EP2511930B1 - Temperature protective switch - Google Patents

Description

The invention relates to a temperature protection switch with the features specified in the preamble of claim 1. A temperature protection switch with the features specified in the preamble of claim 1 is known from US 3,972,016 known.

From the US 5,936,510 a temperature protection switch with a housing is known in which an insulator body, two connecting plates and a bimetallic disc known.

Such a temperature protection switch is used to protect electrical equipment, motors, transformers and the like from overheating. It should open when the temperature at its place of use exceeds a predetermined limit. This limit is hereinafter referred to as the switching temperature. The switching temperature is dictated by a bimetallic disc, which can not change its shape or curvature continuously, but only by leaps and bounds, when a minimum mechanical stress determined by the shape of the bimetallic disc and by its elastic properties has built up by temperature change in the bimetallic disc. For safety reasons, tolerance limits specified for the switching temperature must be observed.

A temperature protection switch with the features specified in the preamble of claim 1 is known from DE 195 09 656 C2 known. In the known switch, the bimetallic disc carries the movable contact. When the switch is closed, the current therefore flows over the bimetallic disc. In this case, heat is generated in the bimetal disc, which depends on the current intensity and the ohmic resistance of the bimetallic disc. This is disadvantageous for some applications, because a temperature can be faked by the current heat generated in the contact spring, which is higher than the temperature at the location to be monitored of the electrical device. It may therefore come to unwanted tripping of the bimetallic switch.

From the EP 1 774 555 B1 a temperature protection switch with an improved current carrying capacity is known in which the bimetallic disc carries a contact bridge which connects a fixed contact of the first terminal plate electrically conductively connected to a fixed contact of the second terminal plate with the switch closed. When the switch is closed, the current therefore no longer flows through the bimetal disc, but instead through the contact bridge, which has a much lower electrical resistance. This switch can therefore carry much higher electrical currents before ohmic heat loss leads to an opening of the switch.

A temperature protection switch for high currents is also from the DE 10 2008 048 554 B3 known. This switch has a flat insulator body, which carries a connecting plate on its top and bottom. The movable contact is electrically connected via a leaf spring with one of the two connection plates. In a recess of the insulator body is a bimetallic disc, against which a buckling of the leaf spring. When snapping the bimetallic disc lifts the leaf spring, so that the attached to the leaf spring movable contact lifts from the fixed contact. Similar to the one from the EP 1 774 555 B1 Thus, the current does not flow through the bimetal disc, so that the permissible currents are not limited by the electrical resistance of the bimetal disc.

From the DE 31 36 312 A1 is a temperature protection switch is known in which the connection plates are attached to the outside of a cup-shaped insulator and over each a rivet are connected to a contact inside the insulator. One of the two contacts is formed as a fixed contact, which is arranged on a side wall of the cup-shaped insulator. The fixed contact cooperates with a movable contact, which is connected via a U-shaped spring bent electrically connected to the rivet of the second connection plate. On the spring leg, which carries the movable contact, loads a plunger, which is passed through a block-shaped insulator closing block and is moved by a bimetallic disc, which is arranged outside of the cup-shaped insulator body in a metal housing. When the sound temperature is exceeded, the bimetal disc presses the two legs of the contact spring together, so that the movable contact is lifted from the fixed contact.

In order to form temperature protection switches as current monitors, i. In the case of a critical current, to force a triggering of the switch, it is known to increase the electrical resistance of the switch, for example by the terminal electrodes are connected in series with a heating resistor or even have a relatively high electrical resistance, which is characterized by its length, cross section and material can be adjusted. But it is much more difficult to prevent a current-induced triggering of a thermal circuit breaker.

US-A-3972016 discloses a temperature protection switch according to the preamble of claim 1.

Object of the present invention is to show a way to realize a compact thermal circuit breaker, which shows a reliable switching behavior, which is largely unaffected by the current heat generated in the temperature protection switch.

