Pyrotechnic circuit breaker

Abstract

The present invention relates to a housing (10); the electrical conductor to be interrupted (20); a piston (30) arranged in the housing (10) for breaking the electrical conductor (20), the piston (30) being movable between an idle position and an operating position in which the electrical conductor (20) is broken; a pyrotechnic actuator (40) disposed within the housing (10) for moving a piston (30) from an idle position to an actuated position, The piston (30) has a proximal end (30A) disposed on a side of the pyrotechnic actuator (40) and a proximal end (30B) opposite the proximal end (30A); The piston (30) is characterized by at least one gas passage (31) disposed between a distal end (30B) and a proximal end (30A).

Description

[Technical field]

[0001] The present invention relates generally to pyrotechnic circuit breakers intended to equip electric vehicles for rapidly interrupting electrical circuits, particularly traction circuits having high current strengths and / or high voltages and / or high inductances. The currents flowing through such electrical circuits in electric vehicles may have strengths of thousands or tens of thousands of amperes, and voltages may range from tens to thousands of volts.

[0002] prior art In the prior art of circuit breakers, it is known to provide a gas passage in the housing between the interrupting chamber, which contains the electrical conductor to be initially interrupted, and the pyrotechnic chamber, which is designed to receive the combustion gases from the pyrotechnic actuator. However, this system may have the disadvantage of large dimensions and / or insufficient insulation resistance after operation (due to conductive deposits left by the combustion gases). For example, DE 10 2019 135 591 A1 shows such a circuit breaker.

[0003] For example, DE 102018125059 A1 shows a circuit breaker with cooling channels. Summary of the Invention

[0004] The object of the present invention is to overcome the drawbacks of the background art mentioned above, in particular to propose a circuit breaker which is firstly compact and / or makes it possible to increase operational safety.

[0005] Therefore, a first aspect of the present invention comprises: -Housing; the electrical conductor to be interrupted; a piston disposed within the housing for disconnecting the electrical conductor, the piston being movable between an idle position and an operating position in which the electrical conductor is interrupted; a pyrotechnic actuator disposed within the housing to move the piston from an idle position to an actuated position; the piston has a proximal end disposed on a side of the pyrotechnic actuator and a distal end opposite the proximal end; The present invention relates to a pyrotechnic circuit breaker characterized in that the piston comprises at least one gas passage disposed between the distal end and the proximal end. According to the above embodiment, the circuit breaker comprises at least one gas passage disposed on or within the piston, providing a simple solution. In addition, the fluid communication between the distal end and the proximal end limits or prevents compression of gas above the piston as it moves, thus increasing operational safety by preventing the piston from moving backwards due to excess pressure exerted by gas compressed by the distal end.

[0006] In one embodiment, the piston (or passage) may include at least one orifice disposed on the distal end side and / or the proximal end side to establish fluid communication between the distal end and the proximal end.

[0007] In one embodiment, the fluid communication may be permanent and / or independent of the piston position. In other words, the passages may be designed to be always open to facilitate / allow the passage of gas from one side of the piston to the other. Such passages may be viewed as a means to increase the volume available for gas in the chamber containing the conductors (which are interrupted before the circuit breaker trips and are interrupted after the circuit breaker trips).

[0008] In one embodiment, the piston and / or passageway and / or circuit breaker may lack a filtering means. The gas does not need to be cooled or filtered to ensure there is no piston return or recoil.

[0009] In one embodiment, the piston and / or the passageway and / or the circuit breaker may be devoid of vents and / or venting means, which facilitates environmental resistance.

[0010] In one embodiment, the proximal end may directly face the pyrotechnic actuator, at least when the piston is in an idle position.

[0011] In one embodiment, the distal end may directly face the electrical conductor to be interrupted, at least when the piston is in the idle position.

[0012] In one embodiment, the piston (or passage) may comprise at least one orifice located at a distal end and directly facing the electrical conductor to be interrupted when the piston is in an idle position.

[0013] According to one embodiment, the proximal end may be a first end of the piston in the direction of piston movement and the distal end may be a second end of the piston in the direction of piston movement.

