WO2013061327A2

WO2013061327A2 - A low profile cooled infra red sensor arrangement configured for aerial vehicles

Info

Publication number: WO2013061327A2
Application number: PCT/IL2012/050421
Authority: WO
Inventors: Shlomo Yehoshua ROTSTAIN
Original assignee: Elbit Systems EW and Sigint Elisra Ltd
Current assignee: Elbit Systems EW and Sigint Elisra Ltd
Priority date: 2011-10-26
Filing date: 2012-10-25
Publication date: 2013-05-02
Anticipated expiration: 2014-04-26
Also published as: IL215961A0; WO2013061327A3

Abstract

An infra red (IR) sensor arrangement is provided herein. The IR sensor arrangement includes: at least one IR detector; at least one cold finger, each connected to a corresponding at least one of the at least one IR detector; a compressor thermally coupled to the at least one cold finger via at least one tube; and at least one package, each shaped to cover at least a corresponding cold finger with the corresponding at least one IR detector, wherein in respect to each cold finger and corresponding at least one IR detector, a center of mass of the cold finger is positioned between the corresponding at least one IR detector and the compressor.

Description

A LOW PROFILE COOLED INFRA RED SENSOR

ARRANGEMENT CONFIGURED FOR AERIAL VEHICLES

BACKGROUND

TECHNICAL FIELD

[0001] The present invention relates to airborne infra red (IR) sensors and more particularly, to such sensors that require cooling means.

DISCUSSION OF THE RELATED ART

[0002] Airborne infra red (IR) sensors are used on board of aerial vehicles for many applications. Standard arrangements of IR sensors commonly utilize a plurality of IR detectors, in which each IR detector covers a cone section with an opening angle of approximately 90°. An aerial vehicle (or air vehicle) is typically equipped with three to six IR detectors but it is understood that any number of IR detectors can be used.

[0003] As these IR detectors require ongoing cooling for their proper operation, a cooling mechanism of some kind is used in conjunction with the IR detectors. Figure 1 shows an IR sensor 100 packed in a cubic housing according to the prior art. IR sensor 100 includes a cubic housing or a package 120 that is attachable to the skin of an aerial vehicle (not shown). Inside package 120, an IR detector 150 is positioned facing an opening that is cut though the package 120. IR detector 150 is connected to a cold finger 140 which is configured to cool IR detector 150 and along which, a temperature gradient is established. Additionally, a compressor 130 is located in parallel to cold finger 140 such that a thermal coupling interface, such as a tube 160 connects cold finger 140 with compressor 130.

[0004] Typically, the entire package 120 is tilted in a specified angle so that the view of IR detector 150 is not interrupted by the aerial vehicle or any object protruding therefrom. This tilt position of the package causes the sensor to protrude well away from the skin of the air vehicle. In some of the current designs, the protrusion is over 20cm. It is therefore not surprising that the protrusion causes sensor arrangement 100 to be associated with very high drag forces as well as vibrations as the cooling mechanism has significant weight. [0005] Additionally, the aforementioned parallel arrangement of cold finger 140 and compressor 130, causes compressor 130 (which is hot) to be in close proximity to IR detector 150 (which is cold). This effect increases the required cooling challenge of the IR detector 150 as well as the challenge of heat dissipation of compressor 130.

[0006] In some of the current designs known in the art, the installation of cubic package 120 is carried out using an opening through the skin of the aerial vehicle. This of course causes major design issues in retrofitting IR sensor arrangement 100 in existing air vehicles. In some other current designs, IR sensor arrangement 100 is shaped such that its package does not necessitate an opening in the skin. However, as explained above, these designs have significantly higher drag and vibrations associated with them.