This object is achieved by a temperature protection switch having the features specified in claim 1. Advantageous developments of the present invention are the subject of dependent claims.

• Die Stromtragfähigkeit eines erfindungsgemäßen Schalters ist höher als bei dem aus der DE 10 2008 048 554 B3 bekannten Schalter, da die Bimetallscheibe in einem größeren Abstand von der Kontaktfeder angeordnet ist. Eine bei höheren Strömen unvermeidliche Erwärmung der Kontaktfeder wirkt sich deshalb deutlich weniger auf die Bimetallscheibe aus. Mit anderen Worten wird die Bimetallscheibe eines erfindungsgemäßen Temperaturschutzschalters durch die Verlustwärme eines durch den Schalter fließenden Stroms noch weniger beeinträchtigt. Zudem lässt sich mit einem erfindungsgemäßen Temperaturschutzschalter auch der Nachteil des aus der DE 10 2008 048 554 B3 bekannten Schalter überwinden, dass die Bimetallscheibe im Inneren des Isolatorkörpers von der Umgebung thermisch isoliert ist und der bekannte Schalter auf Änderungen der Umgebungstemperatur deshalb nur sehr träge reagiert.

In the temperature protection switch according to the invention, the current flows through a contact spring, which carries the movable contact on a first leg and contacts the second connection plate with a second leg. Between the first leg of the spring and the bimetallic disc, a plunger is arranged, the bimetallic disc when the switching temperature is exceeded against the first leg presses and so lifts the movable contact from the fixed contact. The construction according to the invention enables a compact temperature protection switch which can also be used at high electrical powers, for example for currents of more than 10 A at a mains voltage of 230 V. In particular, a temperature protection switch according to the invention has the following advantages over known thermal circuit breakers:

• The current carrying capacity of a switch according to the invention is higher than that of the DE 10 2008 048 554 B3 known switch, since the bimetallic disc is arranged at a greater distance from the contact spring. A heating of the contact spring that is unavoidable at higher currents therefore has a significantly less effect on the bimetallic disk. In other words, the bimetallic disc of a thermal circuit breaker according to the invention is even less affected by the heat loss of a current flowing through the switch. In addition, with a temperature protection switch according to the invention also the disadvantage of the DE 10 2008 048 554 B3 overcome known switches that the bimetallic disc is thermally insulated from the environment inside the insulator body and the known switch therefore reacts only very slowly to changes in ambient temperature.

A temperature protection switch according to the invention advantageously has a construction which is as flat as that of FIG DE 195 09 656 C2 known temperature protection switch. However, the current carrying capacity of a switch according to the invention is substantially greater, since heating of the bimetallic disc is avoided by ohmic heat loss.

The current carrying capacity of a switch according to the invention is as good as the current carrying capacity of the from DE 31 36 312 A1 known switch. However, a switch according to the invention has a much more compact construction and can be produced more easily. The pot-shaped housing of the known thermal circuit breaker has namely a considerable height result that makes a use for the protection of electric motors practically impossible. In addition, the known switch consists of a very large number of items that must be joined together in a large number of complex manufacturing steps. The connection plates and the contact spring must be firmly riveted to the cup-shaped insulator and the metal disk must be fastened to the pot-shaped insulator with a plate-shaped metal housing.

An advantageous development of the present invention provides that the two legs of the spring for opening the switch are bent apart from the plunger. When snapping the bimetallic disc pushes the plunger, the first leg of the spring, which carries the movable contact, ie away from the second leg. In other words, the spring of a thermal circuit breaker according to the invention is thus claimed on the opening of the switch to train, while in contrast to the legs of the contact spring in which from the DE 31 36 312 A1 known temperature protection switch to open the switch of the plunger are pressed together. The inventive measure that the two legs of the spring to open the switch are bent apart from the plunger, allows a particularly compact design of the thermal circuit breaker.

