EP0201002A2 - Thermally controlled electrical switch element, in particular a thermostat or temperature limiter - Google Patents

Abstract

The invention relates to a thermally controlled electrical switching element in the form of a temperature controller or a temperature limiter. A bimetal spring washer and a steel washer that can be arched out on both sides are arranged in parallel on a base. The bimetallic spring washer is mounted in its edge area in such a way that it can bulge centrally above a spring temperature in a first direction and below a springback temperature in an opposite second direction. The steel disc mounted on the edge together with the bimetallic spring washer is also put through in the first direction when the spring washer is arched and thereby opens a switch contact interrupting the current flow to an electric heating element via an actuator acting in the center. In order to enable a manual opening and closing of the switching contact pair present in the switching element in a simple manner, an actuating arm is arranged in the edge region of the steel disk, the actuating arm of which is rigidly connected to the edge region of the steel disk and the actuating end of which is either connected to a manually operable button or is designed as such.

Description

The invention relates to a thermally controlled electrical switching element, in particular a temperature controller or a temperature limiter with the features of the preamble of claim 1.

Switching elements of this type are always used when, in a relatively simple manner, a temperature is to be regulated either around a control point which cannot be influenced by the customer and is therefore preset in the factory or a temperature limitation is to be carried out. Typical areas of application for such thermally controlled electrical switching elements are household appliances, for example electric cooking pots, deep fryers, hairdryers, irons (simple design without the possibility of temperature adjustment by the operator) and the like. The essential elements of such switching elements are a bimetallic spring washer and a switching contact that can be switched into the current path of a heating element, which are arranged together in or on a base. The bimetallic spring washer is mounted in its edge area in such a way that it can bulge centrally above a crack temperature in a first direction A and below a second crack temperature in a second direction B. The moving part of the switching contact is coupled to the jumping movement of the center of the bimetallic spring washer via an actuator (for example an axially displaceable pin) such that the contact is open in one of the directions (for example A) when the bimetallic spring washer bulges. Together with the bimetallic spring washer, there is also a steel washer which, when the bimetallic spring washer is curved in the first direction, can also be passed through or arched through in the first direction. The actuator acts on them in the middle and - depending on the position of the spring washer - opens the switch contact.

From US-PS 4,053,859, for example, a temperature limiter with the features of the preamble of claim 1 is known, in which the switch contacts can be closed again manually by pressing an axially extending pin after thermal triggering of the switching element. If the device provided with the switching element is to be switched off manually, an additional external switch in the current path must be switched on.

The invention has for its object to develop a thermally controlled electrical switching element with the features of the preamble of claim 1 such that manual opening and closing of the pair of switching contacts present in the switching element is made possible in a simple manner. This object is achieved by the characterizing features of claim 1, advantageous developments of the invention result from the subclaims.

First of all, the invention advantageously uses the snap properties of the steel disc to manually move the switch contact either into a permanently open or permanently closed position, the switch contact opening suddenly. The transmission of the movement of a switch-off button on the steel disk has a particularly advantageous effect out. An adjusting arm is fastened in the edge area of the pane, which, in the manner of a two-armed lever supported by the edge-side pane bearing, pushes the steel pane from one arch position to the other arch position. A central action on the steel disc (or the bimetallic disc) by any centrally acting restoring means can be completely omitted, so that the jumping behavior of the disc is not adversely affected. The switch-off rapid-force movement is carried out by the disc center, which ensures a sudden tearing of the contact both with thermal tripping and with manual tripping. With manual release, the edge area of the disk, which is influenced by the return arm, is arched in the opposite direction until the center of the disk follows abruptly and the contact opens.

Claims 2 and 3 relate to the special design of the switching element either as a temperature limiter, in which case the steel disk is designed as a bistable spring washer (claim 2) or as a temperature controller, the steel disk then being designed as a monostable spring washer that can be bulged out on both sides (claim 3).

Due to the features of the following subclaims 4 - 13, the switching element can be manufactured and operated in one or the other compact, simple, robust and very reliable manner. Claims 18-20 describe a particularly advantageous embodiment of a double regulator which is to be used on household appliances in which two different temperatures are to be regulated as an alternative.

