HK1180452A - Temperature-dependent switch - Google Patents

Abstract

A temperature-dependent switch comprises a housing (11) which has an upper part (14) with a first outer surface (16) and a lower part (12) with a second outer surface (15), and a temperature-dependent switching mechanism (19; 46) which is arranged in the housing (11) and, as a function of its temperature, establishes or opens an electrically conductive connection between two outer connections (17, 18). A pressure-uptaking structure (41, 42) is provided on the outside of the upper part (14) and/or the lower part (12), said pressure-uptaking structure protruding approximately perpendicularly outwards beyond the first and/or second outer surface (15, 16) (Fig. 1).

Description

Temperature control switch

Technical Field

The invention relates to a temperature-controlled switch, comprising a housing having an upper part with a first outer surface and a lower part with a second outer surface, and comprising a temperature-controlled switch mechanism which is arranged in the housing and which, as a function of its temperature, establishes or opens an electrically conductive connection between two external connection parts, a pressure-absorbing (pressure-absorbing) structure being provided which projects outwards beyond at least one of the first and second outer surfaces.

Background

This type of switch is known at US5,268,664A.

The temperature of the appliance is monitored using a known temperature-dependent switch similar to the switch known (in a sense known per se) from EP0651411B 1. For this purpose, the switch is in thermal contact with the appliance to be protected, for example via an outer surface, so that the temperature of the appliance to be protected influences the temperature of the switching mechanism.

The switch is electrically connected in series in the power circuit of the appliance to be protected such that a power current of the appliance to be protected flows through the switch below a response temperature of the switch.

If the temperature of the appliance is now not allowed to increase beyond a predetermined switching threshold, the switching mechanism opens the electrical connection between the two external connections of the switch and the flow of current is interrupted, so that the appliance to be protected is switched off and cannot heat up any further.

The switch is electrically connected to the circuit of the appliance, which is directly protected by both outer surfaces when the upper and lower parts are made of an electrically conductive material, or the appliance is directly protected by contacts provided on the outer surfaces, and to which the litz wires are soldered, for example.

The two external connections can be arranged directly on the upper and lower part and in this case the current flows substantially through the temperature-controlled switching mechanism itself. It is known that such a switching mechanism is equipped with a spring-actuated disc (snap-actuated disc) and a bimetallic snap-actuated disc. In this case, the spring snap disc is equipped with what is known as a moving contact part which presses the spring disc against the stationary contact on the inside of the upper part. The spring snap disc is supported by its edge in the lower part of the housing, so that the current flows from the lower part through the spring snap disc and the moving contact part into the stationary contact piece and from said stationary contact piece into the upper part.

Secondly, it is also known that: a so-called contact bridge is fitted to the spring snap disc, which is pressed against by two fixed contacts arranged on the upper part. In this case, the current flows from one fixed contact through the contact bridge into the other fixed contact, so that the operating current does not flow through the spring snap disk itself.

This design is selected in particular when very high currents have to be switched, which can be problematic when these currents are conducted via the spring plate itself.

In both embodiments, a bimetallic snap-action disk is provided for the temperature-dependent switching function, which is located in the switching mechanism in such a way that it is not subjected to forces below its transition temperature, wherein the bimetallic snap-action disk is arranged geometrically between the contact element or the contact bridge and the spring snap-action disk.

If the temperature of the bimetallic snap-action disk now rises above the transition temperature due to an increase in the temperature of the appliance to be protected, the bimetallic snap-action disk changes its configuration and is pressed with its edge against an abutment arranged substantially on the upper part. In the process, the bimetallic snap-action disk presses with its central region against the spring snap-action disk and thus moves or raises the moving contact part away from the fixed contact piece or the current transmission element away from both fixed contact pieces and thus opens the switch.

An example of a temperature-controlled switch is disclosed in DE2121802a1, which has a moving contact part and a stationary contact part, and in which an electric current is conducted through the spring snap disk.

An example of a temperature-controlled switch with a current transmission bridge is described, for example, in DE2644411a 1.

In the case of these constructions, the bimetallic snap-action disk is mounted so that it is not subjected to mechanical forces below its transition temperature, wherein it is not used in any case for transmitting electric current.

In this case, it is advantageous for the bimetallic snap-action disk to have a long mechanical service life and for the switching point, that is to say the transition temperature of the bimetallic snap-action disk, not to change even after a large number of switching operations.

The bimetallic snap-action disk may also have the function of a spring snap-action disk if less stringent requirements on the mechanical reliability and stability of the transition temperature can be tolerated, so that the switching mechanism comprises only a bimetallic snap-action disk which is then equipped with a moving contact part or current transmission element, and the arrangement comprising a moving contact part also transmits current in the closed state of the switch.

