EP3149405A1

EP3149405A1 - Gas/air mixer assembly with improved adjustability for use in a gas burner

Info

Publication number: EP3149405A1
Application number: EP14728903.7A
Authority: EP
Inventors: Guven ERAKTAS; Osman AY; Murat Topsakal; Erol Karaer
Original assignee: Arcelik AS
Current assignee: Arcelik AS
Priority date: 2014-05-30
Filing date: 2014-05-30
Publication date: 2017-04-05
Also published as: WO2015180791A1

Abstract

The present invention relates to a mixer assembly (1) for mixing gas and ambient air for a gas burner (2). The mixer assembly (1) comprises a mixing chamber (3), a first opening (4) for admitting gas, a nozzle element (5) for jetting the admitted gas into the mixing chamber (3), a second opening (6) for admitting ambient air, a third opening (7) for outputting the mixture, a cover element (8) rectilinearly movable across the second opening (6) to change a size of the latter, and a fixing element (9) for securing the cover element (8).

Description

GAS/AIR MIXER ASSEMBLY WITH IMPROVED ADJUSTABILITY FOR USE IN A GAS BURNER

The present invention relates to a mixer assembly for mixing gas and ambient air for use in a gas burner of a gas cooking appliance.
Flammable gases such as liquefied petroleum gas (LPG: butane, propane) or natural gas (NG: methane) have different number of hydrogen and carbon atoms. Therefore, these gases release different amount of energies when they are combusted. As a rule, the heavier the gas the more energy is released during combustion. A minimum amount of oxygen is necessary for totally combusting a gas with ideally zero emission of residual pollutants. Therefore, the oxygen to gas (stoichiometric) ratio for the complete combustion differs for different type of gases. In general, in a conventional gas cooking appliance, a mixer assembly is utilized for mixing the inflowing gas with the correct amount of ambient air to obtain a proper mixture of gas and oxygen. The type of gases approved for use generally varies between countries. To meet the official requirements, a conventional gas cooking appliance is usually manufactured for operation with at least one type of LPG or at least one type of NG approved for use in that country. However, some gas cooking appliances are also manufactured to allow conversion from one type of gas to another type of gas provided that the necessary modifications are performed by a service person. These, modifications involve, among others, the adjustment of the mixer assembly in accordance with the type of gas to be used.
Fig. 1 shows a conventional mixer assembly (1´) for mixing gas and ambient air for use in a conventional gas burner (2´) of a conventional gas cooking appliance. The mixer assembly (1´) comprises a mixing chamber (3´) for mixing gas and ambient air, a first opening (4´) for admitting gas into the mixing chamber (3´), a nozzle element (5´) for jetting the gas which is admitted by the first opening (4´) into the mixing chamber (3´), a second opening (6´) for admitting ambient air into the mixing chamber (3´) by the venturi effect, a third opening (7´) for outputting the mixture of gas and ambient air inside the mixing chamber (3´) to the gas burner (2´), a cover element (8´) for rectilinearly sliding across the second opening (6´) so as to change a size of the second opening (6´), and a fixing element (9´) for securing the cover element (8´) relative to the second opening (6´).
In the conventional mixer assembly (1´), the size of the second opening (6´) is manually adjusted by an operator during a manufacturing process. In the manufacturing process the operator measures a size of the second opening (6´) by using a gauge stick (not shown) and concurrently changes the position of the cover element (8´) until a desired size (A´) of the second opening (6´) is attained. Thereafter, the operator fixes the cover element (8´) by tightening a screw.
A problem with the conventional mixer assembly (1´) is that the adjustment of the size (A´) of the second opening (6´) during the manufacturing process or as the case may be during a maintenance is very time consuming and vulnerable to errors which are likely to be introduced by the operator or the service person. If the mixer assembly (1´) is not properly adjusted, the combustion efficiency degrades and the amount of heat released by the gas burner (2´) decreases. Moreover, in case of an incomplete combustion, the harmful emission of carbon monoxide and hydrocarbons such as soot increases and poses a risk to the health of the customer, particularly when the emission limits are exceeded.
