Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F42—AMMUNITION; BLASTING
  • F42C—AMMUNITION FUZES; ARMING OR SAFETY MEANS THEREFOR
  • F42C15/00—Arming-means in fuzes; Safety means for preventing premature detonation of fuzes or charges
  • F42C15/18—Arming-means in fuzes; Safety means for preventing premature detonation of fuzes or charges wherein a carrier for an element of the pyrotechnic or explosive train is moved
  • F42C15/184—Arming-means in fuzes; Safety means for preventing premature detonation of fuzes or charges wherein a carrier for an element of the pyrotechnic or explosive train is moved using a slidable carrier
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F42—AMMUNITION; BLASTING
  • F42C—AMMUNITION FUZES; ARMING OR SAFETY MEANS THEREFOR
  • F42C15/00—Arming-means in fuzes; Safety means for preventing premature detonation of fuzes or charges
  • F42C15/24—Arming-means in fuzes; Safety means for preventing premature detonation of fuzes or charges wherein the safety or arming action is effected by inertia means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F42—AMMUNITION; BLASTING
  • F42C—AMMUNITION FUZES; ARMING OR SAFETY MEANS THEREFOR
  • F42C15/00—Arming-means in fuzes; Safety means for preventing premature detonation of fuzes or charges
  • F42C15/34—Arming-means in fuzes; Safety means for preventing premature detonation of fuzes or charges wherein the safety or arming action is effected by a blocking-member in the pyrotechnic or explosive train between primer and main charge
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F42—AMMUNITION; BLASTING
  • F42C—AMMUNITION FUZES; ARMING OR SAFETY MEANS THEREFOR
  • F42C15/00—Arming-means in fuzes; Safety means for preventing premature detonation of fuzes or charges
  • F42C15/36—Arming-means in fuzes; Safety means for preventing premature detonation of fuzes or charges wherein arming is effected by combustion or fusion of an element; Arming methods using temperature gradients

Definitions

• the invention relates to a pyrotechnic ignition system of a main engine load of a missile after ejection thereof from a tube or launching support.
• the ignition of the main propulsive charge of a missile occur if the missile has received sufficient acceleration at launch, preferably in value and duration, and after the missile has traveled a sufficient distance.
• a known solution for this purpose is to use a pyrotechnic ignition system which comprises an arming device capable of entering the "armed” state under the effect of the acceleration imparted during the ejection of the missile, a pyrotechnic delay defining a duration between ejection and ignition of the main charge, and a safety device with microbeads interposed between the main charge and a relay charge ignited at the end of combustion of the pyrotechnic delay.
• the microbead security device comprises a bed of microbeads which flow through openings disengaged by the arrival of the arming device in the "armed” state, thus, in case of non-passage to the "armed” state.
• the microbeads could not flow or flow completely and form a screen preventing the charging of the charge the ignition coil is ignited after the pyrotechnic delay has been burned in.
• Such a solution is implemented by the applicant for the "Mistral" tactical missile propulsion systems.
• the object of the invention is to propose a solution with improved reliability, especially in the long term, to the problem of the ignition safety of the main propulsive charge of missiles after ejection.
• a pyrotechnic ignition system of a main charge of propulsion of a missile after ejection thereof comprising: an arming device movable between a rest position, or "unarmed” mode, and an active position, or “armed” mode, in response to the ejection of the missile,
• a pin arranged to be lit when the missile is ejected and to cause the arming delay to come on and the first locking member to be released in order to allow the cocking device to go into the active position
• a pyrotechnic delay of trajectory distinct from the arming delay a first relay charge arranged to be lit at the end of the combustion of the arming delay and to cause the ignition of the trajectory delay and the actuation of the second locking member to lock the cocking device in the active position if it is in this position, and - a second relay load arranged to be lit at the end of the combustion of the trajectory delay and cause the ignition of the main charge if the device of arming is in the active position.
• locking in "armed” mode occurs after a time defined by the combustion of a first delay (arming delay) and is not dependent on the flow of a bed of microbeads.
• Longer-term reliability can then be obtained because the behavior for a long life of a pyrotechnic composition is well controllable and characterizable.
• the pyrotechnic chain may furthermore comprise:
• a moving part bearing the path delay and the second relay load, said movable part being movable between a retracted position in which the second relay load is not in the ignition position of the main load and an advanced position in which the second relay load is in the ignition position of the main load, and - A third locking member of said movable part in the retracted position, the third locking member being released in response to ignition of the first relay load.
• provision may furthermore be made for: a screen device interposed between the second relay load and the main load, and
• the screen device may be a bed of balls that can flow through a closed opening when the cocking device is in the rest position and disengaged when the cocking device is in the active position.
