GB2198816A

GB2198816A - An electrical ignition device

Info

Publication number: GB2198816A
Application number: GB08728549A
Authority: GB
Inventors: Bernhard Kratz; Kurt Fiedler
Original assignee: Diehl GmbH and Co
Current assignee: Diehl Verwaltungs Stiftung
Priority date: 1986-12-18
Filing date: 1987-12-07
Publication date: 1988-06-22
Anticipated expiration: 2007-12-07
Also published as: IT8722999A0; GB2198816B; DE3643301A1; IT1223439B; GB8728549D0

Abstract

An electrical ignition device, especially pyrotechnical force element, comprising the housing 1 which guides a piston 2 with an ignition pellet 6. In order to provide a high-frequency filter which is free from soldering points and which does not hinder the stroke of the piston 2, inside the housing 1 at least onto the one connection wire 10 is placed a tubular part 12 made of ferrite material and onto this a tubular part 13 made of ceramic material having condenser coatings 14, 15, 16 is placed. The central condenser coating 15 is connected by means of an electrically conductive shaped part 25 with the housing 1, and each of the front and rear condenser coatings 14, 16 is connected by means of a respective sleeve 19, 20, superimposed onto the connection wire 10, with the connection wire 10. The sleeves 19, 20 are held between cap parts 23, 24 which are compressible upon piston movement. <IMAGE>

Description

AN ELECTRICAL IGNITION DEVICE The invention relates to an electrical ignition or electrically ignitable devices, of a type comprising a piston supported in a housing containing an ignitable or ignition pellet having electrical connection wires or leads which extend through the housing.

An ignition device is described in DE-GM 83 37 284.

A charge is ignited by the ignition pellet, whereby the piston is moved. The piston movement leads to a mechanical release of a safety element.

In order to avoid faulty ignitions, the ignition pellet is to be protected against high-frequency interference voltages. For this, a high-frequency filter (see DE-OS 35 02 526) is connected prior to the ignition pellet.

The task of the invention is to propose an ignition or ignitable device of the type mentioned at the beginning hereof which is provided with a high-frequency filter which is free from soldered joints, in which respect the high-frequency filter is to be arranged close to the pellet.

To enable the problem to be solved the invention generally provides an electrically ignitable device wherein a piston supported is in a housing containing an ignitable pellet having electrical leads extending out of the housing from the ignitable pellet, and comprising electrical capacitive and inductive filter means connected to at least one of said leads; and characterised in that the electrical filter means comprises electrically conductive, inductive and dielectric parts sandwiched together within the housing to effect mechanically the electrical connections necessary to place said parts in circuit with said leads; and in that some of said parts are compressible to maintain said connections, and, upon ignition of said pellet, to allow said filter means to be compressed by movement of the pistcn.

More particularly there is provided, in accordance with the invention, an ignition device generally of the aforementioned type, and characterised in that inside the housing a tubular part made of ferrite material is placed onto each connection wire and onto this tubular part is placed a tubular part made of ceramic material having on its outside a front, a central and a rear capacitor coating; in that the central coating is electrically connected in a solder-free manner by means of an electrically-conductive shaped part with the housing, and each of the front and the rear coatings is connected with the connection wire in a solder-free manner by a sleeve, superimposed onto the connection wire; and in that the sleeves are held between cap parts which can be pressed towards each other upon piston movement.

The filter is created here by simple superimposing of the filter parts. Solderings are not provided and are not necessary. The overall structure is thus free from soldering points. In this way, temperature stresses, which could lead to a formation of cracks, are prevented from occurring in the tubular part made of ceramic material. The filter action would be jeopardised by such crack formation.

The filter, because it is accommodated in the housing, is on the one hand protected and on the other hand it lies close to the pellet, so that the risk of voltages being generated by high-frequency irradiation between the filter and the ignition or ignitable pellet does not arise.

The cap parts hold the filter parts, and the compressibility of the cap parts allows the piston, upon ignition of the pellet, to carry out the piston stroke in the housing. It is thus ensured that movement of the piston is not prevented by installation measures of any nature in the ignition device.

In preferred development of the invention, the electrically conductive shaped part and the sleeves consist of an electrically conductive elastomer. The cap parts consist of an electrically insulating elastomer.

As a result of the elastic properties, not only the piston stroke, but also a shock-damping mounting of the tubular piece made of ceramic material is ensured.

Further preferred, and advantageous developments of the invention will become apparent from the sub-claims and the following description of an exemplified embodiment shown in the accompanying diagrammatic drawings, wherein FIGURE 1 shows a device of the invention, specifically a pyrotechnical force element, in longitudinal section; FIGURE 2 shows a view of a shaped part of the device; FIGURE 3 shows a view of a cap part of the device, and FIGURE 4 shows the electrical circuit diagram of the device.

The device comprises a housing 1 in which a piston 2 is held in a rest position by means of locking pins 3.

Arranged in the piston 2 is an ignition element 4 having a base plate 5 and an ignitable pellet 6. The piston 2 has an aperture 7 which leads to a sealing ring 8 accommodated in the housing 1.

The piston 2 is provided with a switching or actuator member 9 which projects beyond the housing 1.

Connection wires 10,11 of the pellet 6 are conducted through the housing 1 at the side or end remote from the switching member 9.

