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Title:
HEATING APPARATUS FOR A RECREATIONAL VEHICLE AND METHOD FOR HEATING A FLUID IN A RECREATIONAL VEHICLE
Document Type and Number:
WIPO Patent Application WO/2019/025633
Kind Code:
A1
Abstract:
A heating apparatus (1) for a recreational vehicle, comprising a combustion chamber (2), a burner, including at least one burner module (3), the burner module (3) including a conduit 301 having an inlet port (302), for receiving a mixture of primary air and combustible gas, and an outlet port (303), opened to the combustion chamber (2) to generate a flame in the combustion chamber (2), wherein the conduit (301) is geometrically configured to provide a suction of the mixture of primary air and combustible gas by Venturi effect; the heating apparatus (1) further comprising a passage (4), for providing a flow of secondary air into the combustion chamber (2), a duct (5), for conveying a fluid to be heated, a heat exchanger (6), configured for transferring heat from exhaust gases flowing through a gas conduit (60) of the heat exchanger (6) to the fluid flowing in the duct (5), and a fan (7) configured for forcing the flow of secondary air.

Inventors:
BOTTICELLA, Vito (6th floor, Hemvärnsgatan 15, Solna, 171 54, SE)
PACI, Enrico (6th floor, Hemvärnsgatan 15, Solna, 171 54, SE)
ZANI, Marco (6th floor, Hemvärnsgatan 15, Solna, 171 54, SE)
Application Number:
EP2018/071291
Publication Date:
February 07, 2019
Filing Date:
August 06, 2018
Export Citation:
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Assignee:
DOMETIC SWEDEN AB (Hemvärnsgatan 15, Solna, 171 54, SE)
International Classes:
F24H1/16; B60H1/22; F23D14/04; F23D14/10; F23D14/34; F23D14/36; F23D23/00; F23L5/02; F23L9/00; F24H3/02; F24H3/06; F24H6/00; F24H9/18
Foreign References:
US20160282011A12016-09-29
US2579507A1951-12-25
EP0130742A21985-01-09
US2077424A1937-04-20
JPS59125349A1984-07-19
US20090151654A12009-06-18
EP0967436A21999-12-29
EP2051006A12009-04-22
EP0262546A21988-04-06
EP0926453B12004-04-21
Attorney, Agent or Firm:
GROSSE SCHUMACHER KNAUER VON HIRSCHHAUSEN (Nymphenburger Str. 14, München, 80335, DE)
Download PDF:
Claims:
CLAIMS

1. A heating apparatus (1 ) for a recreational vehicle, comprising:

a combustion chamber (2);

a burner, including at least one burner module (3), the burner module (3) including a conduit

(301) having an inlet port (302), for receiving a mixture of primary air and combustible gas, and an outlet port (303), opened to the combustion chamber (2) to generate a flame in the combustion chamber (2), wherein the conduit (301 ) is geometrically configured to provide a suction of the mixture of primary air and combustible gas by Venturi effect;

a passage (4), for providing a flow of secondary air into the combustion chamber (2);

a duct (5), for conveying a fluid to be heated;

a heat exchanger (6) configured for transferring heat from exhaust gases flowing through a gas conduit (60) of the heat exchanger (6) to the fluid flowing in the duct (5),

characterized in that the heating apparatus (1 ) further comprises a fan (7) configured for forcing the flow of secondary air.

2. The heating apparatus (1 ) of claim 1 , further comprising a feeding chamber (8) that is configured to receive air from an external environment through the fan (7) and is in fluid communication with the inlet port (302) of the conduit (301 ) and with the passage (4) to provide said primary and secondary air.

3. The heating apparatus (1 ) of claim 2, further comprising a gas injector (9) for injecting the

combustible gas into the inlet port (302) of the conduit (301 ), wherein the inlet port (302) is positioned inside the feeding chamber (8) and the gas injector (9) is positioned in the feeding chamber (8), facing the inlet port (302) of the conduit (301 ).

4. The heating apparatus (1 ) of claim 2 or 3, wherein the feeding chamber (8) is at overpressure with respect to the external environment, through the fan (7), and wherein the feeding chamber (8) forms a reservoir of air under pressure.

5. The heating apparatus (1 ) of any of the preceding claims, further comprising a wall (401 ) having a first face (402) and a second face (403), opposite to the first face (402), wherein the first face (402) delimits part of the feeding chamber (8) and the second face (403) delimits part of the combustion chamber (2).

6. The heating apparatus (1 ) of claim 5, wherein the wall (401 ) has a plurality of apertures (404) defining the passage (4).

7. The heating apparatus (1 ) of any of claim 5 or 6, wherein the wall (40 ) is oriented in a

substantially vertical direction (V), substantially parallel to the weight force, or in a substantially horizontal direction (H), substantially perpendicular to the weight force.

8. The heating apparatus (1 ) of any of the preceding claims, further comprising a control unit

connected to the fan (7) and configured to control the fan (7), in dependence to at least one control parameter representative of a thermal power provided by the burner.

9. The heating apparatus (1 ) of any of the preceding claims, comprising:

an additional combustion chamber (2A);

an additional burner including at least one additional burner module (3A), the additional burner module (3A) including an additional conduit (301 A) having an inlet port (302A), for receiving an additional mixture of primary air and combustible gas, and an outlet port (303A), opened to the additional combustion chamber (2A) to generate a flame in the additional combustion chamber (2A), wherein the additional conduit (301 A) is geometrically configured to provide a suction of the additional mixture of primary air and combustible gas by Venturi effect;

an additional passage (4A), for providing an additional flow of secondary air into the additional combustion chamber (2A);

an additional duct (5A), for conveying an additional fluid to be heated;

an additional heat transfer unit (6A) configured for transferring heat from

exhaust gases flowing through a gas conduit (60A) of the heat transfer unit (6A) and the additional fluid flowing in the additional duct (5A);

an additional fan (7A) configured for forcing the additional flow of secondary air.