Claims 25 and 26 claim in a more general form the steel disc that can be bulged on both sides for controlling the movement contact of a thermally controlled electrical switch with an actuating arm attached in the edge zone.

• Fig. 1 einen Temperaturbegrenzer einer ersten Auführungsform - teilweise im Schnitt -;
• Fig. 2 eine Draufsicht auf den Temperaturbegrenzer gemäß Fig. 1;
• Fig. 3 eine Draufsicht auf eine Stahlscheibe mit gesondert angesetztem Rückstellarm;
• Fig. 4 eine Draufsicht auf eine Stahlscheibe mit einstückig angeformtem Rückstellarm;
• Fig. 5 eine vergrößerte Schnittdarstellung der Bimetallscheibe und Stahlscheibe in "Einschaltstellung";
• Fig. 6 eine vergrößerte Schnittdarstellung mit in einem Gehäuseteil geführten Stellgliedern mit Stahlscheibe in "Ausschaltstellung";
• Fig. 7 eine Draufsicht auf einen Temperaturbegrenzer zweiter Ausführungsform,
• Fig. 8 den Temperaturbegrenzer gemäß Fig. 7 im Schnitt gemäß VIII-VIII;
• Fig. 9 eine monostabile Stahlscheibe mit daran einstückig angeordnetem Stellarm;
• Fig. 10 eine monostabile Stahlscheibe mit daran einstückig angeordnetem Stellarm;
• Fig. 11 einen Schnitt durch eine Bimetallsprungscheibe und daran in Parallellage anliegende Stahlscheibe in Stellung B;
• Fig. 12 eine schematische Schnittdarstellung ähnlich Fig. 1 mit angedeutetem Stellglied, Schaltkontakt, Ausschalteinrichtung, Reglersockel und Grundplatte;
• Fig. 13, 13a einen Teilschnitt, zum Teil schematisiert, durch eine weitere Reglerausbildung;
• Fig. 14 einen Schnitt durch einen Doppelregler, wobei der linke Reglerteil in manueller Ausschaltstellung und der rechte Regler in Einschaltstellung ist.

The invention is explained in more detail using exemplary embodiments in the drawing figures. These show:

• 1 shows a temperature limiter of a first embodiment - partly in section -;
• FIG. 2 shows a top view of the temperature limiter according to FIG. 1;
• Figure 3 is a plan view of a steel disc with a separate return arm.
• Figure 4 is a plan view of a steel disc with integrally molded return arm.
• Fig. 5 is an enlarged sectional view of the bimetallic disc and steel disc in the "on position";
• Figure 6 is an enlarged sectional view with actuators guided in a housing part with a steel disk in the "switch-off position";
• 7 is a plan view of a temperature limiter of the second embodiment,
• 8 shows the temperature limiter according to FIG. 7 in section according to VIII-VIII;
• 9 shows a monostable steel disk with an adjusting arm arranged thereon in one piece;
• 10 shows a monostable steel disk with an adjusting arm arranged thereon in one piece;
• 11 shows a section through a bimetallic spring washer and a steel washer resting thereon in parallel position in position B;
• 12 shows a schematic sectional illustration similar to FIG. 1 with an indicated actuator, switch contact, switch-off device, controller base and base plate;
• 13, 13a a partial section, partly schematized, through a further controller design;
• 14 shows a section through a double regulator, the left regulator part being in the manual switch-off position and the right regulator being in the switch-on position.

1 consists of a housing 10, in which an iw circular bimetallic spring washer 12 and a bistable bulging steel washer 14 are arranged in parallel, the bimetallic spring washer 12 being mounted in its edge region 16 in such a way that it is centrally above a jump temperature 5 in a first direction (direction A according to FIG. 5) and in an opposite second direction (direction B) below a return temperature. The be together with the bimetallic spring washer (in the following as spring washer 12 draws) edge-mounted steel disk 14 is also put through in this direction when the spring washer is curved in the first direction A and in doing so presses an actuator 18 in direction A which, with its end 20 facing away from the disks, raises the movement contact of a switching contact 22, which between the Housing 10 protruding terminal tabs 24 is turned on. More precisely, the actuator penetrates a recess 28 of the movement contact with a taper 26, the taper 26 protruding from the top of the housing and serving as a switch. A central pressure in the second direction (B) can be manually exerted on the center of the steel disk 14 by the taper 26, whereby the contact 22 closes and the steel disk 14 springs back into the switch-on position shown in FIG. 5.

