Patent Application
20240266133
This application claims priority to German Application No. 10 2023 200 840.8, filed Feb. 2, 2023, the contents of which are hereby incorporated herein in its entirety by reference.
The invention relates to a switching device for an electrical appliance or an electrical domestic appliance, in particular designed as a cyclic power control unit, and to a method for operating a corresponding switching device.
It is for example known from U.S. Pat. No. 6,211,582 B1 how to design a switching device for a hob as a cyclically operating power control unit. A switch is provided here with a switching spring, at whose end a switch contact is arranged. A bimetal tripping device, on which a heating element is provided for heating, acts on the switch, with the result that the bimetal tripping device deflects or bends, and so trips, in particular opens, the switch. Furthermore, an adjusting device in the form of a contour device with a contour washer of varying radius is provided, using which a power stage can be set at the power control unit for a heating device of the hob. The power stages of the power control unit range here from 0% to 100%, wherein in particular a substantially arbitrary intermediate power stage between zero power and full power may be set. Due to the heating and to the bimetal tripping device, the power control unit with the switch operates in a cyclical manner. At the power stage 100%, heating is permanently active as a rule. This requires energy, which remains unused for functional purposes and can also cause thermal problems.
The object of the present invention is to provide a switching device as stated above and a method for the operation thereof, using which prior art problems can be avoided and which make it in particular possible to effect a permanent operation at full power or to set the power stage permanently at 100%, preferably without consuming energy or causing thermal problems.
This object is solved by a switching device having the features of claim 1 and by a method having the features of claim 23. Advantageous and preferred embodiments of the invention are the subject matter of further claims and are explained in greater detail below. Some of the features are described only for the switching device or only for the method. They should however be applicable, by themselves and independently of one another, for both the switching device and a corresponding method to operate it. The wording of the claims is incorporated by express reference into the content of the description.
In accordance with the invention, it is provided that the switching device has a housing, advantageously a plastic housing. This may be in several parts, advantageously having a lower part and an upper part. The switching device may have in the housing at least one switch which is designed adjustable, in its position inside the housing and/or in its shape, for setting different cycle times for a cyclic operation of the switch. Further switches may be provided as simple disconnecting switches without cycling or the like. The switching device has an adjusting device for setting different cycle times or a different cycle behavior of the switch, wherein the adjusting device acts mechanically on the cyclic switch. The adjusting device has for that purpose a rotary shaft with a varying contour device arranged thereon, or a contour washer arranged on the rotary shaft. It has along the circumferential direction a varying contour, and preferably has a varying radius. Such adjusting devices with contour devices or with a contour washer are known from the prior art, in particular also from similar switching devices, which are also known as energy controllers.
An electrothermic tripping device is also provided in the housing for the switch, wherein this tripping device has a heating element and two electrical connections to the heating element. It also advantageously has a bimetal arm which is heated by the heating element and can deform, so tripping or actuating the switch, i.e. altering its state. At least one connection on the heating element has two disconnectable connecting contacts in the current path of the connection. This allows the current supply to the heating element to be interrupted.
In accordance with the invention, the switching device has a disconnector which is designed to act mechanically on at least one of the connections of the tripping device with the two connecting contacts in order to disconnect the latter from one another, whereby the heating element is safely switched off or deactivated. The disconnector is designed such that it may be moved directly or indirectly in at least one disconnecting rotary angle range of the rotary shaft by the contour device, in order to disconnect the connecting contacts by this movement. Otherwise, the connecting contacts may advantageously be designed such that they are not disconnectable. It may be provided here that the connecting contacts can only be disconnected when the disconnector is in the disconnecting rotary angle range, and otherwise not.
The design of the connection on the heating element with the connections plus connecting contacts, which can be disconnected by means of the disconnector, allows the heating element to be switched off or deactivated in a certain disconnecting rotary angle range of the rotary shaft. It is thus for example possible, whenever the switching device or switch is to be permanently closed/switched on, for which the contour device is advantageously used, that the tripping device and above all the heating element are switched off. They are then no longer needed to keep the switch switched on. Unnecessary energy consumption at the heating element can thus be avoided, and in addition an unnecessary and above all potentially harmful overheating of the switching device due to permanent operation of the heating element can be prevented. Even if the heating element is designed such that it has a relatively low continuous output of less than 20 W or even less than 10 W, a heat buildup can occur due to the arrangement of the switching device inside the housing, which is largely closed. This can damage the housing, meaning that it must consist of high-grade and heat-resistant plastics. The invention allows the housing to be designed simpler and less expensive thanks to the reduced risk of damage from overheating. A continuous maximum temperature can then be reduced by at least 10° C. or even 20° C.
