This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2018/064856, filed on Jun. 6, 2018, and claims benefit to German Patent Application No. DE 10 2017 112 813.1, filed on Jun. 11, 2017. The International Application was published in German on Dec. 20, 2018 as WO 2018/228882 under PCT Article 21(2).
The invention relates to a double-contact switch with vacuum switching chambers which is particularly suitable for use in a hybrid switching arrangement and a hybrid switching device.
International patent application WO 2015/091105 A1 discloses a hybrid switching arrangement for a hybrid switching device; in this document see
In order to ensure as high a functional reliability as possible, in particular when switching currents in the range of a few hundred amps, care must be taken among other things in the design of such switches or switching arrangements that when such high currents are switched on permanent welding of the switching contacts does not occur. A welding of switching contacts can occur above all during the mechanical bounce at the moment of re-contacting.
In case of the aforementioned hybrid switching arrangements, a welding of in particular the commutation contacts can be successfully prevented by briefly activating the parallel-arranged power semiconductor during the switching-on phase so that the load current flows exclusively through said power semiconductor. During this phase which is critical for the welding of contacts, the commutation contact thereby remains load-free.
Under certain circumstances, a welding of the contact pair of the first circuit-breaker to which no semiconductor switch is connected in parallel can occur, for example when it closes at approximately the same time that the commutation contact closes. Since the isolating contact and the commutation contact are arranged in series both electrically and mechanically, a welding of the isolating contact is possible in principle during the phase of the switch-on bounce if, at the moment of its brief lifting, a load current is already flowing through the commutation contact or even through the semiconductor switch.
Japanese Utility Model JP S52 113371 U describes a double-contact switch with vacuum switching chambers and stop means which limit the path of movable contacts.
In an embodiment, the present invention provides a double-contact switch, comprising: a first and second tubular vacuum switching chamber formed as partial switching chambers of a switching tube; an electrode fixed in the switching tube and arranged between the first and second vacuum switching chambers and having a first fixed contact projecting into the first vacuum switching chamber and a second fixed contact projecting into the second vacuum switching chamber; a first electrode arranged in the first vacuum switching chamber and movable within the first vacuum switching chamber in an axial direction thereof, the first electrode having a region which bears a contact and is closed off in a gastight manner relative to an exterior of the first vacuum switching chamber; a second electrode arranged in the second vacuum switching chamber and movable within the second vacuum switching chamber in an axial direction thereof, the second electrode having a region which bears a contact and is closed off in a gastight manner relative to an exterior of the second vacuum switching chamber, the second electrode being fixed with respect to the switching tube, wherein the first electrode for opening and closing the contacts is movable with respect to the switching tube, wherein stop means are provided such that an axial movement of the first electrode for opening the switching contacts in the vacuum switching chambers is limited to a preset distance relative to the switching tube, and when the stop means come up against each other a mechanical impulse acting on the switching tube is generated in a direction of the axial movement of the movable electrode in order to break apart any possibly existing welding of the contacts, and wherein the stop means have a step on a shaft of the first electrode and a stop face for the step, which stop face is formed by an inner end face of a guide collar for the first electrode.
The present invention will be described in even greater detail below based on the exemplary figures. The invention is not limited to the exemplary embodiments. Other features and advantages of various embodiments of the present invention will become apparent by reading the following detailed description with reference to the attached drawings which illustrate the following:
In an embodiment, the present invention provides a further improvement of double-contact switch with vacuum switching chambers that is known from patent application WO 2015/091096 A1.
An idea underlying the present invention consists in structurally modifying the double-contact switch known from WO 2015/091096 A1 in such a way that stop means are provided which, during the opening of the switching contacts, limit the axial movement of a movable electrode of the switch with respect to a switching tube of the switch such that when the stop means come up against each other a mechanical impulse acting on the switching tube is generated in the direction of the axial movement of the movable electrode in order to break apart any possibly existing welding of the contacts. In other words, according to the invention, the axial movement of the movable electrode is limited to such an extent by the stop means that in the case of a normal opening movement in which the movable electrode is moved by a preset distance, it comes up against a stop and an accompanying mechanical impulse occurs which acts on the switching tube. The mechanical impulse is in this case dimensioned such that any existing welding of the contacts, for example between an electrode provided in the switching tube and a fixed electrode, can be broken apart.
