EP0740323B1 - Thermostat with a bimetal switch device switching at overheating - Google Patents

Abstract

The temp monitor (10) has a heating resistance (23) associated with the overtemp switch (15) for providing a self-holding function. The heating resistance is provided on a foil (22) providing electrical and/or thermic insulation. Pref. the foil is coated on one or both sides with a cold conductor resistance material providing a printed resistance path, or is provided as a heating foil with an insulating plastics foil layer and a resistance conductor.

Description

The present invention relates to a temperature monitor a bimetal rear derailleur that switches at overtemperature and a heating resistor connected to it, which in the sense of a Self-holding function acts and is formed on a film, which is intended for electrical insulation.

Such a temperature monitor is for example from the EP-A-0 507 425 known.

In the known temperature monitor, the rear derailleur is below Intermediate layer of an insulating film in a metal housing, wherein the insulating film on the one hand a mating contact fixed to the housing insulated from the metal housing and on the other hand one Heating resistor carries.

A bimetal switchgear is placed with the interposition of the insulating film in the assembly of the known temperature monitor in a one-piece Metal housing, whereupon the section in is filled with a resin near the connections.

The known temperature monitor consequently has a complicated one Build up so that final assembly is difficult.

A temperature monitor known from EP-A-0 284 916 comprises one closed by a cover part made of thermistor material Housing part in which the rear derailleur is arranged. The bimetal rear derailleur comprises a bimetallic snap disk in a known manner as well as a spring washer on which a movable contact part is held. Below the response temperature of the bimetallic snap disc is the movable contact part by the Spring washer pressed against a fixed contact part on the cover, which extends like a rivet through the lid and merges into a head outside. The housing part is made of electrical made of conductive material so that the rear derailleur at low Temperatures a conductive connection between the housing part and the head of the fixed contact part. The lid is in conductive connection with both the fixed contact part as well as with the housing part so that it is electrically parallel is connected to the rear derailleur.

If the rear derailleur is now due to excessive temperature opens, the current flows from the fixed contact part through the PTC resistor to the housing part formed by the cover, whereby the PTC resistor heats up and that Rear derailleur keeps open, even if the one that triggers the switching Excess temperature is no longer present. That way it works the PTC resistor in the sense of a self-holding function.

In a further embodiment from this document the lid comprises a ceramic support part on which a Coal resistor is arranged as the heating resistor for the Self-holding function ensures.

If the cover is made of thermistor material, points he does not have the required pressure stability, which in the rough Daily use of the well-known temperature monitor frequently is required. Such temperature monitors are namely used for temperature monitoring of motors, heating coils etc. often having strong mechanical loads as a result of the operation of the consumers to be protected connected vibrations are exposed. It can also be strong Press on the lid of the temperature monitor.

If the parallel resistor is a carbon resistor, it can the lid itself is made of a mechanically more stable material exist, but the temperature monitor has other disadvantages on. In particular with a carbon resistor it can occur that the bimetal rear derailleur as a result of too high Temperature development of the coal resistance irreparably destroyed becomes. This is parallel with a PTC resistor switched heating resistor not possible because the PTC resistor due to its temperature-dependent resistance value, which increases with increasing temperature, in its temperature output is adjustable, or regulates itself, so that irreversible damage to the rear derailleur as a result of Overheating in self-holding mode is avoided.

DE-OS-43 36 564 is another self-holding Known temperature monitor with which a second heating resistor connected in series for overcurrent sensitivity the well-known temperature monitor ensures.

This known temperature monitor includes one with conductive ceramic insulating plate provided with insulating coatings, on which an encapsulated bimetal rear derailleur is arranged, next to it sits a thermistor module that is electrically parallel is switched to the rear derailleur for the latch function to care. There is also a thick film resistor on the ceramic carrier plate arranged, which leads under the rear derailleur and is connected in series with it.

The well-known temperature monitor is in line with one protective consumer switched so that it from the operating current flow through the consumer. Stands at the same time this temperature monitor in a known manner in thermal Connection with the consumer to be monitored. Increases the operating current of the consumer due to a defect in inadmissible, the thick-film resistor connected in series heats up the switchgear so far that it opens, so that the PTC resistor connected in parallel the current takes over. Because of the high resistance of the PTC resistor the operating current of the consumer now rises a harmless measure back, but sufficient, over the Ohmic power loss in the PTC resistor one Maintain temperature that opens the rear derailleur. Of course, the well-known temperature monitor also opens then when the consumer is too high a temperature, whereupon the bimetal rear derailleur also opens and the PTC resistor takes over the current and a temperature that keeps the temperature monitor open.

