Power contactor with arc clearing shielding device and aircraft comprising same

Abstract

The power contactor (100) comprises: a fixed contact (102A); -a movable contact (104A); and-an electrical insulation shield (112) designed to move between a spaced-apart position and a position inserted between the fixed contact (102A) and the movable contact (104A) in its distant position. The power contactor further comprises:-reset means (116) designed to push the shielding means (112) from its separated position to its inserted position; and-a safety element (118) forming a mechanical stop preventing the shielding device (112) from leaving its separated position, the safety element (118) being designed such that, under the effect of heat generated by an arc occurring between the contacts, the safety element is triggered in such a way that the shielding device (112) leaves its separated position and reaches its inserted position under the effect of a reset device (116).

Description

Technical Field

[0001] The present invention relates to a power contactor having an arc clearing shield device, and an aircraft including such a power contactor.

[0002] As is well known, a power contactor is an electrical device designed to selectively allow or interrupt the flow of current by remote control (e.g., electrical or pneumatic). Background Art

[0003] For the transportation of goods or people within and between cities, vertical take-off and landing (VTOL) aircraft and conventional take-off and landing (CTOL) aircraft with electric or hybrid propulsion represent a market with great promise and demand.

[0004] The propulsion of these different platforms is provided by one or more electric motors, the number of which varies according to the aircraft architecture. The DC levels used in these electric propulsion systems are increasing.

[0005] The failure modes of these systems show that the occurrence of series arcs can have serious consequences for the aircraft structure if the series arcs are not cleared (i.e., stopped).

[0006] However, arcs typically occur between each pair of movable / fixed contacts of a power contactor. If these arcs persist there, they may cause a fire. This is why air-blast arc extinguishing devices are usually associated with power contactors. However, if the air-blast arc extinguishing fails, the arcs can cause a fire.

[0007] In addition, it is known to move an electrical insulation shielding device between two fixed / movable contacts whenever the two fixed / movable contacts separate, see for example International Application WO1985005218A1. Inserting the shielding device between the two contacts causes the arc to disappear. However, each time the shielding device is used, a carbon path may appear and become stronger, gradually rendering the shielding device ineffective.

[0008] Therefore, it is desirable to provide a power contactor capable of overcoming at least some of the above problems and limitations. Summary of the Invention

[0009] Accordingly, there is provided a power contactor including:

[0010] - a fixed contact;

[0011] - A movable contact, the movable contact being designed to move between a position in contact with the fixed contact to allow current to pass therethrough and a position away from the fixed contact to prevent current from passing therethrough with respect to the fixed contact; and

[0012] - An electrical insulation shielding device, the electrical insulation shielding device being designed to move between a separated position and a position inserted between the fixed contact and the movable contact in its away position;

[0013] Characterized in that:

[0014] - A reset device, the reset device being designed to push the shielding device from its separated position to its inserted position; and

[0015] - A safety element, the safety element forming a mechanical stop to prevent the shielding device from leaving its separated position, the safety element being designed to be triggered under the action of heat generated by an arc occurring between the fixed contact and the movable contact, so that the shielding device leaves its separated position and reaches its inserted position under the action of the reset device.

[0016] In any technically possible combination, the present invention may further include one or more of the following optional features.

[0017] Preferably, the power contactor further includes: - another fixed contact; and - another movable contact, the another movable contact being designed to move between a position in contact with the another fixed contact to allow current to pass therethrough and a position away from the another fixed contact to prevent current from passing therethrough with respect to the another fixed contact, and the two movable contacts being fixed to each other to move simultaneously.

[0018] Also preferably, the shielding device is in the form of a plate, preferably, the plate is perpendicular to the closing direction, and the movable contact moves between its separated position and its inserted position along the closing direction.

[0019] Also preferably, the shielding device further includes a bus bar, the fixed contact is fixed to the bus bar, and the safety element is fixed on the bus bar.

[0020] Also preferably, the safety element is in the form of a pin, preferably, the pin extends upward parallel to the closing direction.

[0021] Also preferably, the reset device includes a spring.

[0022] Also preferably, the spring is stretched between a fixed point and the shielding device.

[0023] Also preferably, the power contactor further includes a gas-blast arc extinguishing device for the arc, the arc occurring between the fixed contact and the movable contact.

