Electrical Switch

Abstract

An electrical switch for interrupting a current path, in particular of a voltage supply in a motor vehicle is disclosed. The switch includes a contact point which is formed from a first contact piece and a second contact piece which is mounted such that it can move about a rotation axis. Here, the contact point is electrically closed when the two contact pieces are in contact and is electrically opened when the two contact pieces are not in contact. Furthermore, the electrical switch includes an actuator unit and an electrically non-conductive separating element which can be moved in a translatory manner by means of the actuator unit and is designed to isolate the two contact pieces from one another and then to keep the two contact pieces apart in order to open and to keep open the contact point and to act as an insulator between the contact faces. The actuator unit includes a movement element which is mechanically coupled to the separating element, a drive device which is designed to move the movement element in a first movement direction in order to close the contact point, a device for generating and/or storing kinetic energy, which device is designed to move the movement element and/or the separating element in a second movement direction, which is opposite to the first movement direction, in order to open the contact point, and an electromagnetic actuator.

Claims

1. Electrical switch for interrupting a currant path, with at least: a. a contact point with b. a first contact piece and c. a second contact piece mounted so as to be movable about an axis of rotation d. wherein the contact point is electrically closed when the two contact pieces are in contact, and wherein the contact point is electrically open when the two contact pieces re not in contact, wherein the electrical switch further comprises e. an actuator unit f. an electrically non-conductive separating element which can be moved in translation by means of the actuator unit and which is arranged to separate the two contact pieces from one another, to keep them separate and to act as an insulator between the contact surfaces, wherein the actuator unit comprises at least g. a moving element which is mechanically coupled to the separating element, h. a drive device arranged to move the moving element in a first direction of movement to close the contact point characterized by i. a device for at least one of generating and storing a kinetic energy in the form of potential energy, which is arranged to move at least one of the moving element and the separating element in a second direction of movement opposite to the first direction movement in order to open the contact point, and j. an electromagnetic actuator which is arranged in a first operating state to at least one of block a movement of the moving element in the second direction of movement and lock the moving element in a defined position and thus to hold the moving element in a rest position in order to keep the contact point closed, and in a second operating state to move the moving element in the direction of the drive device and to couple it mechanically with the latter so that the moving element can be moved by means of the drive device in the first direction of movement in order to close the contact point and in a third operating state, to release the moving element so that the moving element and the separating element are moved by the device for at least one of generating and storing a kinetic energy in the form of potential energy which is movable in the second direction of movement in order to open the contact point and/or so that the contact point is opened.

2. An electric switch according to the preceding claim, in which the current path is a current path of a power supply in a motor vehicle.

3. An electric switch according to claim 1, wherein an inclined section of the separating element extends obliquely to the direction of movement and the main direction of extension of the separating element, in the form of a tip, ramp or slope, so that when moving in the second direction of movement, the second contact piece is disconnected from the first contact piece.

4. An electrical switch according to claim 1, wherein the inclined section of the separating element is made of conductive resistive material.

5. An electrical switch according to claim 1, wherein the electrical resistance of the separating element is selected to limit transients at high inrush currents.

6. An electrical switch according to claim 3, in which, when the separating element moves in the second direction of movement, the tip of the separating element is immersed in an electrically insulating base plate after the two contact pieces have been disconnected.

7. An electrical switch according to claim 1, wherein the base plate has a recess which substantially corresponds to the shape of the tip of the separating element and is shaped such that the tip of the separating element substantially completely fills the recess when the tip of the separating element is immersed in the base plate.

8. An electrical switch according to claim 1, wherein the separating element comprises ceramic material.

9. An electric switch according to claim 1, wherein the driving means is formed as an electric motor or an electric motor with a transmission.

10. An electrical switch according to claim 1, in which the device for generating and/or storing a kinetic energy is designed as a spring.

11. An electrical switch according to claim 1, in which the moving element is formed as a rack or alternatively as a spindle.

12. An electrical switch according to claim 1, wherein the rack has a recess, bore or cavity shaped to be engaged by an element of the electromagnetic actuator when the electromagnetic actuator is in the first operating state.

13. An electrical switch according to claim 1, in which at least one of the electromagnetic actuator is designed as a solenoid and the switch comprises a force storage drive or a tension spring.

