EP1108195A1 - Ammunition safety and arming unit - Google Patents
Ammunition safety and arming unitInfo
- Publication number
- EP1108195A1 EP1108195A1 EP99940405A EP99940405A EP1108195A1 EP 1108195 A1 EP1108195 A1 EP 1108195A1 EP 99940405 A EP99940405 A EP 99940405A EP 99940405 A EP99940405 A EP 99940405A EP 1108195 A1 EP1108195 A1 EP 1108195A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- safety
- acceleration
- ammunition
- arming unit
- arming
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
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
- F42C15/40—Arming-means in fuzes; Safety means for preventing premature detonation of fuzes or charges wherein the safety or arming action is effected electrically
Definitions
- the present invention relates to safety and arming systems for ammunition fuzes.
- ammunition is taken to include but is not limited to artillery shells and charges, mortar rounds, rockets and missiles.
- Mechanical safety means capable of enabling a firing circuit of a detonator, for detonating the explosive charge within the ammunition, are known. These safety means may be adapted to respond when ammunition reaches a predetermined position, time or proximity to a target for example.
- Mechanical safety and arming devices for spun rounds that are fired from rifled guns or unspun rounds fired from smooth bore guns, generally comprise an inertia device such as a safety pin or detent which operates only under the high forces generated by firing or launch to arm the fuze by physically moving from a position which prevents detonation of the charge to one which permits this.
- Spun rounds fired from rifled bores may have known mechanical safety and arming devices operated by the effects of centrifugal force, for example on a spring and mass system.
- this type of ammunition may have mechanical safety and arming devices actuated by air pressure.
- US Patent US4526104 proposes to utilise air pressure effects by means of elevating a pitot tube into the surrounding airflow after launch and during flight of the round.
- Electronically operated safety and arming systems are not widely used in fuzes, but electronic devices capable of sensing accelerations, known as accelerometers, have been used in the vehicle industry for crash sensing.
- accelerometers are generally regarded as being unsuitable for use in the safety and arming systems of fuzes as they are separate from the fuzing system, only measuring acceleration and needing to communicate this information to the safety and arming system, and further requiring complex processing of their output signals before the separate safety and arming system can respond.
- it is undesirable to use an accelerometer because of the need to integrate this complex system successfully with the safety and arming system in order to enable the fuze to operate with the required high level of reliability. Indeed it is usually a primary safety requirement that the safety and arming system is one integral system which can be readily integrated into an electronic fuze.
- the present invention seeks to provide an integral safety and arming unit for ammunition which operates by sensing and responding to acceleration. It further seeks to provide a safety and arming unit which is small, light and reliable.
- the predominantly electronic safety and arming unit reduces moving parts and does not require extensive precision engineering. Less complex electronic safety and arming systems are quicker and cheaper to manufacture than known safety and arming systems having mechanical acceleration responsive devices.
- a safety and arming unit for a round of ammunition comprising one or more acceleration sensors for detecting when the acceleration of the ammunition reaches at least two different predetermined linear acceleration values; timer means for measuring the time interval between the detection of two of the predetermined linear acceleration values, means for electronically comparing the said measured time interval with a range of predetermined and pre-set time intervals representing satisfactory firing for the round of ammunition, and means for producing an electronic signal when the said measured time interval falls within the range of predetermined and pre-set time intervals, which signal operates to arm the ammunition ready for detonation.
- the safety and arming unit may comprise at least one acceleration sensor capable of detecting at least two predetermined linear acceleration values.
- the unit may comprise at least two acceleration sensors, each being capable of detecting one predetermined linear acceleration value.
- At least one sensor detects a threshold lower acceleration value and at least one further sensor detects a threshold upper acceleration value.
- at least one sensor detects a threshold lower acceleration value and at least one further sensor detects a threshold upper acceleration value.
- several sensors may be provided to detect the same threshold acceleration value.
- One suitable type of sensor comprises a spring mass system having a first electrical contact on the mass and a second electrical contact initially not in contact with the mass.
- a predetermined force corresponding to a linear acceleration value is capable, in this sensor, of causing the mass to compress a spring and touch the second electrical contact.
- the spring mass system acts as a switch being open initially and closing at a threshold acceleration value to complete an electrical circuit.
- Another suitable type of sensor is in the form of a cantilever threshold switch, where the sensor comprises a cantilever fixed at one end and having an electrical contact and mass at the other, free end, which free end is close to a second electrical contact such that on launch of the ammunition the cantilever moves due to the launch acceleration to make contact with the second electrical contact and complete a circuit.
- a further suitable type of sensor is in the form of a cantilever comprising piezoresistive material such as piezocrystal.
- the cantilever in this sensor is connected to an electrical circuit such that current may flow through the length of the cantilever containing the piezoresistive material.
- the piezoresistive material undergoes strain and therefore a change in its resistivity on launch of the ammunition, such that the current flowing through it is changed and this change may be detected.