As is also clear from FIG. 1, the lower part 30 of the housing 10 is enclosed by a pot-like metallic housing part 32, which is used for heat transfer to the spring washer 12 lying on the inside of the housing part 32.

As can be seen in particular in FIGS. 1 and 3-6, a return arm 36 is provided in the edge zone 34 of the steel disk 14, the rest 38 of which is rigidly connected to the edge region 34 of the disk 14 and the actuating end 40 of which is connected to a switch-off button or is designed as such. The force required to open the contact 22 on the actuating end 40 of the return arm 36 is in the direction of arrow "C" according to FIG. 5.

The position end 38 of the reset arm is fastened flatly on the edge zone 34 of the disk 14 and projects into the disk surface approximately over half the radius “r / 2”. According to FIGS. 3-6, the return arm 36 projects radially from the disk edge 42, its protruding length "1" from the disk edge 42 corresponding approximately to the disk radius "r".

The actuating end 40 of the reset arm 36 is operated by a reset element 44 which can be displaced in the housing 10 (cf. embodiment according to FIGS. 7 and 8). But it is also possible to reset arm 36 i. w. to run perpendicular to the surface of the disc 14, as shown in Fig. 1. There the actuating end 40 of a Z-shaped return arm 36 protrudes from the metallic housing part 32 enclosing the bimetal and steel disk in a pot-like manner. Due to the Z-shaped bend of the return arm 36, the second or middle Z-leg 46 runs approximately parallel to the cylindrical section of the metallic housing part 32, the first or lower Z-leg is attached flat to the edge zone 34 of the steel disk 14, to open the contact the upper or third Z-leg (actuating end 40) must be actuated in the direction of arrow "D" according to FIG. 1.

It is also important that the return arm 36 is made of spring steel in order to cushion excessive hand forces when the actuating end 40 is operated manually and not to transmit it to the sensitive spring washers.

The temperature limiter according to the second exemplary embodiment according to FIGS. 7 and 8 has an approximately flat right angular housing 50, in which the disks 12, 14 are mounted off-center such that the center of the disks lies approximately at point "Z" in FIG. 7. The actuator 18 also runs through the point "Z" and acts - as already mentioned above - on the center of the disk 14. The edge of the disks 12 and 14 is indicated by dashed lines in FIG. 7.

The return arm 36 protrudes radially from the disk 14, as shown in FIGS. 3-6, and is arranged in the housing in such a way that the actuating end 40 comes to rest under the point “X” according to FIG. 7. At this point there is the reset element, which is arranged in the housing 50 so as to be longitudinally displaceable parallel to the actuator 18.

On the flat side of the housing 52 facing away from the disks 12, 14, switch buttons (on button 54, off button 56) are provided which interact with the actuators 18 and 44. It is important that the pressure direction for operating both buttons 54 and 56 is in the same direction in direction 58.

In the exemplary embodiment shown in FIGS. 7 and 8, the terminal contact tabs 60, the switch contact 22 and the switch 54 are in a first housing groove 62, the switch 56 for a second housing groove 64. All elements are connected to the groove bottoms by rivets. As can be seen in particular in the sectional view according to FIG. 8, the switch 54 designed as a spring tongue, the movement contact of the switch contact 22 and the connection contact tab 60 on the right in the drawing are held by a common rivet 66 on the groove base. Thereby there is an approximate parallel position between the switch 54 designed as a spring tongue and the movement contact of the switch contact 22, so that it is possible to apply the switch contact 22 in the contact closing direction by actuating the switch 54 in direction 58. As a result, the contact is closed and, via the actuator 18, the steel disk 14 is brought into the position shown in FIG. 5, provided that the bimetal disk 12 is below its return temperature.

