US 3783791 A
A switch for electrical impact detonators, which comprises an inertial mass effective as a contact member. A housing forms a complementary contact and surrounds the contact member for axial and tiltable movement therein. A spring acts in a direction against the firing direction and retaining the contact member in resting position, and the contact member has the greatest possible mass relative to the external dimensions of the housing.
Description (OCR text may contain errors)
United States Patent [191 Backstein et al. Jan. 8, 1974  SWITC H'FOR ELETRICAL IMPACT 3,657,499 4/1972 Gawlick 102/70.2 R DETONATORS 3,158,705 11/1964 Bliss l02/70.2 R
 Inventors: Giinter Backstein; Lothar Petzsch,
g of Meerbusch'langst Primary ExaminerBenjamin A. Borchelt ermany Assistant ExaminerJ. V. Doramus  Assignee: Rheinmetall GmbH, Dusseldorf, Attorney-Ernest G. Montague Germany  Filed: Oct. 13, 1971  App]. No.: 188,953 57 ABSTRACT  Foreign Application Priority Data A switch for electrical impact detonators, which com- Nov. 7, 1970 Germany P 20 54 839.4 prises an inertial mass effective as a contact member A housing forms a complementary contact and sur-  US. Cl. 102/70.2 R, zoo/61.45 rounds the contact member for axial and tiltable 51 rm. Cl. H01h 35/14 movement therein- A p g acts in a direction against 58 Field of Search 102/70.2 R, 70.2 GA; the firing direction and retaining the contact member 200/5145 R 6152 in resting position, and the contact member has the greatest possible mass relative to the external dimen- 5 R fe Cited sions of the housing.
UNITED STATES PATENTS 3,118,989 l/l964 Gray l02/70.2 R 8 Claims, 1 Drawing Figure 14 V 11 1 t a 9 v 1a 7 'll i i i 6 A ,/1s 1% 1b 1 .7 I i v f 1 SWITCH FOR ELECTRICAk IMPACT DETONATORS The present invention relates to a switch for electrical impact detonators, which switch has an inertial mass operating as a contact member, which is mounted for axial and tilting movements in a housing forming a complementary or co-operating contact and which is held in rest position by a spring force effective against the firing direction.
Such switches are intended for use in impact detonators of projectiles with or without spinning movement, and are supposed to bring about safe detonation with axial and/or lateral impact on the target. Such switches are generally arranged in the projectile nose, and it is therefore an essential requirement, to keep the dimensions of the switch as small as possible. This complicates however the achievement of the further requirement, namely that of high switch sensitivity.
A switch is known, which has a spherical inertial mass as a contact member. The sphere is retained in a ring-shaped bearing seating by aspring effective against the firing direction and is enclosed by a semispherical switch housing forming a complementary or co-operating contact. Due to this form of construction, only a comparatively small mass is available for the spherical contact member with a relatively small mass, in relation with the external dimensions of the switch housing, whereby limits are provided to the sensitivity of the switch.
It is, therefore, one object of the present invention, to provide a switch for electrical impact detonators, which has a high sensitivity with possibly smallest external dimensions.
It is another object of the present invention to provide a switch for electrical impact detonators, wherein the contact member as an inertial mass having the greatest possible mass relative to the outer dimensions of the housing enclosing the contact member. In view of the tolerance of the used spring, which retains the contact member in resting position, an essentially greater sensitivity can be achieved.
Advantageously, the contact member is designed as a substantially cylindrical body, the length of which corresponds at least approximately to its diameter. In this way, a contact member with a comparatively large mass is obtained with a switch housing, whose external dimensions are limited both in length as well as in diameter.
A particularly favorable construction of the switch is obtained in relation to its external dimensions and the obtainable mass of the contact member results, if the switch housing forming the co-operating contact is formed by the projectile casing or its nose.
In an advantageous embodiment of the present invention, the arrangement is such, that the force of the spring holding the contact member in the installed rest position is adjustable. In a very suitable manner the spring may be secured appropriately between two axially-movable bushes, of which one abuts against the contact member and the other abuts against a complementary bearing located in the housing and axially adjustable.
An optimum adjustment in relation to the sensitivity of the switch, can be achieved in a likewise advantageous further development by making measurable the spring force, with the spring in its installed position, by
means of a measuring device which can be inserted into an axial bore provided in the adjustable complementary bearing.
With these and other objects in view which will become apparent in the following detailed description, the present invention, which is shown by example only, will be clearly understood in connection with the accompanydrawing in which the only FIGURE is an axial section of the switch designed in accordance with the present invention.