In an embodiment of the invention, the one connecting contact may be arranged on the housing in a fixed position, preferably at the connection to the tripping device with the two connecting contacts. It may in particular be designed in the form of a fixed metal connecting bridge. The other connecting contact is then advantageously a contact spring arm, flexibly pressing against it, of a metal contact spring, wherein the entire contact spring plus contact spring arms advantageously consists of metal. Another contact spring arm of this contact spring reaches the tripping device in electrically contacting manner, or is in contact therewith or with its heating element. This may also be done in flexible manner, but this is immaterial for the invention.
The contact spring is mounted in an area between the two ends of the contact spring arms, in particular mounted on the housing, for example on a mounting projection, such that it is still movable or rotatable to a certain degree, at least at one contact arm having the disconnectable connecting contacts. The mounting of the contact spring may be preferably in an area which is arranged closer to the tripping device than to the disconnector.
In an embodiment of the invention, the contact spring may consist of metal, to be electrically conductive for good contacting, and preferably also for good spring properties. It may consist of metal wire, in particular of round metal wire, alternatively of strip-like material, for example a flat strip.
In an embodiment of the invention, the contact spring may have, between the contact spring arms or the ends of the contact spring arms, a holding area extending over a mounting projection on the housing. The mounting projection may be molded onto the housing, preferably by injection molding on an underside of the housing. This mounting projection may be such that the contact spring or the two contact spring arms may be rotated about it in such a way that at least one contact spring arm, advantageously both contact spring arms, can rotate in a kind of pivoting movement about this mounting projection. Advantageously, the contact spring may be wound helically around the mounting projection, in particular when it consists of the aforementioned round metal wire.
In a further embodiment of the invention, there may be a movable transmission member between the contour device on the rotary shaft and the connection or connecting contact, which is in particular the aforementioned contact spring. This transmission member is advantageously arranged/mounted and designed such that a movement of the rotary shaft with the contour device arranged thereon is transmitted to the connection or to the contact spring, in order to move the contact spring plus the connection and thus to disconnect the connection or the connecting contacts and to switch off the heating element.
Such a transmission member can generally be a separate part, i.e. be provided additionally to the contact spring, for example also made from another material, and be simply in contact therewith after fitting of the switching device or be fastened permanently or undetachably thereto, for example by clamping or injection molding. Alternatively, the transmission member may be provided on the contact spring by the design of the latter or be formed for example by bending or shaping of the contact spring.
In an embodiment of the invention, the transmission member may be a lever mounted for rotatable movement, such that a rotary movement disconnects the connecting contacts. The lever may be in contact by a first lever end with the connection or with the contact spring, i.e. be in contact depending on the rotary position. It does not necessarily have to be in permanent contact with the contact spring, but in any event whenever it disconnects the connecting contacts. A pivot mounting of the lever may be between the two lever ends, wherein the precise arrangement of a mounting point influences the ratio of the rotary movement.
It may on the one hand be provided that the other, second lever end is in direct contact with the contour device, which is preferably arranged on the rotary shaft, such that a movement of the second lever end tripped by the rotary shaft depending on the rotary position moves/rotates the lever and thus disconnects the connecting contacts. A forced direct disconnection of the connecting contacts is then assured by direct tripping of the lever.
On the other hand, it may be provided that the other, second lever end is in contact with a slider, wherein this slider in turn is or may be in contact with the contour device such that a movement of the slider tripped by the contour device depending on the rotary position is transmitted to the lever in order to move/rotate it and to disconnect the connecting contacts. This is an indirect tripping of the lever or a forced indirect disconnection of the connecting contacts, which may nevertheless take place with sufficient safety.
In an alternative embodiment of the invention, the transmission member may be a pusher, which can be designed in particular slidable in the linear direction, alternatively in a certain arc. A first end of the pusher may be in direct contact with the contour device of the rotary shaft or with an aforementioned slider, in effect as an indirect solution. The other, second end of the pusher may be in contact with the connection or the connecting contact of the tripping device, in particular also with the contact spring or one of its contact spring arms.