[0014] According to one embodiment, when the piston is in an idle position, the housing may form with the piston: a cut-off chamber containing a portion of the electrical conductor to be interrupted; a pyrotechnic chamber designed to receive combustion gases from a pyrotechnic actuator; a side chamber separated from the cut-off chamber by a piston and isolated from the pyrotechnic chamber; The gas passage can put the cut-off chamber in fluid communication with the side chamber. According to the above embodiment, the pyrotechnic chamber is isolated from the side chamber and the cut-off chamber by the piston, so that the combustion gases remain confined within the pyrotechnic chamber and the operational safety is improved by a particularly high post-operation isolation resistance.

[0015] According to one embodiment, The housing may include an ignition well; The piston may be provided with a skirt which is engaged in the ignition well and separates the side chamber from the pyrotechnic chamber. This structure is simple and the skirt provides additional guidance. A gasket may be attached to the skirt.

[0016] According to one embodiment, The housing may comprise a main cylinder; the piston may have a peripheral surface that engages within the main cylinder; The gas passage may be disposed between the peripheral surface and the piston skirt.

[0017] In one embodiment, the piston in the actuated position can divide the cut-off chamber into multiple sub-chambers, and the piston can have at least one gas passageway to a side chamber for each sub-chamber. Even if the cut-off chamber is divided after the piston has moved, the presence of multiple gas passageways ensures that the distal end is not overpressurized and ensures that the piston remains in its final position without retracting.

[0018] In one embodiment, the pyrotechnic circuit breaker can include at least one cooling mechanism arranged to cool gas heated by an electric arc generated when an electrical conductor is interrupted. Such a cooling mechanism further enhances operational safety by preventing the gas from remaining hot and causing a rapid drop in pressure even if an arc occurs during operation.

[0019] In one embodiment, at least one cooling mechanism may be located in the cutoff chamber and / or in the side chamber.

[0020] In one embodiment, at least one cooling mechanism may be attached to the housing and / or the piston. At least one cooling mechanism may be disposed in the gas path to force passage therethrough for more effective cooling. For example, the gas path may provide or lead to the cooling mechanism.

[0021] According to one embodiment, the gas generator comprises: - a through hole formed in the piston, or The piston may include an external groove formed in an outer surface thereof.

[0022] In one embodiment, the gas passages are 15 mm 2 More than that, and 25mm 2 The gas passage can have a cross-sectional area of ​​100 mm or more. This surface can be obtained by one, two or more passes. It is noted that the passage is much larger than the mechanical clearance between two parts that must move relative to each other. Furthermore, whereas the mechanical clearance between two moving parts can vary greatly due to manufacturing tolerances, the gas passage has a surface area that varies little, thus offering greater repeatability.

[0023] According to one embodiment, the at least one gas passage may allow gas communication into the housing to impose a pressure between Pmax and 0.9Pmax in the housing for 1 ms after the peak of the maximum pressure Pmax. The maximum pressure Pmax may be the maximum pressure measured during an operational test, and 0.9Pmax may represent 90% of the maximum pressure. The maximum pressure Pmax may be the maximum pressure measured in the cut-off chamber of the circuit breaker, i.e. in the chamber containing the conductor to be interrupted and at least partially defined by the distal end of the piston. According to this embodiment, the passage of gas avoids excessively high peak pressures, resulting in a flatter pressure curve. After the peak pressure, the pressure changes very little. As a result, the piston is hardly stressed and does not retract once it reaches its maximum displacement.

[0024] In one embodiment, the electrical conductors may pass through the housing.

[0025] In one embodiment, the gas passages can be arranged to allow movement of any gas present when the electrical conductor is interrupted from a side of the piston that faces the electrical conductor when the piston is in an idle position to a side of the piston that faces the pyrotechnic actuator when the piston is in an actuated position.