14. An electrical switch according to claim 1, wherein the solenoid is formed as a monostable solenoid.

15. An electrical switch according to claim 1, in which the first contact piece has an insulating jacket in the region of the contact point.

16. An electrical switch according to claim 1, comprising a control device for controlling the operating states of the electromagnetic actuator and the driving device, the control device having respective control terminals.

17. An electric switch according to claim 1, comprising a condition monitoring device by at least one of means of terminal currant measurement and position detection of the movable element of the electromagnetic actuator.

18. An electrical switch according to claim 1 further comprising a precharge circuit.

19. An electrical switch according to claim 1, wherein the precharging circuit comprises a resistor and a power semiconductor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Further advantages, features and details of the various embodiments of this disclosure will become apparent from the ensuing description of a preferred exemplary embodiment and with the aid of the drawings. The features and combinations of features recited below in the description, as well as the features and feature combination shown after that in the drawing description or in the drawings alone, may be used not only in the particular combination receited, but also in other comnbinations on their own, with departing from the scope of the disclosure.

[0032] In the following, an advantageous example of the present disclosure is explained with reference to the accompanying figures. Wherein:

[0033] FIG. 1-3 is a schematic representation of an electrical switch according to a first example of the execution of the present disclosure;

[0034] FIG. 4-5 is a schematic representation of an electrical switch according to a second example of the present disclosure; and

[0035] FIG. 6-7 is a schematic representation of the mode of action of Holm's narrow force and Lorentz force.

[0036] The figures are merely schematic representations and only serve to explain the disclosure. The same or similar acting elements are consistently marked with the same reference signs.

DETAILED DESCRIPTION

[0037] As used throughout the present disclosure, unless specifically stated otherwise, the term or encompasses all possible combinations, except where infeasible. For example, the expression A or B shall mean A alone, B alone, or A and B together. If it is stated that a component includes A, B, or C, then, unless specifically stated otherwise or infeasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C. Expressions such as at least one of do not necessarily modify an entirety of the following list and do not necessarily modify each member of the list, such that at least one of A, B, and C should be understood as including only one of A, only one of B, only one of C, or any combination of A, B, and C.

[0038] FIG. 1 shows an electrical switch 100 according to a first design example. The electrical switch 100 has two contact pieces 102, 104, which make contact in a contact point 106. The electrical switch is thus closed. The first contact piece 102 is rigid. The second contact piece 104 is arranged so that it can move about a rotation axis 108. Furthermore, the switch has a third contact piece 110. The second contact piece 104 and the third contact piece 110 are electrically connected to one another. This is achieved by a flexible line 112, one end of which is connected to the second contact piece 104 and the other end to the third contact piece 110. On the first contact piece 104 and on the third contact piece 110, a screw contact 114 is provided for connection to a current path, for example a power supply in a motor vehicle. Furthermore, the electrical switch 100 comprises an electrically non-conductive separating element 116 and an actuator unit 118 connected to the separating element 116. The separating element 116 is set up to be moved in translationally. Furthermore, the separating element 116 is designed to separate the two contact pieces 102, 104, i.e. the first contact piece 102 and the movable second contact piece 104 from each other and then to keep them apart. The actuator unit 118 comprises a motion element 120, a drive device 122, an electromagnetic actuator 124 and a device 126 for generating and/or storing a kinetic energy. The movement element 120 is mechanically coupled with the separating element 116. Thus, a movement of the moving element 120 is directly transmitted to the separating element 116 and vice versa. The drive device 122 is set up to move the moving element 120 in a first direction of movement 128 to close the contact point 106. The device 126 for generating and/or storing a kinetic energy is arranged to move the moving element 120 and/or the separating element 116 in a second direction of movement 130 in order to open the contact point. The first direction of movement 128 and the second direction of movement 130 point in two mutually opposite directions.

