COOKING APPLIANCE HAVING A GAS BURNER

Abstract

A cooking appliance includes a housing, an installation space inside the housing, a gas burner, an air intake opening provided in the housing, and an air intake system connecting the air intake opening to the gas burner. The air intake system has an auxiliary intake opening through which air can be drawn in from the installation space.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY

This patent application claims priority from German Patent Application No. 10 2025 108 846.2 filed Mar. 10, 2025. This patent application is herein incorporated by reference in its entirety.

The invention relates to a cooking appliance comprising a housing, an installation space inside the housing, a gas burner, an air intake opening provided in the housing, and an air intake system connecting the air intake opening to the gas burner.

BACKGROUND OF THE INVENTION

Gas-powered cooking appliances are very powerful because an energy carrier having a high power density is used. The gas burner is able to preheat the cooking appliance in a short time and, when large quantities of food are placed in the cooking chamber, to introduce large amounts of heat there during operation.

The combustion of the supplied gas depends crucially on the combustion air being supplied in the correct ratio to the fuel gas. Usually, the combustion air is drawn in from outside the housing through the air intake opening.

The air intake opening is positioned on the cooking appliance such that it can draw in air unhindered, but is so difficult to access that normally, it cannot be accidentally partially or completely closed. In many cooking appliances, the air intake opening is located on the underside of the housing so that it draws in from the free space between the base on which the cooking appliance stands and the underside of the housing. However, even in this case, the free cross-section of the air intake opening can be impaired, for example if an operator places an object in this free space. If the air intake opening is thus unintentionally partially or completely closed, the gas burner can no longer be supplied with as much air as is necessary for optimal combustion. The consequences are incomplete combustion, which not only impairs the efficiency of the appliance but may also result in an increased concentration of harmful exhaust gases. In extreme cases, if (almost) no combustion air can be drawn in, combustion is no longer possible at all.

The object of the invention is to create a cooking appliance in which the operation of the gas burner is not impaired by an insufficient supply of combustion air.

BRIEF DESCRIPTION OF THE INVENTION

To achieve this object, for a cooking appliance of the type initially mentioned, it is provided according to the invention that the air intake system has an auxiliary intake opening through which air can be drawn in from the installation space. The invention is based on the basic idea of providing a bypass through which “secondary air” can be drawn in past the air intake opening if necessary. This secondary air is drawn in from the installation space, i.e., from a space which is not accessible to an operator. Accordingly, there is no risk of the auxiliary intake opening being accidentally obstructed or closed. The auxiliary intake opening is designed such that even if the air intake opening is completely closed, the gas burner can still be supplied with sufficient combustion air such that proper combustion is ensured. In addition, the use of preheated air already present in the installation space leads to improved combustion efficiency, as the temperature of the combustion air is higher than that of the air supplied from outside. This solution also contributes to reducing component temperatures within the device, as a higher air flow through the installation space enables better cooling of the components.

One embodiment of the invention provides that an actuator and a valve flap associated with the auxiliary intake opening are provided. This design allows the auxiliary intake opening to be opened or closed automatically as required, enabling precise control of the cross-section of the auxiliary intake opening. This allows a precise response to be made if the air intake opening is partially or completely blocked. However, it can also be controlled so that, in certain operating phases, part of the combustion air is drawn in from the installation space, even if the air intake opening is not obstructed, for example, if a higher temperature of the combustion air or a higher air exchange in the installation space is desirable.

A pressure sensor which is associated with the air intake system may be provided for this purpose. The integration of a pressure sensor allows the pressure in the air intake system to be continuously monitored. This provides reliable feedback on the current status of the air supply, allowing the control of the gas burner and the air supply to be dynamically adjusted to ensure efficient and safe combustion. A warning may also be issued on a user interface if the pressure sensor detects that the air intake opening is impaired.

In one variant of the invention, a passive valve flap is provided which is associated with the auxiliary intake opening. A passive valve flap opens automatically due to the negative pressure generated when the air intake opening is partially or completely blocked. The advantage of this solution lies in its simplicity and reliability, as no additional drive mechanisms are necessary, which reduces maintenance and increases operational safety.

In one embodiment of the invention, it is provided that the auxiliary intake opening is permanently open towards the installation space. This configuration guarantees a constant availability of additional combustion air, which maximizes operational safety. The technical advantage here is that the design is very simple and cost-effective. Since there are no mechanical parts which can wear out, a long service life with minimal maintenance is achieved.

