Normally closed power contactor

Abstract

The invention relates to a normally closed contactor (21) comprising a fixed contact (22) and a movable contact (23) facing each other within a housing (25), the movable contact (23) being movable between a closed position and an open position. A contact pressure spring (26) pushes the movable contact point toward the fixed contact point. The actuator (27) comprises a movable portion (29) rigidly connected to the movable contact (23), the movable portion moving the movable contact from the closed position to the open position. A return spring (33) urges the movable part (29) to a closed position of the movable part. The mechanical de-jitter device (34) comprises a first locking part (35) rigidly connected to the housing and a second locking part (36) opposite the first locking part and rigidly connected to the movable portion (29), the locking parts (35, 36) being mutually lockingly engaged when the movable contact (23) is in the closed position of the movable contact.

Description

Technical Field

[0001] The technical field of the present invention is the technical field of power contactors, in particular the technical field of normally closed power contactors.

[0002] The present invention relates to a normally closed power contactor, in particular, the normally closed power contactor comprises a mechanical debouncing device. Background Art

[0003] A power contactor is an electrical device used to establish or interrupt the flow of electric current. The power contactor generally includes a fixed contact and a movable contact. When the fixed contact and the movable contact are in mechanical contact, the fixed contact allows the flow of electric current, and when the fixed contact and the movable contact are separated from each other, the flow of electric current is interrupted.

[0004] A so-called normally closed power contactor is a contactor in which, in the inactive state, the fixed contacts are in mechanical contact with the movable contacts, thus allowing current to flow.

[0005] The field of the invention is that of normally closed power contactors, which, for reasons of simplicity, will be referred to hereinafter simply as "contactors".

[0006] Figure 1 The general geometry of such a contactor in its inactive position is shown.

[0007] like Figure 1 As shown, a contactor 1 according to the prior art comprises a fixed contact 2 and a movable contact 3, which face each other and are at least partially housed in a contactor chamber 4 protected by a housing 5. The contactor 1 extends along an axis XX'. A contact pressure spring 6 pushes the movable contact 3 towards the fixed contact 2 so that in the inactive position of the contactor 1, the fixed contact 2 is in mechanical contact with the movable contact 3. The contactor 1 further comprises an actuator 7 extending along the axis XX', the actuator having, for example, a linear motor, the actuator being typically electromagnetic, but the actuator may also be of pneumatic, hydraulic or other type. Figure 1 , an actuator 7 with an electromagnetic motor is shown, comprising a winding 16, an outer protection generally indicated as a body 8, a fixed portion 15 attached to the body 8 and generally indicated as a yoke, and a movable portion 9 generally indicated as a movable core. When the actuator 7 is energized, the movable portion 9 moves the movable contact 3 longitudinally away from the fixed contact 2 along the axis XX', thereby elastically compressing the contact pressure spring 6 and preventing the flow of current. Figure 1 , when the linear motor is actuated, the movable portion 9 of the actuator 7 and the movable contact 3 move to the right.

[0008] according to Figure 1In one embodiment of the prior art shown, the fixed contact 2 includes a contact pad 17 and the movable contact 3 further includes a contact pad 18. These contact pads 17, 18 are designed to contact when the fixed contact 2 and the movable contact 3 come into contact with each other and allow current to flow.

[0009] The displacement of the movable contact 3 by the actuator 7 is guided by a guide subassembly, which includes a movable shaft 10, a first portion of which is connected to the movable contact 3 and a second portion of which is integral with the movable part 9 of the actuator 7 via a connecting rod 14. The movable shaft 10 of the guide subassembly and the movable part 9 of the actuator 7 are slidably guided along the axis XX' (i.e., along the axis of linear displacement of the actuator 7). For the movable shaft 10, this guidance is achieved by a guide ring 11 mounted in the contactor chamber 4 and attached to the housing 5, while for the movable part 9 of the actuator 7, guidance is achieved by a guide part 12 mounted to the body 8 of the actuator 7 or integral with the body of the actuator.