[0039] The electromagnetic actuator 124 has at least three operating states, as well as transitions from one of these operating states to one of the other operating states. The three operating states are shown in FIG. 1 to FIG. 3, in other words, these figures differ in that the operating state of the electromagnetic actuator 124. FIG. 1 shows the electromagnetic actuator 124 in a third operating state in which the movement of the moving element 120 is enabled. In this state, the device 126 for generating and/or storing kinetic energy acts directly on the moving element 120 and indirectly on the separating element 116 or, in a design example not shown, directly on the separating element 116 and indirectly on the moving element 120 via the mechanical coupling of the two. FIG. 2 shows the electromagnetic actuator 124 in a second operating state, in which the electromagnetic actuator 124 presses the moving element 120 in the direction of driving device 122, whereby the driving device 122 is mechanically coupled to the moving element 120. Via a appropriate control of the drive device 122, the moving element 120 can now be moved in first direction of movement 128, as a result of which the contact point 106 closes. FIG. 3 finally shows the first operating state of the electromagnetic actuator 124 in which the latter blocks a movement of the moving element 120 and holds the moving element 120 in a defined position. The device 126 designed as a spring 132 for generating and/or storing kinetic energy is kept under a preload. In other words, the moving element 120 is thus held in a rest position, leaving the contact point 106 closed and thus the two electrical contact pieces 102, 104 create an electrical connection between the two screw contacts 114.

[0040] In the design example shown in FIG. 1 to FIG. 3, the moving element 120 is designed as a toothed rack 134. The drive device 122 is designed as one electric motor 136. Furthermore, when the contact point 106 is closed, the movable second contact piece 104 is pressed against the first contact piece 102 by the restoring force of a contact pressure spring 138.

[0041] For the better suppression of arcing during an opening process, the design example shown shows that the separating element 116 has a section 140 on the side facing the second contact piece 104, which runs at an angle to the direction of movement of the separating element 116. This sloping section 140 is also known as top 142, ramp, wedge or bevel. In the particular design example, as shown in FIG. 1 to FIG. 3, the diagonal section 140 of the separating element 116, designed as a top 142, is made of conductive resistance material in order not to generate an arc in the initial phase of the contact separation, but to allow current to flow for a short time. The current flow does not initially break off and thus no arc is created. Only when the top 142 has moved completely between the first and second contact pieces 102, 104 does the advancing section of the separating element 116 change to an insulating, electrically non-conductive material section. At this point, the top 142 dips into a base plate 144 of the electrical switch 100. The base plate 144 is electrically insulating and has a recess 146 adapted to the shape of the top 142 and is shaped in such a way that the top 142 of the separating element 116 substantially completely fills the recess 146 when the top 142 is immersed in the base plate 144 as described here.

[0042] In addition to the electric motor 136, the drive device 122 further includes a gear wheel 148. In a design example, gear wheel 148 can also be understood as a gearbox. The teeth of the gear wheel 148 are shown in FIG. 2 i.e. in the second operating state of the electromagnetic actuator 124 with the teeth of the rack 134.

[0043] The electromagnetic actuator 124 is essentially a linear solenoid 150, with an additional tension spring 152. The tension spring 152 is designed to move the armature bolt of the solenoid 150 in the direction away from the toothed rack 134 when the solenoid is not energized in order to release it. This ensures that the electromagnetic actuator 124 is monostable. This also sets off as the safe state of the electrical switch.

[0044] If the spring 152 is not used, the solenoid is bistable, which would also be directly transferred to the whole contactor.

[0045] The first contact piece 102 has an insulation jacket 154 which is interrupted in the region of the contact point 106 to make room for a contact area 156. The contact area 156 penetrates the insulation jacket 154 in an electrically conductive manner. This creates an electrical contact between the second contact piece 104 and the contact area 156. The contact area 156 is part of the first contact piece 102, so that electrical contact can still be established between the first contact piece 102 and the second contact piece 104. The insulation jacket 154 helps prevent or reduce electric arcs. The insulation jacket 154, for example, is made of a plastic or a ceramic material.

[0046] The movement element 120 or the toothed rack 134 has a recess 158 or an opening in which an element of the electromagnetic actuator 124 engages in the corresponding operating mode, i.e. the third operating state, to prevent movement of the moving element 120 or the rack 134. In one version, the solenoid 150 has an armature bolt with the section protruding from the solenoid 150, which protrudes from the lifting solenoid 150 on the side opposite the tension spring 152. This protruding section is shaped to engage in the recess 158 in the third operating state, thus blocking the movement of the moving element 120.

