DE6608907U - TEMPERATURE LIMITER FOR ELECTRICAL EQUIPMENT. - Google Patents

Description

Patent attorneys

DIpI. Ing.C. Wallach

Dipl. Ing. G.Koch

Dr. T. Halbach

Munich 2 7-9.1967

_u _

Ernst Dreef's SMMt factory for electrotechnical supplies, GmbH, ünterrodach in the Prankenwald

Temperature limiters for electrical devices

The invention relates to a temperature limiter for electrical devices with manual reset and price release, with a Thermobimetallelfcent as a temperature sensor Has jump characteristics that open the electrical switch when triggered. Such electrical temperature limiters are used to prevent a device from heating up beyond the permissible operating temperature, .by the power supply directly or indirectly via relays, Switching contactors ^ or the like is interrupted. Such Temperature limiters are used in motors, transformers and electrical heaters to aid these devices to protect exceptional operating conditions from damage or destruction. The trigger state is from the outside such a temperature limiter by a cftitliche Change in position of the return element recognizable. This change in position is intended to induce the user of the device, to look for and eliminate the cause of the damage, before moving the hand back to

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advises to be put back into operation. The term "free release" means that a release takes place regardless of the position of the reset element, so even if this Backward eil el ^ jent is blocked.

In known devices, mostly a temperature sensor is used

f A structure made of thermo-bimetal, which, when its temperature-dependent movement exceeds a limit value, creates a latch. In free release simultaneous J is tig cancel the frictional connection swischen contact and return member which is shown in the majority of cases by a toggle mechanism. Such a temperature limiter therefore has a very complicated structure, and high demands are made on the accuracy of its components in order to achieve a precise response.

A special form of the temperature sensor is the curved thermal bimetallic disk, the curvature of which is made by mechanical means ! Embossing achieved, increases or decreases with temperature change. at When dimensioned appropriately, such a disk has the property that its curvature suddenly changes at a certain temperature to reverse. The disc returns to its original position just as abruptly when the temperature drops. Between The two envelope temperatures are relatively large Temperature difference, also called "hysteresis".

It has been known for a long time to produce such domed Thermobi & etailschel «

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3, ii. / ι

Such a limiter, in which the thernobimetallic disk carries the switching contact, which rests against the mating contact in the operating position, represents the simplest form of a temperature limiter with manual reset. It has the disadvantage that an automatic reset occurs at extremely low temperatures, because the "hysteresis" can not be enlarged arbitrarily without accepting other disadvantageous properties. A trip-free mechanism can be hai this type of limiters not realize "

The invention is based on the object of providing an electrical temperature limiter while avoiding the disadvantages mentioned create, the one with little parts and labor with normal Precision öer parts can be produced.

According to the invention, this object is achieved at a temperature

ben as temperature sensors in thermostats for fixed temperatures and temperature limiter ^! to use, and it will! their jumping character to achieve a spontaneous one Activation or deactivation exploited. Since the "hysteresis", i.e. the temperature difference between the two reversal points, is from Depending on the thickness of the material, it can be obtained through a suitable selection of the material in hand to keep the rebound temperature so low that under normal conditions no automatic Reconnection takes place. In order to switch on such a limiter again, the return must be made by one of acting force can be carried out »

86Q8907-9.1271

Larger of the type mentioned at the outset, the fact that the actuating member of the as Totpuit switch trained electrical switch supported is that according to the release movement of the thermal bimetallic element moves the switch from its first stable (on) position to its second stable (off) position and from a reset button via a non-positive. .i ^ e Clutch can be influenced in the sense of a switch-on movement i & t, and that the force that can be transmitted by the clutch is less than the mechanical restoring force of the thermal bimetal element. This structurally simple solution ensures that the restart can only take place when the thermal bimetallic element has returned to its starting position i.e. when the temperature has dropped considerably.

For the reasons explained later, it is expedient a bimetal menibran disk as the bimetal element used, but the invention is not limited thereto.

An embodiment of the invention is illustrated below described in the drawing. In the drawing show:

It is a front view of the limiter;

Flg. 2: a section along the line A - A ¹ in FIG. 1, which is at the same time the housing separation joint, the limiter being in the operating position;

Fig. J5: the same view as Flg., 2 _{t but} in the switch-off position the limiter, and

Pig. 4: the same view and position as FIG. 5, each with an attempt to split the limiter back before its temperature sensor has returned to its starting position.