- the sensor may alternatively comprise an optical spring mass acceleration system which acts on launch of the ammunition in the same way as the spring mass system described above, but instead of utilising electrical contacts, the sensor instead comprises a light beam generator and a receiver, such that as the mass moves it may interrupt a light beam and this interruption may be detected.
- the acceleration sensor or sensors used in the safety and arming unit preferably form an integral part of the safety and arming system of a fuze.
- Figure 1a shows a typical acceleration versus time graph for a particular artillery shell in the period from being fired up to exit from the muzzle for a successful firing.
- Figure 1 b shows an acceleration versus time graph for the same artillery shell
- Figure 2 shows a schematic diagram of sequential operations of a safety and arming unit capable of sensing and responding to a predetermined acceleration in accordance with the present invention.
- Figure 3a shows a spring mass acceleration sensor for use in a safety and arming unit according to the present invention, when it has not yet detected a predetermined acceleration value.
- Figure 3b shows the sensor of Figure 3a when it has detected a predetermined acceleration value.
- Figure 4a shows a three dimensional view of cantilever acceleration sensors for use in a safety and arming unit according to the present invention.
- Figure 4b shows a plan view of a pair of cantilever acceleration sensors similar to those shown in Figure 4a.
- Figure 5 shows a plan view of another spring mass acceleration sensor having an optical switch for use in a safety and arming unit according to the present invention.
- Figure 6 shows a three dimensional view of another cantilever acceleration sensor having piezoresistive characteristics for use in a safety and arming unit according to the present invention.
- Figure 7 shows a fuze for ammunition incorporating a safety and arming unit according to the present invention.
- Figure 1a shows a graph of acceleration against time for an artillery shell undergoing a successful firing, from initiation up to the moment where it leaves the muzzle of the howitzer barrel 5. It can be seen that the shell accelerates rapidly at the initiation of firing and then the acceleration gradually decreases until the shell leaves the muzzle at a near constant velocity.
- Figure 1 b shows a graph of acceleration against time for a similar artillery shell
- acceleration change is due to a successful firing or other circumstances, for example,
- Acceleration sensors can be produced for detecting the acceleration values particular
- point 1A represents a threshold value of acceleration due to firing at which a first acceleration sensor is designed to respond by producing an electrical signal. From Figure 1a it can be seen that this occurs at a time 3A. As the shell accelerates in the barrel of the launcher it will reach, at a time 4A, a second threshold value of acceleration 2A at which a second acceleration sensor is designed to respond by producing another electrical signal.
- the time differential ⁇ t should be the same between points 3A and 4A for all shells fired of that type with the same charge assuming that the shells conform precisely to their design characteristics.
- a timer receives a signal from this sensor and begins to count.
- the second acceleration sensor detects its threshold acceleration 2A and responds in a manner similar to the first sensor, the timer receives a second signal from the second sensor causing it to stop counting.
- the timer records a differential time ⁇ t in this manner and this ⁇ t value is then compared by a comparator with the allowable range of ⁇ t values held in the comparator which represent a successful firing of the ammunition in accordance with the acceleration versus time graph for that ammunition and charge.
- the comparator causes an electrical signal to be sent immediately to the firing circuit and the detonator to cause the fuze to become armed.
- the ammunition would then be detonated by separate position, time, proximity or other detonation means.
- Figure 3a shows a sensor comprising a spring mass system 6 for detecting
- the system comprises a mass 16, capable of linear movement
- the mass 16 has a head portion 80 and a body portion 82.
- spring 8 is located around the body portion 82 with one end 84 of the spring 8
- the end 20 of the mass 16 is not in contact with the contact 10 and so the
- Figure 3b shows the system 6 at a pre-determined acceleration
- the first switch has a lower threshold acceleration value and the second
- a second signal is sent to the timer.
- the timer records the time differential ⁇ t
- Figure 4a shows a sensor comprising cantilevers 24,26.
- 24,26 has one end 92, 98 fixed to a support 90 and another end 94, 100 which is free
- the base plate 96 has electrical contacts
- Each cantilever 24, 26 has a mass 28, 106 incorporated in its free end 94,
- Contact 30 is capable of forming an electrical circuit via the wire 42,
- contact 108 is capable of forming a separate electrical circuit via
- the cantilevers 24, 26 are fixed to the support 90 so that their
- the cantilevers 24, 26 are designed to switch at different threshold
- Figure 4b shows two sensors 22, 34 comprising of cantilevers 21 , 23, 31 , 33
- cantilevers 21 and 23 are designed to switch at the same pre-determined
- acceleration value and cantilevers 31 and 33 are designed to switch at the same
- threshold acceleration which is higher than that acceleration required by the
- Each cantilever is not part of the same circuit as any other
- each circuit sends a separate electrical signal to the timer.