• the beads preferably microbeads, have no delay function. They fulfill a security function.
• the balls In the case where the second relay load is carried by a moving part released during the ignition of the first relay load, the balls also provide a damping function to stop a sudden arrival of the second relay load in the position of ignition of the main charge.
• the ignition chain further comprises: a support of the mobile delay between a rest position and an active position,
• FIG. 1 is a schematic cross-sectional view of a pyrotechnic chain according to a particular embodiment of the invention.
• FIGS. 2 to 5 are sectional views similar to that of Figure 1, but at different successive stages of operation of the pyrotechnic chain.
• the pyrotechnic chain shown in FIG. 1 comprises a cylinder 10 in the rear part of which is housed a pyrotechnic retardation support 20 and in the front part of which is housed a part 30 bearing a pyrotechnic trajectory delay.
• the terms "back” and “front” are used herein with reference to the direction of propagation of the combustion along the pyrotechnic chain.
• the support 20 has a sleeve shape sealingly engaged in the cylinder 10. Inside the sleeve 20 is fixed a pyrotechnic arming delay 22 comprising a pyrotechnic composition block 22a housed in an envelope 22b.
• the arming delay is immobilized by a ring 23 screwed into the sleeve 20 and acting on a gland 24 and a seal 25 at the rear of the arming delay.
• an initiation charge or pin 26 At the rear of the arming delay 22 is disposed an initiation charge or pin 26, a passage 27 communicating the retaining slot 26 with the pyrotechnic composition block 22a through the ring 23, the gland 24 and the envelope 22b.
• the pin 26 (shown only in FIG. 1) is mounted in a support 26a screwed into a ring 28 itself screwed onto the rear wall of the cylinder 10.
• a pyrotechnic relay charge 29 At the front of the pyrotechnic composition block 22a is fixed a pyrotechnic relay charge 29.
• the support 20 is immobilized axially in the cylinder 10 by a pin 11 forming a locking member.
• a split ring 12 prestressed circumferentially is housed in an annular groove formed in the outer surface of the support 20.
• an annular housing 20b is formed by a portion of the support 20 of reduced diameter in the vicinity of the front end 20c of this support.
• the support piece 30 of the pyrotechnic trajectory delay has a hollow piston shape in which is housed a block of pyrotechnic composition 32 forming the trajectory delay.
• the housing of the block 32 in the part 30 is delimited on the rear side by a wall 30a crossed by a passage 31.
• a relay pyrotechnic charge 34 At the front of the path delay 32 is disposed a relay pyrotechnic charge 34.
• the part 30 In the position of Figure 1, the part 30 is immobilized axially in the cylinder 10 by a pin 13 forming a locking member.
• a spring 35 prestressed in compression is housed between the piece 30 and the sleeve 20, the spring 35 bearing at its ends on the wall 30a and an inner shoulder 20a of the sleeve 20. The spring 35 ensures a retention of the pins 11, 13 in their locking position despite possible vibrations when the ignition system is in the non-active state.
• An arming device in the form of a ring 40 is engaged on the cylinder 10 from its front end. At its rear end portion 40a, the cocking ring 40 is engaged on the outer surface of the cylinder 10.
• the rear end portion 40a of the cocking ring 40 abuts against an outer shoulder 10a of the cylinder 10 and is locked in this position by a ball 14 forming a locking member.
• the ball 14 is housed in a bore formed in the wall of the cylinder 10 being retained on the inside by the front end portion 20c of the sleeve 20 engaged in the cylinder 10.
• the ball 14 protrudes outside the cylinder 10 in a housing 41 formed by a portion of the cock ring 40 having an inside diameter greater than that of the rear end portion 40a.
• Another ball 16 is housed in a hole in the wall of the cylinder 10. In the position of FIG. 1, the ball 16 projects internally into a housing 36 formed by a part of the part 30 of reduced outside diameter, while on the outside, ball 16 is blocked by a portion 40b of the arming ring engaged without play on the cylinder 10.
• the pyrotechnic chain is provided with a bottom 50 in the form of a ring screwed on the front end of the cylinder 10.
• An envelope 51 containing a pyrotechnic charge relay 52 is supported in the front part of the cylinder 10 and immobilized by the rear face of a shoulder 50a of the bottom 50.
• the casing 51 opens at the front to communicate through a passage 53 with a load (not shown) forming the ignition charge of the propulsive main charge of the missile.
• a gland 54 compresses a seal 55 against the front face of the shoulder 50a.
• the envelope 51 is provided with a bottom whose central portion 51a of reduced thickness forms a lid.
