CN104034301A - Microminiature angle of attack sensor - Google Patents

Abstract

The invention provides a miniature angle-of-attack sensor, which includes a mounting seat, an integrated arm-type wind vane, a bearing, a counterweight, and an angle-of-attack acquisition device, wherein the mounting seat has an internal accommodation space; the integrated arm-type wind vane The vane includes a vane shaft, a vane arm extending obliquely from one end of the vane shaft, and a vane airfoil supported by the vane arm. The vane arm and the vane airfoil are exposed outside the mount for rotation with the airflow Drive the vane shaft to rotate together; the bearing is installed in the internal accommodation space to support the vane shaft passing through it; the counterweight is installed at the other end of the vane shaft, and the counterweight is located in the inner accommodation space Below the bearing; the angle of attack acquisition device is installed at the bottom of the internal accommodation space and connected with the weathervane shaft. The invention has the advantages of compact structure, clean aerodynamic appearance, little interference to the flow field, convenient miniaturization, small friction force and high measurement accuracy.

Description

Miniature Angle of Attack Sensor

technical field

The present invention relates to the technical field of sensors, and more particularly relates to a micro-miniature angle-of-attack sensor, which is used to measure the local airflow direction on the surface of a model in a wind tunnel experiment, or used for atmospheric data collection of an unmanned aerial vehicle.

Background technique

The angle of attack sensor, also known as the angle of attack sensor, is usually installed on the side of the aircraft fuselage to measure the flight angle of attack. The existing angle-of-attack sensors are mainly divided into two categories: differential pressure zero-type angle-of-attack sensors and windvane-type angle-of-attack sensors. Due to the complex structure and high assembly precision requirements of the pressure difference zero-type angle-of-attack sensor, it is basically replaced by the wind vane-type angle-of-attack sensor. The windvane angle-of-attack sensor mainly includes components such as the windvane (that is, the airfoil blade), the windvane shaft, the angle measurement device, and the housing. It is generally used for the measurement of the angle of attack of real aircraft and UAVs.

In traditional designs, due to factors such as structural maintenance and the volume of the angle measuring device, it is often difficult to miniaturize the windvane angle of attack sensor; the aerodynamic shape of the windvane includes the influence of joints and fasteners connected to the windvane shaft Parts with a clean aerodynamic shape are unfavorable for buildings that need to accurately capture the characteristics of the flow field, so it is difficult to use them in wind tunnel experiments with smaller scale models; traditional angle measurement devices include potentiometers and mechanicals. The device has a frictional moment or gap that is difficult to accurately control, which is very detrimental to the accuracy of the angle of attack measurement, and the wear caused by long-term use will seriously affect the reliability and accuracy of the angle of attack sensor; Although the processing method is relatively simple, its sensitivity is insufficient under the condition of low dynamic pressure and incoming flow.

Contents of the invention

In order to overcome the above-mentioned shortcomings of the prior art, the present invention provides a low-friction miniature angle-of-attack sensor.

According to one aspect of the present invention, a kind of miniature angle-of-attack sensor is provided, it comprises:

The mounting base has an internal accommodation space;

An integrated arm-type weather vane, which includes a vane shaft received in the internal accommodation space, a vane arm extending obliquely from one end of the vane shaft, and a vane airfoil supported by the vane arm. The windvane force arm and the weathervane airfoil are exposed outside the mounting base to rotate with the airflow so as to drive the windvane shaft to rotate together;

a bearing fixed in the inner housing space for supporting the vane shaft passing therethrough;

a counterweight, which is installed on the other end of the weather vane shaft, and the counterweight is located below the bearing in the internal accommodation space;

The angle of attack obtaining device is installed at the bottom of the internal accommodation space and connected with the weathervane shaft.

In this aspect of the present invention, due to the use of the integrated arm-type wind vane, the entire angle of attack sensor has a compact structure and is convenient for miniaturization. The sensitivity of the dynamic pressure to the flow can feel the slight change of the aerodynamic moment brought by the slight change of the angle of attack, so the measurement result is more real; moreover, the existence of the windvane force arm facilitates the work of the windvane airfoil outside the boundary layer, And it is convenient to improve the aerodynamic moment generated by the vane airfoil, which is suitable for providing sufficient sensitivity in wind tunnel experiments with small dynamic pressure; in addition, the cooperation between the vane shaft and the bearing can effectively ensure low friction fit and further increase the angle of attack The ability of the sensor to accurately capture the characteristics of the flow field.