Furthermore, it is known to provide such a switch with a parallel resistor, which is connected in parallel with the external connection. Such a parallel resistor receives a portion of the operating current when the switch is open and maintains the switch at a temperature above the transition temperature so that the switch does not automatically close again after cooling. This type of switch is called self-maintaining.

It is also known to equip this type of switch with a series resistor through which the operating current flowing through the switch also flows. Ohmic heat proportional to the square of the flowing current is generated in this series resistor in this way. If the amperage exceeds an allowable amount, the heat of the series resistor causes the switching mechanism to open.

Thus, the appliance to be protected has been disconnected from its power circuit when it is observed that too high a current has not yet caused the appliance to overheat.

All these different design variants can be realized by the switch according to the invention; in particular, the bimetallic snap-action disk can also have the function of a spring snap-action disk.

The switch known from the initially mentioned EP0651411B1 has a deep-drawn lower part (deep-drawn part) in which an inner circumferential shoulder is provided, on which shoulder the cover part is located. The cover member is held securely on the shoulder by moving or raising and crimping the edge of the lower portion.

Since the upper part and the lower part are made of electrically conductive material, an insulating film is also provided between the upper part and the lower part, which insulating film extends parallel to the upper part and is moved or raised laterally upwards, so that the flanged edge is pressed against the upper part with the interposition of the insulating film.

An opening is provided approximately in the center of the insulating film extending parallel to the upper portion, through which the moving contact member is brought into contact with the fixed contact provided on the inner surface of the upper portion.

In this case, the temperature-controlled switch mechanism includes a spring snap-action disk equipped with the moving contact member, and also includes a bimetal snap-action disk placed on the moving contact member. The spring snap disc is supported by its edges on an inner circumferential shoulder in the lower part.

An outer shoulder recessed relative to the outer surface of the lower portion is provided on the lower portion, to which shoulder a ring connecting the projections is connected.

In this case, the ring is designed such that it projects outwards no further than the outer surface of the lower part.

The ring is conductively connected to the lower part such that the electrical contact is obtained via an outer connection formed by an outer surface of the lower part.

The outer surface of the upper part constitutes a second outer connection part to which the connecting litz wire is welded.

While such switches have many advantages with regard to connection technology and manner of operation, problems arise when such switches are to be arranged on an appliance to be protected, such that high voltages are applied on one or both of the outer surfaces, for example by means of windings or heat contacting surfaces of the appliance.

In particular, such high pressures lead to a possible bending of the lower part, in particular if the lower part is a pull part, which then leads to a bending or deflection of the bearing surface of the edge of the spring snap disc, so that a reliable electrical contact with a low transmission resistance between the lower part and the spring snap disc is no longer ensured in specific situations.

Against this background, known switches are generally not manufactured with an already deep-drawn lower part, but with a turned lower part which is manufactured in a significantly more reliable and precise manner than a deep-drawn lower part.

However, these turned lower parts are significantly more expensive in terms of material costs and production costs than deep drawn lower parts.

The pressure on the outer surface of the upper part can additionally lead to a change in the position of one fixed contact or of both fixed contacts relative to the switching mechanism, so that the switching mechanism can no longer be opened reliably or the opening distance is reduced, so that an undesirably long arc (long arc) is often produced when the switch is opened.

The switch known from the first-mentioned US5,268,664A has a flat cover and a cup-shaped lower part which accommodates the switching mechanism. The lower flange and the flange of the lid are arranged extending laterally one above the other above the cup and are folded twice to form side flanges whose thickness increases slightly more than the thickness of the cup. If any pressure is applied to the switch by surrounding components, the folded side flange, rather than the cup, should absorb the pressure.

The housing of the known switch has a complex design and is difficult and costly to assemble. Furthermore, the lateral dimensions of the known switch are increased far beyond the diameter of the cup, making the known switch unsuitable for many applications.

US5,808,539A discloses a temperature controlled switch having a cup-shaped lower portion with an outwardly extending flange around its periphery, the cup housing a switch mechanism. A flat cover separated from the flange by an annular gasket has a peripheral portion that engages the flange. The peripheral portion, the gasket and the flange are cured together by the application of heat.

From the figure, it appears that the peripheral portion of the lid protrudes by a small amount on the flat upper surface of the lid.

Disclosure of Invention

In view of the above, it is an object of the present invention to increase the stability of the known switch against pressure in a structurally simple and cost-effective manner.

According to the invention, this object is achieved by the switch mentioned at the outset in that a pressure-absorbing structure is arranged on the outside of the upper part and/or the lower part, which pressure-absorbing structure projects substantially perpendicularly outwards beyond the first and/or second outer surface, so that pressure acting on the switch from the outside is conducted into the wall region of the lower part and/or upper part.

The inventors therefore do not take the measures in particular of reinforcing the housing from the inside or equipping it with thick walls.