An objective of the present invention is to provide a mixer assembly for mixing gas and ambient air and a gas cooking appliance having the same which overcomes the aforementioned drawbacks of the prior art in a cost-effective way and which enables a quick and reliable adjustment of the desired mixture of gas and ambient air and also a quick and reliable conversion from one type of gas to another type of gas or vice versa.
This objective has been achieved by the mixer assembly as defined in claim 1, and the gas cooking appliance as defined in claim 12. Further achievements have been attained by the subject-matters respectively defined in the dependent claims.
The mixer assembly of the present invention comprises a mechanical stop which blocks forward movement of the cover element at a stop position where the second opening is partly obstructed by the cover element such that a size of the unobstructed part of the second opening corresponds to a desired mixture ratio of the gas and the ambient air.
In the present invention, the mixture ratio attained when the cover element is at the stop position corresponds to an adjustment for operating the gas burner and the mixer assembly with a predetermined type of gas, including a type of LPG or a type of NG. This can be predetermined in accordance with a specific design to which the present invention is to be applied.
In an embodiment, the cover element is also rotatably movable across the second opening so as to further change a size of the second opening. The cover element has a first cut-out which is formed at its forward end and which is rotatable across the second opening. Thereby, the service person can quickly and reliably convert from one type of gas to another type of gas or vice versa by rotating the cover element about the stop position. The types of gases selectable by the rotation of the cover element can be predetermined in accordance with a specific design to which the present invention is to be applied.
In another embodiment, the cover element is also detachable and reversely attachable so as to further change a size of the second opening. The cover element has a second cut-out which is formed at its reverse end and which is rotatable across the second opening. In this embodiment, the second cut-out is different from the first cut-out. Thereby, the service person can quickly and reliably convert from one type of gas to another type of gas or vice versa by rotating the cover element about the stop position. Similarly, the types of gases selectable by the rotation of the cover element can be predetermined in accordance with a specific design to which the present invention is to be applied.
In another embodiment, the mixture ratio attained when the cover element does not obstruct the second opening also corresponds to an adjustment for operating the gas burner and the mixer assembly with another type of gas, including a type of LPG or a type of NG. Similarly, this can also be predetermined in accordance with a specific design to which the present invention is to be applied.
In another embodiment, the mixer assembly is provided in form of a gas pipe, in particular a venturi pipe. The nozzle element is arranged inside a gas passage of the gas pipe immediately on an upstream side of a through hole which is formed into the gas pipe for the intake of ambient air by the venturi effect.
In a version of this embodiment, the cover element is provided in form of an annular-shaped sleeve which can be rotated about the gas pipe and which can also be slided back and forth along the gas pipe. In this embodiment, the aforementioned cut-outs are formed on the opposing ends of the sleeve.
In another version of this embodiment, the mechanical stop is provided as a step, in particular an annular step which is formed on the gas pipe.
In another version of this embodiment, the fixing element is provided in form of a screw which is inserted into the sleeve to fasten the latter to the gas pipe.
