Low-overload fuel gas launching device for small unmanned aerial vehicle

Abstract

The invention provides a small unmanned aerial vehicle low-overload fuel gas launching device. The small unmanned aerial vehicle low-overload fuel gas launching device comprises a launching cylinder, a base, a piston, a plurality of fuel gas generators and a control system. The base is connected to the bottom of the launching cylinder, the piston is coaxially arranged in the launching cylinder, and the base, the piston and the launching cylinder form a closed chamber. The multiple fuel gas generators are installed on the base in the closed chamber and controlled by the control system to conduct graded ignition, and the interval time of graded ignition of the multiple fuel gas generators is determined according to an algorithm. According to the invention, the launching overload of the small cylindrical launch unmanned aerial vehicle can be reduced to less than 100g, the launching speed can be improved to 25-35m / s, and compared with the development of a fuel gas generator meeting the requirements, the structure can greatly shorten the development period, reduce the development and test cost, reduce the weight of a launching system and a fuselage structure by more than 30%, reduce the standard grade of airborne equipment, and improve the reliability of the small cylindrical launch unmanned aerial vehicle. And the development cost of the whole unmanned aerial vehicle platform is reduced by more than 30%.

Description

Technical Field

[0001] The invention belongs to the technical field of unmanned aerial vehicle launch, and in particular relates to a low-overload gas launch device for a small unmanned aerial vehicle. Background Art

[0002] Small UAVs are mostly launched by catapult, and are mainly used to perform reconnaissance, surveillance and other tasks. They are suitable for individual carrying or platform cluster launching modes.

[0003] The catapult launch methods of small UAVs can be divided into various methods according to the power source, such as gas-hydraulic catapult, rubber band catapult, electromagnetic catapult, etc. The gas catapult + launch tube mode has been a hot research topic in recent years, but the launch overload in existing launch technologies is relatively high, basically around 150g, or even as high as 200g, which puts forward high requirements on the UAV structure, onboard equipment and launch tube structure; the launch speed is generally 18 to 25m / s, which is difficult to meet the initial launch speed requirements of high-performance aircraft. Summary of the invention

[0004] The purpose of the present invention is to solve the problems of high launch overload and low launch speed when firing a small UAV with a gas cylinder in the prior art, and to provide a small UAV low-overload gas launch device, which can reduce the launch overload of the small cylinder-fired UAV to below 100g and increase the launch speed to 25-35m / s.

[0005] To achieve the above purpose, the technical solution provided by the present invention is:

[0006] A low-overload gas launch device for a small UAV, comprising a launch tube, a base, a piston, a plurality of gas generators and a control system;

[0007] The base is connected to the bottom of the launch tube, the piston is coaxially arranged in the launch tube, and the base, the piston and the launch tube form a closed chamber;

[0008] Multiple gas generators are installed on the base in a closed room and are controlled by the control system to perform staged ignition. The interval time of staged ignition of multiple gas generators is determined according to the following algorithm:

[0009] Step 1: Establish the motion equations for the piston and the drone in the launch tube:

[0010]

[0011] Where m1 is the total weight of the piston and the drone, a is the acceleration of the piston and the drone in the barrel, X is the piston stroke, f1 is the thrust of the gas in the closed chamber on the piston, f2 is the external atmospheric pressure force, f3 is the friction between the piston and the drone and the launch barrel, S cis the cross-sectional area of ​​the cylinder, P is the gas pressure in the closed chamber, and is calculated according to the following state equation:

[0012] P = x p (R g m g +R a m a )T / V′

[0013] In the formula, x p is the correction coefficient of the state equation, m g and m a are the gas mass at different times and the air mass in the initial free volume, T is the temperature in the closed room, R g and R a are the gas constants of fuel gas and air respectively, V' is the free volume of the launch tube, V'=X*S c ;

[0014] Step 2, selecting the initial ignition interval time, and obtaining the time-launch overload curve and the time-launch speed curve under the initial ignition interval time according to the established motion equation and state equation;

[0015] Step 3, determine whether the launch overload and the launch speed meet the requirements. If not, adjust the ignition interval time with a preset ignition interval time adjustment accuracy and return to step 2 until the ignition interval time that meets the requirements is obtained.