That is, the inventors of the present invention have realized that a pressure absorbing structure, preferably arranged in the edge region of the lower part and possibly in the edge region of the upper part, can conduct the pressure acting on the switch from the outside into the region of the wall of the lower part and/or the upper part, so that bending of the base region of the lower part or the cover region of the upper part is avoided without the wall thereof needing to be reinforced.

In this way the object underlying the invention is fully achieved.

In this case, the present invention is preferable when the pressure absorbing structure protrudes less than 1/10mm beyond the outer surface.

That is, the inventors of the present application have realized that a protruding length of 1/100mm to 1/10mm is sufficient not to conduct pressure onto the outer surface, but through the pressure absorbing structure into the wall of the lower or upper part, and secondly that this short protruding length does not adversely affect the thermal connection of the temperature-controlled switch to the electrical device to be protected, which protruding length otherwise is merely a meaningless extension.

In this case, when an outer shoulder that is concave with respect to the first and/or second outer surface is provided on the upper and/or lower portion, it is preferable that the pressure absorbing structure is connected to the shoulder.

The advantages of this approach are: a concave outer shoulder is provided in the region of the lower or upper peripheral wall, and a receiving position for the pressure-absorbing structure has been provided by the peripheral shoulder.

A circumferential shoulder of this type, known for example from document EP0651411B1, which explicitly requires a ring joining the male part, which ring is joined to the female shoulder, does not project outwards beyond the outer surface of the lower part.

The inventors of the present application have now recognized that it is possible to design the ring somewhat thicker as before so that the ring projects beyond the outer surface 1/100 to 1/10 mm.

As already mentioned, when the ring simultaneously conducts the pressure exerted on the switch from the outside into the wall structure, an electrical contact can be made with the lower part via the ring by means of the connection projection. Thus, the pressure absorbing structure may also be referred to as a pressure conducting or pressure transferring structure. However, compared to the assumption in EP0651411B1, a thermal connection to the appliance to be protected is sufficient. This is not to be expected in the prior art until now.

In this case, the present invention is preferable when the pressure absorbing structure includes a ring-shaped structure, which is preferably connected to the connecting boss, more preferably integrally connected thereto.

Such means are known per se from EP0651411B 1. Thanks to said means, the advantages of this simple connection technique are now linked to those of the base, and the cover of the new switch can be protected by a slightly thicker ring without being deformed by the pressure applied from the outside.

However, when the switching mechanism does not conduct current through the spring snap disc or the bimetal snap disc, but through the current transmission element, the ring structure serves only to protect the base of the novel switch and can protect the cover of the novel switch from being deformed by pressure applied from the outside.

The lower part and the upper part can therefore now be designed as deep-drawn parts, so that the upper part and the lower part can be manufactured in a simple and cost-effective manner.

No additional measures are required to provide a concave outer shoulder on the lower part and also on the upper part during the manufacture of the deep-drawn part, only one time being required to produce a corresponding forming die for the lower part and/or the upper part.

Since this pressure force is conducted away via the pressure-absorbing structure, it is now possible to use deep-drawn parts instead of the turned parts (formed parts) which are preferred in the latest prior art, while at the same time the pressure force can be kept at least as stable even if there is no higher stability with respect to the pressure force.

In this case, it is preferable that the first circumferential wall is engaged with the second circumferential wall when the first circumferential wall is provided on the upper portion and the second circumferential wall is provided on the lower portion.

The advantage of this measure is that the upper and lower parts can be designed as deep-drawn parts, wherein each of the two circumferential walls absorbs the pressure of the retaining principle outer surface by means of a pressure-absorbing structure which is arranged on the recessed shoulder and, as an alternative, is conducted at least into the area of the circumferential wall.

The switch designed according to the invention then has a pot-shaped lower part and a pot-like upper part which is placed on the lower part, wherein in each case a concave outer circumferential shoulder is provided on the base of the lower part and on the cover of the upper part.

To which shoulder a ring-shaped structure is connected in each case, which ring-shaped structure serves firstly for conducting pressure and secondly for electrical connection to the lower part and the upper part.

This design is advantageous in particular when no current transmission element is provided, but a moving contact part with stationary mating contacts is provided.

The principle of the pressure absorbing structures on the upper and lower part according to the invention can still be realized if the switch according to the invention is to be equipped with a switching mechanism for high currents such that the current transfer element interacts with two fixed contacts on the upper part. Then, the rings on the upper and lower portions are used only for obtaining a pressure absorbing force; the outer connection portion is formed of two outer contacts which pass through the upper portion and are electrically connected to the fixed contacts.

If the upper part and the lower part are manufactured from an electrically conductive material, an insulating film is arranged between the upper part and the lower part in a manner known per se.