10. A recreational vehicle comprising a heating apparatus (1 ) according to any of the preceding claims.

11. A method for heating a fluid in a recreational vehicle, comprising the following steps:

receiving a mixture of primary air and combustible gas at an inlet port (302) of a conduit (301 ) of a burner, opened to a combustion chamber (2);

sucking, by Venturi effect, primary air and combustible gas, to generate a mixture flowing into the conduit (301 );

providing a flow of secondary air into the combustion chamber (2) through a passage (4);

burning the mixture in the combustion chamber (2); conveying a fluid to be heated into a duct (5);

transferring heat from exhaust gases from the combustion chamber (2) to the fluid flowing in the duct (5);

characterized in that the method further comprises a step of forcing the flow of secondary air through a fan (7).

12. The method of claim 11 , further comprising a step of pressurizing air in a feeding chamber (8) through the fan (7), wherein the feeding chamber (8) communicates with the combustion chamber (2) through the passage (4) and through the conduit (301 ), to provide said secondary and primary air, respectively.

13. The method of claim 12, wherein the feeding chamber (8) is at overpressure with respect to both the combustion chamber (2) and an external environment.

14. The method of any of the claims from 1 1 to 13, wherein the conduit (301 ) has an internal surface and an external surface, and the flow of secondary air licks the external surface of the conduit (301 ).

15. The method of any of the claims from 11 to 14, wherein an electronic board is positioned

upstream the fan (7) and is cooled by an air flow derived by the fan (7).

Description:
HEATING APPARATUS FOR A RECREATIONAL VEHICLE AND METHOD FOR

HEATING A FLUID IN A RECREATIONAL VEHICLE

This invention relates to a heating apparatus for a recreational vehicle and to a method for heating fluid in a recreational vehicle.

A heating apparatus for a recreational vehicle usually comprises a burner, for burning a mixture of combustible and air, a combustion chamber, where combustion take place, and a heat exchanger, for transferring heat from the exhaust gases flowing in the combustion chamber and a fluid that has to be heated. The fluid that has to be heated is typically breathable air contained in the recreational vehicle and/or water for sanitary or cooking purposes.

In heating apparatuses, burners with natural aspiration of combustion air are known. For example, EP 0 967 436 A1 is directed to a modular solution with two "bladed" burners, providing a natural aspiration of air through Venturi effect. In this solution, the "bladed" burners are arranged vertically, at different heights on a horizontal plane, to optimize the secondary air flow into the combustion chamber. This system has the inconvenience of requiring a large vertical size of the apparatus. Moreover, the flow of secondary air to the combustion chamber is not limited and could be so great to extinguish the flame.

In EP 2 051 006 A1 another solution having a "bladed" burner is disclosed, having some apertures for adducting an optimized quantity of secondary air to the flames.

Also, heaters with forced ventilation of combustion air are known for example, EP 0 262 546 A describes a solution having a blower for adduction of air and also a second blower for adduction of secondary air. In this solution, a conduit for natural aspiration is not present. The solutions with pure forced ventilation have the inconvenience of requiring energy to move the blowers and, moreover, requiring a mixer for mixing combustible gas and air (while with natural aspiration, combustible gas and air are naturally mixed during their suction through Venturi effect). These inconvenience result in high costs.

The previous solutions are suitable for heating air or water. In addition, combo solutions are also known. Combo solutions provide the heating of both air and water, such as the apparatus described in EP 0 926 453 B1.

This apparatus is suitable for heating air and water for small spaces, and comprises a burner in a combustion chamber formed as a fire tube, a heating chamber surrounding the combustion chamber, a heat exchange insert, which encloses the heating chamber and has an inner jacket, and a water boiler surrounding the heat exchange insert. At its inside which faces the heat exchanger insert, the water boiler comprises regions of different, defined gap geometry which determine the heat transfer from the heat exchanger insert to the water boiler. This solution has a strict dependence of the heating of air on the heating of water. This dependence constitutes a relevant inconvenience during summer season, when the heating of water may be required but the heating of breathable air is not needed and very often undesired. Moreover, the efficiency of this solution is very limited.

Scope of the present invention is to overcome at least one of the aforementioned drawbacks.

This scope is achieved by the heating apparatus for a recreational vehicle according to the appended claims.

The present invention also covers a recreational vehicle comprising the heating apparatus.

The present invention also covers a method for heating a fluid in a recreational vehicle.

According to one aspect of the present invention refers to a heating apparatus for a recreational vehicle. The heating apparatus comprises a combustion chamber and a burner, including at least one burner module. The burner module includes a conduit having an inlet port, for receiving a mixture of primary air and combustible gas, and an outlet port, opened to the combustion chamber to generate a flame in the combustion chamber, wherein the conduit is geometrically configured to provide a suction of the mixture of primary air and combustible gas by Venturi effect. The heating apparatus further comprises a passage, for providing a flow of secondary air into the combustion chamber, a duct, for conveying a fluid to be heated and a heat exchanger configured for transferring heat from exhaust gases flowing through a gas conduit of the heat exchanger to the fluid flowing in the duct. The heat exchanger also can be provided as a heat transfer unit. The heating apparatus also comprises a fan configured for forcing the flow of secondary air. The burner can be a modular burner and preferably is a gas burner. Preferably, the burner or the burner module respectively is a ramp-type burner.

