EP0818796A2 - Thermal switch, in particular adjustable temperature controller - Google Patents

Abstract

The temp. switch has a snap-action switch (25) with a switching spring (26) actuated by an expansion element (14). An actuation element is moved relative to the switching spring, which has an overload protection device, by the expansion element. The overload protection device contains a buffer element (38) arranged between the expansion element and the switching spring whose length can be varied by an applied force greater than the actuation force of the switching spring.

Description

Field of application and state of the art

The invention relates to a temperature switch, in particular an adjustable temperature controller with a snap switch, the one actuated by an expansion element switching spring to which one of the expansion element acts relative to the switching spring movable pressure element, and with an overload protection for the switching spring.

In temperature controllers, especially those with a thermo / hydraulic expansion system works for the switch spring has an overload problem when the temperature controller at or near its switch-off point, that is at warm condition, reset to a lower temperature or is turned off. The expanded expansion box far above the switch-off point in the direction of the Switch spring pressed so that it is overloaded and under Circumstances can be permanently damaged.

There are many suggestions to solve this problem been made. DE 44 35 303 A is a snap spring described, which endures overloads to a greater extent than previous snap springs.

Furthermore, a temperature switch is in DE 20 58 511 C. described, in which the expansion box in a parallelogram of resilient shift levers connected by one Transfer rod, lies. The actual snap spring actuation happens through the second lever in the power flow, the acts on the snap switch under its spring force while the expansion box over the rest of the lever mechanism only is pressed to relieve them. This system works flawless, but is very expensive to manufacture.

It is also a temperature switch from DE 24 22 684 C. has become known in which a double snap spring by one actuated ceramic rod lying in an expansion sleeve becomes. In this case the snap switch works as "Break contact", i.e. the ceramic rod pulls out at elevated temperatures back and opens by relieving the snap spring the contact. With such a system, this would be described Problem does not occur. But it is one non-adjustable temperature limiter.

Task and solution

The object of the invention is a temperature switch to create the kind mentioned at the outset, which has little structural and above all, space requirements without the risk of overloading works flawlessly.

This object is achieved by claim 1 solved. The fact that the overload protection between Expansion element and snap spring activated buffer element contains that at a above the actuating force the compression spring in the switching point compressible force the transfer is direct and without any elasticity or stressing one External power and therefore absolutely free of play. Only when exceeded the maximum actuation force is compressed of the buffer element, this force being measured in this way should be that below the damage to the Snap spring-inducing force lies. It can also help if the spring after overcoming her Switching point is supported on a stop, preferably directly at their point of operation. Although the execution the invention with a compressible buffer element is structurally cheapest, it would also be conceivable to move one use acting buffer element.

The buffer element can be located directly in the actuating element, i.e. the one between the expansion socket and the snap spring Pressure piece or the like may be included. An easy one Version contains a preloaded, travel-limited spring, for example a compression spring. Here is the preload slightly larger than the actuating force of the switch spring and less than that critical for mechanical stress Force.

The buffer element can be a can that consists of two against Pull apart limited but compressible e.g. sleeve-shaped box parts, which is the compression spring enclose. Grasp these two halves of the buffer element thus interlocked and are from the compression spring spread. One of the can parts can be attached directly an expansion box attached, for example instead of of the usual pressure piece soldered, while that interacting box part made of electrically insulating Material can exist and thus the expansion system electrically from the mostly live spring separates. The can parts do not have to be closed Coat, but it could be, for example tin part made of sheet metal also from several lateral There are webs which, like a claw, form the other part of the box seize.

The invention enables the expansion element directly on the mostly designed as an expression of the snap spring Acting point acts. This enables the smallest size. However, it is also possible to increase the gear spring sensitivity a translation lever interpose. But this can also directly in Direction of printing lie and thus without expensive storage be trained. He can, for example, unilaterally according to Art be supported by a cutting edge bearing and with its act on the other side of the spring while the Buffer element at a corresponding to the desired gear ratio positioned place this one arm Lever attacks.

A particularly simple embodiment is with an L-shaped Lever given either on a switch spring carrier is mounted and supported or in a recess this shift spring carrier is guided.

