SENSOR FASTENER ARRANGEMENT

Abstract

The invention relates to a sensor fastener arrangement (10a-f) for holding a sensor device (3). The sensor fastener arrangement (10a-f) comprises a plurality of fastener elements (20a, 20b). The fastener elements (20a, 20b) are configured to arrange the sensor device (3) to a platform (1). Respective fastener element (20a, 20b) is rigid in a first state and reversibly deformable in a second state. When the platform (1) of the sensor device (10a-f), and/or the sensor device (3), is exposed to an impact force, in turn exposing a fastener element (20a, 20b) to a compressive force exceeding a critical load of that fastener element (20a, 20b), the fastener element (20a, 20b) goes from being in the first state to temporarily being in the second state. Thereby the fastener element (20a, 20b) goes from having a first rigid shape to temporarily being reversibly deformed, after which, when the impact force is terminated, the fastener element (20a, 20b) goes from temporarily being in the second state back to being in the first state. Thereby the fastener element (20a, 20b) goes from temporarily being reversibly deformed to having the first rigid shape.

Claims

1. A sensor fastener arrangement (10a-f) for holding a sensor device (3), comprising a plurality of fastener elements (20a, 20b), wherein the fastener elements (20a, 20b) are configured to arrange the sensor device (3) to a platform (1), characterized in that respective fastener element (20a, 20b) is rigid in a first state and reversibly deformable in a second state, wherein when the platform (1) of the sensor device (10a-f) and/or the sensor device (3) is exposed to an impact force in turn exposing a fastener element (20a, 20b) to a compressive force exceeding a critical load of that fastener element (20a, 20b) the fastener element (20a, 20b) goes from being in the first state to temporarily being in the second state, whereby the fastener element (20a, 20b) goes from having a first rigid shape to temporarily being reversibly deformed, after which, when the impact force is terminated, the fastener element (20a, 20b) goes from temporarily being in the second state back to being in the first state, whereby the fastener element (20a, 20b) goes from temporarily being reversibly deformed to having the first rigid shape, wherein the sensor device (3) has a maximum acceleration limit defining the maximum acceleration the sensor device (3) may be exposed to without being damaged, and wherein the critical load of the fastener elements (20a, 20b) are selected such that fastener elements (20a, 20b) deform before the sensor device (3) is exposed to the maximum acceleration limit and wherein the fastener elements (20a, 20b) are rigid in an essentially straight configuration when being in the first state and temporarily reversibly deform by lateral deflection when being in the second state.

2. Sensor fastener arrangement (10a-f) according to claim 1, wherein when the sensor device (3) is exposed to a force in turn exposing respective fastener element (20a, 20b) to a compressive force, the compressive force acts on the fastener element (20a, 20b) along an axis of deformation, and wherein respective fastener element (20a, 20b) is reversibly deformable by a compressive movement along the axis of deformation.

3. Sensor fastener arrangement (10a-f) according to claim 1, wherein respective fastener element (20a) has an extension along a first axis (FE-1), along a second axis (FE-2) and along a third axis (FE-3), and wherein the extension along one of the first, second or third axes (FE-1, FE-2, FE-3) is larger than the extension along the two remaining axes (FE-2, FE-3), and wherein the extension along one of the two remaining axes (FE-2) is larger than the extension along of the finally remaining axis (FE-3).

4. Sensor fastener arrangement (10d, 10e, 10f) according to claim 1, wherein in addition to fastener elements (20a, 20b) the sensor fastener arrangement (10d, 10e, 10f) comprises at least one damper (23, 24).

5. Sensor fastener arrangement (10d, 10e, 10f) according to claim 1, wherein in addition to fastener elements (20a, 20b) the sensor fastener arrangement (10d, 10e, 10f) comprises at least one damper (23, 24) and wherein the at least one damper (23, 24) is arranged to dampen an extending movement along the axis of deformation.

6. Sensor fastener arrangement (10d, 10e, 10f) according to claim 1, wherein in addition to fastener elements (20a, 20b) the sensor fastener arrangement (10d, 10e, 10f) comprises at least one damper (23, 24) and wherein the at least one damper (23, 24) is arranged to dampen a compressive movement along the axis of deformation.

7. Sensor fastener arrangement (10d, 10e, 10f) according to claim 4, wherein the at least one damper (23, 24) is a damper (23, 24) from a group of possible damper arrangements comprising: hydraulic dampers viscous dampers, and/or spring dampers.