The disadvantage of this temperature monitor is that it is a relatively bulky and large construction, which in particular is due to the ceramic base plate.

Furthermore, from DE-OS-41 42 716 is a self-holding Miniature temperature monitor known in which a heating resistor connected in parallel and one in series Heating resistor for current monitoring are available. The series resistor is as an etched or stamped part or as with a Resistance printed film in the immediate vicinity and in thermal and electrical contact with the spring washer of the Bimetallic rear derailleur arranged so that it below in Bottom part of the housing comes to rest.

In addition to the complex assembly of the well-known temperature monitor it is further disadvantage that the here as heating resistors used etched or stamped parts with regard to Resistance value not too precise and only on a small one Resistance range can be manufactured. Furthermore, a additional insulating component between the housing base and the Heating resistor and for reasons of resistance setting usually an additional, high-impedance one placed on the outside Resistance in series with the series resistor mentioned required what is the total manufacturing effort and also the External dimensions enlarged.

Based on this state of the art, it is the task of present invention, a self-holding temperature monitor to create of the type mentioned, which the above overcomes disadvantages mentioned. In particular, the new Temperature monitor with simple construction easy to assemble and to be generally inexpensive to manufacture.

According to the invention, this object is achieved in the aforementioned Temperature monitor solved in that he a the rear derailleur receiving housing lower part made of conductive material, preferably made of metal, as well as a closing part of the housing Cover part made of conductive material, preferably made of metal, has, and that the film at the same time for a required Insulation between the lower housing part and the cover part ensures.

The object on which the invention is based is achieved in this way completely solved. Because the heating resistor on a film trained, he can with different overall dimensions Place easily in a housing that houses the rear derailleur be accommodated.

It is advantageous that the insulating film required anyway between the lower part of the housing and the cover part as a film can be provided with a heating resistor formed thereon. Such temperature monitors with a metal housing are, for example known from DE-AS-21 21 802. Contacting the known Temperature monitor takes place on the one hand via the cover part and on the other hand over the lower part of the housing, so that an insulating film between these two housing parts is required. By the measure mentioned here can therefore be the known temperature monitor in a surprisingly simple way with a self-holding function be equipped, the mechanical very reliable construction can be preserved, the high Withstands pressure. Another advantage is that the construction and the assembly and the devices provided for it, such as. Handling devices etc. not changed must be, rather in the usual assembly process instead of the previously used insulating film, the film with the heating resistor provided according to the invention.

In one embodiment, it is preferred if the Provide film on one or both sides with resistance material, preferably coated or printed with resistance tracks is.

The advantage here is that the resistance value depending on the desired circumstances can be adjusted by either one-sided or one-sided with resistance material provided film is used. Due to the geometry of the resistance tracks the resistance value can be adjusted further.

It is further preferred if the film is a resistance material made of thermistor material.

The advantage here is that even with the new heating resistor on the film the advantages of PTC resistor mentioned at the beginning protection can be realized Overheating through self-regulation.

It is preferred if the film at least at one point is plated through, so that the resistance material on both Sides of the film is electrically connected to each other.

The advantage here is that simple contacting is possible Cover part and lower housing part results. The slide provides two areas of resistance material connected in series, so to speak and / or conductor material, which by simple Insert into the lower part of the housing and come into contact with it. The lid part is then placed on the film, whereby the second contact is made. Then in the usual way flanged the edges of the lower housing part, so that the Cover part is held firmly on the lower housing part. The Heating resistor is now parallel to the bimetal switchgear switched, as mentioned at the beginning, on the one hand via the Spring washer with the lower part of the housing and on the other hand the movable contact part is connected to the cover, when the rear derailleur is closed.

It is further preferred if the film is a heating film, which is an insulating plastic film with as a heating resistor serving conductor tracks.

This measure is also simple Contacting preferred, the heating foil is just like that previously mentioned film used as an insulating film. The conductor tracks are arranged so that they both with the cover part as well as get in contact with the lower housing part if the temperature monitor is assembled in the usual way.

It is further preferred if the film is a thermistor film, is preferably a PTC film.

