WO2008017397A1

WO2008017397A1 - Switching device for a heating device and heating device

Info

Publication number: WO2008017397A1
Application number: PCT/EP2007/006715
Authority: WO
Inventors: Willi Reichert
Original assignee: E.G.O. Elektro-Gerätebau GmbH
Priority date: 2006-08-08
Filing date: 2007-07-30
Publication date: 2008-02-14
Also published as: DE102006037712A1

Abstract

In a so-called temperature regulator (11) for a radiation heating device (50) with an elongate probe (17), three switches (23, 27, 42) are provided in a housing (13). These switches are all triggered by the probe (17) at different switching points or correspondingly different temperatures and can therefore perform different functions, in particular signalling or switching at three different temperature points.

Description

Description Switching device for a heating device and heating device

Field of application and state of the art

The invention relates to a switching device according to the preamble of claim 1, as it is used for heating devices, in particular radiant heaters on hobs, as well as such a heating device with such a switching device.

It is known, for example from DE 30 07 037 A1 or DE 33 33 645 A1, to use so-called rod sensors or temperature limiters to secure a heating device. A sensor, consisting of a metal tube with a ceramic pin therein, which are connected to each other at the end or stuck together, protrudes over a heater and is thus exposed to their influence or heating. Depending on the temperature at the sensor creates a relative movement between the tube and ceramic rod, which can be converted into a switching movement. It is known, for example from DE 33 33 645 A1, to provide two switching devices on a heating device, which are actuated at different temperatures and thus different expansion on the sensor or switching movement for different functions.

Task and solution

The invention has for its object to provide a switching device mentioned above and a heater with which problems of the prior art can be avoided and in particular more functions can be effected, in particular in connection with a temperature control of the switching device or the heater. This object is achieved by a switching device with the features of claim 1 and a heating device with the features of claim 16. Advantageous and preferred embodiments of the invention are the subject of further claims and are explained in more detail below. The wording of the claims is incorporated herein by express reference.

It is provided that the switching device has a thermomechanical temperature detection device with an elongated sensor for temperature detection on the heater. The sensor has two elongated, at least at one point connected or nested sensor parts, which have a different thermal expansion behavior and thus perform a relative movement relative to each other along a switching path with temperature changes. As a result, a switching movement is performed on one or more switches of the temperature detection device, for which purpose a plurality of switching points are provided at different points along the switching path or along the switching movement. At each of these switching points, a switch or an electrical contact is arranged, which is actuated upon reaching the respective switching point, that is closed or opened. According to the invention, the switching device has at least three switches, each with its own switching point.

This makes it possible to distinguish three temperature points or four temperature ranges. This makes it possible, for example, that, for example, in the aforementioned application of a temperature monitoring on a radiant heater on a hob with a hob glass ceramic plate not only a monitoring against maximum temperature of about 650 ⁰ C on the glass ceramic plate and hot display with about 50 ° to 70 ⁰ C is possible but also a kind of cooking point monitoring for automatic cooking or frying, for example, with temperatures of 100 ⁰ C to 200 ⁰ C. How The practical experience show, because of the decades-tested use of the aforementioned switching devices or temperature controller whose operation is very safe and sufficiently well to control to a certain temperature point.

The switching device advantageously has a housing, for example made of ceramic material. All the switches of the switching devices are arranged in this housing, so that the switching device is a well-manageable unit, since it is provided with outwardly facing electrical connections and can be easily installed and connected.

In a further advantageous embodiment of the invention, at least two, preferably more or all, switches are arranged one behind the other or successively in the longitudinal direction of the sensor. It is thus easy to ensure that they can each be adjusted or adjusted to a specific switching point and thus to a specific temperature. It can be provided that actuation areas or points where a switching operation is effected by pressure on it, are close to the sensor or touched by this or related parts and operated.

The switches used may have switching springs or be switching springs. Snap-action switches or snap springs are preferred with a contact head arranged at one end, which have an advantageous contacting behavior.