8. Sensor fastener arrangement (10a-f) according to claim 1, wherein respective fastener element (20a, 20b) is attachable to a sensor device (3) in a first end (21a) and to a platform (1) in a second end (21b), wherein the first end (21a) and the second end (21b) are opposite ends of the fastener element (20a, 20b) along the axis of deformation.

9. Sensor fastener arrangement (10a-f) according to claim 1, wherein at least one of Euler's laws of critical load applies for the fastener elements (20a, 20b) and whereby the fastener elements (20a, 20b) are selected based on their critical load.

10. Sensor fastener arrangement (10a, 10d, 10e) according to claim 1, wherein the first and second ends (21a; 21b) of a fastener element (20a) are configured to be fixedly attachable to the sensor device (3) and to the platform (1), whereby the critical load of the fastener element (20a) is determined by applying Euler's fourth law of critical load.

11. Sensor fastener arrangement (10c, 10f) according to claim 1, wherein the first and second ends (21a; 21b) of a fastener element (20a, 20b) are configured to be hingedly attachable to the sensor device (3) and to the platform (1), whereby the critical load of the fastener element (20a, 20b) is determined by applying Euler's second law of critical load.

12. Sensor fastener arrangement (10b) according to claim 1, wherein one of the first and second ends (21a; 21b) of a fastener element (20a) is configured to be attachable to the sensor device (3) and the other end (21b; 21a) is configured to be attachable to the platform (1), and wherein one of the first and second ends (21a; 21b) of the fastener element (20a) is fixedly attachable and the other end (21b; 21a) is hingedly attachable, whereby the critical load of the fastener element (20a) is determined by applying Euler's third law of critical load.

13. Sensor fastener arrangement (10a-f) for holding a sensor device (3) according to claim 1, wherein the sensor device (3) is an antenna, a rangefinder or an aiming device.

14. An antenna installation (4) comprising a sensor fastener arrangement (10a-f) according to claim 1 and a sensor device (3) in form of an antenna.

15. An antenna installation (4) according to claim 14, wherein the antenna is a panel antenna.

16. An antenna installation (4) according to claim 1, wherein the antenna is a phased array antenna.

17. A ship comprising an antenna installation (4) according to claim 1.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0037] With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

[0038] In the drawings:

[0039] FIG. 1 discloses an exemplary platform provided with an antenna fastener arrangement according to the invention, and

[0040] FIG. 2 schematically discloses Euler's second, third and fourth laws of critical load,

[0041] FIG. 3a and FIG. 3b schematically disclose an exemplary embodiments of antenna fastener arrangements in a first and a second state, and

[0042] FIG. 4a to FIG. 4d schematically discloses exemplary embodiments of antenna fastener arrangements holding sensor devices according to the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

[0043] The following description of exemplary embodiments of the invention is presented only for purposes of illustration and should not be seen as limiting. The description is not intended to be exhaustive and modifications and variations are possible in the light of the teachings herein, or may be acquired from practice of various alternative embodiments of the invention. The exemplary embodiments discussed herein were chosen and described in order to explain the principles and the nature of various embodiments and its practical application to enable one skilled in the art to utilize the exemplary embodiments in various manners, and with various modifications, as are suited to the particular use contemplated. It should be appreciated that the aspects presented herein separately may be practiced in any combination with each other unless otherwise explicitly is stated.

[0044] FIG. 1 discloses a platform 1, in form of a ship, provided with a sensor device 3, in form of an antenna, arranged to the platform 1 by means of a sensor fastener arrangement 10. The sensor fastener arrangement 10 is configured to protect the sensor device 3 from impact force due to for example mine detonation 2.

[0045] In the embodiment shown in FIG. 1 the antenna and the sensor fastener arrangement 10 forms an antenna installation 4. The antenna may for example be a phased array antenna, for example in the form of a panel antenna.

[0046] FIG. 2 schematically discloses three exemplary setups Euler 2, Euler 3, Euler 4 showing Euler's second, Euler's third and Euler's fourth laws of critical load. The laws of critical load are shown by having a column 40a, 40b, 40c attached at a first and a second attachment point AP1, AP2. What determines which of Euler's laws of critical load that apply is primarily controlled by the end conditions at respective first and second attachment point AP1, AP2. In FIG. 2 the first and second attachment points AP1, AP2 are referred to as upper attachment point AP1 and lower attachment point AP2.

