Movable air cannon snow removal device used in greenhouse

Abstract

The invention discloses a movable air cannon snow removal device used in a greenhouse. The movable air cannon snow removal device comprises a sliding rail arranged in the greenhouse, a movable platform moving along the sliding rail, and an orientation platform, a pitching platform and an air storage tank which are mounted on the movable platform. The air cannon body is installed on the pitching platform and composed of a large air chamber, a small air chamber, an electromagnetic valve, a piston and a launching pipeline which are connected with an air storage tank, the horizontal angle and the pitching angle can be adjusted, and directional pointing of different areas of a greenhouse film is achieved. During working, the small air chamber is inflated to enable the piston to move forwards and block the launching pipeline, and then the large air chamber is inflated to build launching pressure; the pressure of the small air chamber is quickly released at the launching moment, high-pressure air in the large air chamber pushes the piston to move backwards and opens the launching pipeline, shock waves are formed through the nozzles and spread along the greenhouse film, and accumulated snow is loosened and falls off. The device can move in the greenhouse and realize spraying direction adjustment, and has the characteristics of non-contact, low cost, low damage, high snow removal efficiency and high safety.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of greenhouse, and relates to a mobile air cannon device for a greenhouse, which generates shock waves by compressed air to achieve non-contact removal of snow on the roof of the greenhouse. BACKGROUND

[0002] Greenhouses have the advantages of strong heat preservation capacity and low construction cost, and have been widely used in the north. However, in winter climate conditions, the roof of large and medium-sized greenhouses is prone to accumulate thick snow, and the snow load can cause the deformation of the greenhouse film and the imbalance of the force on the support, and even cause the local collapse of the greenhouse. Therefore, snow removal in winter is a difficult problem for greenhouses. Currently, the commonly used snow removal methods include: (1) manual snow removal method, that is, using snow removal rakes, scrapers and other tools to push or pull the snow, so that the snow slides along the greenhouse film or the heat preservation; (2) mechanical snow removal method, mainly using snow blower to remove snow or using track-type snow remover to remove snow or vibrating the greenhouse frame by mechanical vibration to achieve snow removal; (3) heating snow melting method; (4) chemical snow removal method. However, the above four snow removal methods have some disadvantages, for example: the manual snow removal method has low efficiency, and it takes a long time to remove snow for a large area, has high labor intensity, needs to invest a lot of manpower, and the greenhouse film may be damaged due to improper operation during the removal process. The snow blower has high noise and long duration, and has high equipment purchase cost, and the snow blowing effect is not good for thick snow. The track-type snow remover has limited snow removal range, and cannot remove the snow outside the track, and has high maintenance and maintenance cost. The mechanical vibration of the greenhouse frame has damage to the greenhouse structure, frequent vibration of the greenhouse frame will shorten the service life of the greenhouse, and the snow removal efficiency is low, and only partial removal can be achieved. The heating snow melting method has high energy consumption and high operation cost, needs to be equipped with special heating equipment and power supply, has high initial equipment investment, and the maintenance is complex and costly if the heating equipment fails. If the snow is too much and too thick, the snow melting speed may not keep up, and if the melted snow water cannot be discharged in time, it will cause water accumulation and ice formation. The chemical snow removal method uses chemical agents (snow melting agent) which can cause environmental pollution to soil and vegetation, and can also corrode the greenhouse film and metal facilities, and for thick snow, the snow melting effect of the chemical agent is limited and needs to be combined with other snow removal methods. Therefore, the existing snow removal methods have some disadvantages and cannot well solve the problem of snow on the roof of the greenhouse. SUMMARY

[0003] To solve the above technical problems and defects, the present application breaks the conventional snow removal method and provides a novel mobile air cannon snow removal device for the interior of a greenhouse, to solve the problems of low efficiency and high cost in the prior art. The device is a mobile air cannon greenhouse snow removal device with a wide range, adjustable jetting direction, controllable launching process, and no contact damage to the greenhouse film, which realizes safe, efficient, and non-contact removal of snow on the top of the greenhouse.