[0026] A second aspect of the invention relates to a motor vehicle comprising at least one pyrotechnic circuit breaker according to the first aspect of the invention. [Brief description of the drawings]

[0027] Other characteristics and advantages of the present invention will become more apparent on reading the following detailed description of embodiments of the invention, given by way of example but in no way limiting, and illustrated by the accompanying drawings, in which:

[0028] [Figure 1] FIG. 1 is a cross-sectional view of a pyrotechnic circuit breaker according to the invention after activation of the pyrotechnic device with the piston interrupting the electrical conductor. [Diagram 2] FIG. 2 shows a perspective view of the piston alone. [Diagram 3] FIG. 3 shows voltage, current and pressure curves measured in a prior art circuit breaker during operation. [Figure 4] FIG. 4 shows voltage, current and pressure curves measured during operation of a circuit breaker according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] FIG. 1 shows a circuit breaker comprising: a housing 10; the electrical conductor 20 to be interrupted, a piston 30 arranged in the housing for disconnecting the electrical conductor 20, the piston 30 being movable between an idle position and an operating position in which the electrical conductor 20 is interrupted; a pyrotechnic actuator 40 disposed within the housing 10 for moving the piston 30 from an idle position to an actuated position; The piston 30 has a proximal end 30A disposed on the side of the pyrotechnic actuator 40 and a distal end 30B opposite the proximal end 30A.

[0030] In detail, the housing 10 of the circuit breaker shown in Fig. 1 comprises a first half shell 11 and a second half shell 12. The first half shell 11 houses an igniter support 15, which allows the mounting of an electric pyrotechnic igniter forming a pyrotechnic actuator 40. The electrical conductor 20 consists mainly of a conductive rod that may be overmolded by a frame 21 sandwiched between the first half shell 11 and the second half shell 12. It is noted that there are several gaskets 18 and 16 between the parts to ensure good environmental resistance.

[0031] Generally speaking, the piston 30 is housed within the housing 10 and is configured as follows: a cut-off chamber 130 comprising the part of the electrical conductor 20 to be interrupted; a pyrotechnic chamber 110 designed to receive combustion gases from the pyrotechnic actuator 40; a side chamber 120 separated from the cut-off chamber 130 by a piston 30 and isolated from the pyrotechnic chamber 110 by the piston 30 .

[0032] To this end, the housing 10 has a main cylinder and the piston 30 has a peripheral surface 33 housed within the main cylinder arranged to allow the piston 30 to slide within the housing 10 . In addition, the piston 30 is - a skirt 36 and a seal 35 at the proximal end 30A; a plurality of blades 34 separated by grooves 37 at the distal end 30B; - a passage 31 (orifice) that establishes fluid communication between the proximal end 30A and the distal end 30B. Opposite the groove 37 that separates the blades 34 from the piston 30, the second half-shell 12 has a die 17 designed to cooperate with the piston 30 to interrupt the electrical conductor 20.

[0033] In fact, as shown in FIG. 1, the pyrotechnic actuator 40 has been triggered and the piston 30 is therefore in an actuated position in which the conductor 20 is cut into several pieces. As can be seen in FIG. 1, the conductor 20 consists of the two outer ends 24 of the conductor 20, the first cut piece 22 and the second cut piece 23. The piston 30 is initially in an idle position in the first half-shell 11, but is moved by the pressurized gas from the pyrotechnic actuator 40 released in the pyrotechnic chamber 110 to occupy the actuated position shown in FIG. 1. When moving from the idle position to the actuated position, the piston 30 cuts the conductor 20, and then the first cut piece 22 and the second cut piece 23 separate from the two outer ends 24 and are pinched between the piston 30 (knife 37 and groove 37) on the one hand and the housing 10 (die 17) on the other hand.

[0034] The circuit breaker comprises cooling mechanisms 13, 14 arranged to cool the gas, and the cut-off chamber 130 also includes a cooling mechanism arranged to cool the gas heated by the electric arc generated during the interruption of the electrical conductor 20. A first cooling mechanism 13 is housed within the cut-off chamber 130 and a second cooling mechanism 14 is housed within the side chamber 120.

