Protection device for sensor means

Abstract: A protection device for sensor means (1) in a vehicle (2) such as a missile is described. The protection device is characterized particularly by a support (3) attached in the vehicle with a first flange means (4) and a protecting cap (7) with a second flange means (8). A flexible tightening means (9) is arranged between the limiting surfaces (10, 11) of the flange means in such a manner that a substantially gastight space is created, partly limited by the cap (7) and in­ cluding the sensor means (1). At least one attaching means (13, 14) is so formed and arranged, that a compressive force on the cap, generated by overpressure in the space (12), brings the cap (7) to perform a movement rela­ tive to the sensor means (1) with a composant of movement in a direction away from the sensor means (1) and at least one compo­ sant of movement perpendicular to said direction, before being released from the vehicle. The limiting surfaces (10, 11) of the flange means are mutually so formed and arranged, that said move­ ment is made possible.

Description: The present invention relates to a protection device for sensor means in a vehicle, preferably an air vehicle, such as a missile. In various connections, especially military, there are vehicles, particularly air vehicles, that are provided with sensors, e.g. for detecting incoming IR-rays, visible light or radar rays, usually in a direction directly opposite to the travelling direction of the vehicle. There is a need for protection devices intended to protect the sensor means up to the moment when it shall be activated. At that moment the vehicle is usually travelling at a relatively high speed through its medium, air or water. When the sensor means is to be activated the protection device must be removed almost instantaneously in order to admit the sensor means to receive radiation. In view of said relatively high speed through a medium, the speed will exert a force directed opposite to the travelling direction of the vehicle, i.e. it will press the protection device towards the vehicle. At the removal of the protection device said force must be overcome and the protection device be taken from the travelling direction of the vehicle, i.e. away from the active direction of the sensor means, which is usually an axis of symmetry through the sensor means. In addition to meeting these said requirements the protection device must be absolutely reliable in the prevailing operating conditions, i.e. in a wide temperature interval, exposed to vibrations etc., and must be reasonably inexpensive to manufacture. According to the invention such a protection device is characterized primarily in that it comprises a support attached in the vehicle with a first flange means surrounding said sensor means about an axis extending in the active direction of vision of the sensor means, further comprising a cap protecting the sensor means, the cap being provided with a second flange means at which a flexible tightening means is so arranged, tightening between the limiting surfaces of said flange means, that a substantially gastight space is created, partly limited by said cap, including the sensor means, at which at least one attaching means is so formed and arranged, that a first compressive force on the cap relative to the vehicle, achieved through overpressure generated by a source of gas in said space, brings the cap to perform a movement relative to the sensor means with a component of movement in the active direction and at least one component of movement perpendicular to the active direction, before it is released from the vehicle, the limiting surfaces of the flange means being so formed, that said movement is made possible. Such a protection device well meets the requirements, and can be designed in numerous different manners within the scope of the claims describing the above-mentioned main principle. In order to make said movement possible, at least either of the limiting surfaces of the flange means for at least a portion of its circumference can be generated by rotating around the axis a line inclined relative to the axis, or by a non-linear, i.e. curved line. In a suitable embodiment one or both limiting surfaces are formed as frustums of a cone, i.e. its inner and outer side. The first flange means, i.e. that which constitutes a part of said support attached in the vehicle, can naturally be formed either with an outer limiting surface as a frustum of a cone, or with an inner limiting surface as a frustum of a cone in the opposite direction, the second flange means in the respective cases being formed with a limiting surface that admits said movement. It is naturally possible to form the flange means with cylindrically generated limiting surfaces, provided that the play between them allows said movement without hindering it. Different embodiments of one or more attaching means are conceivable within the scope of the claims. Although it is fully possible to design the protection device with one single attaching means, it is more suitable to arrange at least two attaching means. In such an embodiment the attaching means are preferably diametrically arranged, in the form of a first and a second shear pin in recesses in the first and the second flange means, respectively, with their directions substantially perpendicular to said axis, the first shear pin showing substantially better resistibility towards shearing than the second shear pin. This difference in resistibility can naturally be achieved either by shear pins made of the same material but with different dimensions in the shearing direction, or by them being made of different materials having different shearing strenght. Under the effect of the force which is achieved by means of a source of gas, the weakest pin will be sheared off first, whereby the composant of movement of the cap, perpendicular to the active direction, is created. Not until then is the second shear pin sheared off, and the cap can be entirely released from the vehicle. In a preferred embodiment of the protection device according to the invention the limiting surfaces show such a dimension in said active direction, and the tightening means is so arranged, that the cap is allowed a certain acceleration length relative to the vehicle before being relased from it. The invention will now be described in more detail with reference to the accompanying figure, which shows a longitudinal section through a protection device according to the invention. In the figure an air vehicle, in this case a missile, is indicated by 2. The vehicle is provided with a sensor means 1, placed in the front of the missile, in this case symmetrically about an axis 5. The active direction of the sensor means is represented by an arrow 6. This is the "direction of vision" of the sensor means. In the missile a support 3 is attached, with a first flange means 4 symmetrically including the sensor means. A cap 7 provided with a second flange means 8 is arranged to protect the sensor means. A flexible tightening means 9, e.g in the form of a ring of rubber or other elastomer, or a spring-loaded tightening means having other construction is arranged in a ring-shaped recess in the first flange means 4, tightening against the limiting surface 11 of the second flange means 8. Thereby, a substantially gastight space 12 is created, partly limited by the cap and including the sensor means. The outer limiting surface of the inner flange means 4 is formed as a frustum of a cone, converging in the active direction 6, and the inner limiting surface of the second flange means 8 is also formed as a frustum of a cone, converging in the same direction. Diametrically positioned in the protection device there is a first shear pin 13 with a relatively coarse diameter and a second shear pin with a relatively small diameter, both made of the same material, e.g. aluminium, with their directions substantially perpendicular to said axis 5 in recesses in the first and the second flange means 4 and 8, respectively. A gas pressure that acts with a compressive force on the cap 7 relative to the missile can now be achieved at the desired moment by means of a source of gas, not shown, so that the cap is first brought to break the second shear pin and then to perform an accelerating movement relative to the sensor means with a composant of movement in the active direction 6 and a composant of movement perpendicular to the active direction 6, until the first shear pin too is broken, and the cap is released from the missile.

