SENSOR FOR A COMBUSTION CHAMBER AND METHOD FOR ITS INSTALLATION

Description

[0001] The invention relates to a sensor, in particular a temperature sensor, for installation in a combustion chamber and to a method for its installation and commissioning. Combustion chambers, in particular of heating appliances, are often equipped with sensors, for example to measure the temperature at specific points. Such instrumentation is particularly useful for heating appliances operated with hydrogen, which will be in greater demand in the future. This applies not only to large systems, but also to wall-mounted units for heating water and, in general, to heating appliances for heating buildings and / or providing hot water. Other types of sensors are also frequently used in combustion chambers. Such sensors typically have a part containing the actual sensor, which is fastened in a holder, in particular a base, foot or flange, through which electrical leads are also routed.The bracket is mounted in a wall in such a way that the actual sensor protrudes into a combustion chamber, and the supply lines are accessible and can be connected on the other side of the wall. CN 208011699U, for example, shows such an arrangement.

[0002] In some sensors, particularly temperature sensors with low heat capacity, the actual sensor is long (e.g., 5 to 15 cm [centimeters]) and thin (cross-sectional area of, e.g., 0.5 to 25 mm2 [square millimeters]) and can therefore easily be bent or otherwise damaged during transport or installation if handled improperly. Especially in the combustion chambers of heating appliances, sensors are preferably mounted on a burner door (or burner flap) next to a burner, and must then be inserted through an opening into the combustion chamber when the door is installed, along with the burner and other components. Similar problems also occur elsewhere.

[0003] For example, US Pat. No. 3,275,479 A discloses immersion pyrometers that can only be used once. Such an immersion pyrometer is inserted into a furnace through a wall opening so that the proximal end is immersed in molten metal. After the measurement has been taken, the consumable part is electrically disconnected and dropped into the furnace. This is achieved by withdrawing the lance so that the distal end of an outer tube strikes an edge of the furnace opening. This tube is thus retained in the furnace together with the disposable unit, the end of which is thus melted, causing the tube to become encrusted with the furnace contents.

[0004] It is common practice to protect sensitive components during transport or installation by providing them with a protective cover, which is generally only removed when the component is accessed for the last time during assembly. However, this does not change the fact that final assembly steps often have to be performed without the protective cover, as has previously been the case, for example, when installing sensors in a burner door.

[0005] The object of the present invention is to at least partially solve the problems described with reference to the prior art. In particular, a method for safely installing a sensor in a combustion chamber and a sensor suitable for implementing this method are to be created.

[0006] To achieve this object, a method and a sensor or protective cover according to the independent claims are provided. Advantageous embodiments and further developments of the invention are specified in the respective dependent claims. The description, particularly in conjunction with the drawings, illustrates the invention and provides further exemplary embodiments.

[0007] A method for installing a sensor in a combustion chamber contributes to this, wherein the sensor is installed at its destination in a measuring area projecting into the combustion chamber and provided with a protective covering which can be shrinked and / or burned off under the influence of heat, and then a combustion is carried out in the combustion chamber, during which the protective covering essentially burns (without leaving any residue) or shrinks to such an extent that the sensor is essentially exposed.

[0008] While with conventional methods, a protective cover must be removed manually at some point, for example, and the installation must be completed without the protective cover, which carries a certain risk of damaging the sensor, the method described here eliminates this risk. The protective cover simply remains on the sensor and burns and / or shrinks during the initial (trial) commissioning of the combustion chamber. The fact that the protective cover burns essentially "residue-free" means that no disruptive residues should remain on the sensor and / or in the combustion chamber; thus, the combustion products of the protective cover can be almost completely removed from the combustion chamber with normal exhaust gases. However, minor residues in the combustion chamber or on a sensor mount would not be disruptive.With a (at least partially) shrinkable material, the shrinkage should be so great that the sensor is essentially exposed and ready for use after the initial heat exposure. However, a shrunken remnant of the protective sheath may remain in the area of ​​a mount.

[0009] Preferably, the sensor is a temperature sensor that is installed in a wall, door or flap of a housing of a combustion chamber of a heating device.