In this case, it is preferable that when the insulating film is formed in such a manner that it is located between the first and second circumferences having the cylindrical portion, wherein the cylindrical portion preferably has a base portion facing the upper portion, the base portion extending parallel to the upper portion and having a central opening through which the switching mechanism is in contact with the upper portion.

This ensures that the upper and lower parts are reliably electrically insulated from each other and that the switching mechanism is still in contact with the upper part.

In this case, it is particularly preferred that the insulating film can preferably be of a self-adhesive design when it is deep-drawn.

If the insulating film is deep-drawn before assembly, the insulating film has a pot-like structure and therefore the assembly of the new switch is even simpler.

The temperature-dependent switching mechanism is first inserted into the lower part, and then a deep-drawn insulating film is placed on the lower part in such a way that the switching mechanism can be brought into contact with the upper part through a central opening in the base part of the insulating film.

Then, the upper portion is placed on the insulating film.

If the insulating film has a self-adhesive design, a reliable mechanical connection between the lower part and the insulating film and between the insulating film and the upper part can be ensured, for example, by means of pressure and heat applied after assembly of the novel switch as just described.

Additionally or alternatively, the lower part and the upper part can also be pressed together, wherein the pressing is preferably performed in an interlocking manner.

Alternatively, it is also possible to lock the lower part and the upper part to each other, that is to say to provide a snap-action connection between the lower part and the upper part.

For this purpose, it is possible, for example, to provide circumferential beads on the outside of the lower circumferential wall and associated circumferential grooves on the inside of the upper circumferential wall, in which case it is obviously also necessary to insert an insulating film.

Thus, the switch according to the invention that has been described so far is characterized in that: firstly the switch can be manufactured in a cost-effective manner, the upper and lower parts can be deep-drawn parts, while the outer circumferential recessed shoulder is also formed during the deep-drawing process.

The temperature-dependent switching mechanism may be a switching mechanism with a moving contact member as described in EP0651411B1, or a switching mechanism with a contact bridge as described in DE2644411a1 may be used.

Particularly preferred are: when the first contact surface is provided on the inner surface of the upper part and the second contact surface is provided on the inner surface of the lower part, when the switching mechanism establishes or opens an electrically conductive connection between the first and the second contact surface as a function of its temperature, wherein the switching mechanism preferably comprises a bimetallic snap disc and a spring snap disc on which the moving contact part is arranged, and when the moving contact part interacts with the first contact surface and the spring snap disc interacts with the second contact surface, wherein the bimetallic snap disc interacts with the spring snap disc in such a way that the switching mechanism lifts the moving contact part away from the first contact surface as a function of its temperature.

Such a design is known per se from EP065141B 1. It is advantageous if the bimetallic snap-action disk is not mechanically loaded and has no current flow in the closed state of the switch.

In this case, the invention is preferred when the moving contact part is captively held (preferably welded) on the spring snap disc, and preferably when the bimetallic snap disc is captively held with play on the contact part.

The advantage of these means is that the switch mechanism can be completely preassembled and stored and handled and tested outside the switch, as before. Since the switching mechanism comprising the spring snap disc, the moving contact part and the bimetallic snap disc forms one unit, the switching mechanism can likewise be simply inserted into the lower part during assembly of the switching mechanism and there is no risk of the bimetallic snap disc sliding onto the moving contact part or jamming against the moving contact part during insertion.

In this case, the bimetallic snap-action disk is held on the contact part with play, in order to hold the bimetallic snap-action disk completely in the closed state of the switch or to at least largely protect the bimetallic snap-action disk against mechanical forces. This ensures that the transition temperature of the bimetallic snap-action disk does not change as a result of mechanical loading.

In this case, it is generally preferred that: when the transverse connecting web is arranged on the spring snap disc, said connecting web is mechanically and electrically conductively connected (preferably soldered) to the second contact surface.

This approach firstly offers the following advantages: the preassembled switching mechanism can be held, for example, on a conveyor belt by means of a connecting web until it has been completely assembled and tested. The connecting web is then separated from the conveyor belt and the switch mechanism can be clamped at the connecting web and inserted into the lower part.

In addition to this advantage with regard to handling and trial selection, the connecting web offers the following advantages: after the connecting web is connected, preferably soldered, to the second contact surface, a mechanically and electrically conductive reliable connection is established.

Firstly, this ensures that the switching mechanism is fixedly located in the lower part, so that the switching mechanism is no longer jammed during subsequent mounting of the insulating film and the upper part.

Furthermore, the welded connecting webs ensure a very low transmission resistance between the spring snap disk and the lower part of the housing, so that the overall contact resistance of the switch is significantly reduced in comparison with the contact resistances known from the prior art.