Advantageously, the sensor consists of an outer sensor part with an inner sensor part, which extends or is stored substantially in the outer sensor part and is simply plugged in, for example. Here, it is advantageously provided that the outer sensor part is an aforementioned metal tube and the inner sensor part is a rod made of ceramic or similar material with very low temperature-dependent expansion behavior. Advantageously, the inner sensor part protrude into the housing of the switching device or the switching device itself. It can be provided that it actuates at least one of the switches directly, for example with a laterally projecting projection or with its end.

In order to always have a well-defined switching movement, it can be provided that the inner sensor part is pushed out with spring load from the switching device, ie into the outer sensor part. In this case, can be dispensed with a fixed connection at the end of the probe and the inner sensor part only needs to be inserted or inserted into the outer sensor part. Such a spring load advantageously engages the end of the inner sensor part with a support or attachment to a housing of the switching device so as to clamp the inner sensor part relative to the outer sensor part connected to the housing.

The inner sensor part or an extension thereof may be provided with a sleeve-like attachment part which is widened over the diameter of the inner sensor part and which is guided over the end thereof or said extension. The aforementioned spring load can advantageously act on this attachment part, which may be in particular a metal sleeve with projecting collar for receiving a coil spring or the like. With relative movement of the sensor or the two sensor parts against each other due to temperature change, the aforementioned attachment moves advantageously together with the end of the inner With sensor parts. Thus, a switch can be actuated at its assigned switching point.

In extension of the invention, it is advantageously possible to make the stop of the inner part of the sensor or its extension to the attachment part in the direction of the switching movement. This means that the attachment part in the adjustment to the inner Moves sensor part and thus also changes the switching point of the switch. For this purpose, a screw can be guided in the attachment, in particular a grub screw, against which the inner sensor part or its extension lie directly.

At the end of the attachment, which faces away from the inner sensor part, it may have a stop for a third switch. Advantageously, this stop is adjustable in the direction of the switching movement, for example, again by means of a guided on or in the attachment part adjusting screw. Advantageously, this is also performed in an internal thread of the attachment as the aforementioned grub screw. This stop for the third switch can protrude, for example, in the extension of the inner part of the sensor behind the attachment and act directly against a switch or a switching spring. If this adjustment screw is guided in the same internal thread of the attachment as the aforementioned grub screw, the structure can be kept simpler.

The inner sensor part or its extension can have at its end a sleeve-like guide, in which they are guided and thus can not deviate from the direction of the switching movement. In particular, the above-described attachment runs in such a sleeve-like guide. In a further development of the invention may abut on this sleeve-like guide an aforementioned spring, in particular as a helical spring which is mounted on the sleeve-like guide and thus can not move.

It is possible that two of said at least three switches are formed by a so-called double switching spring. This means that they are made out of a single piece of material, however, form two contacts or have two contact heads. In particular, they also have two different switching points, at least one of which is individually adjustable, either by variations. that of his position or by changing his interaction with the feeler.

For adjustment or adjustment of the switching points of the switch, there are several possible and considered advantageous temperatures. One may be at 60 ⁰ C to 90 ⁰ C for an aforementioned hot indication. Another temperature can be 100 ° C to 200 ⁰ C, or even 250 ⁰ C for an automated cooking or Bratfunktion. It should be noted in these temperature specifications that they do not necessarily refer to the temperature directly at the sensor, but when used in a glass ceramic hob on the prevailing at the top of this glass ceramic cooktop temperature.

These and other features will become apparent from the claims but also from the description and drawings, wherein the individual features each alone or more in the form of sub-combination in one embodiment of the invention and in other areas be realized and advantageous and protectable Represent embodiments for which protection is claimed here. The subdivision of the application into individual sections and subheadings does not limit the statements made thereunder in their generality.

Brief description of the drawings

Embodiments of the invention are shown schematically in the drawings and are explained in more detail below. In the drawings show:

1 is a sectional view in plan view of a heating device according to the invention with switching device according to a first embodiment of the invention, 2 is an enlarged view of a modification of the switching device of FIG. 1,

Fig. 3 is a circuit diagram for a switching device according to FIG. 1 and

Fig. 4 shows a switching device according to a further embodiment of the invention with four switching contacts on two double snap springs.