[0004] To achieve the above object, the present application adopts the following technical solution: a mobile air cannon snow removal device for the interior of a greenhouse, comprising a slide rail arranged in the greenhouse, a mobile platform moving along the slide rail, an azimuth platform arranged on the mobile platform, a pitch platform connected with the azimuth platform, and an air storage tank. The air cannon body is first fixed by a fixing device, and then the fixing device is installed on the pitch platform by bolts. The air cannon body comprises an atmosphere chamber, a small air chamber, a piston, an electromagnetic valve, and a launching pipeline. The center of the azimuth platform has an opening, which is connected with the mobile platform by a pin shaft. The pitch platform and the azimuth platform each have an opening and are connected by a pin shaft. The air cannon body is fixed by the fixing device, and the fixing device is connected with the pitch platform by bolts. When the air storage tank is inflated, it is communicated with the atmosphere chamber and the small air chamber through a gas supply pipeline. The atmosphere chamber is used to store high-pressure air, and the small air chamber is used to form a locking pressure on the piston, and the position change of the piston is controlled by the pressure difference. The piston is arranged to move axially along the launching pipeline under the pressure action of the small air chamber and the atmosphere chamber, and is used to block or open the launching pipeline.

[0005] The working principle of the technical solution is as follows:

[0006] In the launching preparation stage, first, open the small air chamber inflation electromagnetic valve to inflate the small air chamber, so that the air pressure in the small air chamber rises and pushes the piston to move towards the front end of the jetting pipe, so that the piston is attached to the tail of the jetting pipe, forming an airtight blockage of the jetting pipe. Then close the small air chamber inflation electromagnetic valve and open the atmosphere chamber inflation electromagnetic valve, inject compressed gas into the atmosphere chamber, so that the atmosphere chamber establishes the initial pressure required for launching, and the piston remains in a locked state when the pressure in the small air chamber is greater than that in the atmosphere chamber. When launching, open the small air chamber exhaust electromagnetic valve, so that the pressure in the small air chamber decreases rapidly, so that the high-pressure gas in the atmosphere chamber pushes the piston to move backward, and the launching pipeline is opened instantaneously. The compressed air stored in the atmosphere chamber is sprayed outward through the launching pipeline and the adjustable nozzle, forming a three-dimensional diffused air pulse, and propagating along the greenhouse film, so that the snow on the outside of the film is loosened and slides down under the action of the air pulse.

[0007] Further limited, the azimuth platform realizes horizontal angle adjustment of the air cannon body through a horizontal rotation mechanism; the pitch platform realizes pitch angle adjustment of the air cannon body in a vertical plane through a pitch shaft and an angle adjusting device; the moving platform can cover different areas of the greenhouse shed through sliding rail movement, thereby realizing fixed-point or continuous snow removal operation at different positions of the greenhouse roof.

[0008] Further limited, the air storage tank is provided with a pressure gauge, a safety valve and a gas storage pipeline for real-time monitoring of air pressure and ensuring energy storage safety; the control module is connected with each electromagnetic valve and angle adjusting mechanism for controlling the whole process of inflation, pressure relief, launching and jet direction adjustment.

[0009] Through the above structure and working mode, the present application can loosen accumulated snow through the propagation of air pulses without contacting the shed film, and quickly remove the accumulated snow on the greenhouse roof under the premise of ensuring that the shed film is not damaged by impact.

[0010] Advantages and beneficial effects of the present application:

[0011] (1) The snow removal device uses the mode of air pulse propagation along the shed film to realize non-contact snow removal, avoids mechanical damage to the shed film and the greenhouse shed framework caused by traditional snow removal methods, and has the characteristics of low cost and good effect.

[0012] (2) The snow removal device realizes large-scale controllable jetting through sliding rail movement, azimuth adjustment and pitch adjustment, realizes full coverage of the snow removal range and more accurate positioning;

[0013] (3) The double-cavity cooperative structure of the large air chamber and the small air chamber makes the piston locking and jetting process highly controllable, improves the working stability and safety of the air cannon;

[0014] (4) The air pulse generated by the air cannon in the snow removal device has fast jetting speed, strong impact force and wide propagation range, can timely respond to heavy snow weather in the north, and significantly improves the snow removal efficiency;

[0015] (5) The snow removal device has compact overall structure and high modularization degree, and is convenient for maintenance and replacement of parts;

[0016] (6) The moving platform structure of the snow removal device makes it applicable to different types of greenhouse sheds, has high applicability and engineering popularization value. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to make the technical scheme of the present application clearer and more understandable, the following describes the mobile snow removal device with reference to the drawings. It should be noted that the drawings are only used to illustrate the principles and structures of the present application, and are not a limitation on the scope of protection.