When the moving contact part is also welded to the spring snap disc, a very low transmission resistance can be observed in this case, so that only the remaining non-welded contacts are the contacts between the moving contact part and the stationary contacts.

A very low transmission resistance can in this case be ensured by corresponding galvanization of the surfaces of the contacts.

In addition to these advantages with respect to electrical contact resistance and mechanical design, it is also advantageous: in this case, the function of the switch again becomes less sensitive to the pressure applied from the outside. The slight change in the geometry of the lower part which is produced as a deep-drawn part now no longer causes an electrical connection between the spring snap disk and the lower part (that is to say the second contact surface), but is weakened as far as possible.

Other features and advantages can be obtained from the description and the drawings.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively given combination but also in other combinations or alone without departing from the scope of protection of the present invention.

Drawings

Embodiments of the invention are illustrated in the following drawings and explained in more detail in the following description. In the drawings:

FIG. 1 shows a schematic cross-sectional view of a side view of the novel switch in a first embodiment;

FIG. 2 shows a view similar to FIG. 1 of another embodiment in which a switching mechanism is used, the spring snap disk of which is equipped with a transverse connecting web;

FIG. 3 shows a schematic detailed enlargement of another embodiment of the lower and upper portions in the area of the external recessed circumferential shoulder for the present design;

FIG. 4 shows a plan view of the switch of FIG. 2; and

fig. 5 shows a new switch similar to fig. 1 in another embodiment in which the current is conducted via a contact plate.

Detailed Description

Fig. 1 shows a schematic cross-sectional view through a temperature-dependent switch 10 with a housing 11, which schematic cross-sectional view is not of real dimensions. The housing 11 has a deep-drawn lower part 12 and a similar deep-drawn upper part 14.

An outer surface 15 forming the base of the lower part 12 is provided on the lower part 12. An outer surface 16 forming a footprint of the upper portion 14 is disposed on the upper portion 14.

A recessed outer circumferential shoulder 17 on the lower portion 12 serves as a first outer connection portion of the switch 10 and a recessed outer circumferential shoulder 18 on the upper portion 14 serves as a second outer connection portion of the switch 10.

Since the lower part 12 and the upper part 14 are composed of an electrically conductive material, the circumferential shoulders 17 and 18 are used in particular directly for the external connection.

A temperature-controlled switching mechanism 19 is arranged in the housing 11, said temperature-controlled switching mechanism comprising a spring snap-action disk 21, which spring snap-action disk 21 is fitted with a moving contact part 22, a bimetallic snap-action disk 23 being placed on the moving contact part 22.

In this embodiment, the contact part 22 is loosely inserted into a spring snap disc, wherein the bimetallic snap disc is likewise loosely placed on the collar 24 of the movable contact part 22.

The upper part 14 is fitted with a fixed contact 26 on its inner surface 25, a first contact surface 27 being formed on the fixed contact 26. The lower part 12 has a second contact surface 29 on its inner surface 28, the spring snap disc 21 being supported with its edge 31 on the second contact surface 29.

The moving contact part 22 is supported with its dome-shaped end 32 on the fixed contact 26.

Thus, when the switch is closed (i.e., in the state shown in fig. 1), an electrically conductive connection is made between the recessed shoulder 17, the lower portion 12, the spring snap plate 21, the moving contact member 22, the fixed contact 26, the upper portion 14 and the circumferential shoulder 18.

Since the lower portion 12 and the upper portion 14 are made of a conductive material, the insulating film 33 is disposed between the lower portion 12 and the upper portion 14.

The insulating film 33 has a cup-like shape obtained by deep drawing, which includes a cylindrical portion 34 and a base portion 35 that closes the cylindrical portion 34 at the top and extends parallel to the upper portion 14, and in which a central opening 36 is provided through which the switching mechanism 19 is brought into contact with the fixed contact 26.

The first circumferential wall 37 is provided on the upper part 14 and the second circumferential wall 38 is provided on the lower part 12, so that the upper part 14 and the lower part 12 likewise have a pot-like or cup-like structure.

Thus, the cylindrical portion 34 of the insulating film 33 separates the two circumferential walls 37 and 38 from each other, while the base 35 of the insulating film 33 insulates the circumferential wall 38 of the lower part 12 from the inner surface 25 of the upper part 14.

As already mentioned, the switch 10 in the position shown in fig. 1 is in the off state.

If the temperature of the switch 10 and thus also of the bimetallic snap-action disk 23 now increases, the bimetallic snap-action disk deforms and changes from the convex shape shown to the concave shape in which it is supported with its edge 39 on the base 35 of the insulating film 33. Thus, the bimetallic snap-action disk simultaneously pushes the moving contact part 22 away from the fixed contact 26 against the force of the spring snap-action disk 21, and the switch 10 is thus opened.