[0010] In the actuator 7, the end of the movable part 9 that is not connected to the movable contact 3 is in contact with a return spring (also called a "core return spring") 13, which is elastically compressed when the movable part 9 is displaced away from the fixed contact 2. The return spring 13 is generally located between the fixed part 15 of the actuator 7 and the movable part 9.

[0011] When the actuator 7 is de-energized, the pressure exerted by the contact pressure spring 6 and the return spring 13 pushes the movable contact 3 into mechanical contact with the fixed contact 2. Figure 1 When the linear motor of the actuator 7 is no longer energized, the movable portion 9 of the actuator 7 and the movable contact 3 are displaced to the left.

[0012] When the movable part 9 of the actuator 7 reaches the end of its stroke, it or a component integral therewith strikes a stop, for example, a fixed portion of the housing 5 of the contactor 1 or a component integral therewith. The movable part 9 of the actuator 7, in turn, is a mass suspended on the return spring 13 and is therefore subjected to the shock, and subsequently experiences oscillations related to the damping coefficient of the return spring 13. These oscillations, caused by the return spring 13, cause the movable contact 3 to mechanically vibrate on the fixed contact 2.

[0013] In fact, when a switch, relay, etc. is actuated, what humans perceive as a single instantaneous response for each change in device state may actually involve approximately one hundred opening and closing movements, lasting a few thousandths of a second, before the contacts move into position. These multiple openings and closings are called bounce.

[0014] When the power is turned off, the movable contact closes on the fixed contact, but may bounce via the core return spring.

[0015] These mechanical vibrations may cause arc strikes, which may lead to serious problems such as contact welding and corrosion. Therefore, these vibrations may degrade the performance of the contactor and may even cause the contacts to stick together, rendering the contactor inoperable.

[0016] The characteristics of these jitters depend on multiple parameters, including closing force, the properties of the contact material, the contact geometry, and the characteristics of the circuit. In power contactors, the switching motion of the contacts generates vibrations throughout the system. Typically, these jitters have little or no effect on the circuitry, but if the system includes digital circuitry capable of quickly detecting and responding to multiple jitters, they can have serious consequences.

[0017] Debouncing schemes have been developed to avoid or reduce the bouncing within contactors, or to counteract the effects of the bouncing.

[0018] These include software-based debouncing schemes, but while they can protect the circuit from the harmful effects of bouncing, they cannot protect the contactor itself, especially from damage caused by arcing.

[0019] A common hardware solution to prevent shudder is to increase the stiffness (spring constant) of the springs, particularly the core return spring. While this solution appears simple to implement, it requires a more powerful actuator, which is therefore larger and heavier. These drawbacks are unacceptable for aviation applications, where weight and volume are critical.

[0020] Therefore, there is a need for a hardware debounce solution that is based on not modifying the existing properties of the spring. Advantageously, the solution must be easy to build, reliable, robust, inexpensive, and must not change the mechanical properties of the contactor.

[0021] The device for implementing this solution should be lightweight and should not increase the overall volume of the contactor equipped with it. Summary of the Invention

[0022] The present invention solves the problems discussed above by providing a mechanical debouncing device that fixes a movable portion of an actuator, which is integral with the movable contact, using a fixing force with a load greater than a debouncing load when the fixed contact and the movable contact are in a closed position, to prevent the movable contact from undergoing oscillations caused by a return spring.

[0023] One embodiment of the present invention relates to a normally closed power contactor, comprising:

[0024] -case,

[0025] a fixed contact and a movable contact, at least partially housed in the housing and positioned facing each other, the movable contact being displaceable between a first closed position in which the movable contact is in mechanical contact with the fixed contact and a second open position in which the movable contact is at a distance from the fixed contact,

[0026] a contact pressure spring which exerts a thrust on the movable contact towards the fixed contact,

[0027] The normally closed power contactor is such that it includes a mechanical debounce device comprising:

[0028] - a first locking part, which is integral with the housing, and

[0029] a second locking part facing the first locking part and being integral with the movable contact, such that when the movable part is in the first position, the first locking part and the second locking part are lockingly engaged with each other by elastic deformation.