[0035] The cooling mechanism may be a metal part. A porous part or a part having an internal void may be provided. The cooling mechanism may comprise a metal wire. The metal wire may be compressed onto itself to form the cooling mechanism. In other words, each cooling mechanism is formed of one or more compressed wires. It is also possible to provide a compressed braid or a porous sintered part. Such a part may dissipate energy from the gas heated by the arc.

[0036] In fact, according to one embodiment, the cooling mechanisms may be parts that are porous and / or have voids and / or have passages and / or have gaps and / or have a density much lower than that of the metal they are made of, allowing the gas to easily pass through, thus providing a large exchange surface and interesting cooling capacity for the gas in the cut-off chamber 130. It should be noted that during operation, the gases in the cut-off chamber 130 can be compressed / displaced by the movement of the piston 30, so that these gases move into the cooling mechanism in the free space, which allows an efficient heat exchange to cool the gas in the cut-off chamber 130. In other words, the cooling mechanism can be designed for convection cooling (heat exchange between gas and solid).

[0037] 2 shows a perspective view of distal end 30B, the face of piston 30 carrying blades 34 separated by grooves 37. Note that piston 30 has a non-circular peripheral surface 33 that ensures that piston 30 slides without rotating about its axis, and the assembly is a sliding connection. Thus, blades 34 separated by grooves 37 can cooperate with die 17 of housing 10 properly aligned with grooves 37 to provide an effective mechanical cutting (shearing) of electrical conductor 20.

[0038] There are two passages 31 in the cross section of FIG. 1 and four passages 32 on either side of the cross section of FIG.

[0039] As seen above and can be clearly seen in FIG. 1, the housing 10 defines: at the proximal end 30A, a pyrotechnic chamber 110 and a side chamber 120 separated from the pyrotechnic chamber 110 by the skirt 36 and the seal 35 of the piston 30; - at the distal end 30B, a cut-off chamber 130, isolated or separated from the pyrotechnic chamber 110 and the side chamber 120 by the piston 30. However, the passages 31 and 32 in the piston 30 ensure gas communication between the cut-off chamber 130 and the side chamber 120. The gas passages 31 and 32 are therefore arranged to allow, when the electrical conductor 20 is interrupted, the gas present on the side of the piston 30 facing the electrical conductor 20 when the piston 30 is in the idle position to move towards the side of the piston 30 facing the pyrotechnic actuator 40 when the piston 30 is in the actuated position. This prevents gas overpressure in the cut-off chamber 130, since it should be noted that the gas in the cut-off chamber 130 is compressed by the movement of the piston 30, reducing its volume, and by any electric arcs established between the various parts of the electrical conductor 20, heating the gas in the cut-off chamber 130. Thus, the piston 30 experiences little or no force or pressure applied to the distal end 30B tending to move it rearward. The actuated position of the piston 30 is stronger and more stable.

[0040] It should also be noted that as the piston 30 moves, the initially unitary cut-off chamber 130 is gradually divided into cut-off sub-chambers due to the die 17 engaging with or in the groove 37. However, various passages 31 and 32 are arranged on the piston 30 to ensure communication between the side chamber 120 and each of the cut-off sub-chambers, thus avoiding any risk of overpressure.

[0041] It should also be noted that because side chamber 120 is sufficiently isolated from pyrotechnic chamber 110, gases and combustion residues from pyrotechnic actuator 40 remain contained in pyrotechnic chamber 110 and do not enter side chamber 120 or cutoff chamber 130, and vice versa. Thus, gases and residues from the combustion of pyrotechnic actuator 40 do not affect the insulation resistance between ends 24, and gases and residues from the cutting of conductor 20 do not affect the insulation resistance at the pins of pyrotechnic actuator 40.

[0042] Figure 3 shows measurements taken during operation of a prior art circuit breaker with no gas flow through the piston. The graph in Figure 3 shows: - the voltage curve across the conductor; - the curve of the current through the conductor; - the curve of the pressure in the cut-off chamber.

[0043] At T=0ms the conductor is intact and perfectly conductive of current, so current flows through it but the voltage across it is 0. The igniter is fired and the piston starts moving.

[0044] At T=0.35 ms, the pressure in the cutoff chamber begins to rise, the current strength decreases, the voltage increases, the piston begins to physically cut the conductor, and an electric arc is established.