Detailed description of the embodiments

In Fig. 1, a switching device 11 according to the invention is shown, as it is basically known in principle from the operating principle as the aforementioned rod controller. The switching device 11 has a housing 13, which has a mounting plate 15 on its front side pointing downwards. With this mounting plate 15, the switching device 11 is attached to a heating device 50 according to the invention or a carrier shell 51, for example screwed. The heating device 50 has a planar heating region 52, for example with dashed lines, meandering in the circle running conventional heating conductors 53rd

The switching device 11 has a protruding from the housing 13 sensor 17. This consists, as is generally known, of a sensor tube 18 as an outer sensor part, such as temperature-resistant metal. In the sensor tube 18 is a sensor rod 19 as an inner sensor part, such as a ceramic rod. At the front end, they can either only be plugged into one another or additionally be firmly connected to one another, for example by pressing the sensor tube 18 onto the sensor rod 19 or by welding, in particular by laser welding.

The sensor tube 18 is fixedly connected to the downwardly facing end face of the housing 13 with this. The sensor rod 19 extends out of the sensor tube and far into the housing 13. Just behind you Entry into the housing 13, the sensor rod 19 has a projection 21 which can protrude from it either on one or two sides. Alternatively, it can also as a kind of circumferential collar or the like. be formed, depending on what is easy and easy to handle in the manufacture of the sensor rod 19 as a ceramic rod.

With this projection 21, the sensor rod 19 can be pressed against a trigger region 24 of a first switch 23, wherein the switch 23 is formed as a basically known snap-action switch or snap-action spring with a contact head at its left end. A detailed description of its structure and function is not necessary, instead reference is made to the aforementioned DE 33 33 645 A1, in which this is shown in detail.

The sensor rod 19 extends behind the projection 21 a little further and passes through a trigger region 28 of a second switch 27, which is also designed as a snap-action switch. The end of the sensor rod 19 extends into a sleeve-like attachment part 30, advantageously made of metal or stable plastic. At its end to the sensor rod 19 towards the attachment 30 has a circumferential collar 32. The lower end face of the attachment part 30 is located approximately at the triggering area 28 of the second switch 27an. In the rear region 31 of the attachment part 30, which is formed like a cylinder, an internal thread 33 is provided to just before the collar 32 along the inner bore. More will be done later.

The rear portion 31 of the attachment part 30 extends in a guide sleeve 35, in which it is mounted longitudinally movable. The guide sleeve 35 is secured in the housing 13 with laterally extending arms or shoulders. About the guide sleeve 35, a coil spring 36 is guided, which is supported upwardly against the guide sleeve 35 and abuts down on the collar 32 of the attachment part 30. So she pushes the attachment 30 down. In the internal thread 33 of the attachment part 30, a first adjusting screw 38 is screwed, and at its front end of the sensor rod 19 abuts. The first adjusting screw 38 is designed in the manner of a grub screw and can be adjusted from above with a tool 45 through the inner bore of the attachment part 30. By the spring load of the spring 36, which always pushes the attachment sleeve 30 in the direction of the sensor rod 19, it is ensured that the sensor rod 19 always bears against the first adjustment screw 38. By rotating the first adjusting screw 38, the position of the attachment part 30 and thus also its end face for triggering on the triggering region 28 of the second switch 27 can thus be adjusted.

Furthermore, a second adjusting screw 39 is screwed into the internal thread 33 of the attachment part 30, advantageously with a larger tool 45 than for the first adjusting screw 38. This second adjusting screw 39 rests with its upper region on a triggering region 43 of a third switch 42, which in turn is formed according to the second switch 27. A longitudinal bore or through hole allows the insertion of a smaller tool for adjusting the first adjusting screw 38 when the second adjusting screw 39 is already screwed.