This concrete configuration shows the advantage, that the flow of secondary air can be controlled actively and thus can be adapted to desired operation modes. By varying the flow of secondary air, besides others, the temperature and the flow rate of the heated gas can be set. This results in a very variably operable setup.

Preferably, the outlet of the conduit is opened to the combustion chamber to generate a flame in the combustion chamber, wherein the outlet preferably includes a row of nozzles (apertures) configured to generate the flame. Preferably, the heating apparatus further comprises a feeding chamber that is configured to receive air from an external environment through the fan and is in fluid communication with the inlet port of the conduit and with the passage to provide said primary and secondary air.

This configuration results in a quite simple but practical setup as only one inlet for providing primary air and secondary air has to be provided. Besides, the feeding chamber reduces influences of external conditions like wind, as the sucked air can calm down within the feeding chamber.

Preferably, the heating apparatus further comprises a gas injector for injecting the combustible gas into the inlet port of the conduit, wherein the inlet port is positioned inside the feeding chamber and the gas injector is positioned in the feeding chamber, facing the inlet port of the conduit.

This configuration is quite practical and space-saving due to the small distances between the various components. Providing the gas injector further provides a better controllability of the flow of combustible gas and thus of the combustion process.

Preferably, the feeding chamber is at overpressure with respect to the external environment, through the fan, and wherein the feeding chamber forms a reservoir of air under pressure.

In other words, the fan provides overpressure within the feeding chamber. This configuration results in an improved provision of air, and thus of oxygen, within the combustion chamber, and thus in a more uniform and complete combustion within the combustion chamber.

Preferably, the heating apparatus further comprises a wall having a first face and a second face, opposite to the first face. The first face delimits part of the feeding chamber and the second face delimits part of the combustion chamber.

Providing the wall separating the feeding chamber from the combustion chamber allows to further stabilize the flow characteristics of the heating apparatus by separating the zone of combustion and the zone for providing the air, and thus increases the controllability of the operation of the heating apparatus.

Preferably, transversally to the feeding direction the feeding chamber has a size which is significantly larger than the size of the conduit inlet. Preferably the size of the feeding chamber is at least 3 times, preferably 5 times or preferably 10 times larger.

Preferably, the wall has a plurality of apertures defining the passage. Thus, no separate element has to be provided for forming the passage, which results in a reduced complexity, costs and susceptibility to errors of the heating apparatus.

Preferably, the wall is oriented in a substantially vertical direction, substantially parallel to the weight force, or in a substantially horizontal direction, substantially perpendicular to the weight force. By providing the wall oriented in the respective direction, in particular when the apertures are defined within the wall, the influence of the hardly controllable air transfer from the feeding chamber to the combustion chamber by convection is reduced.

Preferably, the heating apparatus further comprises a control unit connected to the fan and configured to control the fan in dependence to at least one control parameter representative of a thermal power provided by the burner.

This configuration results in an at least partially automated operability of the heating unit, and thus in a reduced susceptibility to errors caused by faulty controlling by a user.

Preferably, the heating apparatus further comprises an additional combustion chamber and an additional burner including at least one additional burner module. The additional burner module includes an additional conduit having an inlet port, for receiving an additional mixture of primary air and combustible gas, and an outlet port, opened to the additional combustion chamber to generate a flame in the additional combustion chamber, wherein the additional conduit is geometrically configured to provide a suction of the additional mixture of primary air and combustible gas by Venturi effect. The heating apparatus according to this embodiment further comprises an additional passage, for providing an additional flow of secondary air into the additional combustion chamber, an additional duct, for conveying an additional fluid to be heated, an additional heat transfer unit configured for transferring heat from exhaust gases flowing through a gas conduit of the heat transfer unit and the additional fluid flowing in the additional duct as well as an additional fan configured for forcing the additional flow of secondary air. Preferably, the additional duct is provided in form of a tank.

In other words, two separate heating units provided for generating and transferring heat to the fluids to be heated are provided. This configuration enables a heating of two separate fluids, like for example breathable air and water for a recreational vehicle, independently from each other and thus in a high versatility of the heating apparatus.

According to another aspect of the present invention, a recreational vehicle comprises one of the above described heating apparatus. This concrete configuration allows transferring the advantageous effect of the various heating apparatus to a recreational vehicle.

According to a further aspect of the present invention, a method for heating a fluid in a recreational vehicle, comprises the steps of receiving a mixture of primary air and combustible gas at an inlet port of a conduit of a burner, opened to a combustion chamber, sucking, by Venturi effect, primary air and combustible gas, to generate a mixture flowing into the conduit, providing a flow of secondary air into the combustion chamber through a passage, burning the mixture in the combustion chamber, conveying a fluid to be heated into a duct, transferring heat from exhaust gases from the combustion chamber to the fluid flowing in the duct and finally a step of forcing the flow of secondary air through a fan.

This method depicts the preferable method of operating the above described heating apparatus to end up at the before described advantageous effects.

Preferably, the method further comprises a step of pressurizing air in a feeding chamber through the fan, wherein the feeding chamber communicates with the combustion chamber through the passage and through the conduit, to provide said secondary and primary air, respectively.

By pressurizing the air into the feeding chamber, the desired amount of air within the feeding chamber is provided reliably which results in a stabilized operability of the heating apparatus.

Preferably, the feeding chamber is at overpressure with respect to both the combustion chamber and an external environment.

Providing the overpressure within the feeding chamber stabilized the combustion process substantially. Preferably, the conduit has an internal surface and an external surface, and the flow of secondary air licks the external surface of the conduit.