[0047] Another embodiment of the electrical switch 100 is further described hereinbelow. For example, a device for switching direct currents, such as the electrical switch 100 shown here, is suitable for establishing and disconnecting a power supply in a motor vehicle under load. The arrangement has a switching range and an actuator range. There are two contacts (first contact piece 102 and second and third contact pieces 104, 110) in the switching area, whereby one contact (second and third contact pieces 104, 110) is deflected via a flexible connection 160. A spring or contact pressure spring 138, particularly designed as a helical or torsion spring, presses the flexible contact part (second contact piece 104) against the other contact (first contact piece 102). Depending on the design of the flexible contact, the attachment to the second contact can be point, zone, area or line shaped. This second contact (first contact piece 102) is rigid and has an upstream surface (contact area 156) where the flexible contact (second contact piece 104) rests when the electrical switch 100 is closed. Beyond this contact area 156, the first contact piece 102 is surrounded by an insulating material, particularly plastic. This ensures that the contact is separated on both sides as the process continues.

[0048] In the actuator area there is an electric motor 136 with a gear not explicitly shown and an electromagnetic actuator 124, especially a reluctance actuator (solenoid 150), as well as a toothed rack 134 and a further spring 132, preferably in the form of a screw. The rack 134 is connected to a separating element 116. The separating element 116 has lateral guides not shown or is passively guided laterally and can thus be moved between the contact pieces 102, 104. The spring 132 can be connected either directly or indirectly via the toothed rack 134 to the separating element 116. The separating element 116 is made of a non-electrically conductive material, preferably ceramic or glass, but its top 142 in a design example is made of an electrically conductive material, preferably metal.

[0049] The gearbox of the electric motor 136 or the gear wheel 148 and the rack 134 do not mesh with one another in the de-energized state. By energizing the electromagnetic actuator 124 which is arranged normal to the rack 134, the actuator presses the rack 134 into the gear of the electric motor 136 or into the gear wheel 148. Subsequently, by energizing the electric motor 136, the separating element 116 is moved out between the two contact pieces 102, 104, thereby preloading the spring 132. At a defined position, rack 134 has a hole or a recess 158, into which the actuator 124, which is still energized, can be immersed. This mechanism separates the rack 134 and the gear of the electric motor 136 and the gear wheel 148 and locks the separating element 116. Compared to the solution known from the prior art, the electrical switch 100 has the decisive advantage that no electromagnetic actuator is required which has to hold the entire force of the pretensioned spring 132. This results in significantly lower holding currents which allow the actuator or the actuator unit 118 is considerably smaller, lighter and therefore more cost-effective.

[0050] The electromagnetic actuator 124 can either be mono or bistable, depending on the intended use. This property would then also be directly transferred to the electrical switch 100, also known to as a contactor. In the following, a monostable arrangement is assumed.

[0051] By switching off the control current on the electromagnetic actuator 124, the actuator 124 is removed from the hole (recess 158) in the rack 134 by a return spring 152. Then the separating element 116 then snaps between the contacts (contact pieces 102, 104) of switch 100. The electrically conductive top 142 of that separating element 116 lifts off the movably designed second contact piece 104. However, since the current can initially continue to flow via the electrically conductive top 142, no switching arc initially occurs at the contact area (contact point 106) of the closed switch 100. The contact point 106 is thus spared. A switching arc only occurs when the conductive top 142 has moved completely past the flexible second contact piece 104. It is then created between this second contact piece 104 and the conductive top 142. To suppress this arc, the separating element 116 is then immediately immersed in a recess in the base plate 144. There the arc is strongly cooled and collapses.

[0052] All these measures result in a significantly higher overall disconnection capacity of hard short circuits compared to the solutions known in the prior art, so that a previous HV fuse can be omitted, which in turn enables the reduction of line cross sections.

[0053] In addition to the arrangement described above according to FIG. 1 to FIG. 3, it is also conceivable, as shown in the following FIG. 4 and FIG. 5, to place the actuator unit 118 between the connection contacts. However, the arrangement described above and shown in FIG. 1 to FIG. 3 has the advantage that the actuator unit 118 and the switching region with the contacts are spatially separated. This allows higher contact connection temperatures to be tolerated. In addition, the contact lengths can be reduced in this way. There is also another advantage of the first version according to FIG. 1 to FIG. 3, since the electromagnetic Lorentz force there additionally increases the contact force when energized.