When the temperature of the bimetal snap disk 23 falls below the transition temperature again, the bimetal snap disk 23 returns to the convex shape shown in fig. 1, so that the spring snap disk 21 can return the moving contact member 22 to contact with the fixed contact 26.

In each case, the pressure-absorbing structure 41 or 42 is arranged on the recessed shoulder 17 and on the recessed shoulder 18, respectively, and projects beyond the outer surface 15 or the outer surface 16, respectively, by an amount indicated by 43. This amount 43 corresponds to 1/10 to 1/100 mm.

If in fig. 1 pressure is now exerted on the switch 10 from above and/or below through a support surface of the appliance to be protected, such a support surface is in contact with the pressure-absorbing structure 41 or 42, respectively, while the outer surfaces 15 and 16 are not exposed to any directed pressure.

The pressure exerted on the pressure absorbing structures 41 and 42 is directed into the circumferential walls 38 and 37, so that the lower part 12 and the upper part 14 are not deformed.

The pressure-absorbing structures 41 and 42 thus ensure that the lower part 12 and the upper part 14 are prevented from deforming, while on the other hand the protruding length 43 is so low that the thermal connection of the switch 10 to the electrical apparatus to be protected is still sufficient.

Thus, it is no longer necessary to design the lower part 12 and the upper part 14 as turned parts, but they can instead be manufactured as deep-drawn parts. In the case of manufacture in this way, the outer shoulders 17 and 18 are manufactured together at the same time, so that no additional manufacturing steps are required for this purpose.

The invention also provides pressure-absorbing structures in the area of the circumferential walls 38 and 37, the circumferential walls 38 and 37 being formed integrally with one another and projecting downward or upward beyond the respective outer surfaces 15 and 16, respectively, by an amount 43, only when the pressure-absorbing structures 41 and 42 in the embodiment of fig. 1 are mounted on the recessed shoulders 17 and 18 at a later time.

In the present case, however, pressure-absorbing structures 41 and 42 are used which can be installed subsequently, since they are also used for the external connection of the switch 10.

For this purpose, the pressure-absorbing structures 41 and 42 are provided with annular structures 44 and 45 which are connected to the connecting tabs in a manner not shown in fig. 1 and as is known from the principle of EP0651414B1 and will be explained below with reference again to fig. 4.

It should be noted that the insulating film 33 is self-adhesive, so that after the new switch is assembled and as far as possible after pressure or heat is applied, the insulating film 33 firmly connects the upper part 14 and the lower part 12 to each other and prevents the ingress of any type of contamination. Additionally or alternatively, the lower and upper portions 12, 14 may also be pushed or locked together.

Similar to the view in fig. 1, fig. 2 shows a temperature-controlled switch 10', the lower part 12 and the upper part 14 of which are provided with circumferential shoulders 17 and 18 known from fig. 1, on which shoulders 17 and 18 a pressure-absorbing structure can subsequently be mounted.

In contrast to the switch 10 of fig. 1, the switch 10' of fig. 2 has a temperature-dependent switching mechanism 46, in which the spring snap disk 21 is provided with a transverse connecting web 47 which is welded to the inner surface 28 of the lower part 12, which inner surface forms the second contact surface 29.

In a variant of the design of fig. 1, for the switch 10', the moving contact part 22 is welded by its collar 24 to the spring snap disc 21, wherein the bimetallic snap disc 23 is placed by its passage opening 48 on the contact part 22 and is held there with play on a peripheral flange, indicated only by 49.

In this way, the switch mechanism 46 is a unit including the spring snap plate 21, the contact member 22 and the bimetal snap plate 23, which are fixedly connected to each other. The switching mechanism 46 preassembled in this way can be held on the connecting web 47 and supplied to an external functional inspection device, for example, before being inserted into the lower part 12. The connecting web 27 is then welded to the inner surface 28 of the lower part 12, so that the switching mechanism 46 is located mechanically immovably in the lower part 12, but the bimetallic snap-action disk 23 can be deformed as described before without mechanical obstruction.

Welding the connecting web 47 to the inner surface 28 also ensures a very low transmission resistance between the lower portion 12 and the switching mechanism 46. Since the moving contact part 22 is also welded to the spring snap disc 21, the transmission resistance can also be negligibly low.

Thus, when the switch 10' is assembled, the switch mechanism 46 is first inserted into the lower portion 12, and then the connecting web 46 is connected to the inner surface 28, for example by spot welding.

Then, the insulating film 33 is placed on the lower portion 12, and thus the moving contact member 22 protrudes upward through the central opening 36.

Then, the upper part 14, which is designed in exactly the same pot-like manner as the lower part 12 and the insulating film 33, is placed from above onto the switch 10' which has been previously assembled so far.

The upper part 14, the insulating film 33 and the lower part 12 are then fixedly connected to one another by the action of pressure and/or heat, for which purpose the insulating film 33 can be provided in a self-adhesive design.