Referring now to the drawing, a projectile nose comprises of housing parts la and 1b, which are inserted in a head 2 of a projectile, shown in dot-dash lines. The projectile nose forms simultaneously a housing for the switch of an electrical impact detonator (not shown) located inside the projectile. A contact bolt 4 surrounded by an insulation sleeve 3 is located in the housing part llb. A contact member 5, consisting substantially of a cylindrical body and effective as an inertial mass, rests on the contact bolt 4. The front housing part la has a cylindrical recess 6 and surrounds the contact member 5 with slight clearance. The housing part 1a forms the co-operating or complementary contact of the switch. In the resting position, the contact member 5 is retained by a coil spring 7, which is clamped between two insulating bushes 8 and 9 mounted to move axially. One bush is spherical at its end pointing towards the contact member 5 and is supported in a conical centering bore 10 in the front face of the contact member 5. The other bush 9 engages against a complementary bearing in the form of a threaded socket 11, which is adjustable axially and which is located in the projectile nose in an axial screwthreaded bore 12. The bore 12 is closed by a screw 13 inserted in the projectile nose, which screw 13 has a shank 14 for guiding the bushes 8 and 9.
In addition, there is provided in the contact bolt 4 a centering and contact pin 16 loaded by a spring 15, whose front end projecting from the contact bolt 4 enters for forcible and intimate engagement in a conical centering bore 17 of the contact member 5.
After removing the bolt 13, the tension of the coil spring 7 can be altered by rotating the threaded socket 11. This can be carried out either by a screw driver or possibly simultaneously by a measuring device for measuring the spring tension. This tool can be guided by the central bore 18 of the threaded socket 11 against the bush 9, which is longitudinally displaceable in the threaded socket 111. In this manner, an extraordinarily accurate fine adjustment of the sensitivity of the switch is possible.
The operation of the switch is as follows:
When the projectile hits a target, the contact member 5 moves forward as a result of the thrust imparted to it during the flight, whereby the electrical contact with the contact bolt 41 remains in force by the spring-loaded contact pin 16. Now, as soon as the contact member 5 comes into contact with the surrounding wall of the re cess 6 forming the co-operating contact, the impact detonator is triggered. This also occurs, in the case of a lateral striking of a target by the projectile. In this case, the contact member 5 tilts about the edge of its contact surface and comes into contact with the housing wall in the same way.
Electrical impact detonators are provided in known manner with capacitors, and the like, which make the detonators live only after a certain time interval, in
which the projectile has covered a safe distance. This precaution is called the masking safety characteristic. If, within this distance, the projectile hits an object, then the switch is actuated in the aforedescribed manner, but no detonation occurs. Therefore, the contact member is guided back into its rest position by the bush 8 acted upon by the spring 7, aided by the spherical support face of the bush 8 engaging the conical centering bore 10.
While we have disclosed one embodiment of the present invention, it is to be understood, that this embodiment is given by example only and not in a limiting sense.
1. A switch for electrical impact detonators, comprismg an inertial mass effective as a contact member,
a housing having a recess forming a complementary contact and substantially complementarily surrounding said contact member, the latter being disposed movably therein for axial as well as laterally tiltable movement relative thereto,
a spring acting in a direction against the firing direction and retaining said contact member in a resting position, and
said contact member being substantially as large as said recess complementarily disposed in said recess and minimally spaced from said housing to permit actuation from axial as well as laterally tiltable movement relative thereto,
a second spring effective in a direction opposite to the force of the said first mentioned spring,
a centering and contact pin biased by said second spring, and engaging continuously forcibly and intimately said contact member.
2. The switch, as set forth in claim 1, wherein said contact member comprises a substantially cylindrical body having an axial length corresponding at least approximately with its diameter.
3. The switch, as set forth in claim 1, which includes means for adjusting the tension of said spring.
4. The switch, as set forth in claim 1, which includes two axially movable bushes disposed in said housing and clamping said spring therebetween,
one of said bushes abuts said contact member, and
the other of said bushes abuts against a member axially adjustable and located in said housing.
5. The switch, as set forth in claim 4, which includes a measuring device for measuring the tension of said spring, and
said member has an axial bore for insertion of said measuring device in said housing.
6. The switch, as set forth in claim 1, wherein said housing forming said complementary contact comprises a projectile nose.
7. A projectile having an electrical impact detonator,
as set forth in claim 1, which includes a projectile nose,
a switch disposed in said projectile nose and operating said electrical impact detonator.
8. The switch, as set forth in claim 1, wherein said contact member comprises a'substantially cylindrical body having an axial length corresponding at least approximately with its diameter,
said housing forming said complementary contact comprises a projectile nose, and
a switch disposed in said projectile nose and operating said electrical impact detonator.