[0054] Depending on the dimensioning of the arrangement, it can be designed for low voltages in the range 40-60 V for especially 48 V applications or for HV applications with voltages in the range 400-1000 V. Furthermore, the electrical switch 100 can be designed in steps so that it can be used for different maximum separation currents. Since, in contrast to the solutions known in the prior art, it is not a contact itself but a third element (here: separating element 116) that is actuated, different conductor cross sections can be used with almost the same actuator arrangement.

[0055] The electromagnetic actuator 124 and the electric motor 136 are generally controlled via control connections not shown here and sequential energization sequence of electromagnetic actuator 124 and electric motor 136 is realized by external electronics.

[0056] Optionally, a terminal current measurement for condition monitoring can also be integrated in addition to the electrical switch 100 to display diagnostic capability. Furthermore, a condition monitoring can be set up by the above described position detection of the bolt from the electromagnetic actuator.

[0057] In a special design, an external precharging circuit, as currently connected in parallel to the electrical switch 100 on the positive side, can be integrated into the electronics. In the prior art, this precharge circuit consists of a relay and a resistor. When the system is switched on, the relay is first switched through so that the components installed in the system, especially the capacitors, are not immediately loaded with the full operating current. This precharge circuit can be replaced by a resistor and a power semiconductor for integration into the electronics of the switch.

[0058] In the second exemplary embodiment of an electrical switch 100 shown in FIG. 4 and FIG. 5, the actuator unit is arranged between the first contact piece 102 and the third contact piece 110. As in the first exemplary embodiment, with respect to the second contact piece 104, a base plate 144 with a recess 146 is arranged on the side opposite the separating element 116. The contact pressure spring 138 is arranged between the second contact piece 104 and the base plate 144, in order to bring the second contact piece 104 back into electrical and mechanical contact with the first contact piece 102 when the electrical switch 100 closes, or to hold it in 102, 104 when electrical and mechanical contact between the two contact pieces is established. When the electrical switch 100 is closed the second contact piece 104 is arranged in at an angle with respect to the first contact piece 102. The corresponding angle between the first contact piece 102 and the second contact piece 104 is usually between 10 and 80, whereas the corresponding angle is preferably between 20 and 45. The incline of the top 142 of the separating element 116 is in relation to said angle. The top 142 preferably has an acute angle.

[0059] As already mentioned above, a particular advantage of the electrical switch 100, 600 described here can be seen in the way in which Holm's narrow force and Lorentz force act on the electrical switch 100, 600. For this purpose, FIG. 6 shows a classic contactor 600. The current flow is symbolically represented by arrows marked with i. Arranged in a coil 670 is a translationally movable armature 672, which is arranged to connect a first busbar 676 to a second busbar 678 by means of a contact piece 674. When the contactor 600 is closed, the contact between the contact piece 674 and the two busbars 676, 678 is closed. In the representation according to FIG. 6, the contact piece 674 moves up in the drawing plane to open the contactor 600. Holm's narrow force 680 acts upwards in the drawing plane at contact points between the bell 674 and the two busbars 676,678. The Lorentz force 682 acts upwards on the contact piece 674 in the drawing plane. Thus, the Lorentz force 682 and the Holm narrow force 680 act in the same direction, which corresponds to the direction of movement for opening the contactor 600.

[0060] The Holm's narrow force 680 and the Lorentz force 682 are different for an electrical switch 100, as is shown in the first exemplary according to FIG. 1 to FIG. 3 is shown. The corresponding force arrows are shown in a simplified representation of such an electrical switch 100 in FIG. 7. The tightening force 780 acts vertically on the contact point 106 of the first contact piece 102 in the direction of the third contact piece 110. Thereby the tightening force 780 can be vectorially considered. A first force vector 780 of the tightening force 780 acts along the second contact piece 104, at the top of which a second force vector 780 is applied and closes the force triangle to the top of the vector of the tightening force 780. The second force vector 780 is perpendicular to the orientation of the tightening force 780 or in other words parallel to the first contact piece 102. The first force vector 780 runs from contact point 106 along the main direction of extension of the second contact piece 104. The Lorentz force 782 acts on the second contact piece 104, whereby the direction of the Lorentz force 782 is exactly opposite to the second force vector 780.

[0061] Since the devices described in detail above are examples of design, they can be modified in an usual way by a skilled person to a large extent without leaving the field of the disclosure. In particular, the mechanical arrangements and the proportions of the individual elements to one another are only shown as examples.