wall (17) is an integral element of the mixer housing (11).

11. Gas/Air mixing device as claimed in one of claims 1 to 9, characterized in that the flow channel wall (17) is provided by an insert (25) positioned within the mixer housing (11).

12. Gas/Air mixing device as claimed in one of claims 1 to 11, characterized in that

the outlet opening (13) for the gas/air mixture has a first outlet opening section (13a) turned away from the mixture unit (14) and a second outlet opening section (13b) facing the mixture unit (14),

wherein said first outlet opening section (13a) is semicircular shaped,

wherein said second outlet opening section (13b) is trapezoidal shaped or rectangular shaped.

13. Assembly comprising

a gas/air mixing device (10) as claimed in one of claims 1 to 12,

a fan (20),

wherein the fan (20) comprises a fan housing (21),

wherein the fan (20) comprises a fan impeller (22) positioned with the fan housing (21),

wherein the fan housing (21) has an inlet opening (23) for the gas/air mixture.

14. Assembly as claimed in claim 13, characterized in that

the plane in which the inlet opening (23) of the fan housing (21) is laying and the plane in which the outlet opening (13) of the mixer housing (11) is lying are running parallel to each other, or the inlet opening (23) of the fan housing (21) and the outlet opening (13) of the mixer housing (11) are lying in the same plane.

15. Assembly as claimed in claim 13 or 14, characterized in that

the fan impeller (22) has a fan impeller rotation axis (24),

the fan impeller rotation axis (24) runs perpendicular the plane in which the inlet opening (23) of the fan housing (21) is lying,

the turning point (18) of bent flow channel wall (17) of the gas/air mixing device (10) is positioned on or approximately on the fan impeller rotation axis (24).

Drawing