Such a configuration is very compact and space-saving.

Preferably, an electronic board is positioned upstream the fan and is cooled by an air flow derived by the fan.

This concrete features also result in a very space-saving and compact configuration as no additional cooling device for cooling the electric board has to be provided. These and other features of the invention will become more apparent from the following detailed description of a preferred, non-limiting example embodiment of the present invention, with reference to the accompanying drawings, in which:

Fig. 1 illustrates a functional scheme of the heating apparatus according to the present invention;

Fig. 2 illustrates the heating apparatus of Fig. 1 in exploded view;

Figs. 3, 4, 5, 6 illustrate the heating apparatus of Fig. 1 in different cross sections; and

Figs. 7A, 7B illustrate different details of the heating apparatus of Fig. 1.

With reference to the accompanying drawings, the numeral 1 denotes a heating apparatus, according to the present invention.

According to one exemplary embodiment of the present invention illustrated schematically in Fig. 1 and spatially in Figs. 2 to 6, a heating apparatus 1 comprises a combustion unit with at least one burner and a combustion chamber 2. The burner has a burner module 3. The burner module 3 includes a conduit 301 with an inlet port 302 for receiving a mixture of primary air and combustible gas. The conduit 301 further has an outlet port 303, opened to the combustion chamber 2 to generate a flame within the combustion chamber 2.

Here, the outlet port 303 of the conduit 301 is a line of nozzles 15 configured to generate the flame. The heating apparatus 1 also includes an igniter 304 (see Figs. 3 to 5 and 7A), which is positioned in the combustion chamber 2.

The conduit 301 is geometrically configured to provide a suction of the mixture of primary air and combustible gas by Venturi effect. In the illustrated configuration, the heating apparatus 1 further comprises a passage 4 (see Fig. 5) configured for provide a flow of secondary into the combustion chamber 2.

The heating apparatus 1 includes a duct 5, for conveying a fluid to be heated. The fluid to be heated can for example be a gas like breathable air.

The duct 5 has an inlet 501 and an outlet 502 (see Figs. 3 to 5). Here, the duct 5 includes a fluid pump 503. The fluid pump 503 is configured to force the fluid flowing through the duct 5. Here, the fluid pump 503 is configured to aspire the air from the recreational vehicle within which the illustrated heating apparatus can be provided, and to force it into the duct 5 from the inlet 501 to the outlet 502. In an alternative embodiment, the fluid pump 503 is configured to aspire air from an external environment and to force it entering into the duct 5. The duct 5 includes a grid, positioned in front of the fluid pump 503 to avoid a pollution of the duct 5. In the illustrated configuration, the fluid pump 503 is an air pump. However, the fluid pump 503 also can be a liquid pump.

The inlet 501 of the duct 5 further includes a filter to avoid pollution of the system. When provided in a recreational vehicle, commonly the outlet 502 of the duct 5 is opened to the inner of the recreational vehicle. The heating apparatus 1 includes a heat exchanger 6.

The heat exchanger 6 in the illustrated embodiment is configured for transferring heat from heated exhaust gases flowing from the combustion chamber 2 through a gas conduit 60 of the heat exchanger to the fluid flowing in the duct 5. As best may be seen in Fig. 5, the gas conduit 60 of the heat exchanger 6 has two heat exchange zones: a first heat exchange zone 601 surrounded by a corresponding gas pipe, configured for heat exchange between the heated exhaust gases, generated in the combustion zone 2, within the first heat exchange zone 601 and the heated exhaust gases within a second heat transfer zone 602, and the second heat exchange zone 602 surrounded by a corresponding chamber, configured for heat exchange between the heated exhaust gases and the fluid to be heated flowing through the duct 5. The combustion zone 2 can be provided at least partially as section of the first heat exchange zone 601 as it is the case in the illustrated embodiment. The gas conduit further has a gas inlet 603 and a gas outlet 604. The gas pipe surrounding the first heat exchange zone 601 is coupled to the gas inlet 603, the second heat exchange zone 602 is connected to the first heat exchange zone 601 and the gas outlet 604 is coupled to the chamber surrounding the second heat exchange zone 602. The gas conduit 60 is geometrically shaped in such a way that heated exhaust gas entering the gas conduit 60 at the gas inlet 603 at first has to flow through the first heat exchange zone 601 and then through the second heat exchange zone 602 before it can leave the gas conduit 60 through the gas outlet 604.

The chamber surrounding the second heat exchange zone 602 and the gas pipe surrounding the first heat exchange zone 601 are provided within the duct 5 of the heat exchanger 6. The gas pipe surrounding the first heat exchange zone 601 is arranged within the chamber surrounding the second heat exchange zone 602 and the gas inlet 603 is provided with respect to the longitudinal axis of the heat exchanger 6 radially within the gas outlet 604. This allows an improved heat exchange and a quite compact spatial structure of heat exchanger 6.

Here, the gas pipe surrounding the first heat exchange zone 601 has smooth walls, communicating with the second heat exchange zone 602. The second heat exchange zone 602 is conformed as a channel-like chamber whose walls include a plurality of lamellas. As illustrated, the walls preferably include some lamellas pointing into the second heat exchange zone and/ or some lamellas pointing into the duct surrounding the gas conduit 60. Both groups of lamellas are configured to optimize the heat exchange between the exhaust gases flowing through the second heat exchange zone and fluid in particular the breathable air, flowing through the duct 5.

Here, the heating apparatus 1 comprises a fan 7 configured for forcing the flow of secondary air through the passage 4.