Preferably, the angle-of-attack obtaining device includes a magnet and a Hall element, wherein the magnet is fixed to the bottom of the counterweight, and the Hall element is installed at the bottom of the internal accommodation space and spaced apart The method is located under the magnet to sense the change of the magnetic field of the magnet so as to generate a voltage signal.

The built-in counterweight and magnet mounting base make the rotating parts of the angle of attack sensor (including the integrated force arm wind vane, counterweight and magnet) achieve weight balance relative to the vane axis, realizing the real follow-up with the incoming flow, The influence of the gravity of the rotating parts on the measurement results is eliminated, and the rotating parts are compact in structure and the aerodynamic shape is clean; in addition, the magnetic field changes are generated through the rotation of the magnet with the windvane shaft, and the non-contact Hall element is used to feel this The magnetic field changes to generate a voltage signal, which realizes the measurement of the angle of attack of the aircraft.

Further preferably, the angle-of-attack acquisition device further includes a mounting plate installed at the bottom of the internal accommodation space, and the Hall element is mounted on the mounting plate by gluing or welding. The reference plane provided by the mounting plate can make the Hall element perpendicular to the axis of the magnetic field, which facilitates accurate measurement.

Further preferably, the Hall element is a non-contact CMOS Hall sensor. Through the arrangement of the Hall element, extremely low frictional force can be realized, and while high precision can be ensured, the miniaturization of the sensor can be realized, and the cost is low.

Further preferably, there is a gap of 0.5-1.5 mm between the Hall element and the magnet. This gap distance is more favorable for the Hall element to sense the magnetic field change of the magnet.

Further preferably, the counterweight has a bottom groove, and the magnet is embedded in the bottom groove by tight fit or glue connection. Through this arrangement, the use of fasteners and other connection structures is avoided, so that the combination of the mechanical device and the electronic device of the entire angle of attack sensor is compact, and the realization of miniaturization is promoted.

Further preferably, the counterweight is arranged such that the integrated moment arm wind vane, the counter weight and the magnet achieve weight balance with respect to the vane axis.

Further preferably, the heavy end of the counterweight is positioned at 180° relative to the vane axis and the vane airfoil. Such an arrangement is more conducive to realizing the weight balance of the integrated moment arm type wind vane, the counterweight and the magnet relative to the shaft of the wind vane.

Further preferably, the counterweight is made of brass or silver alloy. On the one hand, these materials have a high density so that they occupy a small space and facilitate the miniaturization of the angle-of-attack sensor. On the other hand, they are non-magnetizable to avoid affecting the change of the magnetic field and thus affecting the measurement results.

Preferably, the bearing is an oil lubricated ball bearing. This can further ensure the low-friction fit between the vane shaft and the bearing, and further improve the ability of the angle-of-attack sensor to accurately capture the characteristics of the flow field.

Further preferably, the cross-sectional shape of the vane airfoil is wedge-shaped or double-wedge-shaped. This kind of profile manufacturing process is relatively simple, and it is applicable to subsonic, transonic and supersonic flow fields at the same time.

Further preferably, the included angle of the weathervane arm relative to the radial plane of the weathervane axis is within a range of 15° to 30°. This helps to make the airfoil of the vane outside the boundary layer of the plane where the flange is located, so that the vane has a longer rotational arm, and at the same time, the aerodynamic moment will not cause excessive bending of the root of the vane arm. The moment affects the strength of the weather vane arm.

Preferably, the mounting seat includes a housing and a flange screwed to one end of the housing, the inner cavity of the housing and the inner cavity of the flange together constitute the inner accommodating space, wherein the The bearing is located in the inner cavity of the flange, and the counterweight is located in the inner cavity of the housing. The two shells are connected together by fine thread. . Among them, the shell can be used to protect other internal parts, and the entire angle of attack sensor can be fixed on the wall surface to be installed through the flange.

Further preferably, the housing and the flange are machined from hard aluminum alloy or stainless steel. With this arrangement, the processing cost is low, and the metal shell and the flange can also form a shield against external electromagnetic fields.

Further preferably, the top end of the weather vane shaft has a shoulder, the bottom surface of the shoulder adjoins the top surface of the bearing. The shape of the top of the weathervane shaft is a shoulder shape, which can be used to locate and compress the bearing, and at the same time increase the size of the root of the weathervane arm to increase the strength.