With the mixer assembly of the present invention, the use of the gauge stick has been obviated and the serial manufacturing process has been expedited. Thus, the errors introduced by the operator during the serial manufacturing process due to the manual adjustment involving the gauge stick have been eliminated. With the mixer assembly of the present invention, a desired mixture ratio of the gas and the ambient air can be quickly and exactly adjusted in accordance with the type of gas to be used. Thereby, the combustion efficiency has been improved and the harmful emission of carbon monoxide and hydrocarbons such as soot has been effectively reduced. Also the serviceability has been improved. Thus, the service person can quickly and reliably convert from one type of gas to another type of gas or vice versa by sliding and/or rotating the cover element. By virtue of the cover element of the present invention, at least four different adjustments can be performed. By using different cover elements the number of possible adjustments can be further increased in view of the country or countries of interest.
Additional advantages of the mixer assembly of the present invention and the gas cooking appliance of the present invention will become apparent with the detailed description of the embodiments with reference to the accompanying drawings in which:
Figure 1 – is a schematic sectional view of a conventional gas burner having a conventional mixer assembly,
Figure 2 – is a schematic sectional view of a gas burner which has a mixer assembly according to an embodiment of the present invention, wherein a cover element is at a home position, and wherein the mixer assembly is adjusted such that the second opening is completely unobstructed by the cover element,
Figure 3 – is a schematic sectional view of the gas burner which has the mixer assembly of Fig. 2, wherein the cover element is at the stop position, and the mixer assembly is adjusted such that the second opening is partly unobstructed by the cover element,
Figure 4 – is a schematic perspective view of a gas burner which has a mixer assembly according to another embodiment of the present invention, wherein a cover element is at the home position, wherein the mixer assembly is adjusted such that the second opening is completely unobstructed by the cover element, wherein a fixing element is omitted,
Figure 5 – is a schematic side view of the gas burner which has the mixer assembly of Fig. 4, wherein the cover element is at the home position, and wherein the mixer assembly is adjusted such that the second opening is completely unobstructed by the cover element,
Figure 6 – is a schematic perspective view of the gas burner which has the mixer assembly of Fig. 4, wherein the cover element is at the stop position and a first cut-out of the cover element faces the second opening, and wherein the mixer assembly is adjusted such that the second opening is partly unobstructed by the cover element,
Figure 7 – is a schematic side view of the gas burner which has the mixer assembly of Fig. 4, wherein the cover element is at the stop position and the first cut-out faces the second opening, and the mixer assembly is adjusted such that the second opening is partly unobstructed by the cover element,
Figure 8 – is a schematic perspective view of the gas burner which has the mixer assembly of Fig. 4, wherein the cover element is at the stop position and the first cut-out is rotatably removed from the second opening, and wherein the mixer assembly is adjusted such that the second opening is partly unobstructed by the cover element,
Figure 9 – is a schematic side view of the gas burner which has the mixer assembly of Fig. 4, wherein the cover element is at the stop position and the first cut-out is rotatably removed from the second opening, and wherein the mixer assembly is adjusted such that the second opening is partly unobstructed by the cover element,
Figure 10 – is a schematic perspective view of the gas burner having the mixer assembly of Fig. 4, wherein the cover element has been detached and reversely reattached, wherein the cover element is at the stop position and a second cut-out of the cover element faces the second opening, and wherein the mixer assembly is adjusted such that the second opening is partly unobstructed by the cover element,
Figure 11 – is a schematic side view of the gas burner which has the mixer assembly of Fig. 4, wherein the cover element has been detached and reversely reattached, wherein the cover element is at the stop position and a second cut-out faces the second opening, and wherein the mixer assembly is adjusted such that the second opening is partly unobstructed by the cover element.
The reference signs appearing on the drawings relate to the following technical features.