• a spring 42 not prestressed or weakly prestressed in compression is housed between the bottom 50 and an outer shoulder 43 of the cocking ring.
• a bed of balls 60 is disposed between the bottom of the casing 51, on the rear side, and the front of the piece 30 and the trajectory retardation 32.
• the bed of balls 60 is contained in the cylinder 10.
• This one has openings 18 distributed at its periphery, in the vicinity of the bottom of the casing 51.
• the openings 18 are closed on the outer side by the front end portion 40c of the cocking ring which is engaged without play on the cylinder 10.
• the cocking ring 40 has openings 44 disposed at its periphery in the same manner as the openings 18. In the position of the figure 1, the openings 44 are closed on the inside by the cylinder 10.
• the cylinder 10 and the cocking ring 45 are immobilized with respect to each other in rotation in order to avoid misalignment of the openings 18 and 44.
• a pin 45 is engaged and immobilized in a n radial orifice of the cylinder and protrudes into a slot 46 formed longitudinally in the rear part of the cocking ring 40.
• the balls 60 are for example ceramic or glass microbeads whose diameter is typically 100 to 500 microns, for example about 200 microns.
• the pyrotechnic chain is closed at its periphery by a case 62, for example metal, which connects the bottom 50 to the cylinder 10. Seals such as 21, 47, 56, 57 seal between the cylinder 10 and the support 20, between the case 62 and the cocking ring 40 and between the case 62 and the bottom 50.
• the operation of the pyrotechnic chain is as follows.
• the pin 26 is lit when the missile is ejected. As known per se, this ignition can be achieved by power supply by means of contacts provided on a tube or launching support.
• the generated pressure acting on the sleeve 20 causes the pin 11 to break, the sleeve 20 to move forwards from its rest position, against the elastic force exerted by the spring 35, and the ignition of the load 22a of the pyrotechnic braking delay 22.
• the prestressed rod 12 is housed in a housing 19 formed in the inner wall of the cylinder 11, blocking the sleeve 20 in the active position.
• the ball 14 disappears into the housing 20b formed at the rear of the front end portion 20c of the sleeve 20.
• the acceleration imparted to the missile causes a forward movement of the cock ring 40, the locking ball 14 being erased.
• the spring 42 is compressed.
• the cocking ring 40 comes to an advanced position sufficient for the ball 16 to stop being blocked by the part 40b of the cocking ring and is opposite a portion 40d of the cocking ring 40 of inner diameter greater than that of the portion 40b and progressively connecting thereto.
• the openings 44 are then facing the openings 18 and the flow of the balls 60 can begin. Note that the openings 44 are preferably of a size substantially greater than that of the openings 18. It is then in the position illustrated in Figure 2, arming authorization position.
• the spring 42 is calibrated to oppose the arrival in the arming clearance position with release of the ball 16 if the initial acceleration of the missile is less than a predetermined minimum value.
• the duration of combustion of the pyrotechnic trajectory delay 32 is chosen to ensure that the ignition of the main charge takes place at a point on the trajectory of the missile located at a sufficient distance from the launching location.
• the relay charge 34 is turned on and ignites the relay charge 52 to cause the ignition of the main propelling charge, as shown in FIG. 5.
• the ignition security is ensured in the following manner.
• the displacement of the ring 40 forward against the spring 42 is insufficient to bring the ring 40 in the arming authorization position. There is no passage in "armed" mode. If the duration of acceleration of the missile is insufficient and the spring 42 returns the cocking ring 40 to its rest position before the ignition of the relay load 26, the ball 16 is returned to the housing 36 and blocked by the part 40b of the cock ring 40 as in the rest position. There is no displacement of the part 30 and the distance between the relay charge 34 and the cover 51a is such that the combustion gases produced by the relay charge 34 are dispersed and do not can break the lid 51a, microbeads 60 possibly remaining in the cylinder providing additional security. The ignition relay charge of the main engine of the missile is not initiated.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Air Bags (AREA)
• Aiming, Guidance, Guns With A Light Source, Armor, Camouflage, And Targets (AREA)
• Portable Nailing Machines And Staplers (AREA)
• Woven Fabrics (AREA)

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• 2007
  • 2007-06-07 FR FR0755562A patent/FR2917159B1/fr not_active Expired - Fee Related
• 2008
  • 2008-06-03 DE DE602008003925T patent/DE602008003925D1/de active Active
  • 2008-06-03 AT AT08805914T patent/ATE491133T1/de not_active IP Right Cessation
  • 2008-06-03 WO PCT/FR2008/050971 patent/WO2009001000A2/fr active Application Filing
  • 2008-06-03 EP EP08805914A patent/EP2153162B1/de active Active

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