[0047] The critical load is the maximum load that will not cause lateral deflection of the column 40a, 40b, 40c. Lateral deflection is herein also referred to as being bent or being buckled. Applying a force meeting the critical load puts the column 40a, 40b, 40c is in a state of unstable equilibrium. Applying additional force causes lateral deflection. The lateral deflection increases with additional load. The column 40a, 40b, 40c will remain straight for loads less than the critical load.

[0048] Thus, when a compressive force F is applied, as is indicated in FIG. 2, exceeding the critical load of respective exemplary setup Euler 2, Euler 3, Euler 4 the column 40a, 40b, 40c will bend.

[0049] In the first exemplary setup Euler 2 the column 40a is hingedly attached at both the upper and the lower attachment points AP1, AP2, whereby Euler's second low of critical load applies.

[0050] In the second exemplary setup Euler 3 the column 40b is hingedly attached at the upper attachment point AP1 and fixedly attached at the lower attachment point AP2, whereby Euler's third low of critical load applies. If the upper attachment point AP1 would be fixedly attached and the lower attachment point AP2 hingedly attached Euler's third low of critical load would also apply.

[0051] In the third exemplary setup Euler 4 the column 40c is fixedly attached at both the upper and the lower attachment points AP1, AP2, whereby Euler's fourth low of critical load applies.

[0052] Which of Euler's laws that applies for a specific setup determines the properties of an attached column in terms of for example stiffness, physical spring properties and resilience to additional load once lateral deflection of the column has been initiated.

[0053] FIGS. 3a, 3b and 4a to 4e disclose various sensor fastener arrangements 10, i.e. 10a-10f, comprising fastener elements 20, i.e. 20a and 20b. The invention is not to be seen as limited to these particular realizations, but these realizations of antenna fastener arrangements 10a-10f according to the invention are intended to show that the invention may be realized in various ways.

[0054] FIG. 3a discloses a first embodiment of an antenna fastener arrangement 10a holding a sensor device 3 in form of an antenna. The antenna fastener arrangement 10a comprises a number of fastener elements 20a. In FIG. 3a the number of antenna elements is four, two arranged at each of the two opposite sides of the sensor device 3. The opposite sides of the sensor device 3 is herein defined as the two opposite sides facing a perpendicular direction in relation to the direction in which the sensor device 3 is directed.

[0055] Each fastener 20a element has a first and a second end 21a, 21b positioned in opposite ends of the fastener element 20a. The fastener elements 20a are attached to the sensor device 3 in a first end 21a and are attachable to a platform (not shown) in a second end 21b.

[0056] Respective fastener element 20a has an extension along a first axis FE-1, along a second axis FE-2 and along a third axis FE-3. In FIG. 3a the first axis FE-1 coincide with the indicated Y-axis, and is hereinafter referred to as Y, the second axis FE-2 coincide with the indicated X-axis, and is hereinafter referred to as X, and the third axis FE-3 coincide with the indicated Z-axis, and is hereinafter referred to as Z. The extension along one of the first, second or third axes X is larger than the extension along the two remaining axes X, Z.

[0057] The extension along one of the two remaining axes X is larger than the extension along of the finally remaining axis Z. Thus, according to the embodiment of the invention disclosed in FIG. 3a the fastener elements 20a can be said to have the form of essentially flat bars. The first end 21a and the second end 21b are opposite ends of the fastener element 20a along the first axis Y. The first axis Y is perpendicular to the second axis X and the third axis Z. The second axis X is perpendicular to the third axis Z.

[0058] The dimensions of respective fastener element 20a, i.e. the extension along the first, second and third axis X, Y, Z, are configured such that desired properties are obtained in regards to stiffness, physical spring properties and critical load in respective direction. These properties, together with prevailing end conditions, determines the critical load of the fastener element 20a. The desired properties of the fastener elements 20a used are dependent on the contemplated implementation of the sensor fastener arrangement 10a.

[0059] As is shown in FIGS. 3a and 3b, the fastener elements 20a of the sensor fastener arrangement 10a are rigid in an essentially straight configuration when being in the first state, shown in FIG. 3a, and temporarily reversibly deformable by being buckled by lateral deflection when being in the second state, shown in FIG. 3b.