These and other aspects of the invention will be clearly elucidated with reference to the embodiments described below.

Description of drawings

The structure and mode of operation of the present invention, together with further objects and advantages, will be better understood from the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements:

Fig. 1 is a schematic sectional view of a miniature angle-of-attack sensor according to a specific embodiment of the present invention;

Fig. 2 is a three-dimensional schematic diagram of the integrated arm-type wind vane of the miniature angle-of-attack sensor in Fig. 1;

Fig. 3 is a schematic diagram of the cross-sectional shape of the vane airfoil of the integrated arm type vane in Fig. 2;

Fig. 4 is a schematic cross-sectional shape diagram of a variant of the vane airfoil of the integrated moment arm type vane in Fig. 2 .

Detailed ways

As required, specific embodiments of the invention will be disclosed herein. However, it should be understood that the embodiments disclosed herein are merely typical examples of the invention, which can be embodied in various forms. Therefore, specific details disclosed herein are not to be considered limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the invention in any appropriate way in practice, This includes taking various features disclosed herein and combining features that may not be expressly disclosed herein.

It should be noted that herein, directional representations, such as top surface, bottom surface, top, bottom, etc., used to explain the structure and action of various parts of the disclosed embodiments are not absolute but relative. These representations are appropriate when various parts of the disclosed embodiments are located in the locations shown in the figures. If the position or frame of reference of the disclosed embodiments changes, these representations also change according to the change in position or frame of reference of the disclosed embodiments.

Fig. 1 schematically shows a micro-miniature angle-of-attack sensor according to a specific embodiment of the present invention, which includes a housing 1, a flange 2, an integrated arm-type wind vane 3, a bearing 4, and a counterweight 5 , Magnet 6, Hall element 7, mounting plate 8. The top end of the housing 1 is screwed to the main body of the flange 2, for example, through fine thread, thereby jointly forming a mounting seat with an internal accommodation space 9, wherein the inner cavity of the housing 1 and the flange 2 The inner cavities together form the inner accommodating space 9 . The bearing 4 is located in the inner cavity of the flange 2 , and the counterweight 5 is located in the inner cavity of the housing 1 . It should be understood that the arrangement of the housing 1 can be used to protect other internal parts, and the flange 2 can fix the entire angle of attack sensor on the wall to be installed, for example, by means of countersunk screws (not shown) through the method. The countersunk head screw hole 21 on the blue plate 2 is screwed into the wall surface to be installed. In this embodiment, both the housing 1 and the flange 2 can be made of hard aluminum alloy or stainless steel.

As shown in Figure 1, and in combination with Figures 2 to 4, the integrated arm-type weathervane 3 includes a weathervane shaft 31, a weathervane arm 32 (also known as an oblique strut) extending obliquely from one end of the weathervane shaft, and The vane airfoil 33 supported by the vane arm, the vane arm 32 and the vane airfoil 33 are exposed to the outside of the mounting seat formed by the housing 1 and the flange 2, and are used to rotate with the airflow to drive the vane shaft 31 together turn. The planar shape of the weathervane airfoil 33 (that is, the shape seen from the direction of the largest dimension of the weathervane airfoil) is preferably a rectangle with a height-to-width ratio equal to 2, and the cross-sectional shape is preferably wedge-shaped (see FIG. set to 15°) or double wedge (see Fig. 4, in another embodiment the wedge-shaped apex angle is set to 20°), the relative thickness of the section (ie the ratio of airfoil thickness to width) does not exceed 30%. In addition, the included angle of the weathervane force arm 32 relative to the radial plane of the weathervane axis 31 is preferably set within a range of 15° to 30°. The top end of the weathervane shaft 31 preferably has a shoulder 310, the bottom surface of which abuts the top surface of the bearing 4, which can be pressed against the top surface of the bearing 4 to facilitate the positioning of the weathervane shaft 31, while the shoulder 310 The root of the vane arm 32 may be increased in size to increase its strength. The integrated arm-type wind vane is preferably made of stainless steel, for example, it can be machined or wire-cut. It should be noted that the above-mentioned radial plane of the weather vane shaft 31 is the plane where the shaft shoulder 310 is located.