[0010] The problem is also solved by a sensor for a combustion chamber. The sensor has a holder through which supply lines are routed and which serves or can be used for fastening to a wall, door, or flap of a housing of the combustion chamber, so that the sensor can be mounted protruding into the combustion chamber and the supply lines are accessible and can be connected on the other side of the wall. When installed in the combustion chamber, the sensor can be inserted or placed into a (specified) measuring area. It has a protective covering that can shrink and / or burn off under the influence of heat, which can burn off (essentially without leaving any residue) or can shrink to such an extent that the sensor is essentially exposed in the measuring area of ​​the combustion chamber (after the combustion chamber or heater has been put into operation).This means that the actual sensor is protected during transport and installation and is not exposed to any risk by removing the protective cover, as it is shrinkable or burnable and does not have to be removed manually.

[0011] The protective cover rests on the holder, and the measuring area that can be inserted into the combustion chamber lies entirely within the protective cover. The protective cover does not need to be designed to be manually removable, for example, through a sliding fit or a thread on the holder. It is actually advantageous if it is not designed to be easily removable manually, as this prevents incorrect installation without the protective cover. This also simplifies the manufacturing process when attaching the protective cover, as it can be permanently attached.

[0012] The protective cover is particularly advantageous for sensitive and / or easily bendable sensors, where the measuring range that can be inserted into the combustion chamber has a length of 1 to 15 cm [centimeters] and, without the protective cover, a cross-section of 0.5 to 25 mm2 [square millimeters]. Temperature sensors are often designed long and thin because, on the one hand, they are intended to extend far into the combustion chamber, but, on the other hand, they must respond quickly, which is why they should not have a large heat capacity of their own. This requires a very slim design, which usually results in round cross-sections with diameters of, for example, 0.5 to 3 mm [millimeters].

[0013] The protective cover is preferably made of plastic and / or cardboard. Material costs are low, and many plastics, like cardboard, can be easily molded and, if necessary, incinerated with virtually no residue. Instead of incineration, the desired function can also be achieved by shrinking the protective cover through the application of heat. The protective cover can be made of multiple parts or materials, allowing the desired incineration and / or shrinkage to be adjusted.

[0014] In particular, because the protective cover does not need to be removable, it can be cast or molded around the sensor, allowing for quick and easy manufacturing. In this case, the protective cover can surround or enclose the sensor in a contacting manner.

[0015] Alternatively, the protective cover can surround the sensor without contact, protecting it but not affecting it. In other words, this means that the protective cover does not contact the sensitive area of ​​the sensor, but rather surrounds it at a distance. Of course, the protective cover can be attached to a different location on the sensor. This ensures that no damage or residue is left on the sensor when the protective cover is burned or shrunk.

[0016] Also disclosed is a heat-shrinkable and / or burnable cylindrical protective cover for the sensor, wherein the protective cover consists of (at least) one material that can be burned off essentially without residue or can be shrunk to such an extent that the sensor is essentially exposed. The protective cover should be designed to be sufficiently stable and attachable to the sensor and / or its mount to withstand mechanical stresses, in particular lateral impacts, etc., on the sensor.

[0017] The explanations of the method can be used to further characterize the sensors or components thereof, and vice versa. The sensors or components can also be configured to perform the method.

[0018] Schematic embodiments of the invention, to which it is not limited, and the functioning of the method will now be explained in more detail with reference to the drawings. They show: Fig. 1: schematically shows a section through a combustion chamber with a built-in sensor with protective cover, Fig. 2: a schematic perspective view of a sensor with protective cover, and Fig. 3: a schematic longitudinal section through a sensor with a shrunken protective cover.

[0019] Fig. 1 shows a schematic diagram of a combustion chamber 2 of a heater 1, which is operable in particular with hydrogen or a hydrogen-containing fuel gas. In such cases, instrumentation with at least one temperature sensor is frequently provided. In the present exemplary embodiment, the combustion chamber has a housing 3 in which a door 4 (or flap) is located, in which, in addition to a burner 11, at least one sensor 5 is arranged, in such a way that a measuring area 6 (the actual sensor) projects into the combustion chamber 2 and is held in a holder 7. Supply lines 8 of the sensor 5 are also guided through the holder 7. During its installation, the sensor 5 has a protective covering 9 until the first combustion in the combustion chamber 2, which protective covering 9 shrinks during the first combustion in the combustion chamber (typically in the direction of the holder 7) or burns away essentially without leaving any residue.The latter is the preferred option, as the process is more reproducible than shrinkage. Nevertheless, shrinking the protective sheath 9 is sufficient to ensure full functionality of the sensor 5. The temperatures of 800 to over 1000°C [degrees Celsius] prevailing in a combustion chamber during operation are more than sufficient for the protective sheath 9 to burn off or shrink, for example, if it is made of plastic or cardboard.