A further advantageous development of the invention provides that the spring is fastened to the second connection plate with a section which extends transversely to the longitudinal direction of the two spring legs. In this way, the spring can be arranged compactly between the two connecting plates.

A further advantageous development of the invention provides that the insulator body is composed of two sub-bodies, wherein the two connecting plates are located between the sub-bodies. In this way, the production of a thermal circuit breaker according to the invention can be considerably simplified. The connection plates can be inserted together with the spring and the two contacts in a first part body. Thereafter, a second part body made of an electrically insulating material, preferably made of plastic, placed on the contact plates on the contact plates. The two body parts can be positively connected with each other, for example, by crimping or latching, non-positively, for example, by jamming or hot stamping, or are materially connected, for example, glued or welded. However, the two partial bodies can also be combined, for example, by the deferred housing but for example, be held together by the deferred housing. As an alternative to the use of partial bodies, it is also possible to produce the insulator body by encapsulation of the connection plates.

A further advantageous development of the invention provides that the bimetal disc is seated on the outside of the insulator body. The temperature of the bimetallic disc nourishes in this way as far as possible to the ambient temperature of the thermal circuit breaker and remains largely unaffected by heat loss of the current flowing through the thermal circuit breaker current. Preferably, the bimetallic disc sits in a recess on the outside of the insulator body. In this way, it is advantageous to facilitate the assembly of the thermal circuit breaker.

According to the invention it is provided that the housing has an upper side and a lower side, which are connected to each other via narrow sides. Such a housing is flat, which is an important advantage in using the thermal protector to protect motors and similar equipment. The housing is open on one of its narrow sides and attached with this side on the insulator body. Particularly preferred is the housing elongated. The extending in the longitudinal direction of the housing narrow sides then have a greater length than the transverse to the longitudinal direction extending housing opening.

A further advantageous development of the present invention provides that a portion of the insulator body protrudes from the housing, for example, the insulator body form a stop for the housing. Preferably, a portion of the spring is arranged in a protruding from the housing portion. It is particularly preferred that a bent portion of the spring, which connects the two spring legs, arranged in the protruding from the housing portion of the insulator body. This means that a cutting plane defined by the housing opening passes through the spring.

A further advantageous development of the present invention provides that the insulator body has on a front side, from which protrude the terminal plates, a protruding portion which lies between the connecting plates. Prefers lies in this section of the bent portion of the spring, which connects the two spring legs

A further advantageous development of the present invention provides that the housing is made of a ferromagnetic material, for example of steel. In this way, a magnetic shield can advantageously be achieved by simple means.

A further advantageous development of the present invention provides that the plunger protrudes between the two connecting plates when the switch is open. Preferably, the plunger protrudes between the terminal plates even when the switch is closed.

The fixed contact can be formed in a temperature protection switch according to the invention of the first terminal plate. Preferably, however, the fixed contact is a separate component which is fastened on the connection plate.

Figur 1

eine Explosionsdarstellung eines Ausführungsbeispiels eines erfindungsgemäßen Temperaturschutzschalters;

Figur 2

eine Schrägansicht des Temperaturschutzschalters ohne Gehäuse;

Figur 3

eine Ansicht zu Figur 2 mit abgenommenem Teilkörper;

Figur 4

eine Schnittansicht des Temperaturschutzschalters; und

Figur 5

ein weiteres Ausführungsbeispiel eines erfindungsgemäßen Temperaturschutzschalters.

Further details and advantages of the invention will be explained with reference to embodiments with reference to the accompanying drawings. Identical and corresponding components are designated therein by corresponding reference numerals. Show it:

FIG. 1

an exploded view of an embodiment of a temperature protection switch according to the invention;

FIG. 2

an oblique view of the thermal circuit breaker without housing;

FIG. 3

a view too FIG. 2 with removed part body;

FIG. 4

a sectional view of the temperature protection switch; and

FIG. 5

a further embodiment of a temperature protection switch according to the invention.