As shown in FIG. 1 , the bearing 4 is installed in the inner accommodation space 9 , specifically in the inner cavity of the flange 2 , for supporting the weathervane shaft 31 passing through it. The bearing 4 is preferably a miniature extra-light grade ball bearing, which is lubricated with oil with low viscosity. The fit between the weathervane shaft 31 and the bearing 4 is preferably a transition fit with a small gap, which can effectively avoid the deformation of the miniature and ultra-light bearings caused by assembly and generate additional friction torque, and further improve the accuracy of the angle of attack sensor to capture the flow field characteristics Ability.

Again as shown in FIG. 1 , the counterweight 5 is mounted on the other end of the weather vane shaft 31 and is located below the bearing 4 in the inner accommodation space 9 . The angle of attack acquisition device is installed at the bottom of the inner accommodation space 9 and connected with the vane shaft 31 . In this embodiment, the magnet 6, the Hall element 7, and the mounting plate 8 form an angle-of-attack acquisition device, wherein the magnet 6 is fixed to the bottom groove 51 formed on the counterweight 5, for example, by tight fit or glued inlay In the bottom groove 51 , the counterweight 5 plays the double function of a counterweight and a magnet mount. The Hall element 7 is installed at the bottom of the inner accommodation space 9 and is spaced below the magnet 6 for sensing the magnetic field change of the magnet to generate a voltage signal. It should be understood that when the angle-of-attack sensor of this embodiment is applied, the Hall element 7 will be electrically connected with an external signal processing and display device, for example, by means of a transmission line, so as to indicate the aircraft angle of attack corresponding to the voltage signal generated by it. .

The Hall element 7 is preferably mounted on the mounting plate 8 by glue or welding, and the mounting plate 8 is mounted on the bottom of the internal accommodation space 9 . The mounting plate 8 can be an epoxy resin plate, for example, its edge is embedded in the inner side of the housing 1 so as to be positioned by means of the step 11 formed on the inner side of the housing 1. The preferred surface of the mounting plate 8 is perpendicular to the axis of the weather vane shaft 31. It should be understood that the mounting plate 8 is not necessary, and the Hall element 7 can also be directly supported by the inner bottom surface of the housing 1 . Preferably, the Hall element 7 is a miniature 360° non-contact CMOS Hall sensor, and this type of Hall element can sense a 360° magnetic field angle change. The non-contact CMOS Hall sensor has a gap of 0.5-1.5mm between it and the magnet 6, preferably the gap is 1mm. This gap distance is more favorable for the Hall element to sense the magnetic field change of the magnet. In this embodiment, the magnet 6 is preferably a samarium cobalt magnet, a neodymium iron boron magnet or a ferrite magnet.

In addition, preferably, the counterweight 5 is arranged so that the integrated force arm type wind vane 3, the counterweight 5 and the magnet 6 achieve weight balance relative to the vane shaft 31, wherein the heavy end of the counterweight 5 is preferably positioned as Relative to the vane shaft 31 and the vane airfoil 33, the arrangement is 180°, which is more conducive to realizing the weight balance of the integrated moment arm type weather vane, counterweight and magnet relative to the vane shaft. The counterweight 5 is also preferably made of brass or silver alloy, because these materials have a high density on the one hand, so they take up less space and facilitate the miniaturization of the angle of attack sensor, and on the other hand, they are not magnetizable so as to avoid affecting the magnetic field changes and thus affecting the measurement. result. In this embodiment, the counterweight 5 adopts a tubular shape, is sleeved on the wind vane shaft 31, and then fixed to the wind vane shaft 31 through the screw holes 52 on the counterweight 5 by, for example, high carbon steel set screws (not shown in the figure). On the standard shaft 31, it also plays the role of axial positioning for the integrated weathervane 3; the top of the counterweight 5 is provided with a shoulder 53 for positioning and pressing against the bearing. In this embodiment, as shown in Figure 1, during the assembly process, the bearings 4 are loaded one by one from the bottom of the inner hole of the flange 2, and the top of the inner hole of the flange has a step 22 to position the outer ring of the bearing 4. The other end of bearing 4 is just positioned bearing inner ring by shaft shoulder 53; Weathervane shaft 3 is positioned by the shaft shoulder 310 (seeing Fig. 2) of shaft shoulder 53 and self top again.

