EP2876372B1

EP2876372B1 - Arrangement for heat protection of a heat-sensitive material from a heat source, kitchen hob and method for heat protection

Info

Publication number: EP2876372B1
Application number: EP13194060.3A
Authority: EP
Inventors: Giuseppe Lando; Patrizia Ponti; Roberto Cortesi; Maurizio Beghi
Original assignee: Electrolux Appliances AB
Current assignee: Electrolux Appliances AB
Priority date: 2013-11-22
Filing date: 2013-11-22
Publication date: 2018-05-30
Anticipated expiration: 2033-11-22
Also published as: ES2684515T3; EP2876372A1

Description

In present household environments, due to restricted and expensive living space and as a consequence of technological progress, devices and appliances become ever smaller and more integrated. In contrast to former times, there is also a strong desire to neatly integrate home appliances into furniture. Predominantly, a seamless designed environment that follows the life style of the customer has to be adapted. Consequently, also kitchen appliances, such as e.g. kitchen hobs, have to be neatly integrated into kitchen furniture to produce a clean monolithic appearance of the kitchen furniture.
However, with a concentration of functional components on smaller space, in particular the heat-producing devices, such as gas burners, pose risks in terms of sufficient cooling and isolation of the heat that is present in a small area. This is particularly the case once a flush-mounted kitchen hob is placed in a cutout of a workplate made of heat-sensitive material, such as a wooden compound, or massive wood as well as plastic material. Problems may particularly arise in the presence of flames that produce heat radiation as well as heat by conduction into the surface where they are mounted due to the predominant use of metallic parts in e.g. gas burners.
The prior art document DE 4004093 A1 is about a glass ceramic kitchen hob. It discloses the isolation of an area below the heating elements of the glass ceramic hob by an air gap that can also be filled with glass fibres in order to protect the furniture or devices below the glass ceramic hob from heat.
Document DE 7121622 U discloses a flush mounted kitchen hob. Inside the housing of the kitchen hob a reflecting piece of sheet metal is provided that is clamped in a frame area of the flush mounted kitchen hob.
Document WO 2008084918 A1 discloses a built-in cooking appliance that includes a main body, a top plate above the main body, a cabinet supporting the top plate, a support forming an airflow space between a side of the top plate and the cabinet and allowing the top plate to be supported by the cabinet even at the space, and an air outlet allowing internal air of the main body to be discharged through the support.
Document EP 1444942 A1 discloses a cooking apparatus that includes a body, a pair of heating units, a grill unit, a heat reflecting unit, and a cooling fan. The heating units are arranged between the grill unit and the heat reflecting unit. The heat reflecting unit includes inner and outer reflecting plates that are inclined at certain angles to reflect heat radiated from the heating units toward the grill unit.
No other related prior art is known.
The invention is based on the problem to improve the protection of a heat-sensitive material, in particular of a workplate in the presence of a strong heat source, such as a gas burner.
This problem is solved by an arrangement for heat protection according to claim 1, a kitchen hob according to claim 8 and a method for heat protection according to claim 12.
Further developments of the invention are given in the dependent claims.
According to the present invention, a reflective shield on the side of the heat source is provided to protect the heat-sensitive material from heat radiation emitted from the heat source. In this manner, an effective near-area protection can be provided for radiation, the intensity of which diminishes with the square of the radius from the centre of its origin. Thus, only a small area needs to be covered by the reflective shield to provide effective total protection.
According to the present invention, a slit is provided between the heat source and the lateral reflective shield in order to promote convectional air movement, thus further improving the cooling situation next to the heat source in an efficient manner.
Beneficially, according to a further development of an embodiment of the arrangement according to the present invention, the reflective shield comprises the slit. In this manner, only one component is needed for two protective measures, and in case the reflective shield is built of metal, it can be coupled directly to a base where the heat source is mounted, and thus allow further heat transfer by heat conduction along the metal area.