For one embodiment of the switch 10, 10', the area between the circumferential walls 37 and 38 is shown in greater detail in fig. 3 on an enlarged scale.

In fig. 3, the design is chosen such that the circumferential wall 38 of the lower part 12 has a transverse flange 51, a concave circumferential shoulder 17 being formed on the transverse flange 51.

In this way, the circumferential wall 37 of the upper part 14 is positioned with its end face 52 on the flange 51 opposite the annular bearing surface 53.

In each case, the pressure-absorbing structures 41 and 42, which project beyond the outer surfaces 15 and 16, respectively, by an amount 43, are placed again on the shoulder 17 and the shoulder 18, respectively.

The shoulders 17 and 18 are now designed to be wide in a direction parallel to the bearing surfaces 15 and 16, so that a pressure force indicated by an arrow F exerted on the bearing surfaces is introduced into the circumferential walls 37 and 38.

Fig. 4 also shows a plan view of the switch 10 of fig. 2. The contour of the switch 10 does not have a circular structure but is provided with a convex bulge 55, wherein the connecting web 47 is arranged according to fig. 2 and by means of which the spring snap disc 21 is welded to the inner surface 28.

Fig. 4 shows a plan view of the switch 10, so that the cover 14 with its circumferential shoulder 18 can be seen, onto which the ring structure 45 known from fig. 1 is placed and connected mechanically and electrically.

Such a ring structure 45 is integrally connected to the connecting boss 57.

The annular structure 45 now conducts the current directly into the connection boss 57; the ring-shaped structure 45 thus also serves as an outer connection.

A further connection boss 58 is arranged on the lower surface (not shown in fig. 4) of the switch 10, said further connection boss having an annular configuration 45 as understood from fig. 1 and being connected to the circumferential shoulder 17.

Whereas the switches 10 and 10' of fig. 1 and 2 are provided with switching mechanisms 19, 46 in which current flows through spring snap-action disks, fig. 5 shows a switch 10 "in which current is conducted through contact plates, so that such a switch 10" can switch higher currents.

In fig. 5, the temperature controlled switch 10 ″ includes a temperature controlled switch mechanism 111 accommodated in a case 112.

The housing 112 comprises a lower part 114 and an upper part 115 closing the lower part and being held on the lower part 114 by a flanged edge 116 of the lower part. A ring 117 is arranged between the lower part 114 and the upper part 115, said ring being supported on a projection 118 of the lower part 114 and guiding a spring snap disc 121 of the switching mechanism 111 at the edge of the ring.

In addition to the spring snap disc 121, the switching mechanism 111 comprises a bimetallic snap disc 122, a pin-shaped rivet 123 passing through it from the center, and a spring snap disc 121, which are mechanically connected to the current-carrying element by means of said rivet in the form of a contact plate 124. Rivet 123 has a first projection 125 on which bimetallic snap-action disc 122 is positioned by radial and axial action, wherein a second projection 126 is provided on which spring snap-action disc 121 is likewise positioned by radial and axial action.

The bimetallic snap disc 122 is supported with its circumferential edge on the inside of the lower part 114.

The above-mentioned contact plate 124 has two contact surfaces 127 in the direction of the upper part 115, the two contact surfaces 127 being electrically connected to each other and having a large surface area and interacting with two fixed contacts 131, 132, the two fixed contacts 131, 132 being arranged on an inner surface 129 of the upper part 115 and being through inner heads of the contact rivets 133, 134 of the upper part 115 and being through outer heads 135, 136 of the contact rivets on an outer surface 138 of the upper part 115 for external connection.

In the switching position shown in fig. 5, spring snap-action disk 121 and bimetallic snap-action disk 122 press contact plate 124 against stationary contacts 131 and 132, and spring snap-action disk 121 and bimetallic snap-action disk 122 are therefore connected to one another by contact surface 127; thus, switch 10 "is closed.

If the temperature of the bimetallic snap-action disk 122 rises above its response temperature, the bimetallic snap-action disk 122 snaps from the convex shape shown into the concave shape and in the process is supported with its edge in the region of the ring 117 and pulls the contact plate 124 away from the fixed contacts 131, 132 against the force of the spring snap-action disk 121; the switch 10' is now open.

The switches described up to here are known from DE2644411C2 and DE19827113C 2. If the temperature now drops again, the switch known from DE2644411C2 will snap back again to the off state shown in fig. 1.

As in the case of the switch known from DE19827113C2, the upper part 115 is made of a PCT thermistor material, that is to say constitutes a PCT resistor which is electrically connected between the fixed contacts 131, 132. Thus, the upper portion 115 functions as a self-protecting resistor, as has been explained in detail above.