In the illustrated embodiment, the heating apparatus 1 comprises a feeding chamber 8. The feeding chamber 8 is configured to receive air from the external environment. The fan 7 is provided within the passage 4 or like illustrated here at the inlet of the feeding chamber 8 to force air from the external environment into the feeding chamber.

The feeding chamber 8 is in fluid communication with the inlet 302 of the conduit 301 to provide said primary air. The feeding chamber 8 also or alternatively can be in fluid communication with the passage 4 to provide said secondary air.

The heating apparatus 1 comprises a wall 401 having a first face 402 and a second face 403, opposite to the first face 402. The first face 402 delimits the feeding chamber 8 and the second face 403 delimits the combustion chamber 2. The wall 401 has a plurality of apertures 404 defining the passage 4. In an embodiment, the size of said apertures 404 is optimized according to the desired flow of secondary air towards the combustion chamber 2.

The heating apparatus 1 further comprises a gas injector 9. The gas injector 9 is configured for injecting the combustible gas into the inlet 302 of the conduit 30 . Here, the gas injector 9 is positioned inside the feeding chamber 8.

The gas injector 9 is connected to a gas tank 901 configured to stock the combustible gas. In the illustrated embodiment, the gas tank 901 is positioned inside the feeding chamber 8.

The wall 401 is oriented in a vertical direction V, parallel to the weight force. The conduit 301 , at least in its end, is elongated in a horizontal direction H perpendicular to the weight force.

The fan 7 is configured for forcing the flow of secondary air into the combustion chamber 2 substantially along the horizontal direction H. As illustrated, the burner can comprise one or more parallel burner modules 31. Each of the further parallel burner modules 31 comprises one parallel conduit 311. Each of the parallel conduits 31 1 has an inlet 312, for receiving the mixture of primary air and combustible gas, and an outlet 312, opened to the combustion chamber 2 to generate a flame in the combustion chamber 2. Here, each of the parallel conduits 301 and 311 is geometrically configured to provide a suction of the mixture of primary air and combustible gas by Venturi effect. The parallel burner modules 31 are arranged in parallel with said burner module 3. The feeding chamber 8 is in fluid communication with the inlet 312 of the one or more parallel conduits 311. In the illustrated embodiment, the inlets 312 of the one or more parallel conduits 311 are positioned inside the feeding chamber 8.

The apparatus comprises a respective parallel gas injector 91 for each of the one or more parallel burner modules 31. The parallel gas injectors 91 are configured to inject the combustible gas into the inlets 312 of the one or more parallel conduits 311.

Here, the parallel gas injectors 91 also are positioned inside the feeding chamber 8 and are connected to the gas tank 901.

The passage 4 is configured to provide the flow of secondary air into the combustion chamber 2 at the outlet of the one or more parallel conduits 311.

The apparatus also includes a parallel igniter 314 for each parallel burner module 31.

Here, the flow of secondary air flows externally to the conduit 301 and to the one or more parallel conduits 31 1.

In the illustrated embodiment, the heating apparatus 1 comprises an additional burner with an additional combustion chamber 2A. The additional burner 30 comprises at least one additional burner module 3A with an additional conduit 301A. The additional conduit 301A has an inlet port 302A, for receiving an additional mixture of primary air and additional combustible gas and an outlet port 303A, opened to the additional combustion chamber 2A to generate a flame in the additional combustion chamber 2A.

Here, the heating apparatus 1 also comprises an additional passage 4A. The additional passage 4A is configured to provide an additional flow of secondary into the additional combustion chamber 2A.

The heating apparatus 1 further comprises an additional wall 401A having a first face 402A and a second face 403A, opposite to the first face 402A. The first face 402A of the additional wall 401 A delimits the additional feeding chamber 8A and the second face 403A of the additional wall 401 A delimits the additional combustion chamber 2A. The additional wall 401 A has a plurality of apertures 404A defining the additional passage 4A. The size of said apertures 404A in the additional wall 401 A is optimized according to the desired additional flow of secondary air towards the additional combustion chamber 2A.

The heating apparatus 1 includes an additional duct 5A, for conveying an additional fluid to be heated. The additional fluid to be heated for example can be a liquid like water.

The additional duct 5A has an inlet 501 A, an outlet 502A and is at least partially configured as heat transfer tank 504A. Here, the heating apparatus includes an additional fluid pump. The additional fluid pump is configured to force the additional fluid flowing through the additional duct 5A from the inlet 501 A to the outlet 502A. In the illustrated embodiment, the additional pump is a liquid pump.

The heating apparatus 1 also includes a heat transfer unit 6A configured for transferring heat from exhaust gases flowing through a gas conduit 60A of the heat transfer unit 6A to the additional fluid flowing through the additional duct 5A.

The gas conduit 60A of the heat transfer unit 6A has a gas inlet 603A, a gas outlet 604A and two zones: a first heat transfer zone 601 A, configured to transfer heat from the heated exhaust gases to the fluid within the heat transfer tank of the additional duct 5A, and being surrounded by a corresponding chamber, and a second heat transfer zone 602A, also configured for heat transfer from the heated exhaust gases, generated in the additional combustion chamber 2A, and fluid, in particular water within heat transfer tank 504A of the additional duct 5A, and being surrounded by a corresponding gas pipe. The additional combustion zone 2A at least partially can be provided as section of the first heat transfer zone 601 A. The chamber surrounding the first heat transfer zone 601 A is coupled to the gas inlet 603A, the gas pipe surrounding the second heat transfer zone 602A is coupled to the chamber surrounding the first heat transfer zone 601A and the gas outlet 604A is coupled to the gas pipe surrounding the second heat transfer zone 602A.