Slipped onto the connection wire 10 in the housing 1 is a tubular part 12 made of ferrite material which acts as inductance. Slipped onto the tubular part 12 is a tubular part 13 made of ceramic having high dielectric constant. The tubular part 13 is provided on the outside with a front condenser coating 14, a central condenser coating 15 and a rear condenser coating 16. Insulating isolation zones 17,18 lie between the condenser coating 15 and the condenser coating 14 on the one hand and the condenser coating 16 on the other hand.

Slipped onto the connection wire 10 is a sleeve 19 made of an electrically conductive elastomer. This contacts on the one side the connection wire 10 and on the other side the condenser coating 14. An identical sleeve 20 contacts the rear condenser coating 16 with the connection wire 10.

Slipped onto the connection wire 11 as onto the connection wire 10 is a tubular part made of ferrite material and a tubular part made of ceramic material having condenser coatings. The front and the rear condenser coatings are, as described, contacted by means of sleeves with the connection wire 11. The sleeves 19,20 seated on the connection wires 10,11 lie in recesses 21,22 (see FIGURE 3) of a front cap part 23 or rear cap part 24 respectively. The cap parts consist of an electrically insulating elastomer.

Provided in the region of the central condenser coating 15 is a disc-shaped central shaped part 25 which consists of an electrically conductive elastomer. The shaped part 25 has apertures 26,27, which respect the tubular part 13 of the connection wire 10 is placed through the aperture 26 and the ceramic tubular part of the connection wire 11 is placed through the aperture 27.

In this way, the central condenser coatings 15 of both ceramic tubular parts 13 are contacted. The outer circumference of the shaped part 25 contacts the housing 1.

Provided between the central shaped part 25 and the cap part 23 on the one hand and the cap part 24 on the other hand are shaped parts 28,29 which have the same shape as the shaped part 25, but consist of electrically insulating elastomer.

The cap part 23 is pressed by means of a ring 30 in the direction of the cap part 24 which is supported on the base plate 5. The ring 30 is held by a flange 31 of the housing 1. In this way it is on the one hand ensured that the desired electrical contacts exist between the condenser coatings and the housing or the connection wires respectively; and on the other hand, in this way a cushioned mounting of the ceramic tubular parts 13 is ensured. Soldering points are not provided.

In the wiring diagram shown in FIGURE 4, the electrical circuit elements are indicated by the reference numbers used for the component parts by which the respective elements are realised in the device shown in FIGURE 1. In this respect, the component parts arranged on the connection wire 11 are designated with the corresponding reference numbers with an apostrophe.

FIGURE 4 shows that in the immediate vicinity of the ignition pellet 6, on each of the connection wires 10,11, a capacitive/inductive filter is effective.

When tube ignition pellet 6 is ignited by an electrical potential applied to the wires 10,11, the piston 2 is propelled in the direction of the ring 30, and in so moving the parts consisting of elastomer are deformed to allow the switching member 9 to carry out the required stroke. The filter construction thus ensures that the necessary stroke can be effected.

Claims

1. An electrically ignitable device wherein a piston supported is in a housing containing an ignitable pellet having electrical leads extending out of the housing from the ignitable pellet, and comprising electrical capacitive and inductive filter means connected to at least one of said leads; and characterised in that the electrical filter means comprises electrically conductive, inductive and dielectric parts sandwiched together within the housing to effect mechanically the electrical connections necessary to place said parts in circuit with said leads; and in that some of said parts are compressible to maintain said connections, and, upon ignition of said pellet, to allow said filter means to be compressed by movement of the piston.

2. An electrical ignition device comprising a piston which contains an ignition pellet and is supported in a housing, the pellet having connection wires which extend through the housing, characterised in that inside the housing a tubular part of ferrite material is placed onto one or each connection wire and onto this part is placed a tubular part which is made of ceramic material and has on its outside a front, a central and a rear condenser coating; in that the central condenser coating is connected in a solder-free manner by means of an electrically conductive shaped part with the housing, and each of the front and the rear condenser coatings is contacted in a solder-free manner by means of a respective sleeve, superimposed onto the connection wire, with the connection wire; and in that the sleeve is held between cap parts which are compressible upon piston movement.

3. A device as claimed in Claim 2, characterised in that the electrically conductive shaped part consists of an electrically conductive elastomer.

4. A device as claimed in Claim 2 or 3, characterised in that the sleeves consist of an electrically conductive elastomer.

5. A device as claimed in Claim 2, 3 or 4, characterised in that the cap parts consist of an electrically insulating elastomer.

6. A device as claimed in any one of Claims 2 to 5, characterised in that the cap parts have recesses for the sleeves.

7. A device as claimed in any one of Claims 2 to 6, characterised in that provided between the cap parts and the central shaped part is, in each case, a further shaped part made of electrically insulating elastomer.

8. A device as claimed in any one of Claims 2 to 7, characterised in that the outside diameter of the shaped parts corresponds to the inside diameter of the housing and in that the shaped parts have apertures in which butts the tubular part made of ceramic material.

9. A device as claimed in any one of Claims 2 to 8, characterised in that the front cap part is pressed by means of a ring, held by a flange of the housing, in the direction of the rear cap part.

10. A device substantially as hereinbefore described with reference to the accompanying drawings.