[0045] At T=0.40ms, as the piston continues to separate the conductor into several pieces, the pressure in the cutoff chamber rises again, the current decreases further and the voltage increases. Between T=0.5ms and T=0.65ms, the voltage is at its maximum value, a pressure peak is reached, and then the voltage drops and stabilizes at the open electric circuit DC voltage while the current goes to zero, the electric circuit is opened and the arc is interrupted. Note that the pressure peak in this test is about 80 bar at 0.5ms and at 1.5ms (i.e. 1ms after the pressure peak) the pressure is just under 60 bar.

[0046] Figure 4 shows the same measurements as Figure 3, but performed during operation of a circuit breaker according to the invention, such as Figure 1, having at least one gas passage in the piston between the distal end 30B and the proximal end 30A. The remaining construction and geometry of the circuit breaker is identical to the circuit breaker used for the measurements of Figure 3. The graph of Figure 4 shows: - the voltage curve across the conductor; - the curve of the current through the conductor; - the curve of the pressure in the cut-off chamber.

[0047] At T=0ms the conductor is intact and perfectly conductive of current, so current flows through it but the voltage across it is 0. The igniter is fired and the piston starts moving.

[0048] At T=0.35 ms, pressure begins to rise in the cutoff chamber, the current strength decreases and the voltage increases: the piston begins to physically cut the conductor and an electric arc is established.

[0049] At T=0.40ms, as the piston continues to separate the conductor into several pieces, the pressure in the cutoff chamber rises again, the current decreases further and the voltage increases. Between T=0.5ms and T=0.65ms, the voltage is at its maximum value, a pressure peak is reached, and then the voltage drops and stabilizes at an open circuit DC voltage while the current goes to zero, the electrical circuit is open and the arc is interrupted. Note that the pressure peak in this test is about 60 bar at 0.5ms and at 1.5ms (i.e. 1ms after the pressure peak) the pressure is just below 60 bar.

[0050] In comparison with the curve shown in figure 3, it can be seen that the arc exists for a shorter time (it can be considered that the arc exists as soon as the voltage becomes greater than 0 and that the arc is interrupted when the voltage stabilizes at the open circuit voltage, i.e. the battery voltage). Figure 4 also shows that the maximum pressure peak is lower than that of figure 3, which can be explained by the presence of a gas passage that prevents the cut-off chamber from being pressurized. As a result of this lower pressure, the piston cuts the conductor more effectively and more quickly, the piston stays better in its final position without moving backwards, and the division provided by the piston is more effective, for a more rapid interruption, limiting the formation of the electric arc.

[0051] It will be understood that various modifications and / or improvements, apparent to those skilled in the art, can be made to the various embodiments of the invention described herein without departing from the scope of the invention.

[0052] In particular, it is noted that passages 31 and 32 are orifices in piston 30, but could also be grooves in sidewall 33 of piston 30. However, it is noted that the gas passage area, which is equal to the sum of the areas of passages 31 and 32, is much greater than the peripheral clearance of piston 30. In particular, the gas passage area is 6 mm per gas passage between the sub-chamber and the side chamber. 2 Larger, preferably 9mm 2 Larger, even 12mm 2 It can get bigger.

[0053] Additionally, the igniter may be overmolded or crimped onto the housing 10 or igniter support 15 depending on the material selected.

[0054] Apart from the electrical conductors 20 and the cooling mechanisms 13 and 14, all or some of the parts shown in Fig. 1 may be made of plastic and / or polymer and / or filled materials. Polyamide can be used with fiberglass or any other reinforcing material.

[0055] Plastic parts can be overmolded or reinforced with metal elements depending on the stresses they must withstand.

[0056] The piston 30 may be provided in other configurations having more or fewer blades 34 / grooves 37 / dies 17 .

[0057] The cooling mechanism may be located on or in the piston 30. For example, it may be possible to improve cooling of the gas in the cutoff chamber by placing at least one cooling mechanism on, in, or near at least one passageway to force the gas through the cooling mechanism. [Industrial Applicability]

[0058] The circuit breaker and the manufacturing method thereof according to the present invention are industrially applicable.