[0060] According to the invention, when the platform 1 of the sensor device 3, and/or the sensor device 3 directly, is exposed to an impact force, in turn exposing a fastener element 20a to a compressive force, exceeding the critical load of that fastener element 20a, the fastener element 20a goes from being in the first state to temporarily being in the second state. Thereby the fastener element 20a goes from having a first rigid shape to temporarily being reversibly deformed. When the impact force subsequently is terminated, the fastener element 20a goes from temporarily being in the second state back to being in the first state, whereby the fastener element 20a goes from temporarily being reversibly deformed back to having the first rigid shape. A sensor fastener arrangement 10a with fastener elements 20a being in the second state are shown in FIG. 3b. The force referred to herein, i.e. the force which the fastener elements 20a are exposed to, is a compressive force acting on the fastener elements 20a along the first axis Y. The Y-axis is also the axis of deformation, meaning that it is along the Y-axis that the fastener elements 20a deform when the critical load is exceeded by a compressive force resulting from an impact force.

[0061] The critical load is selected such that the fastener elements 20a deform before the sensor device 3 is exposed to a maximum acceleration limit of the sensor device, i.e. the force at which the sensor device may get damaged by the impact force.

[0062] Thus, the compressive movement along the axis of deformation that the fastener elements 20a undergo can be seen in FIGS. 3a and 3b. In FIG. 3a the longitudinal extension of the fastener elements 20a are indicated by LE1. When being deformed the fastener elements 20a undergo lateral deflection whereby the longitudinal extension along a first axis FE-1 of the fastener element is temporarily decreased, as is indicated in FIG. 3b by LE2. This temporary decrease in extension due to buckling of the fastener element 20a is generally referred to as compression.

[0063] In FIGS. 3a and 3b the fastener elements 20a are directly attached to the sensor device 3, but the invention can also be realized by indirectly attaching the fastener elements 20a to the sensor device 3, for example by means of a frame.

[0064] Which of Euler's laws that an antenna fastener arrangement complies with is dependent on how respective fastener element is attached to the sensor device and to the platform to which the sensor device is arranged. Thus, this is one of the parameters that are selectable in order to obtain desired properties of the antenna fastener arrangement.

[0065] For the sensor fastener arrangement 10a shown in FIGS. 3a and 3b, the second end 21b of a fastener element 20a is indicated to be fixedly attachable to a platform (not shown) and the first end 21a is fixedly attached to the sensor device 3. Thereby the critical load of the fastener element 20a shown in FIGS. 3a and 3b is determined by applying Euler's fourth law of critical load.

[0066] FIG. 4a shows another exemplary embodiment of a sensor fastener arrangement 10b according to the invention. The exemplary fastener arrangement 10b shown in FIG. 4a is arranged to the sensor device 3 by means of a frame structure 22, wherein the frame structure 22 is configured for holding the sensor device 3.

[0067] For the exemplary embodiment of a sensor fastener arrangement 10b shown in FIG. 4a, the second end 21b of a fastener element 20a is indicated to be fixedly attachable to a platform (not shown) and the first end 21a is hingedly attached to the sensor device 3. Thereby the critical load of the fastener element 20a shown in FIG. 4a is determined by applying Euler's third law of critical load.

[0068] FIG. 4b shows yet another exemplary embodiment of a sensor fastener arrangement 10c according to the invention. For the exemplary embodiment of a sensor fastener arrangement 10c shown in FIG. 4b the second end 21b of a fastener element 20a is indicated to be hingedly attachable to a platform (not shown) and the first end 21a is hingedly attached to the sensor device 3. Thereby the critical load of the fastener element 20a shown in FIG. 4b is determined by applying Euler's second law of critical load.

[0069] Embodiments of sensor fastener arrangements governed by Euler's second law of critical load provides the highest spring stiffness of the fastener elements before lateral deflection occurs and provides the lowest buckling load, also referred to bending load. This means that the load required for bending of the fastener element once the fastener element has started to bend is low.

[0070] FIG. 4c shows an exemplary embodiment of a sensor fastener arrangement 10d according to the invention. In addition to fastener elements 20a, the sensor fastener arrangement 10d comprises two dampers 23, one damper arranged on each opposite side of the sensor device 3. The dampers 23 may also be arranged to the platform (not shown) to which the sensor fastener arrangement 10d is arrangeable. The dampers 23 are either configured or arranged to dampen a compressive movement along the axis of deformation, i.e. along the Y-axis, or configured or arranged to dampen extending movements along the axis of deformation.