Furthermore, in the case of switch 10 ", an outer circumferential recessed shoulder 17 is also provided on the outside of lower portion 114, on which shoulder pressure-transferring structure 41 is arranged and projects downwards by an amount 43 beyond the outer surface 139 of lower portion 114.

The pressure-absorbing structure 41 again comprises a ring-shaped structure 44, in which case, however, the ring-shaped structure 44 is not used for an external connection, but merely for the transfer of externally applied pressure into the edge 116 and/or the ring 117.

Claims (19)

1. A temperature-dependent switch comprising a housing (11; 112) having an upper portion (14; 115) with a first outer surface (16; 138) and a lower portion (12; 114) with a second outer surface (15; 139), and a temperature-dependent switch mechanism (19; 46; 111) which is arranged in the housing (11; 112) and which establishes or opens an electrically conductive connection between two outer connection portions (17, 18; 135, 136) as a function of its temperature, a pressure-absorbing structure (41, 42) being provided projecting outwardly beyond at least one of the first and second outer surfaces (15, 16; 138, 139),

characterized in that the pressure-absorbing structure (41, 42) is arranged outside the upper part (14; 115) and/or the lower part (12; 114), the pressure-absorbing structure projecting substantially perpendicularly outwards beyond the first and/or the second outer surface (15, 16; 138, 139).

2. Switch according to claim 1, characterized in that the pressure absorbing structure (41, 42) protrudes less than 1/10mm beyond the outer surface.

3. Switch according to claim 1 or 2, characterized in that an outer shoulder (17, 18) is provided on the upper part (14) and/or the lower part (12; 114), which outer shoulder is recessed with respect to the first and/or the second outer surface (15, 16; 139), to which shoulder the pressure-absorbing structure (41, 42) is connected.

4. A switch according to claim 3, wherein the pressure absorbing structure (41, 42) comprises an annular structure (44, 45).

5. Switch according to claim 4, characterized in that the pressure-absorbing structure (41, 42) is preferably integrally connected to a connecting boss (57, 58).

6. Switch according to any one of claims 1 to 5, characterized in that a first circumferential wall (37) is provided on the upper part (14) and a second circumferential wall (38) is provided on the lower part (12), the first circumferential wall (37) engaging on the second circumferential wall.

7. The switch according to any of claims 1 to 6, characterized in that said upper portion (14) and said lower portion (12) are made of an electrically conductive material, an insulating film (33) being arranged between said upper portion (14) and said lower portion (12).

8. The switch according to claim 6 or 7, characterized in that the insulating film (33) is formed to be located between the first and second circumferential walls (37, 38) by a cylindrical portion (34).

9. Switch according to claim 8, characterized in that said cylindrical portion (34) has a base (35) facing said upper portion (14), said base extending parallel to said upper portion (14) and having a central opening (36) through which said switching mechanism (19) is in contact with said upper portion (14).

10. Switch according to claim 8 or 9, characterized in that the insulating film (33) is deep-drawn.

11. The switch according to any of claims 7 to 10, characterized in that the insulating film (33) is a self-adhesive film.

12. Switch according to any of claims 1 to 11, characterized in that the upper part (14) and the lower part (12) are pressed together, preferably in an interlocking manner.

13. Switch according to any of claims 1 to 12, characterized in that a first contact surface (27) is provided on the inner surface (25) of the upper part (14) and a second contact surface (29) is provided on the inner surface (28) of the lower part (12), and that the switch mechanism (19, 46) establishes or opens an electrically conductive connection between the first and the second contact surface (27, 29) as a function of its temperature.

14. Switch according to claim 13, characterised in that the switching mechanism (19, 46) comprises a bimetallic snap-action disc (23) and a spring snap-action disc (21), on which a moving contact part (22) is arranged, which moving contact part (22) interacts with the first contact surface (25), which spring snap-action disc (21) interacts with the second contact surface (29), and which bimetallic snap-action disc (23) interacts with the spring snap-action disc (21) in such a way that the bimetallic snap-action disc (23) moves or raises the moving contact part (22) away from the first contact surface (27) as a function of its temperature.

15. Switch according to claim 14, characterized in that said mobile contact element (22) is captively held on said spring snap disc (21), preferably welded thereto.

16. Switch according to claim 14 or 15, characterized in that the bimetallic snap-action disc (23) is captively held with play on the contact part (22).

17. Switch according to any of claims 14 to 16, characterized in that a transverse connection plate (47) is provided on the spring snap disc (21), which connection plate is mechanically and electrically conductively connected to the second contact surface (29), preferably welded to the second contact surface (29).

18. Switch according to any of claims 1 to 17, characterized in that the upper part (14) is a deep-drawn part.

19. Switch according to any of claims 1 to 18, characterized in that the lower part (12) is a deep-drawn part.