One embodiment of the invention provides that the cross-section of the auxiliary intake opening is between 15% and 100% of the cross-section of the air intake opening. The advantage of this dimensioning is, first of all, that the gas burner can still draw in sufficient combustion air through the auxiliary intake opening even when the air intake opening is completely closed. It is furthermore advantageous that during normal operation, i.e. when the air intake opening is unobstructed, part of the combustion air is permanently drawn in from the installation space due to the ratio of the flow resistances of the air intake opening and the auxiliary intake opening, so that, on the one hand, preheated combustion air is used and, on the other hand, the installation space is better cooled by the ambient air flowing in from outside.

The auxiliary intake opening and the air intake opening can be formed in an intake fitting inserted into an opening in the housing. Combining both air intake openings in one component simplifies the design of the device and reduces the installation effort.

The intake fitting may have a stop for an inlet pipe, the auxiliary intake opening being provided between the stop and a contact collar which rests on the inside of the housing. This design ensures that the inlet pipe cannot be pushed onto the fitting so far that the auxiliary intake opening is covered. In addition, the auxiliary intake opening is located close to the inner wall of the housing, minimizing the risk of the auxiliary intake opening being unintentionally obstructed.

A pressure sensor may be provided which measures the pressure in the installation space. The pressure sensor can be used to detect when the pressure in the installation space falls below a threshold value, which indicates that either the air intake opening is obstructed or that the supply air openings through which ambient air can flow into the installation space are obstructed, for example because a filter assigned thereto is dirty. A warning can then be issued that the air intake opening or the supply air openings should be checked.

Depending on the change in pressure in the installation space, it is possible, if desired, to determine the cause or the affected opening. A sudden change in negative pressure in the installation space indicates that someone has placed an object in front of the air intake opening. A slow change in negative pressure in the installation space indicates that the filter of the supply air openings is clogged with dirt.

The auxiliary intake opening may be composed of a plurality of individual openings. This configuration offers the advantage that if individual openings are blocked, sufficient air can still flow through the remaining openings. A further advantage is that the auxiliary intake opening can also be “accommodated” in confined conditions, for example by distributing a plurality of individual openings around the circumference of an intake fitting, so that less space is required in the axial direction than with a single auxiliary intake opening having the same cross-section.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below on the basis of various embodiments, which are illustrated in the accompanying drawings in which:

FIG. 1 schematically shows a cooking appliance according to a first embodiment,

FIG. 2 shows a first perspective view of an intake fitting used in the cooking appliance of FIG. 1,

FIG. 3 shows the intake fitting of FIG. 2 in a second perspective view,

FIG. 4 shows the intake fitting of FIG. 2 in a third perspective view,

FIG. 5 shows a first variant embodiment of the intake fitting of FIG. 2,

FIG. 6 shows a second variant embodiment of the intake fitting of FIG. 2,

FIG. 7 shows a third variant embodiment of the intake fitting of FIG. 2,

FIG. 8 schematically shows part of a cooking appliance according to a second embodiment, and

FIG. 9 schematically shows part of a cooking appliance according to a third embodiment.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 schematically describes a cooking appliance 5 according to one embodiment. It is a cooking appliance for professional use, for example in restaurants, canteens, and large-scale catering.

The cooking appliance 5 has a housing 10 in which a cooking chamber 12 and an installation space 14 are delimited. Food can be cooked in the cooking chamber 12 in a cooking chamber atmosphere, and components for generating and maintaining a desired cooking chamber atmosphere are arranged in the installation space 14.

One of these components is an appliance control 16, by means of which the various components of the cooking appliance 5 can be driven.

Another of these components is a gas burner 18, by means of which air can be heated or steam can be generated. This allows a desired cooking temperature and/or humidity to be set in the cooking chamber 12.

The gas burner 18 is located partly in the installation space 14 and partly in the cooking chamber 12. In particular, a heat exchanger section of the gas burner 18 extends into the cooking chamber 12.

The gas burner 18 obtains its combustion air through an air intake system 20 connecting the gas burner 18 to the outside of the cooking appliance 5. In the normal state, at least a substantial portion of the combustion air is drawn in from outside the cooking appliance 5, namely through an intake passage 22, which is formed here on the underside of the cooking appliance 5 in the housing 10 thereof.

An intake fitting 24 which is located in the installation space 14 and is connected to the gas burner 18 by means of an inlet pipe 26 is arranged at the intake passage 22.