In an advantageous embodiment of the invention, the transmission member may above all if it is a part separate from the contact spring, i.e. provided additionally to the contact spring, consist of plastic, preferably exclusively of plastic.
In a further embodiment of the invention, the contact spring may extend or be arranged in a different plane, extending vertically to the rotary shaft, than the contour device or contour washer for the disconnector. Additionally or alternatively, the contact spring may extend in a different plane than the transmission member, at least than a major part of the transmission member. In this way, an optimum arrangement in the housing may be found in each case.
In another embodiment of the invention, a contact spring may be provided in the switching device for the one connection contact, said spring being shaped such that a protruding section fastened thereto or formed therefrom is in contact with the contour device of the rotary shaft. It is advantageously formed on a contact spring arm which is not in contact with the heating element. This protruding section may replace the aforementioned transmission member or perform a corresponding function. The protruding section may be either additionally attached to the contact spring or integrally formed thereon.
Such a protruding section may for example be bent outwards from a wire of the contact spring or of a contact spring arm, advantageously as a U-shaped section, such that the contact spring arm extends on both sides of the protruding section. This wire may form at least one contact spring arm of the contact spring, and in particular form the entire contact spring, such that in this case the protruding section too is made by bending of the wire relative to the contact spring.
In an embodiment of the invention, the rotary angle range in which the disconnector disconnects the connecting contacts may be 1° to 45° or even 1° to 60°, or at a rotary angle between 260° and 360°, in particular when no end stop is provided, or between 270° and around 308° when such an end stop is provided. Alternatively, it may be between 300° and 360°. Preferably, the rotary angle range may be 5° to 20°. Alternatively or additionally, the rotary angle or rotary angle range may be arranged wherever the cycle times of the switch are such that the switch is permanently closed/switched on. This is a rotary angle range in which the switching device effects permanent operation of an electrical consumer operated therewith. This rotary angle range may be at an end of a possible rotary movement, for example at the high end of a power setting for the consumer. This is usually at the end of a rotation range.
In an embodiment of the invention, the contour device may have not only one, but at least two contour washers, which are arranged one above the other in the direction along the rotary shaft and on the rotary shaft, or are molded thereon, preferably by plastic injection molding. A first contour washer may be advantageously provided for the switch or for its adjustment in a cyclic operation, and another, second contour washer for the disconnector, in particular for an all-pole disconnector, i.e. for its actuation or activation in order to switch the heating element.
With the method in accordance with the invention for operating an electrical appliance with a previously described switching device, an electrical connection to the heating element is therefore disconnected for permanent closing of the switch with a certain setting of the rotary shaft plus contour device in a disconnecting rotary angle range. The heating element is thus deactivated when the switch is closed, i.e. it does not consume any energy and does not generate any disruptive or harmful heat. At the same time, the switch is closed for continuous operation of the electrical appliance or of an electrical function unit thereof, for example of a heating device.
These and further features are found in the description and in the drawings as well as in the claims, where the individual features can each be realized singly or severally in the form of sub-combinations in one embodiment of the invention, and in other fields, and can represent designs advantageous and protectable per se, for which protection is claimed here. The subdivision of the application into individual sections and subheadings does not limit the general validity of the statements made thereunder.
Further advantages and aspects of the invention can be found in the claims and in the description of exemplary embodiments of the invention that are explained in the following on the basis of the figures. The drawing shows in:
The switching device 11 is largely designed as known from the prior art. It has a switch 20, described at the outset, which is designed as a so-called quick-break switch. The switch 20 has a switch base 21 of thin springy metal, in particular sheet copper, which is fastened to a sturdy slider 22, preferably riveted on or welded on in its left-hand area. The slider 22 consists of thick metal and is connected at its left-hand end via the extended switch base 21 to a metal connecting bridge, with mechanical mounting and electrical contact. In the right-hand area, the slider 22 has a downward-projecting or outward-bent slider projection 23.