[0030] According to one embodiment of the present invention, the normally closed power contactor comprises:

[0031] an actuator comprising a fixed portion and a movable portion connected to the movable contact, the movable portion being displaceable between a first position and a second position, wherein displacement of the movable portion from the first position to the second position causes the movable contact to be displaced from the first closed position to the second open position under the action of a displacement force provided by the actuator when it is energized, and

[0032] The displacement force provided by the actuator when energized is greater than the sum of the elastic deformation force of the locking parts and the thrust of the contact pressure spring.

[0033] According to another embodiment of the present invention, the normally closed power contactor is such that:

[0034] the first locking part or the second locking part comprises a flexible elastic blade having an elastic portion and a protruding portion opposite to the elastic portion, and

[0035] The second locking part or the first locking part, respectively, comprises a recessed receiving portion, in which the projection is received when the first locking part and the second locking part are in mutually locking engagement.

[0036] According to another embodiment of the present invention, the recessed receiving portion is an annular groove.

[0037] According to one embodiment of the invention, the first locking part or the second locking part is a male part having a protrusion, and the second locking part or respectively the first locking part is a female part having a housing, and when the first locking part and the second locking part are mutually lockingly engaged, the protrusion is inserted into the housing of the female part.

[0038] According to another embodiment of the invention, the female part has flexible elastic blades in the form of an annular crown.

[0039] According to another embodiment of the invention, the female part comprises a plurality of flexible elastic blades arranged as a crown.

[0040] According to one embodiment of the present invention, the fixing force applied by the mechanical de-shaking device is greater than 5 Newtons.

[0041] According to another embodiment of the present invention, the normally closed power contactor is such that:

[0042] - the actuator comprises a fixing portion,

[0043] - the power contactor comprises a return spring located between the fixed part and the movable part of the actuator, the return spring urging the movable part to its first position using a thrust force, and

[0044] The displacement force provided by the actuator when energized is greater than the sum of the elastic deformation force of the locking part, the thrust of the contact pressure spring and the thrust of the return spring.

[0045] According to another embodiment of the present invention, the normally closed power contactor is such that:

[0046] - the normally closed power contactor comprises a movable shaft and a guide ring attached to the housing,

[0047] - the movable contact is integral with the movable part via the movable shaft, the movable shaft being slidably guided by the guide ring, and

[0048] The first locking part is attached to the guide ring or is a single piece with the guide ring.

[0049] In addition to the features discussed in the preceding paragraphs, the normally closed power contactor according to an embodiment of the present invention may also have one or more of the following additional features, which may be considered individually or in any technically possible combination:

[0050] The first locking part and the second locking part are each a rotary part.

[0051] - A return spring is located between the fixed part and the movable part of the actuator.

[0052] On its face comprising the recessed receptacle, the male part has a tapered portion, situated in front of the recessed receptacle, on the actuator side.

[0053] The second locking part comprises a sleeve attached to the face of the movable part of the actuator facing the fixed contact and the movable contact.

[0054] By means of the present invention, a hardware debouncing solution is provided which is based on not modifying the existing characteristics of one or more springs.The hardware debouncing solution provides a harpoon which tends to lock the two contacts in order to prevent or limit the debouncing phenomenon.

[0055] The mechanical debounce device supplements the insufficient elastic force of the return spring to prevent the movable part of the actuator from moving backward after the impact caused by contact with the stopper.

[0056] The mechanical debounce device according to the present invention is advantageously reliable, robust, and inexpensive, and is easy to implement without requiring major modifications to existing contactors or significantly changing the mechanical characteristics of the contactors. The mechanical debounce device is lightweight and can be easily accommodated in the contactor body without increasing its overall volume.

[0057] The mechanical debouncing device according to the invention generates an additional load provided by the actuator when displacing the movable contact from the closed position to the open position, but this load is advantageously absorbed by the motor drive of the actuator because said load must be provided within the operating range of the actuator, which does not lie within its critical usable area.

[0058] Finally, the mechanical debouncing device according to the present invention advantageously provides improved cut-off performance, with tests having shown that the cut-off capability at short-circuit current is doubled.