The gas conduit 60A is geometrically shaped in such a way that due to convection, heated gas entering the gas conduit 60A at the gas inlet 603A at first has to flow through the first heat transfer zone 601 A and then through the second heat transfer zone 602A before it can leave the gas conduit 60A through the gas outlet 604A. The chamber surrounding the first heat transfer zone 601 A and the gas pipe surrounding the second heat transfer zone 602A are provided within the heat transfer tank 504A of the additional duct 5A.

The chamber surrounding the first heat transfer zone 601 A is provided as triangular chamber and the gas pipe surrounding the second heat transfer zone 602A is coupled to the triangular chamber surrounding the first heat transfer zone 601 A in the area of one of its corners. Here, the heating apparatus 1 comprises an additional fan 7A configured for forcing the additional flow of secondary air through the additional passage 4.

In the illustrated embodiment, the heating apparatus 1 comprises an additional feeding chamber 8A configured to receive air from the external environment. The additional fan 7A is provided within the passage 4 or like illustrated here at the inlet of the additional feeding chamber 8A to force air from the external environment into the feeding chamber 2A.

The additional feeding chamber 8A is in fluid communication with the inlet 302A of the additional conduit 301 A to provide said primary air. The additional feeding chamber 8A also or alternatively can be in fluid communication with the additional passage 4A to provide said additional flow of secondary air.

The heating apparatus 1 further comprises an additional gas injector 9A. The additional gas injector 9A is configured for injecting the additional combustible gas into the inlet 302A of the additional conduit 301A. Here, the additional gas injector 9A is positioned inside the additional feeding chamber 8A.

The additional gas injector 9A is connected with an additional gas tank 901A configured to stock the additional combustible gas. In the illustrated embodiment, the additional gas tank 901A is positioned inside the additional feeding chamber 8A.

In an embodiment, the additional wall 401A is oriented in the vertical direction V. The additional conduit 301A, at least in its end, is elongated in the horizontal direction H.

The additional fan 7A is configured for forcing the additional flow of secondary air into the additional combustion chamber 2A substantially along the horizontal direction H.

The heating apparatus 1 also comprises a feeding mouth 10 being in communication with the external environment. The feeding mouth 10 has a main inlet 101 opened to the external environment. The feeding mouth 10 also has an outlet communicating with the feeding chamber 8 through the fan 7 and an additional outlet communicating with the additional feeding chamber 8A through the additional fan 7A.

An electric board 12 is positioned inside the feeding mouth 10.

The heating apparatus 1 further includes an exhaust gases pipe 11.

The combustion chamber 8 and the additional combustion chamber 8A are in fluid communication with the exhaust gases pipe 11 via the corresponding combustion chambers 2 and 2A and the gas conduits 60 and 60A of the corresponding heat exchanger 6 respectively heat transfer unit 6A. The exhaust gases pipe 11 has an end opened to the external environment.

As illustrated, the exhaust gases pipe 11 is partially surrounded by the inlet 101 of the feeding mouth 10 such that the exhaust gases flowing through the exhaust gases pipe 11 release heat to the air entering into the feeding mouth 10 to increase the overall efficiency of the heating apparatus 1.

The heating apparatus 1 further includes a gas valve 13 and a parallel gas valve 131 for each parallel burner 31. The gas valve 13 is connected to the gas injector 9 and the parallel gas valves 131 are connected to the parallel gas injectors 91.

The heating apparatus 1 includes an additional gas valve connected to the additional gas injectors 9A.

The heating apparatus 1 comprises a single control unit connected to the fan 7. The control unit further is connected to the additional fan 7A and to the gas injector 9. The control unit also is connected to the additional gas injectors 9A, the fluid pump 503 and the additional fluid pump 503A.

The control unit is configured for controlling and coordinating the fan 7, the gas injector 9 and the fluid pump 503 as well as the additional fan 7A, the additional gas injector 9A and the additional fluid pump 503A.

The illustrated heating apparatus 1 includes a fluid temperature sensor, for measuring a temperature of the fluid (that preferably is air). The fluid temperature sensor can be placed inside the recreational vehicle in which the heating apparatus is provided, to measure the temperature of the fluid (air) inside the recreational vehicle. Alternatively, the fluid temperature sensor can be placed outside the recreational vehicle to measure the temperature of the fluid (air) outside the recreational vehicle. The fluid temperature sensor is connected to the control unit.

Here, the heating apparatus includes an additional fluid temperature sensor, for measuring a temperature of the additional fluid (that preferably is water). The additional fluid temperature sensor is placed in a water tank containing the water that has to be fed to the heating apparatus. The additional fluid's temperature sensor also is connected to the control unit.

The control unit is connected to the gas valve 13 and to the parallel gas valves 131 as well as to the additional gas valve.

The control unit is connected to the fan 7 and is configured to control the fan 7. Here, the control unit is programmed to control the fan 7 in dependence of at least one control parameter, wherein the control parameter is representative for a thermal power provided by the burner. The control parameter may be set (directly or indirectly) by the user through an interface. The control parameter also may be derived as a function of a target temperature (which can be set by the user through the interface) and of a measured parameter, which may be representative for the temperature of the fluid (or additional fluid) to be heated (at input to the heater). AS illustrated, the burner preferably includes a plurality of burner modules (e.g. 2, or 3 or 4, or more); let us assume it includes N modules; the heater is configured to turn on a subset of the plurality of burner modules, keeping the remaining ones off. In this case, the control parameter may be representative of a number (any natural number from 0 to N), corresponding to the number of burner modules to be set on, wherein the others are to be set off (or vice versa). The same features may (or may not) be provided to the additional burner.