[0016] Furthermore, the number of the gas generators is two.

[0017] Further, the gas generators are connected in series.

[0018] Furthermore, the preset ignition interval time adjustment accuracy is 1 to 5 ms.

[0019] Furthermore, the preset ignition interval time adjustment accuracy is 1.5ms.

[0020] Further, the ignition interval time of the gas generator is determined to be 10 to 65 ms.

[0021] Furthermore, the ignition interval time of the gas generator is determined to be 25-45 ms.

[0022] The advantages of the present invention are:

[0023] The low-overload gas launch device for a small UAV of the present invention is provided with a plurality of gas generators, which are ignited in stages. The ignition interval of the gas generators is obtained through theoretical calculation and experimental verification to balance the low overload and high speed of the UAV launch. The launch overload of the small tube-launched UAV can be reduced to below 100g, and the launch speed can be increased to 25-35m / s. Compared with the development of gas generators that meet the requirements, the structure of the present invention can greatly shorten the development cycle, reduce the development and testing costs, reduce the weight of the launch system and fuselage structure by more than 30%, reduce the standard level of airborne equipment, and reduce the overall UAV platform development cost by more than 30%. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or other features and advantages of the present invention will become more easily understood through the following description with reference to the accompanying drawings, which are not drawn to scale and some features are exaggerated or reduced to show details of specific components. In the accompanying drawings:

[0025] Figure 1 is a schematic cross-sectional view of a low-overload gas launch device for a small UAV of the present invention;

[0026] Figure 2 is a comparison diagram of the time-transmission overload curve in Example 1 of the present invention;

[0027] Figure 3 is a time-emission speed curve comparison diagram of the present invention in Example 1;

[0028] Figure 4 is a comparison diagram of the time-transmission overload curve in Example 2 of the present invention;

[0029] Figure 5 It is a comparison diagram of the time-emission speed curve in Example 2 of the present invention;

[0030] In the figure: 1-launching tube; 2-base; 3-piston; 4-gas generator; 5-control system; 6-sealed chamber. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below with reference to the accompanying drawings by means of exemplary embodiments of the present invention. It should be noted that the following detailed description of the present invention is only for the purpose of illustration, and is not intended to limit the present invention.

[0032] The present invention provides a low-overload gas launch device for a small UAV, which is used for launching the small UAV in a cylinder-type manner by means of gas launch, aiming to reduce the launch overload of the UAV and increase the launch speed of the UAV.

[0033] Reference Figure 1As an exemplary embodiment of the present invention, a small UAV low-overload gas launch device includes a launch tube 1, a base 2, a piston 3, a plurality of gas generators 4 and a control system 5.

[0034] The launch tube 1 is made of composite materials and is the main structure of the launch device. The base 2 is connected to the bottom of the launch tube 1 to support the launch tube. The piston 3 is coaxially arranged in the launch tube 1. The base 2, the piston 3 and the launch tube 1 form a closed chamber 6.

[0035] The gas generator 4 is the power source of the entire launch device. Multiple gas generators 4 are installed on the base 2 in the closed room 6 and are controlled by the control system 5 for staged ignition, that is, the next stage gas generator is ignited after a certain interval after the ignition of the previous stage gas generator. The gas generators 4 can be connected in series or in parallel. The number of gas generators 4 is preferably two.

[0036] When the launch device launches the UAV, the control system sends a signal to the gas generator, and the gas generator starts to work, generating high-pressure gas, which rapidly increases the pressure of the closed chamber 6, pushes the piston 3 to move toward the barrel mouth, and the piston 3 pushes the UAV to accelerate in the barrel until it exits the barrel. The present invention controls each gas generator to start working at different time points, and through the gas supplement of the multi-stage generator, reduces the tendency of the piston movement thrust to drop rapidly with the piston movement, so as to achieve the effect of accelerating to a higher speed within a shorter launch stroke, while not generating an instantaneous high overload.