The in the FIGS. 1 to 4 illustrated thermal circuit breaker has a first terminal plate 1, which carries a fixed contact 2, and a second terminal plate 3, which is electrically connected via a spring 4 with a movable contact 5. The connection plates 1, 3 are in the FIGS. 1 and 3 shown as a one-piece stamped part. After assembly, the connection plates 1, 3 are separated by a connecting the connecting plates web is removed.

The fixed contact 2 can be attached to the first connection plate 1, for example by welding or riveting. Likewise, the preferably U-shaped bent spring 4 can be welded or riveted to the movable contact 5 and to the second connecting plate 3. The connection plates 1, 3 and the contacts 2, 5 and the spring 4 can be pre-assembled into an assembly. The connection plates 1, 3 can still be formed as a common component, as in FIG. 1 is shown. In particular FIG. 3 shows, the spring 4 is arranged over a gap between the two terminal plates 1, 3.

The two connection plates 1, 3 protrude out of an insulator body, which is composed of two part bodies 6a, 6b. The two partial bodies 6a, 6b consist of an electrically insulating material, for example of plastic. The first part body 6a forms a receptacle for the connection plates 1, 3, which is then closed by the second part body 6b.

On the outside of the insulator body, preferably in a recess of the first part body 6a, a bimetallic disc 7 is arranged, which separates a conductive connection between the two connection plates 1, 3 when a switching temperature is exceeded. The bimetallic disc 7 acts via a plunger 8 on the contact spring 4, which projects between the two connection plates 1, 3 passes. The plunger 8 is arranged in a channel of the first part body 6a. When the bimetal disc 7 snaps over its sound temperature is exceeded, the plunger 8 is pressed by the bimetallic disc 7 against the first leg 4 a of the contact spring 4, which carries the movable contact 5. In this case, the first leg 4 a of the second leg 4 b, which rests against the second connection plate 3, bent away. In other words, the two legs 4a, 4b of the spring 4 to open the temperature protection switch from the plunger 8 are bent apart. The contact spring 4 is So a bow spring, which is bent to open the thermal circuit breaker.

The bimetallic disc 7 is held in the recess of an outer side of the first part body 6 a by a ring 9. The ring 9 is preferably made of metal, since so the thermal coupling of the bimetallic disc 7 is improved to the environment of the switch. The ring 9 covers the edge of the bimetallic disc 7 and can be attached to the part body 6a of the insulator body, for example by gluing or clamping, for example by hot stamping. The bimetallic disc 7 is in the illustrated embodiment on a bead of the insulator body. In this way, the contact surface between bimetallic disc 7 and insulator body can thus minimize the heat coupling of the bimetallic disc.

The insulator body 6a, 6b is inserted into a housing 10 after assembly. The housing 10 is a flat housing cap. The housing 10 thus has a top and a bottom, which are connected by narrow sides. On one of the narrow sides of the housing 10 is open, so that in this end of the preferably elongated housing 10 of the insulator body 6a, 6b can be inserted. Preferably, the terminal plates 1, 3 project with one end out of the housing 10. In particular Fig. 4 shows, the insulator body 6a, 6b protrudes from the housing 10. In the protruding from the housing 10 portion of the insulator body, a portion of the spring 4 is arranged, namely the two spring legs 4a, 4b connecting bent portion. The spring 4 is thus only partially arranged in the housing 10.

The connection plates 1, 3 protrude from an end face of the insulator body 6a, 6b. At the front side of the insulator body 6a, 6b has a protruding portion which lies between the two connecting plates. This projecting portion protrudes from the housing 10 and contains the bent portion of the spring 4, which connects the two spring legs.

The housing 10 may be made of ferromagnetic metal, such as steel, to magnetically shield the derailleur of the thermal circuit breaker. This is for example when using the temperature protection switch important for electric motors or transformers, since in such applications typically strong magnetic fields occur.