The three switches 23, 27 and 42 are connected in a known manner via plug contact tongues 46 as the entire switching device 11 from the outside.

Function according to FIG. 1

As is known from the aforementioned DE 33 33 645 A1, the length of the sensor rod 19 does not change over the temperature actually. The metal sensing tube 18, on the other hand, expands with increasing temperature, that is, when the heating region 52 becomes hot. In case of expansion It is longer and the sensor rod 19 is pushed out of the housing 13 against the guide sleeve 35 by its abutment via the first adjusting screw 38 in the attachment part 30 and the pressure spring 36 resting against the attachment part 30 or the collar 32. FIG. 1 shows a state at a certain temperature, which is clearly above the room temperature, since the projection 21 has already moved beyond the triggering region 24 of the first switch 23. The switch 23 is thus closed. In particular, it is designed as a so-called detector contact or hot-contact contact. This means that a signal is triggered and a display on a hob is activated when the temperature at the heating area 52 is so high that more than 50 ⁰ C or 60 ⁰ C are present at the top of the glass ceramic hob.

The second switch 27 is designed here as a so-called temperature monitor. This means that it is opened at a temperature and thus a position of the sensor rod 19 when an inadmissibly high temperature is applied or threatening the heating region 52, which could damage a glass-ceramic cooktop panel. However, this temperature is not reached in Fig. 1, since the switch 27 is still closed. However, it can be seen that the front side of the attachment part 30 requires only little movement against the triggering region 28 of the second switch 27 in order to trigger it and thus to separate its contact.

While, as can be seen, to trigger the first switch 23 via the projection 21 on the sensor rod 19 no adjustment of its switching point is possible, an adjustment to the second switch 27 can be performed via the first adjusting screw 38. If the first adjusting screw 38 is screwed further into the internal thread 33 of the attachment part 30 or onto the feeler rod 19, the attachment part 30 moves further upwards and the switching point at which the second switch is actuated by the attachment part 30 when the feeler moves - Bar 19, is moved to higher temperatures or to areas in which the sensor tube 18 is further extended due to higher temperature.

These functions of the first switching device 23 as a detector contact and the second switching device 27 as a guard contact are well known. The provision of a third switching device 42 is now new and it can be provided with a further temperature-dependent function. For example, this may be a switching point which is about 100 ^° C. or slightly higher, for example 105 ^° C. This means that at the mentioned temperature at the heating area 52 or at the sensor 17 the third switch 42 is to be triggered or opened. This can be set to a temperature of about 100 ⁰ C, for example, at the hob or the hob of the heating area 52 for an automatic cooking of water, so to speak, a temperature-controlled heating control. Alternatively, frying with a switching point at a temperature of about 200 ⁰ C to 250 ⁰ C is possible.

An adjustment of the third switch 42 is possible by inserting or unscrewing the second adjusting screw 39 in the internal thread 33 of the attachment part 30. If the second adjusting screw 39 is further screwed in, the switching point of the third switch 42 is shifted toward lower temperatures, and vice versa. As can be seen from Fig. 1 and of the arrangement of the adjusting screws 38 and 39 is of course, only the first adjusting screw 38 is to introduce and adjust, before this is done for the second adjusting screw 39. Alternatively, it is possible to provide the second adjusting screw 39 as shown with an inner bore for the passage of a significantly thinner tool 45 to the first adjusting screw 38. Thus, both adjusting screws 38 and 39 can be adjusted with different tools 45, while both adjusting screws already in the Attachment 30 are screwed. The switching path with the switching movement runs in Fig. 1 along the dash-dotted line, ie along the longitudinal or central axis of the sensor rod 19. The switching points for the respective switches are where the switches are triggered or actuated, for example, the projection 21 this Point happened. They are not explicitly drawn in the drawings. However, it is easily possible for the skilled person to take them from the drawings.