[0024] An aircraft including a contactor according to the invention is also proposed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention will be better understood by reading the following description given by way of example only and with reference to the drawings, in which:

[0026] - Figure 1 is a perspective view of an example of a power contactor according to the invention;

[0027] - Figure 2 is Figure 1 a block diagram of an example of an operating method of the power contactor;

[0028] - Figure 3 is similar to Figure 1 the view, showing the arc; and

[0029] - Figure 4 is Figure 1 a perspective view of the power contactor after triggering the arc clearing shield device. DETAILED DESCRIPTION

[0030] With reference to Figure 1 an example of a power contactor 100 according to the invention will now be described.

[0031] The power contactor 100 includes at least a pair of two contacts, one contact 102A, 102B being fixed and the other contact 104A, 104B being movable. Thus, the movable contacts 104A, 104B are designed to move between a position in contact with the fixed contacts 102A, 102B to allow current to pass and a position away from the fixed contacts 102A, 102B to prevent current from passing, relative to the fixed contacts 102A, 102B. For example, this movement is along a straight line in the closing direction F.

[0032] For example, as in the example shown, the power contactor 100 is of the double-break type and includes two pairs of fixed contacts 102A, 102B and movable contacts 104A, 102B. In this case, the two movable contacts 104A, 104B are fixed to each other to move simultaneously. For example, the power contactor 100 includes a movable busbar 106 having two ends, and the two movable contacts 104A, 104B are respectively fixed at the two ends. Thus, the two movable contacts 104A, 104B are designed to move simultaneously with the busbar 106 along the closing direction F to contact the associated fixed contacts 102 substantially simultaneously.

[0033] For each fixed contact 102A, 102B, the power contactor 100 may further include fixed busbars 108A, 108B to which the fixed contacts 102A, 102B are fixed.

[0034] The power contactor 100 may further include a gas-blast arc quenching device 110 for the arc that occurs between each movable contact 104A, 104B and the associated fixed contact 102A, 102B (especially when the power contactor 100 is opened). The gas-blast arc quenching device 110 is designed to displace and extinguish the arc. The displacement of the arc is achieved, for example, by applying a magnetic field, and the extinction of the arc is achieved, for example, by dividing the arc into a plurality of smaller arcs.

[0035] The power contactor 100 further includes an electrical insulation shielding device 112 associated with a pair of fixed / movable contacts (in the illustrated example, a pair 102A, 104A). The shielding device 112 is designed to move between a separated position and an inserted position. In the separated position, the shielding device 112 allows the movable contact 104A to move. In the inserted position, the shielding device is located between the fixed contact 102A and the movable contact 104A in its retracted position to prevent the movable contact 104A from reaching the position of contact with the fixed contact 102A. For example, the shielding device 112 is in the form of a plate and, for example, is perpendicular to the closing direction F. Thus, when the shielding device 112 is in the separated position, the contacts 102A, 104A can be selectively moved away from and into contact with each other according to the command received by the power contactor 100. In addition, it is obvious that the shielding device 112 is designed such that when the movable contact 104A is already in a position separated from the fixed contact 102A after receiving an opening command, the shielding device moves from its separated position to its inserted position in order to cut off the arc that will appear between the separated contacts 102A, 104A.

[0036] Preferably, the shielding device 112 is made of an electrical insulation material having a high Comparative Tracking Index (CTI) in order to prevent the formation of a carbon path that could re-ignite the arc, the Comparative Tracking Index being, for example, at least 500V, for example 600V.

[0037] For example, the shielding device 112 is designed to move in a straight line, for example, perpendicular to the closing direction F. To guide the movement of the shielding device 112, the power contactor 100 includes, for example, a slider 114 for guiding the shielding device 112.

[0038] The power contactor 100 further includes a reset device 116 which is designed to push the shielding device 112 from its separated position to its inserted position. For example, the reset device 116 includes a spring which is stretched, for example, between a fixed point A (such as the guide 114) and the shielding device 112. Alternatively, the spring can be in a compressed state.

[0039] The power contactor 100 further includes a fuse 118 which forms a mechanical stop for the shielding device 112 to prevent the shielding device from leaving its separated position (even if the reset device 116 applies a force on the shielding device 112). The fuse 118 is designed to be triggered by the heat generated by an arc occurring between the fixed contact 102A and the movable contact 104A. The fuse 118 is designed to: disintegrate when triggered and thus lose its stopping function, thereby allowing the shielding device 112 to leave its separated position and reach its inserted position under the action of the reset device 116. For example, the fuse 118 can be fixed to the bus bar 108. Also, for example, the fuse 118 is shaped as a pin which preferably extends upward parallel to the closing direction F. For example, the fuse 118 is made of a tin alloy. The triggering temperature (also called the melting temperature) of the fuse is, for example, between 200 °C and 250 °C, for example, 230 °C.