Claims: A protection device for sensor means (1) in a vehicle (2), preferably an air vehicle, such as a missile, characterized in that it comprises a support (3) attached in the vehicle (2) with a first flange means (4) surrounding said sensor means (1) about an axis (5) extending in the active direction of vision (6) of the sensor means (1), further comprising a cap (7) protecting the sensor means (1), the cap being provided with a second flange means (8) at which a flexible tightening means (9) is so arranged, tightening between the limiting surfaces (10, 11) of said flange means (4, 8), that a substantially gastight space (12) is created, partly limited by said cap (7), including the sensor means (1), at which at least one attaching means (13, 14) is so formed and arranged, that a first compressive force on the cap (7) relative to the vehicle (2), achieved through overpressure generated by a source of gas in said space (12), brings the cap (7) to perform a movement relative to the sensor means (1) with a component of movement in the active direction (6) and at least one component of movement perpendicular to the active direction, before it is released from the vehicle (2), the limiting surfaces (10, 11) of the flange means (4, 8) being so formed, that said movement is made possible. A protection device according to claim 1, characterized in that at least either of the limiting surfaces (10, 11) of the flange means (4, 8) for at least a portion of its circumference is generated by rotation around the axis (5) of a line inclined relative to that axis (5) and converges in the active direction of vision (6). A protection device according to claim 1, characterized in that at least either of the limiting surfaces (10, 11) of the flange means (4, 8) for at least a portion of its circumference is generated by rotation around the axis (5) of a non-linear line and converges in the active direction of vision (6). A protection device according to any one of claims 1 to 3, characterized in that at least one limiting surface (10, 11) has the form of the inner or outer side of a frustum of a cone which converges in the active direction of vision (6). A protection device according to any one of claims 1 to 4, characterized in that at least two attaching means (13, 14) are preferably diametrically arranged, in the form of a first and a second shear pin in recesses in the first and the second flange means (4, 8), respectively, with their directions substantially perpendicular to said axis (5), the first shear pin showing substantially better resistibility towards shearing than the second shear pin. A protection device according to any one of claims 1 to 5, characterized in that the limiting surfaces (10, 11) show such a dimension in said active direction (6), and the tightening means (9) is so arranged, that the cap is allowed a certain acceleration length relative to the vehicle (2) before being released from it.

Inventors: KRANTZ INGEMAR, KRANTZ, INGEMAR
Applicants: SAAB MISSILES AB, SAAB MISSILES AKTIEBOLAG
Application year: 1989
Main classification: G12B17
IPC codes: G01J5, F42C19