In the illustrated embodiment, the control unit further is programmed for receiving (from the fluid temperature sensor) the temperature of the fluid, for comparing it with a target temperature of the fluid. The target temperature of the fluid can be set by a user. The control unit also is programmed for receiving (from the additional fluid temperature sensor) the temperature of the additional fluid, for comparing it with the target temperature of the additional fluid. The target temperature of the additional fluid can be set by a user. The control unit is programmed for controlling the burner, switching on or off (selectively) one or more of the burner modules 3, if the temperature of the fluid is lower than the target temperature of the fluid. The control unit is programmed for controlling the additional burner, switching on or off (selectively) one or more of the additional burner modules 3A, if the temperature of the additional fluid is lower than the target temperature of the additional fluid.

The control unit is programmed for controlling the burner, switching off one or more of the burner modules 3 if the temperature of the fluid is equal or higher than the target temperature of the fluid. In an embodiment, the control unit is programmed for controlling the additional burner, switching off one or more of the additional burner modules if the temperature of the additional fluid is equal to or higher than the target temperature of the additional fluid.

The heating apparatus includes a panel where the user can manually set the number of the burner modules 3 that he wants to switch on or off. In addition thereto, the heating apparatus includes a panel where the user can manually set the number of the additional burner modules 3A that he wants to switch on or off.

The number of burner modules 3 switched on (or off) provides a parameter representative for a thermal power provided by the burner. The difference between the target temperature of the fluid (air) and the measured temperature of the fluid (air) provides another parameter representative for a thermal power provided by the burner. The number of additional burner modules 31 switched on (or off) provides a parameter representative for a thermal power provided by the additional burner. The difference between the target temperature of the additional fluid (water) and the measured temperature of the additional fluid (water) provides another parameter representative for a thermal power provided by the additional burner.

The control unit is configured to receive at least one parameter representative for the thermal power provided by the burner and one parameter representative for the thermal power provided by the additional burner.

The control unit is connected to the fan 7 and configured to control the fan 7 in dependence to the at least one parameter representative for a thermal power provided by the burner.

Moreover, the control unit is connected to the additional fan 7A and configured to control the additional fan 7A in dependence to the at least one parameter representative for a thermal power provided by the additional burner.

The control unit switches on the burner module 3 by opening the gas valve 13 and switches off the burner module 3 by closing the gas valve 13. The control unit switches on the additional burner module 3A by opening the additional gas valve and switches off the additional burner module 3A by closing the additional gas valve.

The present invention covers a recreational vehicle comprising the heating apparatus 1 , one of the described heating units, the described heat exchanger and/ or the described heat exchanger.

The heating apparatus 1 can be fixable outside the recreational vehicle like for example on the roof of the recreational vehicle.

The present invention also covers a method for heating a fluid in a recreational vehicle. An exemplary embodiment of a preferred method according to the present invention is described in the following.

At first, a mixture of primary air and combustible gas is received at the inlet port 302 of the conduit 301 of the burner module 3 of the burner. Then the burner is opened to the combustion chamber 2.

In the next step the mixture of primary air and combustible gas is sucked into the conduit 301 by Venturi effect. Simultaneously a flow of secondary air is provided by the fan 7 into the combustion chamber 2 Next, the mixture of primary air and combustible gas is burned within the combustion chamber 2. Therefore, air is pressurized in the feeding chamber 8 by the fan 7. The feeding chamber 8 communicates with the combustion chamber 2 through the passage 4 and through the conduit 301 , to provide said secondary and primary air.

The feeding chamber 8 is at overpressure with respect both to the combustion chamber 2 and to an external environment. The secondary air flows externally to the conduit 301.

The electric board is intercepted and cooled by the air flowing in the feeding chamber 8.

The fluid to be heated is conveyed into the duct 5 and then heat from the heated exhaust gases flowing through the gas conduit 60 is transferred to the fluid flowing through the duct 5.

Moreover, the invention covers a method for heating air and water in a recreational vehicle. An exemplary embodiment of such a method is described in the following.

At first a mixture of primary air and combustible gas is received at the burner, opened to the combustion chamber 2. The burner includes at least one burner module 3.

Simultaneously, a flow secondary air is provided into the combustion chamber 2.

Then, the mixture of primary air and combustible gas is burned within the combustion chamber 2.

Then, air is conveyed into the duct 5 and water is conveyed into the additional duct 5A.

Finally, the heat is transferred from the heated exhaust gases flowing through the conduit 60 of the heat exchanger 6, to the air flowing through the duct 5.

Simultaneously, an additional mixture of primary air and combustible gas is received at the inlet of the additional burner, opened to the additional combustion chamber 2A. The additional burner includes at least one additional burner module 3A.

An additional flow of secondary air is provided into the additional combustion chamber 2A.

The heat, from exhaust gases flowing through the gas conduit 60A of the heat transfer unit 6A, is transferred to the water flowing through the heat transfer tank of the additional duct 5A. The method comprises a step of providing a flow of air from an external environment into a feeding mouth 10 and a step of feeding the air from the feeding mouth 10 to the feeding chamber 8, to provide the primary air and the flow of secondary air. The method also comprises a step of feeding the air from the feeding mouth 10 to the additional feeding chamber 8A, to provide the primary air of the additional mixture and the additional flow secondary air.

The air is fed from the feeding mouth 10 to the feeding chamber 8 through a fan 7. The air is fed from the feeding mouth 10 to the additional feeding chamber 8A through the additional fan 7A. The feeding chamber 8 and the additional feeding chamber 8A are at overpressure with respect to an external environment through the fan.