Mixer assembly
Gas burner
Mixing chamber
First opening
Nozzle element
Second opening
Third opening
Cover element

8a. First cut-out
8b. Forward end
8c. Second cut-out
8d. Rear end
9. Fixing element
10. Mechanical stop
11a. Stop position
11b. Home position
12. Gas pipe (venturi pipe)
13. Threaded inlet
14. Threaded outlet
15. Gas passage
16. Through-hole
17. Annular step
18. Constricted section
19. Sleeve
20. Screw
21. Threaded hole
22. Transition piece
23. External thread
24. Internal thread
25. Intake port
A1: Size of the completely unobstructed second opening (6)
A2: Size of the partly unobstructed second opening (6)
A3: Another size of the partly unobstructed second opening (6)
A4: Another size of the partly unobstructed second opening (6)
different than A3
R1: A desired mixture ratio of the gas and the ambient air corresponding to A1
R2: Another desired mixture ratio of the gas and the ambient air corresponding to A2
R3: Another desired mixture ratio of the gas and the ambient air corresponding to A3
R4: Another desired mixture ratio of the gas and the ambient air corresponding to A4
The mixer assembly (1) is suitable for mixing gas and ambient air for use in a gas burner (2) of a gas cooking appliance. The mixer assembly (1) comprises a mixing chamber (3) for mixing gas and ambient air, a first opening (4) for admitting gas into the mixing chamber (3), a nozzle element (5) for jetting the gas which is admitted by the first opening (4) into the mixing chamber (3), a second opening (6) for admitting ambient air into the mixing chamber (3), a third opening (7) for outputting the mixture of gas and ambient air inside the mixing chamber (3) to the gas burner (2), a cover element (8) for rectilinearly moving across the second opening (6) so as to change a size of the second opening (6), and a fixing element (9) for securing the cover element (8) relative to the second opening (6) (Fig. 2 to 7).
The mixer assembly (1) of the present invention comprises a mechanical stop (10) which is configured to block forward movement of the cover element (8) at a stop position (11a) where the second opening (6) is partly obstructed by the cover element (8) such that a size (A2, A3, A4) of the unobstructed part of the second opening (6) corresponds to a desired mixture ratio (R2, R3, R4) of the gas and the ambient air (Fig. 2 to 7).
In the present invention, the mixture ratio of the gas and the ambient air when the cover element (8) is at the stop position (11) corresponds to an adjustment for operating the gas burner (2) and the mixer assembly (1) with a certain type of LPG or a certain type of NG. This can be predetermined in accordance with a specific design to which the present invention is to be applied.
In an embodiment, the cover element (8) is also rotatably movable across the second opening (6) so as to further change a size of the second opening (6) (Fig. 2 to 7). In this embodiment, the cover element (8) has a first cut-out (8a) which is formed at its forward end (8b) (Fig. 4 to 9). In this embodiment, a size (A3) of the unobstructed part of the second opening (6) corresponds to another desired mixture ratio (R3) of the gas and the ambient air when the cover element (8) is at the stop position (11a) and the first cut-out (8a) faces the second opening (6) (Fig. 6 to 7). In this embodiment, the cover element (8) can be selectively rotated in a clockwise or anticlockwise direction in order remove the first cut-out (8a) from the second opening (6) (Fig. 8 to 9). In this embodiment, the service person can quickly and reliably convert from one type of gas to another type of gas by rotating the cover element (8) about the stop position (11b) from a state where the first cut-out (8a) faces the second opening (6) to a state whether the first cut-out (8a) is removed from the second opening (6) or vice versa (Fig. 6 to 9). In a version of this embodiment, the mixture ratio of the gas and the ambient air when the cover element (8) is at the stop position (11b) and the first cut-out (8a) faces the second opening (6) corresponds to an adjustment for operating the gas burner (2) and the mixer assembly (1) with a type of LPG (Fig. 6 to 7). In this version of the embodiment, the mixture ratio of the gas and the ambient air when the cover element (8) is at the stop position (11b) but the first cut-out (8a) is removed from the second opening (6) corresponds to an adjustment for operating the gas burner (2) and the mixer assembly (1) with a type of NG (Fig. 3, and 8 to 9). Thereby, the service person can quickly and reliably convert from one type of LPG to one type of NG or vice versa by rotating the cover element (8) about the stop position (11a) (Fig. 6 to 9).
In another embodiment, the cover element (8) is also detachable and reversely attachable so as to further change a size of the second opening (6) (Fig. 2 to 7). The cover element (8) has a second cut-out (8c) which is formed at its reverse end (8d) (Fig. 4 to 11). In this embodiment, the second cut-out (8c) has a different size than the first cut-out (8a). In this embodiment, a size (A4) of the unobstructed part of the second opening (6) corresponds to another desired mixture ratio (R4) of the gas and the ambient air when the cover element (8) is at the stop position (11a) and the second cut-out (8c) faces the second opening (6) (Fig. 10 to 11). In this embodiment, the cover element (8) can be selectively rotated in a clockwise or anticlockwise direction in order remove the second cut-out (8c) from the second opening (6) (Fig. 10 to 11). In this embodiment, the service person can quickly and