[0037] The interval time of the staged ignition of the gas generator 4 can be determined according to the algorithm described below.

[0038] The algorithm includes: step S1, establishing the state equation of the piston 3 and the UAV moving in the launch tube 1:

[0039]

[0040] Where m1 is the total weight of the piston and the drone, a is the acceleration of the piston and the drone in the barrel, X is the piston stroke, f1 is the thrust of the gas in the closed chamber on the piston, f2 is the external atmospheric pressure force, f3 is the friction between the piston and the drone and the launch barrel, which can be determined based on experience, S c is the cross-sectional area of ​​the cylinder, and P is the pressure of the gas in the closed chamber, which is calculated according to the following formula:

[0041] P = x p (R g m g +R a m a )T / V′

[0042] In the formula, x pis the correction coefficient of the state equation, m g and m a are the gas mass at different times and the air mass in the initial free volume, T is the temperature in the closed room, R g and R a are the gas constants of fuel gas and air respectively, V' is the free volume of the launch tube, V'=X*S c .

[0043] After the establishment of the equation of motion and the equation of state is completed, step S2 is performed: the initial ignition interval time is selected, and according to the established equation group, the time-launching overload curve and the time-launching speed curve under the initial ignition interval time are obtained.

[0044] Then proceed to step S3: determine whether the launch overload and the launch speed meet the requirements. If not, adjust the ignition interval time with a preset ignition interval time adjustment accuracy and return to step S2 until the ignition interval time that meets the requirements is obtained.

[0045] The initial ignition interval time may be an interval time value increasing from 0 to a preset ignition interval time adjustment precision, and the preset ignition interval time adjustment precision may be 1 to 5 ms, preferably 1.5 ms, and more preferably 1 ms. For example, if the preset ignition interval time adjustment precision is 1 ms, the initial ignition interval time may be 1 ms. In addition, a preset ignition interval time range may also be set, such as 0 to 100 ms, and the ignition interval time may be gradually increased from 1 ms to 100 ms according to the preset ignition interval time adjustment precision.

[0046] By obtaining the time-emission overload curve and the time-emission speed curve, the working sequence of each gas generator can be flexibly adjusted to obtain a balance between low overload and high speed and obtain an ignition interval time that meets the requirements.

[0047] Next, the above theoretical calculation and simulation test are combined to verify and determine the ignition interval time that meets the requirements. Only two examples are given here.

[0048] Example 1

[0049] Applying the design ideas and solutions provided by the present invention, a 12kg-class small UAV gas launch device is designed. Two gas generators are connected in series. The initial closed chamber volume is 2.6L. At t0, the first-stage generator is started. At t0+40ms, the second-stage generator is started. According to theoretical calculations and experimental verification, the launch overload of the launch device is 74g and the launch speed is 25m / s under the condition of a launch stroke of 0.7 meters. The time-launch overload curve and time-launch speed curve optimization comparison diagram are shown in detail. Figure 2 , Figure 3 .from Figure 2 , Figure 3 It can be seen that when a single gas generator is used, the overload is greater than 100g and the speed is less than 20m / s; when two gas generators are connected in series with a time interval of 30ms, the speed is significantly increased, but the overload is still greater than 100g; when two generators are connected in series with the time interval adjusted to 40ms, the overload is significantly reduced and the speed reaches 25m / s, which is better than the previous two solutions and meets the design requirements.

[0050] Example 2

[0051] Applying the design ideas and solutions provided by the present invention, a 10kg-class small UAV gas launch device is designed. Two gas generators are connected in series. The initial closed chamber volume is 3.0L. At t0, the first-stage generator is started. At t0+30ms, the second-stage generator is started. According to theoretical calculations and experimental verification, the launch device has a launch overload of 93g and a launch speed of 36m / s under the condition of a launch stroke of 1.0m. Since this example requires a higher speed, two generators are directly connected in series, and the interval time is optimized. For details, see the time-launch overload curve and time-launch speed optimization comparison chart. Figure 4 , Figure 5 .from Figure 4 , Figure 5 It can be seen that when two generators are connected in series and the time interval is 20ms, the overload is greater than 120g and the speed is 40m / s; when the time interval is 25ms, the speed is reduced, but the overload is still greater than 100g; when the time interval is adjusted to 30ms, the speed continues to decrease, but is still greater than 35m / s, and the overload is reduced to below 100g, which meets the design requirements.