Advantageously, according to a further development of an embodiment of the arrangement according to the present invention, a housing of the heat source features a heat barrier to prevent heat conduction from a floor area of the housing into the sidewalls of the housing. In this manner, efficiently, heat transfer into a heat-sensitive material where e.g. the heat source is mounted can be further prevented. Usually, e.g. in case a kitchen hob is fixed into a workplate, it is coupled via the sidewalls of the housing of the hob to the cutout. Thus, such an arrangement further improves the protection of the heat-sensitive material.
Favourably, according to a further development of an embodiment of the arrangement according to the present invention, the shield comprises a U-shaped profile which e.g. is located between a heat source and the reflective area of the shield. In this manner, an area for air convection along the slit can be provided as well as heat conduction can be promoted along the slit. Further, the U-shaped profile favourably allows a height adaption from a surface level of e.g. a workplate to the surface level of an area where e.g. heaters, e.g. gas burners, are mounted. In this manner, an air flow can be directed to provide fresh air to the gas burners in order to improve the gas combustion.
Favourably, according to a further development of an embodiment of the arrangement according to the present invention, the slit is provided in a vertical wall of the U-shaped profile. Thus, fresh air from underneath the U-shaped profile, respectively a workplate, can be allowed to stream out at the area of the U-shaped profile to further improve the cooling effect and also, at the same time, provide fresh oxygen to improve the combustion in a gas burner.
Favourably, a U-shaped profile that is not symmetrical and has a shorter arm next to an area where heat sources are mounted allows it to direct an air flow precisely to optimize the combustion process.
According to the present invention, the reflective shield also provides for thermal conduction. In this manner, two heat protective measures can be combined in one device and thus further improve the heat protection of the heat-sensitive area, such as a workplate. This can, for instance, be achieved by manufacturing the reflective shield from a metallic part or another suitable material that has high heat conductivity.
Advantageously, according to a further development of an embodiment of the arrangement according to the present invention, the reflective shield with its shorter arm of the U-profile contacts the housing of a heat source and thus builds a thermal bridge to further improve thermal conductivity away from the heat source. Heat that is not present within a cutout of e.g. a kitchen hob in e.g. a workplate creates no more thermal problems.
Beneficially, according to a further development of an embodiment of the arrangement according to the present invention, a smaller gap is provided between the reflective shield and the heat-sensitive material in order to further improve the protection against thermal stress in the heat-sensitive material.
Advantageously, a kitchen hob according to the present invention built into a workplate comprises an arrangement for heat protection according to the present invention in order to protect a workplate against the heat emanated from the kitchen hob. Thus, several protective effects, such as thermal conduction, thermal convection and reflection of heat radiation are combined in order to protect the workplate.
Advantageously, according to a further development of an embodiment of the kitchen hob according to the present invention, the heat source is implemented as a gas burner. In this manner, a highly effective heat source is provided, but at the same time heat sources that produce outwardly directed heat radiation in an exposed position can be well accommodated by the arrangement according to the present invention.
Advantageously, according to a further development of a kitchen hob according to the present invention, a pot support located next to the gas burner rests on the reflective shield. In this manner, the area for cooking of a kitchen hob according to the present invention can be expanded over e.g. a standard cutout for household appliances and provide a larger cooking area as a benefit to the customer.
Advantageously, the kitchen hob according to the present invention has dimensions that fit into a standard cutout defined for home appliances such as kitchen hobs.
Advantageously, the method according to the present invention provides a minimum number of measures in order to achieve a maximum protection from a heat source such as a gas burner built into a heat-sensitive workplate, such as a flush-mounted kitchen hob using gas burners, built into a wooden workplate.
Subsequently, the invention will be further explained on the basis of embodiments and examples shown in drawings wherein:

Fig. 1: shows an example of a heat source;
Fig. 2: shows another example of a heat source;
Fig. 3: shows an example of a reflective shield for thermal protection;
Fig. 4: shows an example of heat barriers built into a housing of a heat source; and
Fig. 5: shows some examples of heat transfer according to an embodiment of the present invention.

Fig. 1 shows a preferred embodiment of an arrangement for heat protection. There is a first perspective view 100 and a second side view 200. The inventors have realized that thermal effects can be combined to improve the protection against heat. This embodiment shows a flush-mounted kitchen hob as an example that utilizes gas burners 115 as a heat source. The heat-sensitive material here is a workplate 105, and the kitchen hob is built into a cutout of this workplate. A pot support 110 is shown to be surrounding the gas burner 115.
Further, a side shield in the form of a reflective shield 120 is also depicted. On its outer periphery, it has an elevated rim 125. Underneath that elevated rim 125 there is a smaller gap 140 that is mostly 1 mm, preferably less than 0.7 mm, beneficially 0.5 mm. The lateral shield 120 can be beneficially built from metal in order to provide good thermal conductivity. It is also shown that the housing of the kitchen hob has a slit 150.
It can further be recognized from Fig. 1 that there is no gap between the heat-sensitive material 105 and the housing 4025. On the perspective view 100, a U-shaped profile 3200 is to be identified that is located between the area where the gas burner 115 is mounted and the lateral reflective shield 120.
Fig. 2 shows a partial view of an arrangement for heat protection according to an embodiment of the present invention. Here, in addition to the details of Fig. 1, an air flow 2010 is shown. By means of lateral holes, the air stream 2010 may enter the area of the gas burners through lateral holes in the U-shaped profile, as will be explained later. The path of the thus forced air stream reduces the turbulence in the area of e.g. gas injectors and strongly enhances the flame stability of the flames produced by the gas burner. In case electrical heat sources, such as inductive heaters or resistive heaters, are used, the cooling effect is comparable.
As shown in Fig. 3, a reflective shield 3010 may comprise a U-shaped profile 3200 which has a gap width 3250. The lateral wall of the U-shaped profile may comprise a slit 3100 or a hole 3140. In another perspective view 3500, arrows 330 are depicted that indicate the thermal conduction along the lateral reflective shield. Thermal conduction is improved if a shield material is used that has a higher thermal conductivity such as metal.
Fig. 4 shows an example of an embodiment of an arrangement according to a further development of the present invention built into a housing of a heat source. The housing 4025 has thermal barriers 4010, 4020, 4030, 4040, 4050, 4060 built into it in order to prevent thermal conduction into sidewalls 4510. In this case, the thermal barriers are slits, because they are easy to manufacture. However, also materials of different thermal conductance than the housing material may be used in order to impede the heat distribution along the floor plane of the housing and to prevent heat conductance into the side wall 4510. This is particularly important, because along the sidewalls usually a housing is fixed within a cutout of a workplate. In case the workplate is heat-sensitive, it is a prerogative not to expose the sidewalls of the housing adjoining the heat sensitive material to a high temperature which is above an admissible temperature of e.g. a workplate to avoid setting e.g. a workplate into flames by too high temperatures.
Thermal conductance is further shown in the form of arrows 4015, 4025, 4035, 4045 and 4065. A side view 4500 is shown to better indicate the location of the side wall. Some of the side walls may be contacted by the U-shaped profile 3200 of the reflective shield 3010 which serves to further lower the temperature of the housing 4025 by drawing heat away through thermal conductance.
Fig. 5 shows an example of a kitchen hob 5700 built into a workplate 105. The kitchen hob comprises five gas burners 115, 5150, 5120, 5130 and 5140. A perspective view 5300 is also shown as well as an enlarged view of a small area 5500.
From the representations of Fig. 5, it can be seen that this kitchen hob is flush-mounted into the workplate and fits neatly into a cutout. It has a length 5333 and a depth 5444 which may be standardized by kitchen manufacturers to provide interchangeable devices and allow the customer a large selection of household appliances for his kitchen furniture.
The representation in Fig. 5 further also exemplifies three different thermal effects that are used to protect the workplate/heat-sensitive material 105 against the heat emanated from the gas burners 115, 5150, 5120, 5130, 5140.
Arrows 5510 and 5530 stand for firstly the thermal conduction inside of the lateral reflective shield. This shield transports heat away from the housing of the kitchen hob and thus protects the heat-sensitive workplate. On the other hand, secondly heat radiation is also reflected from the reflective shield indicated by arrows 5600 and 5620. The reflective shield works on radiation that originates at the gas burners, and in particular from the flames there. On the other hand, the third effect is caused by the convectional air motion indicated by arrow shapes 5650 and 5680. The air may enter 5685 in the lateral reflective shield.
In the perspective view 5300, examples for heat reflection are given in arrows 5350, 5360 and 5370, whereas heat conduction is exemplified by arrows 5310 and 5330. On the other hand, in the top view 5700, heat conduction is exemplified by arrows 5710 and 5730, whereas heat reflection is indicated by arrows 5750 and 5100.
The superposition of the three effects, i.e. thermal conduction, thermal convection and reflection of thermal radiation, leads to a high protection of heat-sensitive material around a heat source, in particular a gas burner, and is particularly suitable for a flush-mounted kitchen hob. It allows the use of flush-mounted gas burners in a standard cutout and reduces a temperature to appropriate levels during appliance usage in case of bottom breather burners. It allows using standard interfaces for the housing and can adapt variations due to the different dimensioning of the lateral shields 3010 which can be manufactured with a size of 0.6 m and a size of 0.7 m, while just standardizing the fixing points, respectively the interface, to the housing. Especially by properly dimensioning the lateral reflective shield and the coupling of the hob to the workplate in combination with the housing, the temperature over the heat-sensitive material 105 respectively furniture can be significantly reduced.