The ON button 54 and the OFF button 56 are of identical design and are located parallel to one another in their respective housing grooves 62, 64. Both buttons 54, 56 act with their central region on the actuator 18, 44 assigned to them in the direction of the disks 12, 14. Both buttons 54, 56 stand with their free ends out of the housing grooves 62, 64 and can deflect with the upward bent free ends into the groove without fear of destruction or bending of the switching elements.

In the following, reference is first made to FIG. 12. There, a temperature controller 101 is shown schematically, which has a controller base 102, a bimetallic spring washer 103, a switch contact 104 which can be switched into the current path of a heating element, not shown, and a monostable steel disk 105. The bimetallic spring washer 103 is supported in its edge region 106 on a base plate 107 in such a way that its center 108 is above a first jump temperature in a first direction A and below a second jump temperature in an opposite direction B. can arch. In Fig. 12 the bimetal spring washer is shown in position B.

The moving part 109 of the switching contact 104 is connected to the center 108 of the bimetal spring washer via an actuator 110 in such a way that the switching contact 104 is pressed open in the direction A when the bimetal spring washer bulges.

Between the actuator 110 and the bimetallic spring washer 103, the aforementioned steel washer 105 is located in a parallel position on the latter. This steel washer is a so-called monostable bulging steel washer, i. H. a steel disc, which can be put through from a first direction of curvature to a second direction of curvature by manual action, but automatically springs back to its original direction of curvature when the manual action decreases.

In order to carry out this through movement, an actuating arm 112 is arranged in the edge zone 111, the adjusting end 113 of which is connected to the edge region of the steel disk 105 in a flexurally rigid manner and the actuating end 114 is acted upon by a switch-off device 115. In the example shown in FIG. 12, the switch-off device 115 is designed as a push button with a self-holding function, which acts on the actuating end 114 with its inner end 116. If the switch-off device 115 is pressed in in the direction of the arrow 117, the steel disk 105 jumps in the direction A, moves the actuator 110 in the direction of the arrow 118 and suddenly opens the switch contact 104. The bimetallic snap disk 103 remains unaffected in the curved position B during this manual switch-off.

11 shows particularly clearly how the bimetal spring washer 103 and the steel washer 105 - both in the rest state (position B) - lie against one another in a parallel position. If the bimetallic spring washer 103 jumps over to the bulge position A as a result of a temperature rise above the first jump temperature, it also takes the monostable steel washer into the A position. In other words, the steel plate performs a forced movement together with the bimetal spring plate.

9 and 10 show two exemplary embodiments of the monostable steel disk.

As can be seen particularly clearly from FIG. 9, the adjusting arm 112 can be arranged with its adjusting end 113 flat on the edge zone 111 of the steel disk 105, for example welded or soldered on. Its protruding length 1 beyond the disc edge 119 corresponds approximately to the radius r of the steel disc 105, and the actuating arm also projects into the disc surface approximately over half the radius r / 2. In Fig. 10 it is indicated that the actuating arm can also be formed in one piece with the steel disc.

In the following, reference is made to FIGS. 13 and 13a. There is shown a controller in which the bimetallic spring washer and the steel washer are arranged in a pot-shaped metallic housing part 130. Bimetal spring washer 103 and steel washer 105 lie in parallel position (as in the other embodiments) on the bottom 131 of the housing part s 130, the actuator 132 is perpendicular to the middle plane of the bimetal spring washer and the steel washer and is guided in an iw circular base part 133, which is completely enclosed by the housing part 130. In the upper part 134 of the controller 105, the switching contact (not shown in more detail) is arranged, which (as in the other exemplary embodiments also) is opened or closed by the actuator 132 as a result of the arching movements of the bimetallic spring washer and / or the steel washer. The terminal lug 135 is connected to the switch contact.

After it is expedient to design the pot-shaped housing part 130 as closed as possible in its lower region (this can dip into heat reservoirs and therefore react very immediately to the heat present there), the actuating arm i. w. Bent in a Z-shape, the first Z-leg 140 being arranged flat on the edge region of the steel disk 105 or merging into it, the second Z-leg 141 runs approximately parallel to the cylindrical section 135 of the housing part 130 and the third Z-leg 142 as the actuating end protrudes from the housing part 130.