The housing, consisting of two identical shell halves 11, accommodates a snap switch with two stable working positions, which consists of the connection terminals fixedly arranged in the housing with contact rivets 9, a switching bridge 1 with contacts 2, dead center springs J and a plunger 4 consists. In the plunger 4, the reset button 6 is axially displaceable and rests against the stop 5 of the plunger 4 by the compression spring 7 Serve limiter in a machine housing 14 by means of screws IJ. At the rear end of the switch housing carries a curved ThermoDiiretallscheibe 10 whose curvature is remote% n operating position the Genäuse, ie, the concave side of which faces the switch housing. The dead center feathers 3 press in the operating position \ t on the one hand SchaltbrÜc'ce 1 to 9 and subsequently Pestkontakte ρ other hand, the plunger 4 to the Thermobiraetallscheibe 10. hand, the Thermobimetallscheibe upon reaching the upper üraschlagtemperatur their curvature in a way, thereby the plunger 4 postponed. The container exceeds the dead center position of its springs j5 and goes into the switch-off position, in which both the plunger 4 with its stop 5 and the switching bridge rest against stops on the housing * lsi this position (FIg = 2) _v hold the dead center springs 5 dan switch aaen then »if the

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j Tbermobimetallschei.be 10 reverts to its original position,

! as long as no external force acts on the reset button 6.

If a reset is attempted before the Therraobimetallseifce

! 10 has returned to its original position (Fig. 4), so

the reset button 6 only works against the compression spring 7, whose force is less than the force required for mechanical

It is necessary to reset the thermal bimetallic disk 10, a *. »

on the other hand, however, greater than the axial force component d ^ r dead center springs 5

If the reset button 6 is blocked in its holding position, so has the thermal bimetallic disk 10 when jumping over except the Force to operate the switch to overcome the pressure of the spring 7. This is about an order of magnitude lower than the force that the thermal bimetal disc applies, and therefore increases their transition temperature only insignificantly.

It would be conceivable instead of a curved thermal bimetallic disk a flat Therraobiia metal strip with jumping characteristics to use, which moves continuously according to the temperature. It is possible to use a Adjustment possibility to equip, which is impossible with a curved pane. However, this has several disadvantages. The contact pressure of a dead point switch decreases the more it is approaches its dead center in order to reach it completely To become zero, a state that can only be swung into Purchase takes. In the case of a continuously operating temperature sensor, the switch would always have a low contact pressure

operated, dft for safety reasons the response temperature should be close to the operating temperature. With a slow rise in temperature, the contact pressure would just as slowly go from this low value to zero before the switch opens. The sudden snap of a cnermo bimetallic disc, which covers a relatively long distance, brings the switch momentarily from one extreme position to the other and thereby shortens the critical switching phases to a minimum. A further disadvantage of a flat bimetallic strip lies in the fact that _t his resilience bsdeutssd greater than actual dl "a bulging disc. Thus clie dimensioning Aer spring T is critical, the force of which must be between DER axial component of the dead-center and the mechanical Rücbiegung of Remperaturfühlers xm to ensure proper trip-free mechanism.

Claims;

66089-67-9.12.71

Claims (7)

: .t claims; 1. Temperature limiter for electrical devices with manual reset and release, which has a ThermobiiEetallelement with Sprungcharakxeristik as a temperature sensor, which opens the electrical switch when triggered, characterized in that on the Thermobimetallelecient (10) the actuator (^) of the electric as dead center he trained Sciü_ters (1, Zj 5, 4, 8, 9) is supported, which, according to the external movement of the Thermobiraetalleleaentes, moves the switch from its first stable (switch-on) position to its second stable © (switch-off) position and is activated by a reset button ( 6) can be influenced via a force-acting clutch in the sense of a switch-on movement, and that the force that can be transmitted by the clutch is less than the mechanical restoring force of the thermal bimetallic element. 2 * temperature limiter according to claim 1, characterized in that the thermal bimetallic element is designed as a membrane disc (10) known per se. 3 * temperature limiter according to claims 1 and 2 characterized in that the actuating member of the dead center switch, designed as a tappet (4) in the first stable switch position Position) of the dead center switch due to the axial force component the dead center springs (3) frictionally on the concave side of the Thennobiiaetallscheibe (10) is biased. 4. Temperature labeled in according to claims 1 to 3 as eichnet _s that is coupled to that of the reset button (6) in the Stö'Sel (4) axially displaceable ^ · supported and frictionally via a compression spring (7) istlz. 5 · Temperature limiter according to claims 1 to 4 characterized ge mark 55 eichnet _t that the force of Kupplvngsfeder (7) between Rückstcllknopf (6) and actuator (4) is smaller 1st than the greater the mechanical resetting of the Thermobimetä & seheibe (10) force required, however, than the axial force component of the dead center springs 6. Temperature limiter according to claims 1 to 5, characterized in that the contact bridge l [l) of the dead center switch is guided through an opening of the actuating member (4) designed as a plunger and is freely movable axially therein and that two dead center springs (J>) are diametrically opposite are supported on the plunger (4) on the other hand and on the other hand at the radially outer end on the contact bridge. 7. Temperature limiter according to claims 1 to 6 thereby, g ^ kennaieiu .net, I β β 8 β * that the control button (6) by the clutch spring (7) against a stop (5) of the actuating plunger (4) is pressed. Temperature limiter according to Claim 7, characterized in that the stop (5) in turn passes through in the switch-off position the dead center springs is pressed against a housing stop. 6888987-9.1171