Due to the small size and the possibility without expensive Double lever etc. to work even when a translation is provided, the actual contact area is in which the movable contact sitting on the switch spring and the associated counter-contact (s) are free so far that they were easily enclosed by an insulating cover can be around this area against contact and pollution to protect. This also enables the reduction in Size because it makes the legally required minimum clearances easier (Clearances and creepage distances, high voltage resistance) from live parts to touchable parts can be. Such a contact chamber can suitable plastic material as an integral component of an im remaining housing made of metal may be provided. she can be used as a substantially U-shaped hood in a recess of the upper part of the housing by clipping in, guide grooves etc. are attached. It thus acts as one of the contacts largely surrounding "spark chamber" and separates the touchable Parts from the live.

The invention thus enables an advantageous embodiment for example the following structure:

One working with a hydraulic expansion box Temperature controller with screw thread setting points as Intermediate link between the expansion socket and the snap switch a buffer element. This may have an effect on you L-shaped gear lever on the actuation point of the Snap switch.

The buffer element consists of a button-shaped, entirely closed can, which consists of two pot-shaped, each other overlapping halves, between which a compression spring is biased. The buffer element transfers the Switching force of the expansion socket in the range of forces in which the snap spring actuation takes place without any elasticity, so completely rigid while going beyond one Overload collapses telescopically.

These and other features go beyond the claims also from the description and the drawings, wherein the individual features individually or separately several in the form of sub-combinations in one embodiment of the invention and in other fields be and advantageous as well as protective designs can represent, for which protection is claimed here.

The division of the application into individual sections as well Inter-headings limit those made under them Statements are not generally applicable.

Brief description of the drawings

Fig. 1

einen Längsschnitt durch einen Temperaturregler,

Fig. 2

eine Draufsicht auf den Basisteil des Temperaturreglers (entlang Schnittlinie II in Fig. 1),

Fig. 3

eine stark vergrößerte Ansicht eines Details in Richtung des Pfeils III in Fig. 1 und

Fig. 4

einen Teilschnitt durch die Funktionskomponenten eines Temperaturreglers in einer anderen Ausführungsform

An embodiment of the invention is shown in the drawings and is explained in more detail below. The drawings show:

Fig. 1

a longitudinal section through a temperature controller,

Fig. 2

a plan view of the base part of the temperature controller (along section line II in Fig. 1),

Fig. 3

a greatly enlarged view of a detail in the direction of arrow III in Fig. 1 and

Fig. 4

a partial section through the functional components of a temperature controller in another embodiment

Description of a preferred embodiment (Fig. 1 to 3)

1 to 3 show the switching component of a temperature controller 11. To it belongs only one indicated schematically Temperature sensor 12, e.g. in the form of one with an expansion fluid filled tube over a capillary tube 13 is connected to an expansion box 14. The Expansion box consists of two bowl-shaped corrugated Sheet metal membranes that are connected at the edge. over a connecting nipple 15, the capillary tube 13 is connected. At the top of the expansion box 14 is a retaining bolt 16 welded, the in a hollow setting shaft 17th plugged. This has an external thread 18 with an internal thread 19 works together in a metal housing 20 drawn sleeve 21 is provided. The adjusting shaft 17 is flattened on one side so that it cannot rotate about an adjustment knob to record. An adjusting screw 22 is provided in it, which acts on the retaining bolt 16.

The housing 20 is made of sheet metal and has the shape of a rectangular, partly openwork box whose top fastening claws 22 for installing the Temperature controller are formed. The bottom is from a base part 23 made of temperature-resistant, shape-resistant and electrically insulating material, for example steatite or another ceramic material. At this the housing is fixed by twist straps 24.

The plate-shaped base part 23 carries a snap switch 25. This has a switching spring 26 which on a Switch spring carrier 27 is attached. The shift spring carrier 27 is a relatively small solid sheet metal part, which is a shift tongue abutment 28 in the form of a turn. On him is a shift tongue 29 supported by an approximately U-shaped Cut separated from the rest of the switch spring is. Due to their deflection and preload, which they the Switching spring there, with the end remote from contact Rivets 30 on the switch spring carrier with fixed switch spring their front, the switch contact 31 carrying end at their Snap the switching point between two stable switching positions. In the switch-on position shown in Fig. 1 is her Contact 31 on a counter contact 32, which is on a Mating contact bridge 33 is located. In the off position is the front end of the switch spring on one of the Base part formed projection 34 forming a counter bearing on.