[0059] The present invention and its various applications will be better understood by reading the following description and examining the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] These drawings are provided for the purpose of illustrating the present invention and not for the purpose of limiting the present invention.

[0061] [ Figure 1 ] Figure 1 It is a longitudinal cross-sectional view of a normally closed power contactor in a closed state according to the prior art.

[0062] [ Figure 2 ] Figure 2 is a longitudinal cross-sectional view of a normally closed power contactor according to the present invention in a closed state.

[0063] [ Figure 3 ] Figure 3is a longitudinal cross-sectional view of a normally closed power contactor according to the present invention in an open state.

[0064] [ Figure 4 ] Figure 4 yes Figure 2 Detailed diagram.

[0065] [ Figure 5 ] Figure 5 yes Figure 3 Detailed diagram. DETAILED DESCRIPTION

[0066] Unless otherwise stated, identical elements appearing in different drawings have a single reference number.

[0067] In this specification, the term "integrated" means that a mechanical part is directly or indirectly mechanically joined to another part, but without any gap, so that any displacement of one part will cause the same displacement of the other part, for example, which is integral with it, without any possible gap.

[0068] Likewise, the term "connected" means that a mechanical part is mechanically linked directly or indirectly to another part, possibly with play, such that any displacement of one part may cause, but does not necessarily cause, displacement of another part to which it is connected, possibly with play.

[0069] Finally, a "part of revolution" refers to a three-dimensional part whose overall body shape can be formed by rotating a planar surface about an axis. Examples of known parts of revolution are hollow or solid cones and cylinders. In practice, some parts of the normally closed power contactor according to the present invention may have a generally cylindrical shape, including conical portions, grooves, and / or ribs. The term "part of revolution" is used to denote parts that may have such complex shapes.

[0070] As a reminder, the normally closed power contactor will be referred to as a "contactor" in the following text.

[0071] Generally speaking, the contactor 21 of the present invention includes a fixed contact 22 and a movable contact 23, which are disposed facing each other in a contactor chamber 24 protected by a housing 25. The movable contact 23 is movable between a closed position, in which the movable contact is in mechanical contact with the fixed contact 22, and an open position, in which the movable contact is spaced a certain distance from the fixed contact 22. A contact pressure spring 26 is preferably housed in the contactor chamber 24, urging the movable contact 23 toward the fixed contact 22.

[0072] The contactor 21 of the present invention extends along the axis XX' and also includes an actuator 27 having an electromagnetic, pneumatic, hydraulic or other type of linear motor. The actuator 27 includes a fixed portion 47 and a movable portion 29, which is connected to the movable contact 23 and is preferably displaced by the linear motor. The movable portion 29 of the actuator 27 can be moved along the axis XX' between a first position and a second position, the first position and the second position corresponding to the closed position and the open position of the fixed contact 22 and the movable contact 23, respectively. In fact, the movable portion 29 is connected to the movable contact 23 so that the displacement of the movable portion 29 from the first position to the second position causes the movable contact 23 to be displaced from the closed position to the open position along the axis XX'.

[0073] The actuator 27 comprises a return spring 33 which pushes the movable part 29 to its first position. The return spring 33 is preferably located between the fixed part 47 of the actuator 27 and the movable part 29.

[0074] exist Figures 2 to 5 In FIG. 2 , the actuator 27 is exemplified in the form of an electromagnetic actuator 27 comprising a winding 48 and an outer protective member called body 28 in which the fixed portion 47 , the movable portion 29 , the winding 48 and the return spring 33 are housed.

[0075] according to Figures 2 to 5 In one embodiment of the present invention shown in FIG, the movable portion 29 of the actuator 27 is fixed to the movable shaft 30 by a connecting rod 46, and the movable shaft moves the movable contact 23 away from the fixed contact 22 when the movable portion 29 is displaced from a first position to a second position, the second position corresponding to the open position of the fixed contact 22 and the movable contact 23.