The switch 20 has a switching spring arm 24 which is fastened, for example welded or riveted, onto the right-hand free end of the switch base 21. By means of a tensioned arc 26 bent outwards from the left-hand area of the switching spring arm 24, the switch 20 is tensioned for the snap function, in that the right-hand free end of the tensioned arc 26 is on contact with or supported on a hook-like support 27 is and thus tensioned. At the left-hand free end, the switching spring arm 24 has a switch contact 29. This is, in the state shown here, in contact with a counter-contact 31 which is fastened to a contact carrier 32. This is the substantially closed contact of the switch 20. Via this, heating devices, for example of an electrical appliance in which the switching device 11 is installed, are supplied with power. In particular, these may be heating devices of an electric hob which are cyclically operated, such that the switching device 11 operates in a known manner as a so-called energy controller. In this regard, reference is made to the prior art stated at the outset.
An adjusting device 35 is provided to achieve a different behavior for the cycles of the switching device 11 or of the switch 20. A rotary shaft 36 mounted in the housing 13 has a contour washer 37, in particular made in one piece therewith. The contour washer 37 extends in a plane vertical to the rotary shaft 36 and has a varying radius. The aforementioned slider projection 23 of the slider 22 or of the switch 20 extends in the same plane and flexibly presses against the outside of the contour washer 37. Due to the varying radius of the contour washer 37, the position of the slider 22 alters and thus also the position of the support 27 fastened thereto; in this connection reference is made to the prior art. The contour washer 37 has a recess 38 which in
The switching device 11 has an electrothermic tripping device 40, as is also known from the prior art. It mainly has a heating element 41, consisting of a carrier, in particular a ceramic carrier, on whose upper side a thick-film heating conductor or other heating conductor is arranged. The heating element 41 is provided on the left with a first electrical connection 43, which discernably leads via the switch base 21 to the same connection as the switch 20.
Another, second electrical connection 44 is provided on the right of the heating element 41. A left-hand first contact spring arm 51 of a contact spring 50 is pressed against it with its free end. Since the heating element 41 has as a rule only low power, for example below 20 W or even below 10 W, no high currents need be expected, and thus contact of the contact spring 50 or of the first contact spring arm 51 is sufficient for this. Switching should also not take place at this point, as this contact should actually be permanent. It can therefore be designed relatively simple.
The contact spring 50 is bent outwards from a round metal wire and is wound in a middle area, for example three to five times, around a mounting projection 54 injection-molded on the housing lower part 14. The second contact spring arm 53 projects from the middle area downwards and is in contact with a connecting contact 55. These electrical connections 43 and 44 form the current supply to the heating element 41.
A lever 60, which has in a middle area a pivot point 61, is provided as a disconnector in
The rightward-facing second lever arm 65 is in contact with the lower end area of the second contact spring arm 53 or is only a very short distance to it. The lever 60 advantageously consists of plastic, for example similar plastic to the housing 13. It should in any event be electrically insulating.
For the functioning of the invention or of the disconnector in the form of the lever 60, it is firstly pointed out that the position shown in
As a result however, operation of the heating element 41 is also not necessary here, as it would on the one hand only unnecessarily consume energy; on the other hand, however, a relatively large amount of heat would be generated, as explained in the foregoing, and even with a relatively low power of the heating element 41 per se this may lead to thermal problems in the housing 13, which is usually closed except for a few vent openings. The disconnector in the form of the lever 60 is used for this. The movement of the slider 22 downwards moves the left-hand first lever arm 63 downwards too, so that the entire lever 60 rotates counter-clockwise for some distance. The second lever arm 65 is also rotated here, and comes into contact with the lower area of the second contact spring arm 53 or presses the latter away from the connecting contact 55. Hence the tripping device 40 and its heating element 41 are switched off; the heating element 41 thus does not generate heat unnecessarily, or at all, and does not unnecessarily consume energy.
The switching device 11 and the switch 20 may remain in the state shown in
It is thus discernable that the disconnector is only active precisely in the rotary position of
The linear guide 167 for the pusher 166 may be simply molded onto the bottom 15. The pusher 166 may be inserted from the right into the linear guide and then held captively in the linear guide by pressure from the contact spring 50 or from the downwards-facing second contact spring arm 53.
Another further embodiment of the invention is shown in
Based on the examples shown, the basic function of the invention may be deduced per se and also in detail. Furthermore, it is discernable how the invention can be achieved with separate or with integrated disconnector, i.e. with additional components or with reshaped components. Instead of the lever 60 from
In another, further embodiment of the invention, a plastic piece might be injection-molded or fastened on the end of the U-section 257 of the specially designed contact spring 250 in
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2023 200 840.8 | Feb 2023 | DE | national |