According to one embodiment, the invention now relates to a double-contact switch having a first and a second tubular vacuum switching chamber that are designed as partial switching chambers of a switching tube; an electrode fixed in the switching tube and arranged between the first and second vacuum switching chambers and having a first fixed contact projecting into the first vacuum switching chamber and a second fixed contact projecting into the second vacuum switching chamber; a first electrode arranged in the first vacuum switching chamber and movable within it in the axial direction and having a region that bears a contact and is closed off in a gastight manner from the exterior of the first vacuum switching chamber; a second electrode arranged in the second vacuum switching chamber and movable within it in the axial direction and having a region that bears a contact and is closed off in a gastight manner from the exterior of the second vacuum switching chamber. The second electrode is fixed with respect to the switching tube while for opening and closing the contacts the first electrode is movable with respect to the switching tube. Stop means are provided in the switch in such a way that the axial movement of the first electrode for opening the switching contacts in the vacuum switching chambers is limited to a preset distance relative to the switching tube and, when the stop means collide, a mechanical impulse acting on the switching tube is generated in the direction of the axial movement in order to break apart any possibly existing welding of the contacts.
The preset distance is in particular shorter than a maximum possible switching stroke of the first electrode for opening the switching contacts in the vacuum switching chambers. This makes it possible to ensure that a sufficiently strong mechanical impulse is generated when the stop means collide in order to break apart any welds.
In particular, the switch may have a housing in which the second electrode is fixed and which has an opening for movable mounting of the first electrode. The maximum possible switching stroke is defined here by a stop on an upper end face of the switching tube on the housing. The housing can also serve for the attachment of an electromechanical drive for the first movable electrode.
The stop means may have a step on the shaft of the first electrode and a stop face for the step formed by a cover of the switching tube. In this case, the step abuts against the inside of the cover of the switching tube when the first electrode is moved out of the switching tube.
The stop means may also have a step on the shaft of the first electrode and a stop face for the step formed by the inner end face of a guide sleeve for the first electrode. A guide sleeve has the advantage that with a suitable choice of material the impact loads occurring when the stop means collide result in no or substantially less impairment of the other, in some cases more sensitive components of the switching tube, since the step does not impact directly on these components.
The step may be incorporated into the shaft of the first electrode. However, the step can also be formed by a separate component attached to the shaft of the first electrode.
The outer diameter of the step is dimensioned in particular such that no contact with the inside of the gastight barrier can occur during an axial movement of the first electrode.
In the closed state of the contacts, the distance between the step and the stop face can be dimensioned such that it corresponds substantially to a preset nominal opening distance of the first fixed contact and of the range of the first electrode carrying a contact.
The stop means may also comprise a shield of a gastight barrier of the first vacuum switch chamber and a stop face for the shield formed by the inside of a cover of the switching tube.
Further advantages and possible applications of the present invention result from the following description in conjunction with the exemplary embodiments illustrated in the drawings.
In the following description, the same functionally equivalent and functionally related elements may be provided with the same reference numerals. Absolute values are given below by way of example only and are not to be construed as limiting the invention.
The principle of operation of the double-contact switch according to the invention will now be explained with reference to
A stationary electrode 18 which divides the switching tube 16 into the two partial switching chambers 12 and 14 is arranged approximately centrally in the switching tube 16. The fixed electrode 18 has a first fixed contact 20 and a second fixed contact 22. The two fixed contacts 20 and 22 can be implemented, for example, by the two end faces of the fixed electrode 18. The first fixed contact 20 projects into the first vacuum switching chamber 12 and the second fixed contact projects into the second vacuum switching chamber 14.
A first electrode 24 movable in the axial direction is arranged in the first vacuum switching chamber 12. The electrode 24 has a region 26 which bears a contact, which serves to contact the first fixed contact 20 of the electrode 18 and forms a first isolating contact of the switch 10 which can serve, for example, as a commutation contact in a hybrid switching arrangement. The region 26 and a part of the electrode 24 are closed off in a gastight manner by means of a metal bellows 28. For this purpose, the metal bellows 28 is connected at one end to the shaft of the electrode 24 and at the other end to the front end of the first vacuum switching chamber 12.