[0076] according to Figures 2 to 5 In a preferred embodiment of the present invention shown in FIG, the fixed contact 22 includes a contact pad 50, and the movable contact 23 further includes a contact pad 51. These contact pads 50, 51 are designed to contact each other when the fixed contact 22 and the movable contact 23 come into contact with each other and allow the flow of current. The fixed contact 22 and the movable contact 23 are made of copper, for example, while the contact pads 50, 51 are made of silver oxide, for example, and are soldered to their respective contacts.

[0077] Due to manufacturing tolerances of the actuator 27 and corrosion of the contacts 23 and 22 or the contact pads 50, 51 of the contacts 23, 22, the displacement of the movable portion 29 from the first position to the second position causes the displacement of the movable contact 23 from the closed position to the open position, but with some delay, after a very short stroke (e.g., on the order of 1 mm) due to the gap between the movable shaft 30 and the movable contact 23. This delay of the order of 1 mm corresponds to the effective stroke of the contact pressure spring 26.

[0078] In the case where both contacts 23 and 22 are equipped with contact pads 50, 51, this value of the order of 1 millimeter corresponds to the corrosion that the contact pads 50, 51 will experience during their lifetime. Therefore, at the beginning of the life of the contact pads 50, 51, the effective travel of the contact pressure spring 26 is of the order of 1 millimeter, while at the end of the life of the contact pads 50, 51, this effective travel tends to 0 millimeter. Between these two values, the contact pressure decreases slightly, but only minimally, and the contact pressure spring 26 is selected accordingly.

[0079] To this end, according to the example given and Figures 2 to 5 In one embodiment shown in FIG, when the intermediate part 49 is driven into abutment with the movable contact 23 by the connecting rod 46 via the movable shaft 30 and the connecting rod 46, the movable contact 23 is driven away from the fixed contact 22 by the intermediate part 49 integrally mounted on the movable shaft 30. When the movable portion 29 of the actuator 27 is displaced from the first position to the second position, the connecting rod 46, the movable shaft 30, and the intermediate part 49 are similarly displaced. After a very short stroke (e.g., less than 1 mm), during which the movable contact 23 has not displaced, a stopper 52 located on the intermediate part 49 and facing the movable contact 23 contacts the movable contact 23 and drives it away from the fixed contact 22. The stopper will continue to move the movable contact away from the fixed contact as long as the movable portion 29 of the actuator 27 is displaced from the first position toward the second position. This displacement stops when the movable part 29 of the actuator 27 is in the second position, with the movable contact 23 being in the open position at a distance from the fixed contact 22 .

[0080] according to Figures 2 to 5 In an exemplary embodiment of the present invention shown in , the displacement of the movable part 29 of the actuator 27 along the axis XX' is guided by a guide part 32 (which is for example mounted to the body 28 of the actuator 27 or is a single part with the body), while the displacement of the movable shaft 30 along the axis XX' is guided by a guide ring 31 (which is for example attached to the housing 25).

[0081] When the movable part 29 is displaced from its second position toward its first position, the movable part 29 or a part integral therewith (e.g., the movable shaft 30) strikes an end-of-stroke stop, which tends to move the end-of-stroke stop backwards and thus moves the movable part 29 away from its second position. The return spring 33 then tends to push the movable part 29 back to its second end-of-stroke position, which again strikes the end-of-stroke stop and continues in an oscillating manner, resulting in a plurality of opening and closing movements between the movable contact 23 and the fixed contact 22, which are referred to as chattering.

[0082] In order to prevent the jitter caused by the return spring 33 when the movable part 29 shifts from its second position to its first position, the contactor 21 of the present invention includes a mechanical de-jitter device 34, which is designed to freeze these movable mass blocks in the closed position before they jitter due to the end-of-stroke stop and oscillate due to the return spring 33.

[0083] The mechanical debouncing device 34 of the present invention includes a first locking part 35 integral with the housing 25, and a second locking part 36 positioned facing the first locking part 35 and integral with the movable portion 29 of the actuator 27. When the movable portion 29 is displaced from the second position to the first position, the first locking part 35 and the second locking part 36 are mutually lockingly engaged. This locking engagement exerts a securing force on the second locking part 36 that is greater than the tension exerted by the return spring 33, so that when the second locking part is locked with the first locking part 35, the second locking part 36 no longer deboils due to the return spring 33.