The advantage here is that the foil as a whole as a PTC resistor can be formed, whereby the contact designed very simple for the cover part and lower part of the housing.

On the other hand, it is preferred if the film is partially is provided with resistance material.

The advantage here is that by choosing the size and possibly Resistance material geometry the resistance value of the Heating resistor can be set precisely.

It is further preferred if the film is coated on one side with resistance material is provided and on the other side of the Has contacting serving conductor tracks.

This is another advantageous way, like that of electrical insulation between cover part and lower part of housing serving film without causing a short circuit for a Parallel connection of the heating resistor to the bimetal switchgear can worry.

In general, it is preferred if the film is optionally with an intermediate layer of additional insulating material between the lower part of the housing and the cover part is clamped.

The advantage here is that the new temperature monitor is not can be easily assembled, but also in a simple manner on the one hand a short circuit avoided and on the other hand a Contacting the heating resistor is effected.

Further advantages result from the description and the attached drawing.

It is understood that the above and those below Features to be explained not only in each case specified combination, but also in other combinations or can be used alone, without the scope of leaving the above invention.

Fig. 1

einen neuen Temperaturwächter in einer geschnittenen Seitenansicht, bei dem an der Isolierfolie ein aus Übersichtlichkeitsgründen nicht dargestellter Heizwiderstand ausgebildet ist;

Fig. 2

eine für den Einbau in den Temperaturwächter aus Fig. 1 geeignete Isolierfolie, vor dem Einbau, vergrößert und nicht maßstabsgerecht;

Fig. 3

in einer Darstellung wie Fig. 2 ein weiteres Ausführungsbeispiel der mit einem Heizwiderstand versehenen Isolierfolie;

Fig. 4

eine Draufsicht auf die Isolierfolie aus Fig. 3.

The invention is illustrated in the drawing and is explained in more detail in the following description. Show it:

Fig. 1

a new temperature monitor in a sectional side view, in which a heating resistor is not shown for clarity is formed on the insulating film;

Fig. 2

an insulating film suitable for installation in the temperature monitor from FIG. 1, before installation, enlarged and not to scale;

Fig. 3

in a representation like FIG. 2, another embodiment of the insulating film provided with a heating resistor;

Fig. 4

3 shows a plan view of the insulating film from FIG. 3.

In Fig. 1, an embodiment of the new temperature monitor 10 shown. The temperature monitor 10 comprises a pot-shaped lower housing part 11 and a Lower housing part 11 closing cover part 12, which on a circumferential shoulder 13 of the housing part 11 rests. The Temperature monitor 10 is over a flange 14 of the lower housing part 11 closed, the cover part 12 on the circumferential shoulder 13 presses.

In the interior of the lower housing part 11 there is a Bimetal rear derailleur 15, which is of conventional construction. It includes a spring washer 16 which is a movable contact member 17 carries, over which a bimetallic snap disk 18 is placed is. The spring washer 16 is supported on a bottom of the cup-shaped Lower housing part 11 and thus clamps the movable Contact part 17 against a fixed contact part 20, the inside is provided on the cover part 12.

In this temperature monitor 10 housing lower part 11 and Cover part 12 made of conductive material, preferably made of metal manufactured so that an insulating film 22 is provided, which Cover part 12 isolated from the lower housing part 11. The Contacting of the temperature monitor 10 takes place on the one hand the cover part 12 and on the other hand via the lower housing part 11, as is known per se.

In the state shown in FIG. 1, the switching mechanism 15 has one Temperature below its response temperature so that it is in the closed state in which it is for one conductive connection between the fixed contact part 20 and thus the cover part 12 and the bottom 19 and thus the lower housing part 11 cares.

If the temperature of the switching mechanism 15 is now increased, it snaps the bimetallic snap disk 18 suddenly from that shown convex shape to a concave shape and is based on the Bottom of the cover part 12 from such that it is the movable Contact part against the force of the spring washer 18 from the fixed Contact part 20 lifts off.

In this respect, the construction of the new temperature monitor 10 known, the one because of its metal housing has high pressure stability.