reliably convert from one type of gas to another type of gas by rotating the cover element (8) about the stop position (11a) from a state where the second cut-out (8c) faces the second opening (6) to a state whether the second cut-out (8c) is removed from the second opening (6) (Fig. 10 to 11). In a version of this embodiment, the mixture ratio of the gas and the ambient air when the cover element (8) is at the stop position (11a) and the second cut-out (8c) faces the second opening (6) corresponds to an adjustment for operating the gas burner (2) and the mixer assembly (1) with another type of LPG (Fig. 10 to 11). In this version of the embodiment, the mixture ratio of the gas and the ambient air when the cover element (8) is at the stop position (11a) but the second cut-out (8c) is rotatably removed from the second opening (6) corresponds to an adjustment for operating the mixer assembly (1) and the gas burner (2) with a type of NG as in the preceding embodiment (cf. Fig. 8 to 9). Thereby, the service person can quickly and reliably convert from another type of LPG to one type of NG or vice versa by rotating the cover element (8) (Fig. 10 to 11).
In another embodiment, the cover element (8) has a home position (11b) where the second opening (6) is completely unobstructed such that a size (A1) of the completely unobstructed second opening (6) corresponds to another desired mixture ratio (R1) of the gas and the ambient air (Fig. 2, Fig. 4 to 5). In a version of this embodiment, the mixture ratio of the gas and the ambient air when the cover element (8) is at home position (11b) corresponds to an adjustment for operating the gas burner (2) and the mixer assembly (1) with another type of LPG.
In another embodiment, the mixer assembly (1) has a gas pipe (12), in particular a venturi pipe which comprises a treaded inlet (13) which defines the first opening (4), a threaded outlet (14) which defines the third opening (7), a gas passage (15) which is formed between the threaded inlet (13) and the threaded outlet (14), wherein the gas passage (15) defines the mixing chamber (3), and a through-hole (16) which is formed into a wall of the gas pipe (12), wherein the through-hole (16) defines the second opening (6), and wherein the nozzle element (5) is arranged along the gas passage (15) at an upstream side of the through-hole (16) (Fig. 2 to 7).
In another embodiment, the cover element (8) comprises an annular-shaped sleeve (19), in particular an adjustment ring which is slidably and rotatably arranged around the gas pipe (12) (Fig. 2 to 7). In this embodiment, the first cut-out (8a) and the second cut-out (8c) are formed on opposing ends of the annular-shaped sleeve (19) (Fig. 2 to 7).
In another embodiment, the gas pipe (12) has two diametrically opposing second openings (6). In this embodiment, the annular-shaped sleeve (19) has two diametrically opposing first cut-outs (8a) and two diametrically opposing second cut-outs (8c). In a version of this embodiment, the first cut-out (8a) and the second cut-out (8c) are alternatingly formed in a circumferential direction.
In another embodiment, the mechanical stop (10) comprises a step (17), preferably an annular step (17) which is formed on the gas pipe (12) (Fig. 2 to 7). In a version of this embodiment, the step (17) is integrally formed with the gas pipe (12) as a single piece.
In another embodiment, the fixing element (9) comprises a screw (20) for screwing into the threaded hole (21) which is formed into the sleeve (19). In a fixed state, the screw (20) abuts against an outer surface of the gas pipe (12) (Fig. 2 and 3).
In another embodiment, the gas passage (15) comprises a constricted section (18) which is formed on a downstream side of the through-hole (16) (Fig. 2 and 3).
In another embodiment, the mixer assembly (1) comprises a transition piece (22) which retains the nozzle element (5). The transition piece (22) is screwed together with the treaded inlet (13) of the gas pipe (12) (Fig. 2 to 7). Thereby, the nozzle element (5) can be easily replaced with another one when converting from one type of gas to another type of gas.
In another embodiment, the nozzle element (5) has an external thread (23) which is screwed into an internal thread (24) of the transition piece (22) (Fig. 2 to 7).
The present invention also provides a gas cooking appliance (not shown) which comprises one or more than one gas burner (2).
The gas cooking appliance of the present invention comprises one or more than one mixer assembly (1). Each mixer assembly (1) is assembled with a corresponding gas burner (2) (Fig. 2 to 7).
When assembling the mixer assembly (1) with the corresponding gas burner (2), the third opening (7) is connected to a gas intake port (25) of the gas burner (2) (Fig. 2 to 7).
With the mixer assembly (1) of the present invention, a desired mixture ratio (R1,R2,R3,R4) of the gas and the ambient air can be quickly and exactly adjusted by the cover element (8) in accordance with the type of gas to be used. By virtue of the same cover element (4) at least four type of adjustments is rendered possible. The present invention is not limited to the use of a particular cover element (8). Thus, a set of cover elements (8) can be utilized to increase the number of desired adjustments so as to meet the conditions in different countries approving different types of LPG and NG. Thereby, the serial manufacturing process has been expedited and the serviceability has been simplified. Also, the combustion efficiency has been improved and the emission of harmful residual pollutants has been effectively reduced.