A slight modification of the switching device 11 of Fig. 1 is shown in the switching device 11 in Fig. 2 in enlargement. This modification consists in that the second adjusting screw 39 'is a kind of set screw without own head but with inner tool engagement surfaces, for example for a hexagon socket wrench. About the upper end of a loose ring 40 'is guided, which in turn rests with its upper side on the trigger region 43 of the third switch 42.

A circuit diagram of the switching device 11 including control and heating 50 is shown in FIG. On the left is dashed an energy regulator 55 shown, as it is known as an electromechanical adjusting device, for example from DE 198 33 983 A1. In the middle dashed lines, the switching device 11 is shown with the first switch 23 between the external terminals S and H. Further, the second switch 27 is present in the supply line to the heater 50 and the heating conductor 53, which are shown in dashed lines on the right, and third switches 42 in a separate branch.

To take advantage of the function of the third switch 42, the current is not adjusted via the contact 4 of the energy regulator, but via the contact 4a, so that the current path via the third switch 42 and the contact 2 to the switching device on the e ner regulator 55 11 is running. In this current path and the second switch 27 is looped, which must always be looped because of its safety-relevant function. If the third switch 42 is limited to a temperature range of For example, set the above 105 ⁰ C, so he regulates the temperature of the Heinzeinrichtung 50 to 105 ° C this. The second switch 27 with the watchdog function will probably not be used, the first switch 23 with the detector function for the heating indicator, however, already. Of course, it is possible to set the third switch 42 to a much higher switching point, for example 200 ⁰ C for an automatic frying function with corresponding pans.

Yet another embodiment of a switching device 111 is shown in Fig. 4. While the sensor 117 is the same and is secured to the housing 113, the switches are constructed differently there. Namely, four switches 123, 127, 142 and 148 are provided. However, these switches are formed on double control springs or double snap springs, so in each case two switches on a contiguous piece of sheet metal.

Bottom left, the first switch 123 is provided for the aforementioned detector function. On the right side of this double switching spring, the second switch 127 is provided, for example, with the above-mentioned guard function against overtemperature. The triggering of the switches 123 or 127 via a projection 121 on the sensor rod 119, which can press against a common triggering portion 124 of the double shift spring. Although both switches 123 and 127 have the common trip area 124, the switching points are different or the switches are triggered at different switching points of the switching path of the projection 121. This can be recognized by the fact that for the right switch 127, an adjusting screw 129 is provided, with which the abutment for the middle part of the switch 127 can be adjusted in height and thus, as the skilled person knows, the switching point at which the switch 127th is activated. The rear end of the sensor rod 119 abuts against a trigger region 143 of a second double-shift spring, which forms the third switch 142 and the fourth switch 148. These two switches also have a common trip area 143, and they are again, as with the switch 127, adjustable with adjusting screws 144 and 149 with respect to their switching points and thus their switching temperatures. Thus, for example, in extension to the explanations for Fig. 1 and Fig. 3, the third switch 142 with the adjusting screw 144 can be set back to a temperature at about 100 ⁰ C for an automatic cooking function with a boiling point of water. The fourth switch 148 can be adjusted with the adjusting screw 149 to a temperature of about 200 ⁰ C to 250 ⁰ C and thus to the point of a roasting function odgl ..

Another difference of the switching device 111 of FIG. 4 to that of FIG. 1 is that here no pressure spring or the like. For the sensor rod 119 is provided. The sensor rod 119 is connected to the 118 so that it always participates with its end portion, with which the switches 142 and 148 are triggered, always the movements that are caused by the changes in length of the sensor tube 118. In this respect, this structure is mechanically very simple and also functionally very reliable.

Claims

claims

1. Switching device (11, 111) for a heating device (50), in particular a heating device with at least one planar heating region (52), wherein the switching device (11, 111) comprises a thermomechanical temperature sensing device with an elongate sensor (17, 117) for the temperature detection of the heating device (50), wherein the sensor (17, 117) by different thermal expansion behavior at two elongated, at least one point interconnected sensor parts (18, 19, 118, 119) generates a relative movement along a switching path for performing a Switching movement of a switch (23, 27, 42, 123, 127, 142, 148) of the temperature detecting device, wherein the switching movement has a plurality of switching points at different locations along the switching path and wherein each switching point, a switch (23, 27, 42, 123, 127, 142, 148) or electrical contacts are assigned to the actuation upon reaching the respective Schaltpu nktes, characterized in that the switching device has at least three switches (23, 27, 42, 123, 127, 142, 148), each with its own switching point.