[0071] As previously stated, and as is shown in FIGS. 3a and 3b, compressive movement may be defined as deformation decreasing the longitudinal extension, i.e. from LE1 to LE2. Extending movement is the opposite movement to compressive movement, i.e. the increase or extension in longitudinal direction, LE1.

[0072] Dampers configured for dampen compressive movement provide the exemplary advantage that, once the fastener elements of the sensor fastener arrangement starts to deform the reversible deformation by the compressive movement is dampened. Thereby the acceleration the sensor device is exposed to when the fastener elements reversibly deform is decreased. Once the critical load of a fastener element is exceeded, and the fastener element has started to deform, the load required for further deformation is lower. This is particularly true for realizations where Euler's second law of critical load apply.

[0073] Dampers configured for dampening extending movement provide the exemplary advantage that once the fastener elements has been reversibly deformed, use of a damper prevents that the deformed fastener element forcefully springs back whereby a whiplash effect can be avoided. Thereby, it may for example be avoided that the fastener element deforms when springing back or that the sensor device may be damaged due to the whiplash.

[0074] For the exemplary embodiment of a sensor fastener arrangement 10d shown in FIG. 4c both the first and the second ends 21a, 21b of the fastener elements 20a is indicated to be fixedly attached or attachable to the sensor device 3 and to a platform (not shown) respectively. Thereby the critical load of the fastener element 20a shown in FIG. 4c is determined by applying Euler's fourth law of critical load.

[0075] FIG. 4d shows another exemplary embodiment of a sensor fastener arrangement 10e according to the invention. The sensor fastener arrangement 10e of FIG. 4d comprises just two fastener elements 20a arranged at a front side 30 of the sensor device 3. The front side 30 herein is defined as the side facing in the direction in which the sensor device 3 is directed. A backside 31 of the sensor device 3 is herein defined as the side being directed in opposite direction as the front side 30. The sensor fastener arrangement 10 shown in FIG. 4d also comprises two dampers 24, one damper 24 arranged at each side of the sensor device 3. The dampers 24 of the sensor fastener arrangement 10e of FIG. 4d are arranged at an angle A in relation to the fastener elements 20a. The dampers 24 are thereby capable of dampening movements not only in the direction of the axis of deformation, i.e. along the Y-axis, but also in the direction of the X-axis. The sensor fastener arrangement 10e of FIG. 4d further comprises a number of pivot arms 25. Pivot arms 25 may be used to control movements of the sensor device 3, for example along the Y-axis as for the exemplary embodiment shown in FIG. 4d.

[0076] Also for the exemplary embodiment of a sensor fastener arrangement 10e shown in FIG. 4d both the first and the second end 21a, 21b is indicated to be fixedly attached or attachable to the sensor device 3 and to a platform (not shown) respectively. Thereby the critical load of the fastener element 20a shown in FIG. 4c is determined by applying Euler's fourth law of critical load.

[0077] FIG. 4e shows another exemplary embodiment of a sensor fastener arrangement 10f according to the invention. The exemplary embodiment of a sensor fastener arrangement 10f shown in FIG. 4e comprises fastener elements 20b in the form of essentially circular rods, i.e. rods with an essentially circular cross section. The fastener elements 20b are configured to be hingedly attached to the sensor device 3 and to be hingedly attachable to a platform (not shown), whereby the critical load of the fastener elements 20b are determined by applying Euler's second law of critical load. As previously stated, Euler's second law of critical load provides the highest spring constant against buckling load of Euler's second, third and fourth laws of critical load.

[0078] Two of the four fastener elements 20b of the exemplary embodiment of a sensor fastener arrangement 10f shown in FIG. 4e are provided at a backside 31 of the sensor device 3. The two remaining fastener elements 20b are arranged at opposite sides of the sensor device 3. The sensor fastener arrangement 10f of FIG. 4e is further provided with four dampers 23.

[0079] The various exemplary embodiments of sensor fastener arrangements 10c, 10d, 10e, 10f of FIGS. 4a, 4b, 4c and 4d are intended to show various embodiments of how a sensor fastener arrangement according to the invention may be realized. The invention is not to be seen as being limited to these particular realizations. It is considered to be obvious that the number of, and positioning of, fastener elements according to the invention, dampers and/or pivot arms may be different between various realizations, and may for example be determined by the implementation of a specific sensor fastener arrangement.