BRIEF SUMMARY

[0007] One aspect of the invention provides a low profile cooled infra red (IR) sensor arrangement for aerial vehicles. The sensor arrangement includes the following elements: one or more IR detectors; one or more cold fingers each connected to an IR detector of the one or more IR detectors; a compressor thermally coupled to the one or more cold fingers via one or more tubes; and one or more packages, each one of the packages shaped to cover: one or more of the IR detectors, and one or more of the cold fingers. Additionally, the compressor is spatially positioned farther from the IR detectors than most portions of the one or more cold fingers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] For a better understanding of embodiments of the invention and to show how the same may be carried into effect, reference will now be made, purely by way of example, to the accompanying drawings in which like numerals designate corresponding elements or sections throughout.

[0009] In the accompanying drawings:

Figure 1 is a perspective diagram illustrating an IR sensor according to the prior art;

Figure 2 is a perspective diagram illustrating an IR sensor according to some embodiments of the present invention; Figure 3A is a perspective diagram illustrating another aspect of the IR sensor according to some embodiments of the present invention; and

Figure 3B is a perspective diagram illustrating yet another aspect of the IR sensor according to some embodiments of the present invention.

[0010] The drawings together with the following detailed description make apparent to those skilled in the art how the invention may be embodied in practice.

DETAILED DESCRIPTION

[0011] Prior to setting forth the detailed description, it may be helpful to set forth definitions of certain terms that will be used hereinafter.

[0012] The term "IR detector" as used herein refers to the an array of IR sensitive cells which is configured to receive IR radiation and convert it to electrical signals which are processed in turn and yield an IR image of the scene. IR detectors in the spectral range usable for embodiments of the present invention require ongoing cooling throughout their operation.

[0013] The term "cold finger" as used herein refers to a thermal interface member that is configured to constantly cool the IR detector. The cold finger establishes a temperature gradient along its length and is connected in one end to the IR detector and is coupled to the compressor on its other end.

[0014] The term "IR sensor" as used herein refers to the entire arrangement that includes the IR detector (sometimes referred to as "IR sensor head), the aforementioned cold finger and the compressor. The IR sensor is usually packed in a housing that protects it from the ambient.

[0015] With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

[0016] Embodiments of the present invention overcome the drawbacks of the prior art by providing a so-called distributed architecture of the cooling mechanism for the IR sensors. Specifically, in a manner not dissimilar to some air-conditioning arrangements, the compressor and the cold finger are separated from each other by a tube, so that the cold finger is connected directly to the IR detector and thus the compressor may be located in series, rather than in parallel to the cold finger.

[0017] The tube between the compressor and the cold finger is configured to transfer the cooling fluid being either liquid or gas. This way, the compressor needs not be necessarily located in close proximity with the IR detector and it may be possible to design packages which are far more aerodynamic than those known in the art.

[0018] Geometrically, as will be shown below in some embodiments, taking out the compressor from the package enables to further reduce the size of the package and to lower the profile of it and thus achieve a shape that is far more aerodynamic than existing packages. As will be described below, the package profile could be significantly reduced even with the compressor inside the packaging by merely rearranging the components within the package from a so called parallel layout to a serial layout of the compressor and the cold finger.

[0019] Figure 2 shows an IR sensor 200 in accordance with some embodiments of the present invention. IR sensor 200 includes: one or more IR detectors 210 facing a predefined direction (shown by broken line arrow) located within a package 260 in which the portion of the package overlapping IR detector 210 is IR transparent. Alternatively IR detector 210 faces an opening in package 260.

[0020] Inside package 260, one or more IR detector 210 (only one detector is shown in the figure for the sake of simplicity) is connected to cold finger 220 which is thermally coupled to a compressor 230 via a tube 235. More specifically, cold finger 220, compressor 230, and tube 235 are positioned such that compressor 230 is spatially positioned farther from one or more IR sensors 210 than most of the portions of cold finger 220. This arrangement enables to significantly reduce the protruding level of package 260 from the skin of the air vehicle. [0021] Package 260 may be designed in a nut-shell shape which has aero-dynamic virtues and may be connected to the skin of the aerial vehicle (not shown) via connecting means 240.