[0084] The fixing force applied by the mechanical debouncing device 34 is preferably greater than 5 Newtons, so as to avoid the bouncing phenomenon, but at the same time allow the actuator 27 commonly used for the contactor 21 to have sufficient power to shift the movable part 29 from the first position to the second position and thereby separate the first locking part 35 and the second locking part 36 that are lockedly engaged with each other.

[0085] According to a preferred embodiment of the present invention, the first locking part 35 and the second locking part 36 are respectively rotary parts.

[0086] According to a preferred embodiment of the present invention, the first locking part 35 or the second locking part 36 includes a flexible elastic blade 37, which has a protrusion 38 relative to the rest of the body of the flexible elastic blade 37, and when the first locking part 35 and the second locking part 36 are lockedly engaged with each other, the protrusion is received in a recessed receiving portion 39 provided in the other locking part (i.e., the second locking part 36 or the first locking part 35, respectively), and the other locking part 36 is the second locking part 36 or the first locking part 35, respectively.

[0087] According to this embodiment, the protrusion 38 engages in the recessed receiving portion 39 to lock the first locking part 35 with the second locking part 36 in a clamping manner. The load required to deform the flexible elastic leaf 37 is not significant compared to the closing load caused by the contact pressure spring 26 and the return spring 33. Similarly, the elastic deformation force of the flexible elastic leaf 37 is less than the force when the actuator 27 is energized, so the locking force of the first locking part 35 and the second locking part 36 greatly exceeds the force generated by the actuator 27.

[0088] exist Figures 2 to 5 , a preferred embodiment of the present invention is shown, the second locking part 36 comprises a flexible elastic blade 37 and the first locking part 35 has a recessed receiving portion 39.

[0089] The recessed receiving portion 39 is preferably an annular groove 40. This annular groove 40 is preferably designed to receive a projection 38 of a flexible elastic blade 37 in the form of an annular crown, or a plurality of projections 38 of flexible elastic blades 37 arranged as a crown.

[0090] According to a preferred embodiment of the present invention, the first locking part 35 or the second locking part 36 is a male part having a protrusion 41, and the other locking part (the second locking part 36 or the first locking part 35, respectively) is a female part having a housing 42, and when the first locking part 35 and the second locking part 36 are lockedly engaged with each other, the protrusion 41 is inserted into the housing 42 of the female part.

[0091] The female part preferably comprises a flexible elastic blade 37 in the form of an annular crown, or a plurality of flexible elastic blades 37 arranged as a crown.

[0092] exist Figures 2 to 5 In FIG. 3 , a preferred embodiment is shown, the first locking part 35 being a male part and the second locking part 36 being a female part.

[0093] According to a preferred embodiment of the present invention, the male part is provided with a tapered portion 43 on its face including the recessed receiving portion 39, which is located in front of the recessed receiving portion 39, on the side of the actuator 27, so as to form a guide and sliding ramp for the protrusion 38 of each flexible elastic blade 37.

[0094] The second locking part 36 preferably has a sleeve 44 (eg substantially orthogonal to the flexible elastic blade 37 ) attached to a face 45 of the movable part 29 of the actuator 27 facing the fixed contacts 22 and the movable contact 23 .

[0095] According to one embodiment of the invention, the movable contact 23 is connected to the movable part 29 via a movable shaft 30 which is slidably guided by a guide ring 31 attached to the housing 25. According to this embodiment, the first locking part 35 is preferably attached to the guide ring 31 and made in one piece therewith.

[0096] Of course, the first locking part 35 may be attached to another element of the contactor 21 , even in the case where the contactor comprises a guide ring 31 .

[0097] It will also be noted that the mechanical debounce device 34 may comprise a plurality of first locking parts 35 and second locking parts 36. Likewise, the contactor 21 according to the invention may comprise a plurality of mechanical debounce devices 34.