[0020] Fig. 2 shows a schematic perspective view of a sensor 5 with a protective sheath 9, wherein the protective sheath has a support 10 on the holder 7 and is therefore stable against lateral mechanical loads. The protective sheath 9 is pushed freely over the sensor 5 and does not touch it, which is particularly advantageous for shrinkable materials. Alternatively, the protective sheath 9 can also be solid or filled with a material such as synthetic resin, i.e. it can completely envelop the sensor 5. This increases the stability, but does not change the combustibility. The measuring range 6 of the sensor 5 protruding into the combustion chamber 2 has a length L of e.g. 1 to 15 cm and a cross-sectional area QF of 0.5 to 25 mm 2< , preferably 2 to 10 mm 2< . For round cross-sections, this means a diameter DS of the sensor of approximately 0.5 to 3 mm. The protective sheath 9 has an outer diameter DH of e.g. B. 5 to 25 mm, preferably 10 to 15 mm.This also depends on the size of the opening into which the sensor 5 is installed, since the installation takes place with a protective cover 9.

[0021] Fig. 3 shows a sensor 5 with an already shrunk protective cover 9, which has retracted towards the holder 7 and essentially exposes the measuring area 6 of the sensor 5, which projects into the combustion chamber (at least the part that is important for its function).

[0022] The present invention provides comprehensive transport and installation protection for a sensor 5 for a combustion chamber 2 and allows error-free installation even under unfavorable space conditions when installing a heater. List of reference symbols

[0023] 1Heater 2Combustion chamber 3Housing 4Door (flap) 5Sensor 6Measuring area (projecting into the combustion chamber) 7Bracket 8Supply lines 9Protective cover 10Support / mounting 11Burner L Length QF Cross-sectional area DS Diameter of sensor DH Outer diameter of protective cover

Claims

1. Method for installing a sensor (5) into a combustion chamber (2), wherein the sensor (5) is installed at its intended destination in a measuring area (6) projecting into the combustion chamber (2) provided with a protective casing (9) that can shrink or burn off under the effect of heat and then combustion is performed in the combustion chamber (2) during which the protective casing (9) burns off or shrinks to the extent that the sensor (3) is exposed.

2. Method according to claim 1, wherein the sensor (5) is a temperature sensor which is installed into a wall (3), door or flap (4) of a housing (3) of a combustion chamber (2) of a heating appliance (1).

3. Sensor (5) for a combustion chamber (2), wherein the sensor (5) comprises a holder (7), through which supply lines (8) are guided, for fastening in a wall (3), door or flap (4) of a housing (3) of a combustion chamber (2), so that the sensor (5) can be mounted so as to project into the combustion chamber (2) and the supply lines (8) are accessible and can be connected on the other side of the wall (3), characterized in that the sensor (5) has in a measuring area (6), which can be inserted into the combustion chamber (2) on installation, a protective casing (9) which can shrink or burn off under the effect of heat to the extent that the sensor (3) is exposed, and wherein the protective casing (9) is supported on the holder (7) and the measuring area (6) which can be introduced into the combustion chamber (2) is located fully within the protective casing (9).

4. Sensor (5) according to claim 3, wherein the measuring area (6) which can be introduced into the combustion chamber (2) has a length (L) of 1 to 15 cm and without a protective casing (9) has a cross-sectional area (QF) of 0.5 to 25 mm2.

5. Sensor (5) according to any one of claims 3 or 4, wherein the protective casing (9) consists of plastic or cardboard.

6. Sensor (5) according to any one of claims 3 to 5, wherein the protective casing (9) is cast or molded around the sensor (5).

7. Sensor (5) according to any one of claims 3 to 5, wherein the protective casing (9) surrounds the sensor (5) without making contact.