Create snap switch carrier 27 and counter contact bridge 33 through U-shaped training mounting tabs on the one hand as twisting tabs 35 and on the other hand as well formed by twisting tabs 36, 37 formed are also the electrical connection on the bottom of the plate-shaped base part.

On the underside of the expansion box 14 is a buffer element 38 trained and effective actuator appropriate. It consists of one at the bottom of the Expansion box welded in the form of a sheet metal shell trained can part 39, which by means of a bent edge or tooth-like edge projections 40 under the protruding outer edge 41 of a second can part 42 which grips the shape one made of electrically insulating material, for example Steatite, existing crucible. Inside the two Can parts 39, 42, a compression spring 43 is arranged. she is clamped between the two can parts so that they have a Has a preload that is certainly greater than that Actuating force that the snap switch needs to over to be pushed away from its switching point.

The buffer element thus designed as a closed pressure can acts on a pronounced pressure point 44 of an L-shaped Lever 45, which is turned on as a translation lever is. With its also to create clear It affects the pronounced front end 46 an actuation point 47 of the switching spring, which by a transverse bead is formed.

At the opposite end of the lever, which is wider than long, two are far apart from each other down bent support leg 48 provided, the ends of the cutting edge bearing 49 form by being on the surface of the base part 23 are supported. As can be seen from FIG by a curved lower edge of the support leg 48 therefor ensured that there are clear support conditions.

The two support legs protrude from both sides a recess 50 in the side edge of the snap switch carrier 27 in, so that the support legs are guided therein. Protruding lugs 51 on the inside of the support legs 48 are barbed and care after the Lever 45 under pressure from above into the recesses 50 is pressed in, for securing against lifting the Lever. A stop 52 is located on the switch spring support 27 below the actuating point 47 of the snap spring provided so that he catches them after executing their snap movement and prevents further deflection.

Fig. 1 shows that the contact area, i.e. the front end the switching spring 26 with the contact 31 and the counter contact 32, of a cover 53 made of insulating material is surrounded. It covers the top, front and the from both sides. Because the bottom of the base plate 23 is formed, so it only becomes the inside of the switch open chamber formed, the risk of contamination and contact excludes. The cover 53 is snapped into place fixed to a slot 54 of the housing.

function

The assembly of the temperature controller according to the invention can be done individual components that can be prefabricated by simple plugging, bending or flanging operations are carried out will. The filled and soldered component sensor / capillary tube / expansion socket 12, 14 contains the upper one Can part 39. It is then only necessary to use spring 43 insert, squeeze so that they have their bias receives and then bend the claws or teeth 40 so that the buffer element 38 held together as a button-shaped unit becomes.

The parts of the snap switch are on the base part 23 by inserting into the slots 53 and twisting the tabs 36, 37 and the twist straps 35 set.

The lever 45 is from above the snap switch carrier pressed and clicks due to a formed by the lugs 51 Snap lock there.

The adjustment is made using the adjusting screw 22.

In operation, the setting shaft 17 for setting a certain temperature rotated so that the thread 18, 19th the expansion box 14 and thus the buffer element 38 in one determined position along the axis 55 of the adjusting shaft brought.

When the temperature sensor 12 is warmed up, it expands Sensor 12 contained expansion fluid and expands the Expansion box 14 so that the buffer element 38 after moved down, the lever 45 pivoted clockwise and acts on the snap spring via the actuation point 47. The lever 45 is supported on its cutting edge bearings 49 from. Due to the shorter lever arm between the cutting edge bearings and the pressure point 44 on the lever opposite the distance operating point 47 to cutting edge bearing 49, the switching movement translated approximately in a ratio of 2: 1.

The switching spring is supported via the switching tongue 29 made that in the unloaded state of the switching spring outer end with the contact 31 on the mating contact, which Switch is closed. The one about the tabs 36, 37 connected circuit is via the snap spring closed and the switch is on.

If the switching point is exceeded by the fact that the switch spring moves down so far that it snaps and rests on the projection 34, then the Switch turned off. This force is from the buffer element 38 transmitted without own compression. It works so as a rigid actuator.