[0098] Finally, although the figures show a single-pole contactor 21, it is clear that a multi-pole (e.g., two-pole or three-pole) contactor can be equipped with a mechanical debounce device 34. In these configurations, a single mechanical debounce device 34 can be used that holds the movable masses of all poles, or alternatively, a separate mechanical debounce device 34 can be provided for each pole, the principle always being to cancel the back-and-forth oscillating load caused by the vibration of the movable mass.

Claims

1. A normally closed power contactor (21), comprising: - a housing (25), a fixed contact (22) and a movable contact (23), the fixed contact and the movable contact being at least partially housed in the housing (25) and positioned facing each other, the movable contact (23) being displaceable between a first closed position, in which the movable contact is in mechanical contact with the fixed contact (22), and a second open position, in which the movable contact is at a distance from the fixed contact (22), a contact pressure spring (26) which exerts a thrust on the movable contact (23) towards the fixed contact (22), - an actuator (27), comprising a fixed portion (47) and a movable portion (29) connected to the movable contact (23), the movable portion (29) being displaceable between a first position and a second position, the displacement of the movable portion (29) from the first position to the second position causing the movable contact (23) to be displaced from the first closed position to the second open position under the action of a displacement force provided when the actuator (27) is energized, - a return spring (33) which pushes the movable part (29) to its first position using a thrust force, - A normally closed power contactor (21) is characterized in that it comprises a mechanical debouncing device (34), the mechanical debouncing device comprising: - a first locking part (35) integral with the housing (25), and a second locking part (36) facing the first locking part and integral with the movable contact (23); - when the movable portion (29) is in the first position, the first locking part (35) and the second locking part (36) are mutually lockingly engaged by elastic deformation, the mutually locking engagement exerting a fixing force on the second locking part (36) that is greater than the tension exerted by the return spring (33), the fixing force being a locking engagement force; and - the actuator (27) has sufficient power to displace the movable part (29) from the first position to the second position, thereby separating the first locking part (35) and the second locking part (36) and releasing the mutual locking of the first locking part and the second locking part.

2. The normally closed power contactor (21) according to claim 1, characterized in that The displacement force provided by the actuator (27) when energized is greater than the sum of the elastic deformation force of the locking parts (35, 36), the thrust of the contact pressure spring (26) and the thrust of the return spring (33).

3. The normally closed power contactor (21) according to claim 1 or 2, characterized in that: - the first locking part (35) or the second locking part (36) comprises a flexible elastic blade (37) having an elastic portion and a raised portion (38) opposite to the elastic portion, and The second locking part (36) or the first locking part (35), respectively, comprises a recessed receiving portion (39), in which the projection is received when the first locking part (35) and the second locking part (36) are in mutually locking engagement.

4. Normally closed power contactor (21) according to the preceding claim, characterized in that The recessed receiving portion (39) is an annular groove (40).

5. A normally closed power contactor (21) according to any one of the preceding claims, characterized in that The first locking part (35) or the second locking part (36) is a male part having a protrusion (41), and the second locking part (36) or the first locking part (35) is a female part having a housing (42), and when the first locking part (35) and the second locking part (36) are mutually lockingly engaged, the protrusion (41) is inserted into the housing (42) of the female part.

6. Normally closed power contactor (21) according to the preceding claim, characterized in that The female part has flexible elastic blades (37) in the form of an annular crown.

7. The normally closed power contactor (21) according to claim 5, characterized in that The female part comprises a plurality of flexible elastic leaves (37) arranged as a crown.

8. A normally closed power contactor (21) according to any one of the preceding claims, characterized in that The fixing force applied by the mechanical debounce device (34) is greater than 5 Newtons.

9. A normally closed power contactor (21) according to any one of the preceding claims, characterized in that The return spring (33) is located between the fixed portion (47) and the movable portion (29) of the actuator (27).

10. A normally closed power contactor (21) according to any one of the preceding claims, characterized in that: - the normally closed power contactor comprises a movable shaft (30) and a guide ring (31) attached to the housing (25), - the movable contact (23) is integral with the movable part (29) via the movable shaft (30), which is slidably guided by the guide ring (31), and - The first locking part (35) is attached to the guide ring (31) or is a single piece with the guide ring.

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