[0022] Figure 3A shows an alternative embodiment of the present invention in which package 260 includes two IR detectors 212A and 212B each directly connected to its cold finger, 220A and 220B, respectively. Each one of cold fingers 220A and 220B is thermally coupled by a respective tube 214A and 214B to compressor 230. Advantageously, in this configuration both IR detectors 212A and 212B are directed at generally opposing directions, one at the front and one at the rear of package 260 while maintaining the low profile of the IR sensor. It is understood that a single compressor can operate in a one-to-many configuration in which a single compressor supplied the required cooling to several cold fingers and several IR detectors.

[0023] Figure 3B shows yet another alternative embodiment of the present invention in which package 260 includes two IR detectors 212A and 212B, each directly connected to its cold finger, 220A and 220B, respectively. Each one of cold fingers 220A and 220B is thermally coupled by respective tubes 240A and 240B to compressor 230 that is located outside of package 260 and within the skin of the air vehicle (not shown). Advantageously, IR detectors 212A and 212B and cold fingers 220A and 220B being relatively small, and compressor 230 being outside package 260 may significantly reduce the profile of package 260. Another advantage of this embodiment is that by positioning compressor 230 within the skin of the air vehicle, it may be possible to dissipate heat from the compressor by using the heat dissipating means readily available within the skin such as heat sinks or through the large area of contact with the skin of the aerial vehicle. Additionally, by this feature, the compressor no longer imposes structural constraints on the package.

[0024] Consistent with some embodiments of the present invention, in cases that the compressor is positioned inside the package, the one or more IR detectors, the compressor, and the cold finger may all be substantially aligned on a common line which is substantially parallel to a line of flight of the aerial vehicle. This embodiment reflects the so-called "in series" configuration as opposed to the currently available "in parallel" configuration, wherein the "in series" configuration renders a significantly lower aerodynamic profile. [0025] Consistent with some embodiments of the present invention, the tube is sufficiently long so that the compressor does not affect a height of the package above the skin. In other words, only the size of the IR detectors and the cold fingers within the package impose constraints on the height of the package. This feature enables the system designers to eliminate the dimension of the compressor as constraints for the size and shape of the package for the airborne IR sensors.

[0026] Consistent with some embodiments of the present invention, the one or more IR detectors are located and tilted by connecting them to cold fingers that may be either tilted or rotated. Additionally, in another embodiment, each one of the IR detectors may be connected to the package via universal joints (not shown) or any other tilting means so that a designer may be able to adjust the predefined pointing angle of each one of the IR detectors in the IR sensor.

[0027] Consistent with some embodiments of the present invention, the compressor is located within the package and along a line parallel to the aerial vehicle. The compressor is located such that it is farther from the IR sensor than any portion of the cold finger. In other words, from a spatial point of view, most of the cold finger (in terms of mass, for example) is located nearer to its respective IR detector, than the compressor. It may also be noted that during the operation of the IR sensor, the coldest parts of the cold finger are located farthest from the compressor whereas the hottest parts of the cold finger are located nearest to the compressor. It is understood that there are many geometric configurations that follows this constraint and only examples are described herein in details.

[0028] Consistent with some embodiments of the present invention, the package is shaped as a nut-shell a semi-sphere or any low profile shape which is much more aerodynamic than the cubic packages known in the prior art.

[0029] Advantageously, embodiments of the present invention, separating the compressor from the cold finger(s), significantly reduces the vibrations and the excessive drag associated with the airborne IR sensors of the prior art. As explained above, the aforementioned vibrations of the prior art stem from positioning a significant mass farther from the skin of the aerial vehicle. By employing embodiments of the present invention, the mass of the IR arrangement is brought closer to the skin of the aerial vehicle thus reducing the vibrations. [0030] In the above description, an embodiment is an example or implementation of the inventions. The various appearances of "one embodiment," "an embodiment" or "some embodiments" do not necessarily all refer to the same embodiments.