Also arranged in the second vacuum switching chamber 14 is a second electrode 30 with a region 32 bearing a contact, which second electrode in principle is movable in the axial direction like the first electrode 24, but which in the switch 10 shown is fixed with respect to the switching tube 16. The second electrode 30 can be attached in different ways; in the switch 10 shown in
In the case of the switch 10 with housing 42 shown in
To open the switch contacts 20, 26 and 22, 32 which in
The axial movement of the first electrode 24 with respect to the switching tube 16 is limited by stop means 36, 38. The stop means comprise a step 36 on the shaft of the first electrode 24 and a stop face 38 formed by the top cover of the switching tube 16. In this way, during outward movement or axial movement of the first electrode 24 in order to open the isolating contact comprising the contacts 20 and 26, the step 36 after a preset distance D comes up against the stop face 38 or the cover of the switching tube 16. A mechanical impulse is generated by this coming together or collision, in particular if the first electrode 24 connected to the switching drive has not yet reached its final position. Due to the mechanical impulse, the switching tube 16 experiences a shock load which is transferred directly to the contact pair 22, 32. Depending on the force reserve and the electro-mechanical switching drive as well as on the contact material of the contact pair 20, 32 the shock or impulse load is generally sufficient to break apart any welding of contacts 22 and 32. With the separation of the contacts 22 and 32, a movement of the switching tube 16 is thus initiated in such a way that it also sets said switching tube in motion in the direction of action of the electromechanical drive and thereby brings about the further opening of the contacts 22, 32 of the second isolating contact; see
The opening movement of the contacts of the switch 10 is stopped as soon as the outer end face of the top cover of the switching tube 16 meets the inner wall of the housing 42 serving as stop face for the switching tube 16, thereby producing the contact opening distances of the two contact pairs of the switch 10 after switch-off.
In contrast to the switches shown in
Several design options for the switches described above are explained below: with regard to repetitive impact loads in the case of welded contacts, the top cover of the switching tube, if it serves as a stop face for a step or a shield, can be manufactured, for example, from a stainless steel of sufficient wall thickness. The cover's edge face facing the first vacuum switching chamber can be soldered to the latter via a special metalization layer of a ceramic ring 16′ serving as an electrical insulator, which in practice can ensure a sufficiently high strength of this vacuum-tight soldered connection even at high numbers of switching operations as in the case of contactors.
While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. It will be understood that changes and modifications may be made by those of ordinary skill within the scope of the following claims. In particular, the present invention covers further embodiments with any combination of features from different embodiments described above and below. Additionally, statements made herein characterizing the invention refer to an embodiment of the invention and not necessarily all embodiments.
The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.
Number | Date | Country | Kind |
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10 2017 112 813.1 | Jun 2017 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2018/064856 | 6/6/2018 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2018/228882 | 12/20/2018 | WO | A |
Number | Name | Date | Kind |
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2264024 | Glashan | Nov 1941 | A |
3405245 | Toshio Ito | Oct 1968 | A |
4492837 | Crouch | Jan 1985 | A |
5543598 | Duffour | Aug 1996 | A |
8947188 | Hammer | Feb 2015 | B2 |
9165726 | Dohnal | Oct 2015 | B2 |
9196439 | Gentsch | Nov 2015 | B2 |
9293273 | Albrecht | Mar 2016 | B2 |
20160322184 | Meissner et al. | Nov 2016 | A1 |
20160322185 | Meissner et al. | Nov 2016 | A1 |
Number | Date | Country |
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3020800 | Dec 1981 | DE |
S52113371 | Aug 1977 | JP |
WO 2015091096 | Jun 2015 | WO |
WO 2015091105 | Jun 2015 | WO |
Entry |
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Written Opinion of the International Searching Authority of PCT/EP2018/064856 dated Sep. 20, 2018, p. 1-7. |
Number | Date | Country | |
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20200312593 A1 | Oct 2020 | US |