In addition, although the angle-of-attack obtaining device described in this embodiment is composed of a magnet 6, a Hall element 7 and a mounting plate 8, it should be understood that other implementations can be used for the angle-of-attack obtaining device, for example, existing The wind direction acquisition components commonly used in the art include the azimuth dial code and the wind direction conversion circuit. When this structure is adopted, the azimuth dial code is connected to the wind vane shaft 31, and the azimuth marking part of the azimuth dial code is driven by the rotation of the wind vane shaft. Rotate to mark the azimuth, and the wind direction conversion circuit and the azimuth disk code convert the azimuth into an electrical signal by sending and receiving infrared photoelectric elements such as sending and receiving infrared photoelectric tubes.

The technical content and technical characteristics of the present invention have been disclosed above, but it can be understood that under the creative idea of the present invention, those skilled in the art can make various changes and improvements to the above-mentioned structure and shape, including those disclosed or claimed separately herein. Combinations of technical features obviously include other combinations of these features. These variations and/or combinations all fall within the technical field involved in the present invention, and fall within the protection scope of the claims of the present invention. It should be noted that, according to convention, the use of a singular element in a claim is intended to include one or more of such elements. Furthermore, any reference signs in the claims should not be construed as limiting the scope of the invention.

Claims (15)

1. A miniature angle-of-attack sensor, characterized in that it comprises: The mounting base has an internal accommodation space; An integrated arm-type weather vane, which includes a vane shaft received in the internal accommodation space, a vane arm extending obliquely from one end of the vane shaft, and a vane airfoil supported by the vane arm. The windvane force arm and the weathervane airfoil are exposed outside the mounting base to rotate with the airflow so as to drive the windvane shaft to rotate together; a bearing mounted in the inner housing space for supporting the vane shaft passing therethrough; a counterweight, which is fixed to the other end of the weathervane shaft, and the counterweight is located below the bearing in the internal accommodation space; The angle of attack obtaining device is installed at the bottom of the internal accommodation space and connected with the weathervane shaft. 2. The micro-miniature angle-of-attack sensor according to claim 1, wherein the angle-of-attack acquiring device comprises a magnet and a Hall element, wherein the magnet is fixed to the bottom of the counterweight, and the Hall element The element is installed at the bottom of the inner accommodation space and is spaced below the magnet for sensing the magnetic field change of the magnet to generate a voltage signal. 3. The micro-miniature angle-of-attack sensor according to claim 2, wherein the angle-of-attack acquisition device also includes a mounting plate installed at the bottom of the internal accommodation space, and the Hall element is glued together. Or welded on the mounting plate. 4. The miniature angle-of-attack sensor according to claim 2, wherein the Hall element is a non-contact CMOS Hall sensor. 5. The miniature angle-of-attack sensor according to claim 2, characterized in that there is a gap of 0.5-1.5 mm between the Hall element and the magnet. 6. The micro-miniature angle-of-attack sensor according to claim 2, wherein the counterweight has a bottom groove, and the magnet is embedded in the bottom groove by tight fit or glue. 7. The micro-miniature angle-of-attack sensor according to claim 2, characterized in that, the counterweight is arranged so that the integrated moment arm type weathervane, counterweight and magnet realize relative to the vane axis. weight balance. 8. The miniature angle-of-attack sensor according to claim 7, wherein the heavy end of the counterweight is positioned at 180° relative to the vane axis and the vane airfoil. 9. The micro-miniature angle-of-attack sensor according to claim 2, wherein the counterweight is made of brass or silver alloy. 10. The micro-miniature angle-of-attack sensor according to claim 1, wherein the bearing is an oil-lubricated ball bearing. 11. The micro-miniature angle-of-attack sensor according to claim 1, wherein the cross-sectional shape of the vane airfoil is wedge-shaped or double-wedge-shaped. 12 . The miniature angle-of-attack sensor according to claim 1 , wherein the included angle of the weathervane force arm relative to the radial plane of the weathervane axis is in the range of 15° to 30°. 13. The micro-miniature angle-of-attack sensor according to claim 1, wherein the mount includes a housing and a flange screwed to one end of the housing, and the inner cavity of the housing and the flange The inner cavity of the plate together constitutes the inner accommodating space, wherein the bearing is located in the inner cavity of the flange plate, and the counterweight is located in the inner cavity of the housing. 14. The micro-miniature angle-of-attack sensor according to claim 13, characterized in that, the housing and the flange are made of hard aluminum alloy or stainless steel. 15. The miniature angle-of-attack sensor according to claim 13, wherein the top end of the weathervane shaft has a shoulder, and the bottom surface of the shoulder is adjacent to the top surface of the bearing.