2. Switching device according to claim 1, characterized in that it comprises a housing (13, 113) and all switches (23, 27, 42, 123, 127, 142, 148) are arranged in the housing.

3. Switching device according to claim 1 or 2, characterized in that the switches (23, 27, 42, 123, 127, 142, 148) arranged in succession in the longitudinal direction of the sensor (17, 117), wherein in particular actuating portions (24, 28 , 43, 124, 143) of the switches are close to the probe.

4. Switching device according to one of the preceding claims, characterized in that the switches (23, 27, 42, 123, 127, 142, 148) have switching springs or snap-action switch are each having a contact head.

5. Switching device according to one of the preceding claims, characterized in that the sensor (17, 117) consists of an outer sensor part (18, 118) and a substantially mounted therein inner sensor part (19, 119), wherein preferably the inner sensor part ( 19, 119) projects into the housing (13, 113) of the switching device (11, 111) and actuates at least one switch (23, 27, 42, 123, 127, 142, 148) directly.

6. Switching device according to claim 5, characterized in that the inner sensor part (19) with spring load (36) from the switching device (11) is pushed out, wherein preferably the spring load (36) at the end of the inner sensor part (19) is arranged, in particular with a support or fastening (35) on the housing (13) of the switching device (11).

7. Switching device according to claim 6, characterized in that the inner sensor part (19) or an extension thereof is provided with a sleeve-like, over its diameter enlarged attachment part (30) which extends beyond the end of the inner sensor part (19) or the extension is guided, wherein preferably the spring load (36) acts on this attachment part (30).

8. Switching device according to claim 7, characterized in that the attachment part (30) moves together with the end of the inner sensor part (19) or its extension for actuating a switch (23, 27, 42) at its corresponding switching point.

9. Switching device according to claim 7 or 8, characterized in that a stop of the inner sensor part (19) or its extension to the attachment part (30) is adjustable in the direction of the switching movement, preferably by a in the attachment part (30) guided screw (38 ), on which the inner sensor part (19) or its extension abut directly.

10. Switching device according to one of claims 7 to 9, characterized in that on the side facing away from the inner sensor part (19) end of the attachment part (30), a stop (39) for a further switch (42) is provided, in particular this stop (39) is adjustable in the direction of the switching movement, in particular by means of a in an internal thread (33) of the attachment part (30) guided screw (39).

11. Switching device according to one of the preceding claims, characterized in that the inner sensor part (19) or its extension at the end of a sleeve-like guide (35) for exact compliance with the switching movement, in particular in the manner of a surrounding sleeve, preferably an attachment ( 30) according to any one of claims 7 to 10 in the sleeve-like guide (35) runs.

12. Switching device according to claim 11, characterized in that on the sleeve-like guide (35) a coil spring (36) is guided, which abuts in the manner of a compression spring on the attachment part (30) according to one of claims 7 to 10 for generating the spring load.

13. Switching device according to one of the preceding claims, characterized in that two switches (123, 127, 142, 148) are formed by a double shift spring, wherein preferably the two shift springs of the double shift spring have two different switching points, wherein in particular at least one of the shift points is individually adjustable.

14. Switching device according to one of the preceding claims, characterized in that a switching point of a switch (23, 123) at about 6O ⁰ C to 90 ⁰ C, preferably at about 80 ⁰ C.

15. Switching device according to one of the preceding claims, characterized in that a switching point of a switch (42, 142, 148) is at several 100 ° C.

16. Heating device with a switching device (11, 111) according to one of the preceding claims, characterized in that the heating device (50) has at least one planar heating region (52).