The intake fitting 24 has an air intake opening 28, which is a primary intake opening and extends centrally through the intake fitting 24 from the outside of the housing 10 to the inside.

The intake fitting 24 also has a plurality of auxiliary intake openings 30, which constitute a flow connection from the interior of the installation space 14 to the interior of the intake fitting 24. This allows part of the air required for the operation of the gas burner 18 to be drawn in from the installation space 14.

The total air mass flow drawn in by the gas burner 18 therefore consists of a portion originating from outside the cooking appliance 5 and a portion originating from the installation space 14. The specific proportions on the total air mass flow depend essentially on the ratio of the flow cross-sections and the flow resistances of the air intake opening 28 and the auxiliary intake openings 30.

During normal operation, a major part of the combustion air is drawn in from outside the cooking appliance 5 and a smaller portion from the installation space 14. The air mass flow from the installation space 14 usually has a higher temperature than the air from outside the cooking appliance 5, so that the combustion air is “preheated.”

If the air intake opening 28 is obstructed or completely closed, a larger portion or even all of the combustion air is drawn in through the auxiliary intake openings 30 and thus from the installation space 14.

FIGS. 2 to 4 show the intake fitting 24 in detail. The air intake opening 28 is first visible here.

A protective grille 32 is assigned to the air intake opening 28. The protective grille 32 prevents foreign objects or contaminants from entering the air intake system 20, thereby increasing the operational safety of the gas burner 18.

The intake fitting 24 has a contact collar 34 which rests against the inside of the housing 10 when the intake fitting 24 is mounted in the intake passage 22 of the housing 10.

Two wings 36 which are formed on the intake fitting 24 and are part of a bayonet locking system are located on the outside of the housing 10.

In the circumferential direction, the intake fitting 24 is locked by pins 38 provided on locking tabs 39. The pins 38 snap into openings in the housing 10 as soon as the intake fitting 24 is correctly inserted axially into the intake passage 22 and rotated circumferentially into the position in which the wings 36 secure it in the axial direction.

The intake fitting 24 has a stop 40 for the inlet pipe 26 at an axial distance from the contact collar 34 and a plurality of elastic latching noses 42, only one of which is shown in the figures.

The inlet pipe 26 is pushed onto the intake fitting 24 until it rests against the stop 40 and the latching noses 42 fix it in the axial direction.

Between the contact collar 34 and the stop 40, the intake fitting 24 is provided with two auxiliary intake openings 30, which have a rectangular shape here. The height of the auxiliary intake openings 30 corresponds to the distance between the contact collar 34 and the stop 40. in the example embodiment shown, each auxiliary intake opening 30 extends over an angular range of 10° to 30° in the circumferential direction.

In alternative designs, each auxiliary intake opening 30 can extend over a larger angular range of up to 170°. It is only important that a web remains which has sufficient strength to support the stop 40 and the area thereabove.

The auxiliary intake openings 30 are dimensioned so that they can contribute a variable proportion of air from the installation space 14, depending on the respective flow cross-sections and resistances. During normal operation, with the air intake opening 28 intact, only part of the air flows in from the installation space 14, wherein the higher temperature thereof has a positive influence on the preheating of the combustion air. However, if the air intake opening 28 is closed, the entire air supply is provided via these auxiliary intake openings 30, so that the gas burner 18 is still supplied with sufficient combustion air.

FIG. 5 shows a variant embodiment of the intake fitting 24. The same reference numerals are used for the components and features known from the first embodiment, reference being made to the above explanations in this respect.

The difference between the intake fitting 24 of FIGS. 2 to 4 and the intake fitting 24 of FIG. 5 is that in the intake fitting 24 of FIG. 5, the auxiliary intake openings 30 are designed with a round cross-section. This is advantageous in that no notch effect occurs in the corners of the auxiliary intake openings 30.

FIG. 6 shows a second variant embodiment of the intake fitting 24. The same reference numerals are used for the components and features known from the first embodiment and the first variant embodiment, reference being made to the above explanations in this respect.

The difference between the intake fitting 24 of FIG. 5 and the intake fitting 24 of FIG. 6 is that the intake fitting 24 of FIG. 6 has a plurality of auxiliary intake openings 30 with a round cross-section arranged next to each other. In this way, the total cross-section of the auxiliary intake openings 30 can be adjusted to a desired value, in particular relative to the cross-section of the air intake opening 28.