In normal operation, there is no significant expansion the expansion box more because yes, the controller addressed and the heating of the sensor 12 any electrical heating device or other elements is normally turned off. But if now User by rotating the adjusting shaft 17 by means of the shown push button the regulator to a low Sets temperature or wants to turn it off, so it moves so that the expansion box continues towards the switch, i.e. "From" direction.

Now the buffer element 38 comes into effect. With one clearly above that for turning off the snap switch necessary force on the actuation point 47 can Compress spring 43 so that the two halves of the can 39, 42 telescopically push together through the buffer element formed button thus yields. The Switch spring can sit on the stop 52 so that it is not bent unnecessarily. The forces and the deflections are in any case in the elastic area of the switch spring, so that no permanent damage occurs. When canceled the overload, e.g. when cooling the regulated Device, the buffer element expands under the effect of Spring 43 again at exactly the same length as before Squeeze out.

It can be seen that the invention is a special simple method of overload protection was created. The actuation takes place via an absolute in the operating state rigid and only yielding when overloaded after that, however, a precisely expanding, transfer link in Form of an operating button on the pressure cell itself. The transmission lever can be very short and compact be so that it does not affect the size. There are no spring elements necessary on the switching spring itself Act. Rather, the spring is only effective in the buffer element, if the switching has already taken place and only serves for overload protection.

Embodiment according to FIG. 4

Fig. 4 shows an embodiment in which that in a similar manner formed buffer element 38 on a metal pressure piece 56 the expansion box is attached and immediately, i.e. without Translation lever 45, on the operating point 47 of the Switch spring 26 acts. This execution that preferred is when no translation is necessary is special simple and with direct switching effect. Otherwise, the Training and function the same as described in FIGS. 1 to 3.

Claims (12)

Temperature switches, in particular adjustable temperature controllers, with a snap switch (25), one of an expansion element (14) actuated switching spring (26) on which one of the expansion element (14) Actuating element movable relative to the switching spring (26) acts, and with an overload protection for the switching spring (26), characterized in that the Overload protection between the expansion element (14) and the switching spring (26) switched on Contains buffer element (38), which at one above the Actuating force of the switching spring (26) in the switching point lying force is changeable in length. Temperature switch according to claim 1, characterized in that the buffer element (38) is a pressure element is that by the above the operating force of the Switch spring (26) lying force is compressible. Temperature switch according to claim 1 or 2, characterized characterized in that the buffer element (38) in the actuating element is included. Temperature switch according to one of the preceding claims, characterized in that the buffer element (38) contains a preloaded, path-limited spring (43). Temperature switch according to one of the preceding claims, characterized in that the buffer element (38) is a can made of two against pulling apart limited, but compressible, possibly sleeve-shaped Can parts (39, 42), which is a compression spring (43) enclose, preferably one of the can parts (39) on an expansion socket (14) one thermo / hydraulic expansion system (12, 13, 14) attached and / or that another of the can parts (42) electrically insulating material. Temperature switch according to one of the preceding claims, characterized in that the switching spring (26) has a pronounced actuation point (47), on which the actuating element (38, 45) acts. Temperature switch according to one of the preceding claims, characterized in that the switching spring (26) after overcoming their switching point at one Stop (52) is supported, preferably immediately at their operating point (47). Temperature switch, in particular according to one of the preceding Claims, characterized in that Expansion element (14) via a lever (45) on it Switch spring (26) acts, the lever on one side supported in the manner of a cutting edge bearing and with its other side (46) on the switching spring (26) acts. Temperature switch according to claim 8, characterized in that the counter bearing of the cutting edge bearing a switch spring support (27) is provided and the Lever (45) is attached to this. Temperature switch according to claim 8, characterized in that the lever (45) has an L-shape and in particular in at least one recess (50) Switch spring carrier (27) is guided. Temperature switch according to one of claims 8 to 10, characterized in that the vaginal position (49) forming support leg (48) of the L-shaped lever (45) a bifurcated form with two spaced apart has bearing points (49) lying apart from one another, wherein the support legs (48) preferably in lateral recesses (50) of the switch spring support (27) engage and secured there by a snap lock (51) are. Temperature switch according to one of the preceding claims, characterized in that the area of Switch contacts (31, 32) of the snap switch (25) from an insulating cover (53) is surrounded.

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