[0052] Through a large number of experiments, the ignition interval of the gas generator 4 can be determined to be 10 to 65 ms, especially 25 to 45 ms. The specific suitable ignition interval can be calculated specifically for a specific situation.

[0053] Therefore, the small UAV gas launch device of the present invention includes multiple gas generators, which are ignited and started at different time points. By obtaining the gas generator ignition interval time that balances the low overload and high launch speed of the UAV, the launch overload of the small tube-launched UAV can be reduced to below 100g, and the launch speed can be increased to 25-35m / s. Compared with the development of gas generators that meet the requirements, this structure of the present invention can greatly shorten the development cycle, reduce the development and testing costs, reduce the weight of the launch system and fuselage structure by more than 30%, reduce the standard level of airborne equipment, and reduce the overall UAV platform development cost by more than 30%.

[0054] Finally, it should be noted that the features mentioned and / or shown in the above description of the exemplary embodiments of the present invention may be combined in the same or similar manner into one or more other embodiments, combined with the features in other embodiments or substituted for the corresponding features in other implementations. The technical solutions obtained by these combinations or substitutions shall also be deemed to be included in the protection scope of the present invention.

Claims

1. A low-overload gas launch device for a small UAV, characterized by: It includes a launch tube, a base, a piston, multiple gas generators and a control system; The base is connected to the bottom of the launch tube, the piston is coaxially arranged in the launch tube, and the base, the piston and the launch tube form a closed chamber; The multiple gas generators are installed on the base in the closed room and are controlled by the control system to perform staged ignition. The interval time of staged ignition of the multiple gas generators is determined according to the following algorithm: Step 1: Establish the motion equations for the piston and the drone in the launch tube: Where m1 is the total weight of the piston and the drone, a is the acceleration of the piston and the drone in the barrel, X is the piston stroke, f1 is the thrust of the gas in the closed chamber on the piston, f2 is the external atmospheric pressure force, f3 is the friction between the piston and the drone and the launch barrel, S c is the cross-sectional area of ​​the cylinder, P is the gas pressure in the closed chamber, and is calculated according to the following state equation: P=x p (R g m g +R a m a )T / V′ In the formula, x p is the correction coefficient of the state equation, m g and m a are the gas mass at different times and the air mass in the initial free volume, T is the temperature in the closed room, R g and R a are the gas constants of fuel gas and air respectively, V' is the free volume of the launch tube, V'=X*S c ; Step 2, selecting the initial ignition interval time, and obtaining the time-launch overload curve and the time-launch speed curve under the initial ignition interval time according to the established motion equation and state equation; Step 3, determine whether the launch overload and the launch speed meet the requirements. If not, adjust the ignition interval time with a preset ignition interval time adjustment accuracy and return to step 2 until the ignition interval time that meets the requirements is obtained.

2. The low-overload gas launch device for a small UAV according to claim 1 is characterized by: The number of the gas generators is two.

3. The low-overload gas launch device for a small UAV according to claim 1 or 2, characterized in that: The gas generators are connected in series.

4. The low-overload gas launch device for a small UAV according to claim 1 or 2, characterized in that: The preset ignition interval time adjustment accuracy is 1 to 5 ms.

5. The low-overload gas launch device for a small UAV according to claim 4 is characterized in that: The preset ignition interval time adjustment accuracy is 1.5ms.

6. The low-overload gas launch device for a small UAV according to claim 1 or 2, characterized in that: The ignition interval time of the gas generator is determined to be 10 to 65 ms.

7. The low-overload gas launch device for a small UAV according to claim 6 is characterized by: The ignition interval time of the gas generator is determined to be 25-45 ms.

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