Claims

1. A pyrotechnic circuit breaker comprising: a housing (10), the electrical conductor to be interrupted (20), a piston (30) arranged in said housing (10) for interrupting said electrical conductor (20) and movable between an idle position and an operating position in which said electrical conductor (20) is interrupted; a pyrotechnic actuator (40) arranged in said housing (10) for moving said piston (30) from said idle position to said actuated position, The piston (30) has a proximal end (30A) arranged on a side of the pyrotechnic actuator (40) and a distal end (30B) opposite the proximal end (30A); The piston (30) is characterized by having at least one gas passage (31, 32) disposed between the distal end (30B) and the proximal end (30A).

2. 2. The pyrotechnic circuit breaker of claim 1, wherein the at least one gas passage (31, 32) allows gas communication into the housing (10) to apply a pressure within the housing (10) of between Pmax and 0.9Pmax for 1 ms after the peak of maximum pressure Pmax.

3. When the piston (30) is in the idle position, the housing (10) together with the piston (30) a cut-off chamber (130) containing the part of said electrical conductor (20) that is to be interrupted; a pyrotechnic chamber (110) designed to receive combustion gases from said pyrotechnic actuator (40); A pyrotechnic circuit breaker according to claim 1 or 2, forming a side chamber (120) separated from the cut-off chamber (130) by the piston (30) and isolated from the pyrotechnic chamber (110), Here, the gas passages (31, 32) fluidly connect the cut-off chamber (130) with the side chamber (120).

4. - said housing (10) comprises an ignition well, A pyrotechnic circuit breaker as claimed in claim 3, wherein said piston (30) comprises a skirt (36) engaged in said ignition well and separating said side chamber (120) from said pyrotechnic chamber (110).

5. - said housing (10) comprises a main cylinder, A pyrotechnic circuit breaker according to claim 4, wherein said piston (30) has a peripheral surface (33) engaged in said main cylinder, The gas passages (31, 32) are disposed between the peripheral surface (33) and the skirt (36) of the piston (30).

6. 6. The pyrotechnic circuit breaker according to claim 3, wherein the piston (30) in the actuated position divides the cut-off chamber (130) into a number of sub-chambers, the piston (30) having at least one gas passage (31, 32) for each sub-chamber to the side chamber (120).

7. A pyrotechnic circuit breaker according to any one of claims 1 to 6, comprising at least one cooling mechanism (13, 14) arranged to cool a gas heated by an electric arc generated during said interruption of said electrical conductor (20).

8. 8. The pyrotechnic circuit breaker according to claim 7 when dependent on any one of claims 3 to 6, wherein the at least one cooling mechanism (13, 14) is arranged in the cut-off chamber (130) and / or in the side chamber (120).

9. 9. A pyrotechnic circuit breaker according to any one of claims 7 or 8, wherein the at least one cooling mechanism (13, 14) is attached to the housing (10) and / or to the piston (30).

10. The gas passages (31, 32) a through hole formed in said piston (30), or A pyrotechnic circuit breaker according to any one of the preceding claims, characterized in that it is an external groove formed on the outer surface of said piston (30).

11. The gas passages (31, 32) are 15 mm or more, and further 25 mm ２ A pyrotechnic circuit breaker according to any one of claims 1 to 10, having a cross-sectional area of ​​at least 10 mm.

12. A pyrotechnic circuit breaker as claimed in any one of the preceding claims, wherein the electrical conductor (20) passes through the housing (10).

13. 13. The pyrotechnic circuit breaker according to any one of claims 1 to 12, wherein the gas passages (31, 32) are arranged to allow movement of gas present when the electrical conductor (20) is interrupted from a side of the piston (30) facing the electrical conductor (20) when the piston (30) is in the idle position towards a side of the piston (30) facing the pyrotechnic actuator (40) when the piston (30) is in the actuated position.

14. A motor vehicle comprising at least one pyrotechnic circuit breaker according to any one of the preceding claims.

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