If the actuating end is pressed in the direction of arrow 143 according to FIGS. 13 and 13a, the steel disk 105 (and only this) jumps from the arched position B shown in FIG. 13a into the arched-out position A which is arched upwards.

In the double regulator shown in FIG. 14, two regulators 101, 101 ′ are arranged side by side in a parallel position on a common heat-transferring base plate 150. In the example shown in FIG. 14, the switch-off device 151, 151 'is again designed and suitable as an axially displaceable pin which protrudes laterally from the controller bases 102, 102' Actuating arms 112, 112 'jointly or alternatively. Common application means that the current paths are interrupted by both regulators and the heating element downstream of the two regulators is thus completely switched off. If only one controller is switched off by the associated switch-off device 151 or 151 ', control is carried out in the target temperature range associated with the switched-on controller. If both controllers are switched on, the regulation takes place due to the parallel connection of the two controllers by the higher control setpoint.

As can also be seen from the sectional views of the controllers 101, 101 ', the actuating arms 112, 112' protrude from an opening 152, 152 'arranged between the base plate 107, 150 and the controller base 102, 102', which at the same time provides a certain guidance for the actuating arms 112, 112 'against rotation together with the steel discs.

It can also be seen from FIG. 14 that the common base plate 150 projects laterally beyond the bases 102, 102 'of the controllers 101, 101' and the standoff length Z, Z 'of the actuating arms 112, 112' is smaller than the standover length Ü, Ü of the base plate 150. As a result, the forces of the switch-off device directed against the base plate can be effectively absorbed.

Claims (26)