If a comparatively large number of auxiliary intake openings 30 are used, this has the advantage that any blockage or clogging of an auxiliary intake opening 30 has only a very minor effect on the total cross-section provided by the auxiliary intake openings 30.

FIG. 7 shows a third variant embodiment of the intake fitting 24. The same reference numerals are used for the components and features known from the first embodiment and the first and second variant embodiments, reference being made to the above explanations in this respect.

The difference between the intake fitting 24 of FIG. 6 and the intake fitting 24 of FIG. 7 is that, in the intake fitting 24 of FIG. 7, the plurality of auxiliary intake openings 30 arranged side by side each have a rectangular cross-section, as is known from the first embodiment.

FIG. 8 schematically shows a cooking appliance 5 according to a second embodiment. The same reference numerals are used for the components and features known from the preceding embodiments and variant embodiments, reference being made to the above explanations in this respect.

In the second embodiment, each auxiliary intake opening 30 is assigned a passive valve flap 44. These are acted upon by a spring, a weight arranged on a small arm, or due to the arrangement of the pivot axis thereof relative to the center of gravity in a closed position. The closing force is symbolized by the arrows P.

If the force exerted on the valve flap 44 due to the difference between the pressure on the inside of the intake fitting 24 and the pressure in the installation space 14 is greater than the closing force, the valve flaps 44 open so that part of the combustion air is drawn in from the installation space 14.

The advantage of this embodiment is that, up to a certain low volume flow, the entire combustion air is drawn in from outside the cooking appliance 5, and only when a threshold negative pressure is reached is additional air drawn in from the installation space 14.

FIG. 9 schematically shows a cooking appliance 5 according to a third embodiment. The same reference numerals are used for the components and features known from the previous embodiments and variant embodiments, reference being made to the above explanations in this respect.

In the third embodiment, each auxiliary intake opening 30 is assigned an active valve flap 52, i.e., a valve flap 52 actuated by an actuator 54. The actuator 54 can be driven via the appliance control 16.

The appliance control 16 can process a signal from a pressure sensor 56 associated with the air intake system 20. As soon as the negative pressure in the air intake system 20 exceeds a predetermined threshold, the valve flaps 52 can be opened by means of the actuators 54.

The appliance control 16 can also process a signal from a temperature sensor which detects the temperature in the installation space 14. As soon as the temperature exceeds a threshold value, the valve flaps 52 are opened so that air is drawn in from the installation space 14. This causes air from outside the cooking appliance 5 to flow into the installation space 14. Overall, this results in the warm air in the installation space 14 being replaced by cold outside air.

Claims

1. A cooking appliance comprising a housing, an installation space inside the housing, a gas burner, an air intake opening provided in the housing, and an air intake system connecting the air intake opening to the gas burner, wherein the air intake system has an auxiliary intake opening through which air can be drawn in from the installation space.

2. The cooking appliance of claim 1 wherein an actuator and a valve flap are provided, which are associated with the auxiliary intake opening.

3. The cooking appliance of claim 1 wherein a pressure sensor is provided, which is associated with the air intake system.

4. The cooking appliance of claim 1 wherein a passive valve flap is provided, which is associated with the auxiliary intake opening.

5. The cooking appliance of claim 1 wherein the auxiliary intake opening is permanently open towards the installation space.

6. The cooking appliance of claim 5 wherein the cross-section of the auxiliary intake opening is in the range between 15% and 100% of the cross-section of the air intake opening.

7. The cooking appliance of claim 5 wherein the auxiliary intake opening and the air intake opening are formed in an intake fitting which is inserted into an opening in the housing.

8. The cooking appliance of claim 5 wherein the intake fitting has a stop for the inlet pipe and in that the auxiliary intake opening is provided between the stop and a contact collar, wherein the contact collar rests against the inner side of the housing.

9. The cooking appliance of claim 5 wherein a temperature sensor is provided, which detects the temperature in the installation space.

10. The cooking appliance of claim 1 wherein the auxiliary intake opening is composed of a plurality of individual openings.

11. A cooking appliance comprising a housing, an installation space inside the housing, a gas burner, an air intake opening provided in the housing and adapted for admitting ambient air to the gas burner, and an air intake system connecting the air intake opening to the gas burner, the air intake system having an auxiliary intake opening adapted for through which air can be drawn in from the installation space for being admitted to the gas burner.