According to the invention, there is now an insulating film 22 in FIG. 1 Heating resistor 23, not shown for the sake of clarity trained in parallel to the way to be described the bimetallic switching mechanism 15 is switched. As long as that Bimetal rear derailleur 15 in the closed shown in FIG. 1 Position, the heating resistor 23 is bridged and has no effect. If the bimetal rear derailleur If an overtemperature opens, the heating resistor takes over 23 part of the previously used by the temperature monitor 10 flowed current, the heating resistor 23 so far heats up that a 10 inside the temperature monitor Temperature is generated, even when the switching drops causing external overtemperature is sufficient to the bimetal rear derailleur 15 at least for a while in that to keep it open. The insulating film 22 can be designed so that they lose heat too quickly prevented from inside the temperature monitor 10. So can it can be provided, for example, that the lower housing part 11 and cover part 12 made of plastic or a similar not conductive material, so that the insulating film 22 per se is not required for the function. Of course in such a case, the fixed contact part 20, for example Kind of a rivet contacted through to the outside, while on the other hand an electrical connection to the outside via the base 19 will be produced. For reasons of clarity, this is Alternative not shown in Fig. 1.

Although - as I said - the insulating film 22 is not the one here electrical insulation must be provided because of them yet the advantage of being further thermal insulation the inside of the temperature monitor 10 causes, so that in temperature prevailing inside the temperature monitor 10 does not degrade too quickly. The heating resistor 23 can in in this case be such that it is alone for a long time the required temperature inside the temperature monitor 10 can not hold, but contributes to the fact that this The temperature only decreases so slowly that the desired one Switch-on delay is reached. Of course you can this additional function of thermal insulation from the insulating film 22 can also be exercised when cover part 12 and Lower housing part 11 are made of metal.

In both of the above-mentioned embodiments, the Insulating film 22 has two functions, on the one hand it serves electrical and / or thermal insulation and on the other the heating resistor 23 is formed on it, which has the self-holding function effected or supported.

A particular advantage of the new temperature monitor 10 is in that known constructions that already have an insulating film for the reasons mentioned above for electrical insulation use, can be fully retained, the insulating film 22 only has to have a heating resistor 23 be provided. But that means that in the usual Manufacturing process only the previously used pure insulating film against an insulating film according to the invention with a heating resistor must be replaced, so that no set-up costs for the production devices occur. The new temperature monitor 10 has all the known and desired mechanical ones and electrical properties that are already in the market are introduced and now get extremely simple on this In addition, a self-holding function.

How this heating resistor 23 is formed on the insulating film 22 can now be used as an example in connection with the Figures 2 to 4 discussed.

An insulating film is enlarged and not to scale in FIG. 2 22 shown in cross section, as in the temperature monitor 10 from Fig. 1 can be used.

The insulating film 22 has a film 24 as a carrier, for example Teflon, Kapton, Nomex or similar. On both sides the film 24 is provided with resistance material 25, e.g. a PTC thermistor material, a carbon film resistor or the like can be. There is an opening in the film 24 in a known manner 26 is provided, which is placed over the movable contact part 17 becomes, as can be seen in Fig. 1.

The insulating film 22 arrives in the temperature monitor during installation 10 over its upper resistance material 27 at its edge 28 in contact with the lid member 12 while over its lower one Resistance material 29 on its edge 31 on shoulder 13 rests and is in electrical contact with the lower part of the housing 11 is located.

Since the film 24 itself in the exemplary embodiment shown Insulating, vias 32 are provided the upper resistance material 27 with the lower resistance material 29 connect. This way the one from the top is and the lower resistance material 27, 29 formed heating resistor 23 on the one hand with the cover part 12 and on the other hand connected to the lower housing part 11 so that it is parallel to the bimetallic switching mechanism 15 is switched. That way the heating resistor 23 for the already discussed in detail Ensure the self-holding function of the new temperature monitor 10.

About the distance of the vias 32 from the outer The resistance value can also be set at edges 28, 31, the more this through-contacting at the edges 28, 31 lies, the lower the series connection of the two Resistance ranges, provided the other geometrical and electrical properties are not changed.

Should the film 24 be conductive or even some Have resistance, so the vias 32 also be dispensed with, provided that between the upper resistance material 27 and lower resistance material 29 in axial The measured resistance value is large enough to the direction to achieve the desired heating function when the bimetal switchgear is open. When the bimetal rear derailleur is closed 15 the heating resistor 23 is bridged by the latter anyway, so that its resistance value the function of the temperature monitor 10 not affected.