- cantilevers in set 22 have closed their circuits, thereby sending electrical signals to
- the timer starts to count. Only when both cantilevers in set 34 have closed their circuits, thereby sending electrical signals to the timer, will the timer stop
- This double switch system acts as a further safety measure to ensure that
- Figure 5 shows a photoelectric optical spring mass acceleration threshold
- switch 40 suitable for use as the acceleration sensor of Figure 2.
- a light beam 46 is directed between the base 18 and the end 20 of the mass 16 from
- receiver 44 detects this difference in light levels it sends an electrical signal to the
- the predetermined position can be fixed by the location of the light beam, the
- Figure 6 shows a cantilever piezoresistive acceleration sensor 48 suitable for
- the cantilever 50 forms part of an electrical circuit comprising electrical
- this mechanical strain causes its resistive properties to change, influencing the current in the circuit.
- One such sensor 48 may be
- Figure 7 shows a schematic fuze 64 at the forward part of an artillery shell 62
- the fuze having a safety and arming unit 76 according to the present invention.
- fuze 64 has a safety and arming unit 76 comprising an acceleration sensor 70, an
- integrated electronics pack 68 which includes an electronic timer 72, a comparator
- the safety and arming unit can be adapted for use with different natures of
- ammunition of the same calibre and, for artillery can be adapted to different charges.
- the unit can be adapted to permit external programming of the unit with different
- the soldier such as ring burning or irregular burning of the propellant producing a
- the invention may therefore be adapted to avoid collateral damage by a shell falling short
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9818673 | 1998-08-28 | ||
GBGB9818673.7A GB9818673D0 (en) | 1998-08-28 | 1998-08-28 | Ammunition safety and arming unit |
PCT/GB1999/002799 WO2000012953A1 (en) | 1998-08-28 | 1999-08-24 | Ammunition safety and arming unit |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1108195A1 true EP1108195A1 (en) | 2001-06-20 |
EP1108195B1 EP1108195B1 (en) | 2003-03-26 |
Family
ID=10837907
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99940405A Expired - Lifetime EP1108195B1 (en) | 1998-08-28 | 1999-08-24 | Ammunition safety and arming unit |
Country Status (7)
Country | Link |
---|---|
EP (1) | EP1108195B1 (en) |
JP (1) | JP2001506361A (en) |
AU (1) | AU5438599A (en) |
CA (1) | CA2341247A1 (en) |
DE (1) | DE69906315T2 (en) |
GB (1) | GB9818673D0 (en) |
WO (1) | WO2000012953A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102006047549B4 (en) * | 2006-10-07 | 2010-04-22 | Junghans Microtec Gmbh | Igniter for a spin-free projectile |
DE102009058718B4 (en) * | 2009-12-17 | 2011-12-08 | Junghans Microtec Gmbh | Safety device for an igniter of a projectile |
CN109388852B (en) * | 2018-09-07 | 2023-07-28 | 陕西中天火箭技术股份有限公司 | Rocket projectile firing number accurate counting method |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3851531A (en) * | 1971-03-04 | 1974-12-03 | Westinghouse Electric Corp | Electronic fuze system |
US4013012A (en) * | 1974-11-18 | 1977-03-22 | Altus Corporation | Electronic safe arming and fuzing system |
US5251548A (en) * | 1981-11-27 | 1993-10-12 | Alliedsignal Inc. | Missile acceleration and arming device |
US4526104A (en) | 1982-10-14 | 1985-07-02 | The United States Of America As Represented By The Secretary Of The Navy | Safety-arming device |
DE3543938C1 (en) * | 1985-12-12 | 1987-07-09 | Buck Chem Tech Werke | Method for preventing premature detonation of a destruction charge, and a detonator arrangement |
DE3925000C1 (en) * | 1989-07-28 | 1997-09-18 | Honeywell Regelsysteme Gmbh | Flight time measuring method for shell |
-
1998
- 1998-08-28 GB GBGB9818673.7A patent/GB9818673D0/en not_active Ceased
-
1999
- 1999-08-24 AU AU54385/99A patent/AU5438599A/en not_active Abandoned
- 1999-08-24 DE DE69906315T patent/DE69906315T2/en not_active Expired - Lifetime
- 1999-08-24 JP JP56283899A patent/JP2001506361A/en active Pending
- 1999-08-24 WO PCT/GB1999/002799 patent/WO2000012953A1/en active IP Right Grant
- 1999-08-24 CA CA002341247A patent/CA2341247A1/en not_active Abandoned
- 1999-08-24 EP EP99940405A patent/EP1108195B1/en not_active Expired - Lifetime
Non-Patent Citations (1)
Title |
---|
See references of WO0012953A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO2000012953A1 (en) | 2000-03-09 |
DE69906315D1 (en) | 2003-04-30 |
EP1108195B1 (en) | 2003-03-26 |
DE69906315T2 (en) | 2003-08-21 |
CA2341247A1 (en) | 2000-03-09 |
GB9818673D0 (en) | 1999-09-15 |
JP2001506361A (en) | 2001-05-15 |
AU5438599A (en) | 2000-03-21 |
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