The bimetal disc 7 is preferably a circular disc, but may also have a different shape and be formed for example as an elongated strip.

FIG. 5 shows an exploded view of another embodiment of a thermal circuit breaker. This embodiment differs from the embodiment described above substantially only in that a self-holding function of the switch has been added. This self-holding function causes enough heat to be produced after opening the switch to prevent the switch from automatically closing. For the self-holding function is in the illustrated embodiment, a resistor 11, preferably a ceramic resistor, such as a PTC resistor, is provided, which connects the two terminal plates 1, 3 electrically conductive with each other. The resistor 11 can be pressed by a leaf spring 12 against the two connecting plates 1, 3.

An electrical resistance for a self-holding function, for example, outside of the housing, for example, on a protruding from the housing opening end face of the insulator body 6a, 6b are arranged. It is also possible to form the insulator body 6a, 6b as an electrical resistance for a self-holding function. In this case, the insulator body 6a, 6b or at least one of the two body parts 6a, 6b, a poor insulator or a bad electrical conductor, so that when the switch is open by the insulator body flows a current that generates sufficient heat loss to cool the To prevent bimetallic disc 7 below its switching temperature.

reference numerals

1

first connecting plate

2

fixed contact

3

second connecting plate

4

contact spring

4a

first thighs

4b

second leg

5

moving contact

6a

first part body

6b

second part body

7

bimetal disc

8th

tappet

9

ring

10

casing

11

resistance

12

leaf spring

Claims (9)

1. A thermal protection switch comprising
   a first connection plate (1) having a fixed contact (2),
   a second connection plate (3), which is electrically conductively connected to a movable contact (5),
   an insulator body (6a, 6b), and
   a bimetallic disk (7), which separates a connection between the two contact plates (1, 3) when a switching temperature is exceeded, wherein the movable contact (5) is attached to a first leg (4a) of a spring (4), which contacts the second connecting plate (3) via a second leg (4b), wherein a plunger (8) is disposed between the first leg (4a) of the spring (4) and the bimetallic disk (7), which presses the plunger (8) against the first leg (4a) when the switching temperature is exceeded and thereby lifts the movable contact (5) away from the fixed contact (2),
   characterized in that
   the two connecting plates (1, 3) protude from the insulator body (6a, 6b),
   the insulator body (6a, 6b) is inserted into a housing (10), which has a top side and a bottom side, which are connected to one another via narrow sides, the housing (10) is open on one of the narrow sides thereof and, via this side, is slipped onto the insulator body (6a, 6b), and
   the two legs (4a, 4b) of the spring (4) are bent away from one another by the plunger (8) in order to open the thermal protection switch (8).
2. The thermal protection switch according to claim 1, characterized in that the second leg (4b) of the spring (4) rests against the second connecting plate (3).
3. The thermal protection switch according to any one of the preceding claims, characterized in that the insulator body is composed of two partial bodies (6a, 6b), wherein the two connecting plates (1, 3) lie between the two partial bodies (6a, 6b).
4. The thermal protection switch according to any one of the preceding claims, characterized in that the housing (10) is made from a ferromagnetic material, preferably being made from steel.
5. The thermal protection switch according to any one of the preceding claims, characterized in that the bimetallic disk (7) is situated on the outside of the insulator body.
6. The thermal protection switch according to claim 5, characterized in that the bimetallic disk (7) is seated in a recess on the outside of the insulator body.
7. The thermal protection switch according to any one of the preceding claims, characterized in that, when the switch is open, the plunger (8) extends between the two connecting plates (1, 3).
8. The thermal protection switch according to any one of the preceding claims, characterized in that the insulator body supports a ring (9), which covers the edge of the bimetallic disk (7).
9. The thermal protection switch according to any one of the preceding claims, characterized in that at least one of the two legs (4b) of the spring (4) has a lateral projection, which extends transversely to the longitudinal direction of the leg (4b).

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