Claims

A mixer assembly (1) for mixing gas and ambient air for use in a gas burner (2) of a gas cooking appliance, the mixer assembly (1) comprising a mixing chamber (3) for mixing gas and ambient air, a first opening (4) for admitting gas into the mixing chamber (3), a nozzle element (5) for jetting the gas which is admitted by the first opening (4) into the mixing chamber (3), a second opening (6) for admitting ambient air into the mixing chamber (3), a third opening (7) for outputting the mixture of gas and ambient air inside the mixing chamber (3) to the gas burner (2), a cover element (8) for rectilinearly moving across the second opening (6) so as to change a size of the second opening (6), and a fixing element (9) for securing the cover element (8) relative to the second opening (6), characterized in that

a mechanical stop (10) which is configured to block forward movement of the cover element (8) at a stop position (11a) where the second opening (6) is partly obstructed by the cover element (8) such that a size (A2,A3,A4) of the unobstructed part of the second opening (6) corresponds to a desired mixture ratio (R2,R3,R4) of the gas and the ambient air.
The mixer assembly (1) according to claim 1, characterized in that the cover element (8) is also rotatably movable across the second opening (6) so as to further change a size of the second opening (6), wherein the cover element (8) has a first cut-out (8a) which is formed at its forward end (8b) and which is rotatable across the second opening (6), and wherein a size (A3) of the unobstructed part of the second opening (6) corresponds to another desired mixture ratio (R3) of the gas and the ambient air when the cover element (8) is at the stop position (11a) and the first cut-out (8a) faces the second opening (6).
The mixer assembly (1) according to claim 2, characterized in that the cover element (8) is also detachable and reversely attachable so as to further change a size of the second opening (6), wherein the cover element (8) has a second cut-out (8c) which is formed at its reverse end (8d) and which is rotatable across the second opening (6), and wherein the second cut-out (8c) has a different size than the first cut-out (8a), and wherein a size (A4) of the unobstructed part of the second opening (6) corresponds to another desired mixture ratio (R4) of the gas and the ambient air when the cover element (8) is at the stop position (11b) and the second cut-out (8c) faces the second opening (6).
The mixer assembly (1) according to any one of claim 1 to 3, characterized in that the cover element (8) has a home position (11b) where the second opening (6) is completely unobstructed such that a size (A1) of the completely unobstructed second opening (6) corresponds to another desired mixture ratio (R1) of the gas and the ambient air.
The mixer assembly (1) according to claim 1, characterized in that a gas pipe (12) comprising a treaded inlet (13) which defines the first opening (4), a threaded outlet (14) which defines the third opening (7), a gas passage (15) which is formed between the threaded inlet (13) and the threaded outlet (14), wherein the gas passage (15) defines the mixing chamber (3), and a through-hole (16) which is formed into a wall of the gas pipe (12), wherein the through-hole (16) defines the second opening (6), and wherein the nozzle element (5) is arranged along the gas passage (15) at an upstream side of the through-hole (16).
The mixer assembly (1) according to claim 5, characterized in that the cover element (8) comprising an annular-shaped sleeve (19) which is slidably and rotatably arranged around the gas pipe (12).
The mixer assembly (1) according to claim 5 or 6, characterized in that the mechanical stop (10) comprising an annular step (17) which is formed on the gas pipe (12).
The mixer assembly (1) according to any one of claims 5 to 7, characterized in that the fixing element (9) comprising a screw (20) for screwing into a threaded hole (21) which is formed into the sleeve (19), wherein in a fixed state, the screw (20) abuts against an outer surface of the gas pipe (12).
The mixer assembly (1) according to any one of claims 5 to 8, characterized in that the gas passage (15) comprising a constricted section (18) which is formed on a downstream side of the through-hole (16).
The mixer assembly (1) according to any one of claims 5 to 9, characterized in that a transition piece (22) which retains the nozzle element (5), wherein the transition piece (22) is screwed together with the threaded inlet (13) of the gas pipe (12).
The mixer assembly (1) according to claim 10, characterized in that the nozzle element (5) has an external thread (23) which is screwed into an internal thread (24) of the transition piece (22).
A gas cooking appliance, comprising one or more than one gas burner (2), and one or more than one mixer assembly (1) as defined in any one of claims 1 to 11, wherein each mixer assembly (1) is assembled with a corresponding gas burner (2).