List of reference numerals

100 partial view of a kitchen hob
105 heat-sensitive material /workplate
110 pot support
115 gas burner
125 elevated rim
140 gap
150 slit
200 side view
2000 partial view of embodiment
2010 convectional air stream with forced entry
3010 reflective shield
3200 U-shaped profile
3050 width of U-shaped profile
3100 hole in lateral wall of U-shaped profile
3140 slit in lateral wall of U-shaped profile
3500 perspective view of reflective shield
330 thermal conduction
4000 top view of housing
4500 perspective view of housing
4025 housing
4010, 4020, 4030, 4040, 4050, 4060 barriers for thermal conduction
4015, 4025, 4035, 4045, 4055, 4065 thermal conduction
4510 side wall of housing
5700, 5300, 5500 different views of an embodiment of the invention kitchen hob flush-mounted into workplate
5350, 5360, 5370, 5750, 5100, 5600, 5530 thermal reflection
5510, 5310, 5330, 5710, 5730 thermal conduction
5333 length
5444 depth
5650, 6580 thermal convection
5685 opening in reflective shield 3010
3290 lower arm of U-shaped profile
5000 kitchen hob
5120, 5130, 5140,
5150 burner

Claims

Arrangement (100) for heat protection of a heat-sensitive material (105) of a workplate (105) from a heat source (115, 5150, 5120, 5130, 5140) of a kitchen hob (5700) flush-mounted into the workplate (105) and fitted neatly into a cutout having a length (5333) and a depth (5444), at least comprising:
- a reflective shield (120, 3010) lateral to the heat source (115, 5150, 5120, 5130, 5140) and in proximity to it covering the heat-sensitive material (105) of the workplate to reflect heat radiation (5350, 5360) emanated from the heat source (115, 5150, 5120, 5130, 5140) upwards above the heat-sensitive material (105) of the workplate and to provide thermal conduction inside the reflective shield (120, 3010), and

- a slit (5685) between the heat source (115, 5150, 5120, 5130, 5140) and the reflective shield (120, 3010) to promote convectional air movement (5680), wherein

- three different thermal effects, i.e. the reflection of thermal radiation, thermal conduction and thermal convection, are provided for protecting the heat-sensitive material (105) around the heat source (115, 5150, 5120, 5130, 5140).
Arrangement (100) according to claim 1 comprising a housing (4025) for the heat source (115, 5150, 5120, 5130, 5140), wherein the housing comprises at least a thermal barrier (4010, 4020, 4030, 4040, 4050, 4060) to prevent thermal conduction (4015, 4025, 4035, 4045, 4055, 4065) along the housing into a side wall (4510) of the housing (4025).
Arrangement (100) according to claim 2, wherein the reflective shield (120, 3010) comprises a U-shaped profile (3200) substantially arranged in a right angle to the reflective shield (120, 3010).
Arrangement (100) according to claim 3, wherein the slit (56, 85) is located in a vertical wall of the U-shaped profile (3200).
Arrangement (100) according to any one of the claims 3 to 4, wherein the arms of the U-shaped profile have a different length with a shorter one next to the heat source (115).
Arrangement (100) according to any one of the previous claims 3 to 5, wherein the shorter arm (3290) of the U-shaped profile (3200) contacts the housing (4025).
Arrangement (100) according to any one of the previous claims, further comprising a gap (140) between the reflective shield (120, 3010) and the heat-sensitive material (105).
Kitchen hob (500) built into a workplate of a heat-sensitive material (105) comprising an arrangement for heat protection according to any one of the claims 1 to 7 and the heat source (115, 5150, 5120, 5130, 5140).
Kitchen hob (5000) according to claim 8, wherein the heat source is a gas burner (115, 5120, 5130, 5140, 5150).
Kitchen hob (5000) according to any one of the claims 8 to 9, wherein a pot support (110) forming part of the kitchen hob rests on the reflective shield (120, 3010).
Kitchen hob (5000) according to any one of the claims 8to 10, adapted to fit into a regular cutout of a workplate in standard dimensions (5333, 5444).
Method for heat protection of a flush-mounted gas kitchen hob (5000) according to any one of the claims 8 to 11 at least comprising:
- preventing thermal conduction (4030) in a housing (4025) of the kitchen hob (5000),

- providing a heat reflective shield (120, 3010) to reflect heat radiated from a gas burner (115, 5120, 5130, 5140, 5150),

- promoting convectional air movement (5680) between the housing (4025) and the reflected shield (120, 3010); and

- providing heat conduction (5330) into the reflective shield (120, 3010).