1. thermally controlled electrical switching element, in particular temperature controller or temperature limiter,
with the following features: - An essentially circular bimetal spring washer and a bulging steel washer are arranged in parallel on a base, whereby - The bimetallic spring washer (12, 103) is mounted in its edge region (16) in such a way that it bulges centrally above a spring temperature in a first direction (A) and below a springback temperature in an opposite second direction (B), - The together with the bimetallic spring washer (12, 103) on the edge of the steel washer (14, 105) is also passable in the first direction (A) when the spring washer is arched and thereby a current flow is applied via an actuator (18, 110) which acts on it in the middle switch contact (22, 104) which interrupts an electrical heating element and can be reset in the second direction (B) to close the switch contact (22, 104),
characterized by the following features: an adjusting arm (36, 112) is arranged in / on the edge zone (34, 111) of the steel disc (14, 105), - The position end (38, 113) with the edge region of the steel disc (14, 105) is rigidly connected and - The actuating end (40, 114) is either connected to a manually operated button or is designed as such. 2. Switching element according to claim 1,
characterized,
that it is designed as a temperature limiter and the steel disc (14) is designed as a bistable spring washer. 3. switching element according to claim 1,
characterized,
that it is designed as a temperature controller (101) and the steel disk (105) is designed as a monostable spring washer that can be bulged out on both sides. 4. switching element according to claim 3,
characterized,
that the actuating end (114) of the actuating arm (112) can be acted upon by a switch-off device (115) which transfers and / or holds the monostable steel disk (105) in the first bulging direction (A). 5. Switching element according to one of the preceding claims 3 or 4,
characterized,
that the steel disc (105) between the bimetallic spring washer (103) and the actuator (110) is arranged. 6. Switching element according to one of the preceding claims,
characterized,
that the actuating arm (112) protrudes laterally from the base (102). 7. switching element according to claim 6,
characterized,
that the actuating arm (112, 112 ') protrudes from an opening (152) arranged between a heat-transmitting base plate (107) and the regulator base (102). 8. switching element according to claim 6,
characterized,
that the longitudinal direction of the actuating arm (112) extends approximately at right angles to the longitudinal direction of the moving part (109) of the switching contact (104). 9. Switching element according to claim 1,
characterized,
that the adjusting arm (36, 112) with its adjusting end (38, 113) is fixed flat on the edge zone (34, 111) of the steel disc (14, 105). 10. Switching element according to one of the preceding claims,
characterized,
that the positioning end (38, 113) protrudes approximately over half the radius (r / 2) of the circular steel disk (14, 105) into the disk surface. 11. Switching element according to claim 1,
characterized,
that the actuating arm (36, 112) protrudes radially from the edge of the disc and its length (1) from the edge of the disc corresponds approximately to the radius of the disc (r). 12. Switching element according to claim 1,
characterized,
that the adjusting arm (36, 112) is designed as a resilient metal strip, the adjusting end (38, 113) of which is glued, welded or soldered to the steel disc (14, 105). 13. Switching element according to claim 1,
characterized,
that the adjusting arm (36, 112) extends approximately at right angles to the surface of the pane. 14. Switching element according to claim 3,
characterized,
that the actuating end (114) of the actuating arm (112) protrudes from a metallic housing part (130) enclosing the bimetal (103) and the steel disc (105) in a pot-like manner. 15. Switching element according to claim 14,
characterized,
that the actuating arm (112) is bent in a Z-shape such that the first Z-leg (140) is arranged flat on the edge region of the steel disc (105) or merges into it, the second Z-leg (141) approximately parallel to the cylindrical section of the metallic housing part and the third Z-leg (142) protrudes from the housing part (130) as the actuating end. 16. Switching element according to one of the preceding claims,
characterized,
that the adjusting arm (36, 112) is integrally formed with the steel disc (14, 105). 17. Switching element according to one of the preceding claims,
characterized,
that the width of the actuating arm (36, 112) is approximately 15% - 35% of the disk diameter (2r). 18. Switching element according to one of the preceding claims,
characterized,
that in parallel position two controllers (101, 101 ') are arranged on a common heat-transferring base plate (150) and the switch-off device is designed for simultaneous and / or alternative loading of the actuating arms (112). 19. Switching element according to one of the preceding claims,
characterized,
that the common base plate (150) protrudes laterally beyond the base (102, 102 ') of the controllers (101, 101') arranged on it and the stand-off length (Z, Z ') of the actuating arms (112, 112') is less than or equal to the protruding length (Ü, Ü ') of the base plate (150). 20. Switching element according to one of the preceding claims,
marked by
its use on household appliances, in which two different temperatures are alternatively controlled. 21. Switching element according to one of the preceding claims,
characterized,
that the disks (12, 14) are mounted eccentrically in an approximately flat-rectangular housing (50) which is penetrated by two longitudinally displaceable actuators (actuator 18, reset member 44) which run parallel to one another and on which the disks (bimetallic disk 12, steel disk 14) facing away from the flat side of the housing (52) with switch buttons (on button 54 / off button 56) which are connected to the actuators (18, 44). 22. Switching element according to claim 21,
characterized,
that the terminal contact lugs (60), the switch contact (22) and the switch (54) in a first housing groove (62) and the switch (56) are arranged in a second housing groove (64) and the housing grooves (62, 64) parallel to each other run. 23. Switching element according to claim 21,
characterized,
that the switch (54) acts on the switching contact (22) acted upon by the actuator (18) in the contact closing direction. 24. Switching element according to claim 21,
characterized,
that the two switch buttons (ON button 54 / OFF button 56) are designed as spring tongues arranged in the housing grooves (62, 64), which are fastened with their fastening ends to the respective groove base, with their movement ends protrude from the grooves (62, 64) and with their Actuate the actuating element (18) or the resetting element (44) in the central area via the movement contact. 25. A steel spring washer (14, 105) that bulges out on both sides, the center of which acts on the movement contact of a thermally controlled electrical switch and is in turn acted on centrally by a bimetal element,
characterized,
that an actuating arm (36, 112) is arranged in its edge zone, the actuating end of which is connected to the edge region of the steel disc (14, 105) in a flexurally rigid manner and the actuating end of which is either connected to a switch-off button or is designed as such. 26. steel spring washer according to claim 25,
marked by
their use as a holding element in a temperature limiter or as a snap element in a temperature controller.

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