The exhaust gases and the additional exhaust gases, after flowing respectively through the gas conduit 6 and the gas conduit 6A, merge in the single exhaust pipe 11. The exhaust gases and the additional exhaust gases are emitted in the external environment through the exhaust pipe 11.

Simultaneously, the exhaust gases and the additional exhaust gases, flowing through the exhaust pipe 11 , release heat to the air flowing into the feeding mouth 10.

Some further preferable features and some clarifications are given in the following.

Preferably, the burner (the burner module 3) is an atmospheric burner; this means that the burner, per se, does not require a pre-mixing unit, for providing the mixture of air and gas to be fed to the burner itself. Preferably, the burner (the burner module 3) is a "bladed" or "ramp-type" burner, which is a low-cost commercial component.

Preferably, the gas injector 9 is positioned in the immediate vicinity of the inlet port 302 of the conduit (preferably less than 60 millimeters, more preferably less than 20 millimeters from the inlet of the conduit). The conduit 301 , at the inlet port 302 thereof, preferably has a stretch oriented (extended) along a first axis. In an embodiment, the gas injector 9 is oriented along that first axis, substantially aligned with the stretch of the burner positioned proximate to the inlet port 302 of the conduit 301.

At the inlet port 302 of the conduit 301 , (primary) air is sucked naturally, together with the gas provided by the injector 9; hence, the mixture of air and gas is provided naturally at the inlet port 302 of the conduit 301 , by Venturi effect. Preferably, the nozzles (apertures 404) provided at the outlet port 303 of the conduit 301 are oriented in respective second axes. In an embodiment, the second axes of the nozzles are parallel to each other. In another embodiment, the second axes of the nozzles are transversal (perpendicular) to the first axis. In one embodiment, the second axes are oriented in a same plane which includes the first axis.

The primary air is necessary to have combustion in a flammability range, the secondary air is adduced to the flames to optimize the combustion efficiency, to reduce the harmful emissions and to control the temperature of the combustion chamber.

Preferably, the fluid to be heated is breathable air. For breathable air, it is intended the air that people in the recreational vehicle are going to breath. Moreover, the fluid to be heated is water. For water, it is intended the water that people in the recreational vehicle are going to use for sanitary purposes, for cleaning or for cooking.

The suction of primary air preferably is naturally provided by the Venturi effect, while the aspiration of secondary air is forced by the fan. This combination of natural and forced aspiration improves the efficiency and the flexibility of the heating apparatus.

Preferably, transversally to the feeding direction, the feeding chamber has a section (size) which is significantly larger (for example at least 3 times, preferably at least 5 times, for example approximately ten times) than the section of the conduit inlet port (for primary air and gas). In one preferably embodiment, the feeding direction is transversal to the first axis (along which the inlet of the conduit extends).

Preferably, the number of the burner modules 3 is greater than the number of the additional burner 3A modules.

In a preferred embodiment, in which the fluid is breathable air and the additional fluid is water, the number of burner modules 3 (dedicated to the heating of the air) is three and the number of additional burner modules 3A (dedicated to the heating of the water) is one. This embodiment reflects the average request for warm air and warm water in a recreational vehicle.

The structure of the heating apparatus 1 , with two distinct combustion chambers 2 and 2A and two distinct heat exchangers 6 respectively heat transfer units 6A, the one dedicated to the water, and the other dedicated to the air, gives to the apparatus a high flexibility and a good efficiency. Actually, it is possible to heat air but not water, and to heat water but not air.

Preferably, the heating apparatus 1 is fixable on the roof of the recreational vehicle. This placement outside the recreational vehicle is possible because of the high efficiency of the apparatus 1 and because of the main horizontal size of the apparatus 1 , thanks to the fan configured for flowing secondary air along the horizontal direction. This placement outside the recreational vehicle allows to have more available place inside the recreational vehicle.

Preferably, the heating apparatus 1 includes an automatic frost valve. The automatic frost valve is connected to a water circuit, that also includes the additional duct. The automatic frost valve is configured for automatically opening when the recreational vehicle is parked in response to a cold temperature detection, allowing the water to flow away. This feature avoids the freezing damaging the water circuit. The automatic frost valve is configured for automatically setting back to close when the water circuit is empty. This feature avoids someone having to close the valve.

REFERENCE SIGNS : heating apparatus

: combustion chamber

A: additional combustion chamber

: burner module

01 : conduit

02: inlet port

03: outlet port

04: igniter

1 : parallel bumer module

11 : parallel conduit

12: inlet port

13: outlet port

14: igniter

A: additional burner module

01 A: additional conduit

02A: inlet port

03A: outlet port

04A: igniter

: passage

01 : wall

02: first face

03: second face

04: aperture

A: additional passage

01A: additional wall

02A: first face

03A: second face

: duct

01 : inlet

02: outlet

03: fluid pump

A: additional duct

01A: inlet

02A: outlet

03A: additional fluid pump 504 A: heat transfer ta n k

6: heat exchanger

60: gas conduit

601 : first heat exchange zone

602: second heat exchange zone

603: gas inlet

604: gas outlet

6A: heat transfer zone

60A: gas conduit

601 A: first heat exchange zone

602A: second heat exchange zone

603A: gas inlet

604A: gas outlet

7: fan

7A: additional fan

8: feeding chamber

8A: additional feeding chamber

9: gas injector

901 : gas tank

9A: additional gas injector

901A: additional gas tank

91 : parallel gas injector

10: feeding mouth

11 : exhaust gases pipe

101 : main inlet

12: electric board

13: gas valve

131 : parallel gas valve

H: horizontal direction

V: vertical direction