[0040] Reference Figure 2 , an example of an operating method 200 of the power contactor 100 will now be described. Figure 1 of the power contactor 100.

[0041] Initially, the power contactor 100 is closed. The movable contacts 104A, 104B are in contact with the fixed contacts 102A, 102B respectively. Thus, the current flows in the following manner: through the fixed bus bar 108A, then through the fixed contact 102A, then through the movable contact 104A, then through the movable bus bar 106, then through the movable contact 104B, then through the fixed contact 102B, and then through the fixed bus bar 108B.

[0042] During step 202, the power contactor is disconnected. The movable contacts 104A, 104B move away from the fixed contacts 102A, 102B. Then an arc appears between each pair of the movable contact and the fixed contact, as Figure 3 shown. These arcs generate heat. In particular, a part of the heat generated by the arc between the movable contact 104A and the fixed contact 102A diffuses into the fixed contact 102A by conduction and then into the fixed bus bar 108A until it reaches the fuse 118, heating the fuse.

[0043] During normal operation of the power contactor 100, these arcs should be blown out by the air-blast arc extinguishing device 110 before the temperature of the fuse reaches the triggering threshold.

[0044] During step 204, when the arc persists for too long, for example due to a malfunction of the air blast arc quenching device 110, such as for more than a few tens of milliseconds, the temperature of the fuse member 118 reaches the threshold value, and the fuse member 118 is triggered and disintegrated. This will release the shielding device 112.

[0045] Therefore, during step 206, the reset device 116 pushes the shielding device 112 from its retracted position to the inserted position where the shielding device is located between the movable contact 104A and the fixed contact 102A, as Figure 4 shown. Since the shielding device 112 causes the arc to suddenly elongate, this generates sufficient arc impedance against the back electromotive force of the series arc to counteract the mains voltage until the current is cut off.

[0046] In summary, it should be noted that the present invention is not limited to the above embodiments. In fact, it is obvious to those skilled in the art that various modifications can be made to the above embodiments according to the teachings disclosed herein.

[0047] In the detailed description of the present invention above, the terms used should not be construed as limiting the present invention to the embodiments described in this specification, but should be construed as including all equivalents that can be expected by those skilled in the art by applying their general knowledge to the teachings of this disclosure.

Claims

1. An electric contactor (100), comprising: - a fixed contact (102A); - a movable contact (104A), which is designed to move between a position in contact with the fixed contact (102A) to allow current to pass through and a position away from the fixed contact (102A) to prevent current from passing through, relative to the fixed contact (102A); and - an electrical insulation shielding device (112), which is designed to move between a separated position and a position inserted between the fixed contact (102A) and the movable contact (104A) in its away position; characterized in that: - a reset device (116), which is designed to push the shielding device (112) from its separated position to its inserted position; and - a safety element (118), which forms a mechanical stop to prevent the shielding device (112) from leaving its separated position, and the safety element (118) is designed such that, under the action of heat generated by an arc occurring between the fixed contact (102A) and the movable contact (104A), the safety element is triggered to cause the shielding device (112) to leave its separated position and reach its inserted position under the action of the reset device (116).

2. The electric contactor (100) according to claim 1, further comprising: - another fixed contact (102B); and - another movable contact (104B), which is designed to move between a position in contact with the another fixed contact (102B) to allow current to pass through and a position away from the another fixed contact (102B) to prevent current from passing through, relative to the another fixed contact (102B), and the two movable contacts (104A, 104B) are fixed to each other to move simultaneously.

3. The power contactor (100) according to claim 1 or 2, wherein, The shielding device (112) is in the form of a plate, preferably, the plate is perpendicular to the closing direction (F), wherein the movable contact (104A) moves between its separated position and its inserted position.

4. The power contactor (100) according to any one of claims 1 to 3 further comprises: A bus bar (108A), to which the fixed contact (102A) is fixed, and wherein the safety element (118) is fixed on the bus bar (108A).

5. The power contactor (100) according to any one of claims 1 to 4, wherein, The safety element (118) is in the form of a pin, preferably, the pin extends upward parallel to the closing direction (F).

6. The power contactor (100) according to any one of claims 1 to 5, wherein, The reset device (116) includes a spring.

7. The power contactor (100) according to claim 6, wherein, The spring is stretched between a fixed point (A) and the shielding device (112).

8. The power contactor (100) according to any one of claims 1 to 7 further comprises: An air-blast arc extinguishing device (110) for the arc, which appears between the fixed contact (102A) and the movable contact (104A).

9. An aircraft, comprising a contactor according to any one of claims 1 to 8.

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