In an embodiment not shown in Fig. 2 can the film 24 itself a PTC film 24 ', so that on the upper and lower resistance material 27, 29 and on the Vias 32 can be dispensed with entirely.

3 is another embodiment of the new one Insulating film 22 shown as in the temperature monitor 10th 1 can be used.

The film 24 here has 33 conductor tracks 34 on its upper side on that through the vias 32 with lower resistance material 29 are connected on their underside 35. The Conductor tracks 34 extend essentially radially on the Top 33 and open into a preferably circular Conductor 36 in the area of the edge 28. With this insulating film 22, the heating resistor 23 is essentially the lower Resistance material 29 formed, the conductor tracks 34, 36 and the vias 32 are used only for electrical Connection between the lower resistance material 29 and the Cover part 12. At the edge 31 is the lower resistance material 39 on shoulder 13 again, so that here too the heating resistor 23 connected in parallel to the bimetallic switching mechanism 15 is.

In a modification of the embodiment of Fig. 3, the Conductor tracks 32, 34, 36 also tracks made of resistance material be on both the top 33 and the bottom 35 can be arranged. In this case the heating resistor 23 only through the resistance values of the resistance tracks 32, 34, 36 formed. In such a case speaks one of a heating foil 37, in which an insulating foil 24 with Resistance tracks 32, 34, 36 is provided.

4 is a top view of the insulating film 22 from FIG. 3 in which it can be seen that the resistance tracks 34, 36 cover the film 24 only in regions, the dimension of the Coverage, so the selected geometry the resistance value of the Heating resistor 23 determined.

Of course, it can in a modification of the embodiment 4 also be provided that the insulating film 22 both on their top 33 and on their underside 35 resistance tracks 34, 36, as shown in Fig. 4 are shown.

The film 24 can generally be made of a thermistor material be produced, the non-specific a positive temperature coefficient having. However, it is also possible as a film 22, 24 directly a PTC film with precisely set temperature-dependent To use resistance behavior.

If the film 24 is made of conductive material, and the Conductor or resistance tracks 32, 34, 36 for the resistance value of the heating resistor 23, then it may be necessary the free area 38 between the conductor tracks 34 with a Intermediate layer of additional insulating material 39 to provide on both sides of the insulating film 24 for partial insulation the lower housing part 11 and cover part 12 provides and at Switched derailleur 15 opposite the bimetallic disc 18 the heating resistor 23 may be insulated.

Claims (10)

1. A temperature controller having a bimetallic switching device (15) that switches at an excess temperature, and a heating resistor (23) that is connected to said bimetallic switching device, provides for a self-locking function and is provided on a film (22, 24) that is provided for electrical insulation, characterized in that a housing base part (11) made of conductive material and for receiving the switching device (15), as well as a cover part (12) made from conductive material and closing the housing base part (11) are provided, and that the film (22, 24) provides for the necessary insulation between the housing base part (11) and cover part (12).
2. The temperature controller of claim 1, characterized in that the housing base part (11) and/or the cover part (12) are fabricated of metal.
3. The temperature controller of claim 1 or claim 2, characterized in that the film (22, 24) is provided with a resistor material (25, 27, 29; 34, 36) on one or both sides, preferably coated or printed with resistor paths (34, 36).
4. The temperature controller of any of claims 1-3, characterized in that the film (22, 24) comprises a resistor material (25) from PTC material.
5. The temperature controller of any of claims 1-4, characterized in that the film (22, 24) is through connected at least at one point (32) so that resistor material (27, 29; 34, 36) on both sides (33, 35) of the film (22, 24) are electrically connected with each other.
6. The temperature controller of any of claims 1-5, characterized in that the film (22, 24) is a heating film (37) which comprises an insulating plastic film (24) with printed conductor paths (34, 36) serving as heating resistor (23).
7. The temperature controller of any of claims 1-6, characterized in that the film (22, 24) is a film with positive temperature coefficient, preferably a PTC film.
8. The temperature controller of any of claims 1-7, characterized in that the film (22, 24) is provided with resistor material (25) in certain areas.
9. The temperature controller of any of claims 1-8, characterized in that the film (22, 24) is provided on one side with resistor material (25) and on the other side with printed conductors (34, 36) for contact purposes.
10. The temperature controller of any of claims 1-9, characterized in that the film (22, 24) is clamped between the housing base part (11) and the cover part (12), possibly with an intermediate layer of additional insulating material.

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