[0031] Although various features of the invention may be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although the invention may be described herein in the context of separate embodiments for clarity, the invention may also be implemented in a single embodiment.

[0032] Reference in the specification to "some embodiments", "an embodiment", "one embodiment" or "other embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments, of the inventions.

[0033] It is to be understood that the phraseology and terminology employed herein is not to be construed as limiting and are for descriptive purpose only.

[0034] The principles and uses of the teachings of the present invention may be better understood with reference to the accompanying description, figures and examples.

[0035] If the specification or claims refer to "an additional" element, that does not preclude there being more than one of the additional element.

[0036] It is to be understood that where the claims or specification refer to "a" or "an" element, such reference is not be construed that there is only one of that element.

[0037] It is to be understood that where the specification states that a component, feature, structure, or characteristic "may", "might", "can" or "could" be included, that particular component, feature, structure, or characteristic is not required to be included.

[0038] Meanings of technical and scientific terms used herein are to be commonly understood as by one of ordinary skill in the art to which the invention belongs, unless otherwise defined.

[0039] The present invention may be implemented in the testing or practice with methods and materials equivalent or similar to those described herein. [0040] Citation or identification of any reference in the description of some embodiments of the invention shall not be construed as an admission that such reference is available as prior art to the present invention.

Claims

1. An infra red (IR) sensor arrangement comprising:

at least one IR detector;

at least one cold finger, each connected to a corresponding at least one of the at least one IR detector;

a compressor thermally coupled to the at least one cold finger via at least one tube; and

at least one package, each shaped to cover at least a corresponding cold finger with the corresponding at least one IR detector,

wherein in respect to each cold finger and corresponding at least one IR detector, a center of mass of the cold finger is positioned between the corresponding at least one IR detector and the compressor.

2. The IR sensor arrangement according to claim 1, wherein the at least one package is attached to a skin of an aerial vehicle.

3. The IR sensor arrangement according to claim 1, wherein the compressor is located outside the at least one package.

4. The IR sensor arrangement according to claim 2, wherein the compressor is located within the skin of the aerial vehicle.

5. The IR sensor arrangement according to claim 1, wherein the at least one IR detector is connected to the at least one package via a tilting means that allows adjusting a pointing angle of the at least one IR detector.

6. The IR sensor arrangement according to claim 2, wherein inside each of the at least one package, the at least one cold finger and the corresponding at least one IR detector are aligned on a common line which is parallel to a line of flight of the aerial vehicle.

7. The IR sensor arrangement according to claim 1, wherein the compressor is connected via the at least one tube to a corresponding one of the at least one cold finger, and each one of the at least one IR detector is single packed in a single package.

8. The IR sensor arrangement according to claim 1, comprising at least two cold finger and at least two corresponding IR detectors, wherein the compressor is connected via the at least one tube to a corresponding one of the at least two cold fingers, and at least two of the IR detectors are packed together in one of the at least one package.

9. The IR sensor arrangement according to claim 2, wherein a specified height of the at least one package above the skin of the aerial vehicle is determined by dimensions of the at least one cold finger and corresponding at least one IR detector that are packaged within the at least one package, and a length of the at least one tube is selected to accommodate a height of the compressor within the specified height of the at least one package.

10. The IR sensor arrangement according to claim 1, wherein the at least one IR detector is located and tilted so that: (i) the aerial vehicle does not interfere with a respective view of the at least one IR detector and (ii) an specified scene coverage is achieved by the at least one IR detector.

11. The IR sensor arrangement according to claim 2, wherein the compressor is located within the at least one package and along a line parallel to a line of flight of the aerial vehicle.

12. The IR sensor arrangement according to claim 1, wherein the at least one package is shaped as a nut shell.

13. The IR sensor arrangement according to claim 1, wherein a size and a shape of the at least one package is restricted only by a size and shape of the at least one cold fingers and by a size and shape of the corresponding at least one IR detector packaged within the at least one package.