[0018] Figure 1An isometric side view of a mobile air cannon snow removal device;

[0019] Figure 2 An air cannon working principle Figure 1 ;

[0020] Figure 3 An air cannon working principle Figure 2 ;

[0021] The figure marks: greenhouse 1, slide rail 2, roller 3, moving platform 4, azimuth platform 5, pitch platform 6, fixed frame 7, air cannon main body 8, conveying pipeline 9, air storage tank 10, launching pipeline 8.1, piston 8.2, small air chamber 8.3, large air chamber 8.4, large air chamber electromagnetic valve 8.5, small air chamber electromagnetic valve 8.6, small air chamber pressure sensor 8.7, large air chamber pressure sensor 8.8. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme of the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present application.

[0023] In the description of the present application, it should be further explained that, unless otherwise explicitly specified and limited, the terms "set", "connected" should be understood broadly, for example, it can be fixedly connected, or detachably connected, or integrally connected; it can be mechanically connected, it can be directly connected, or indirectly connected through an intermediate medium, it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0024] The embodiments of the present application will be further described in detail below in combination with the drawings.

[0025] As Figure 1As shown, the mobile air cannon snow removal device for greenhouse in the embodiment comprises a greenhouse 1, a slide rail 2, a roller 3, a mobile platform 4, an azimuth platform 5, a pitch platform 6, a fixing frame 7, an air cannon main body 8, a conveying pipeline 9, and an air storage tank 10. The slide rail 2 is arranged inside the greenhouse along the length direction of the greenhouse. The mobile platform 4 is slidably connected with the slide rail 2 through the roller 3 or a sliding block, and can be moved to any position of the greenhouse along the slide rail to cover different snow removal areas. The azimuth platform 5 is arranged on the mobile platform 4 and can rotate around the vertical direction to adjust the horizontal angle of the air cannon main body. The pitch platform 6 is installed on the azimuth platform 5. The air cannon main body 8 is fixed by the fixing frame 7 and installed on the pitch platform 6, and can rotate around the horizontal shaft to adjust the pitch angle of the air cannon main body. Finally, the air cannon main body 8 is adjusted in three-dimensional direction with the azimuth platform 5 and the pitch platform 6 to act on different areas of the greenhouse.

[0026] As shown in the figure, Figure 2 The air cannon main body 8 mainly comprises a launching pipeline 8.1, which is used as a high-pressure airflow channel during launching; a small air chamber 8.3, which is used to lock the front chamber of the piston before launching and is equipped with a small air chamber electromagnetic valve 8.6 for realizing the pressurization and rapid pressure relief of the small air chamber; a large air chamber 8.4, which is used to store compressed air for launching energy and is equipped with a large air chamber electromagnetic valve 8.6 for establishing launching pressure; a piston 8.2, which is arranged between the large air chamber 8.4 and the small air chamber 8.3 for blocking or rapidly opening the injection pipe; a small air chamber pressure sensor 8.7 for monitoring the pressure in the small air chamber 8.3; and a large air chamber pressure sensor 8.8 for monitoring the pressure in the large air chamber 8.4. During the operation of the device, high-pressure air is delivered from the conveying pipeline 9 to the small air chamber 8.3 and the large air chamber 8.4 through the air storage tank 10.

[0027] Further, as shown in the figure, Figure 1 , Figure 2 In the embodiment, the air cannon mobile snow removal device further comprises a controller for controlling the movement of the mobile platform 4, the movement of the azimuth platform 5, the movement of the pitch platform 6, the opening and closing of the small air chamber electromagnetic valve 8.6, and the opening and closing of the large air chamber electromagnetic valve 8.5.

[0028] Further, as shown in the figure, Figure 1 , Figure 2 In the embodiment, the mobile platform 4 is an electric mobile platform, the azimuth and pitch angle adjustment is completed by using a driving motor (not shown), and the lower part of the fixing frame 7 is connected with the pitch platform 6 through a bolt (not shown).

[0029] Further, as shown in the figure, Figure 2 , Figure 3As shown, the small air chamber 8.3 is first inflated before the launch, and as the pressure of the small air chamber rises, the piston 8.2 is pushed to the tail of the launch pipe 8.1 and forms an airtight seal, when the pressure of the small air chamber 8.3 reaches the preset value, the small air chamber electromagnetic valve 8.6 is closed, and the piston remains in the locked state, at this time, the small air chamber pressure ≥ the large air chamber pressure, and the injection pipe is in a completely closed state. Under the condition that the small air chamber maintains the locking pressure, compressed air is injected into the large air chamber 8.4 to gradually increase the pressure of the large air chamber; the piston 8.2 remains stationary due to the reverse pressure of the small air chamber 8.3; when the large air chamber pressure reaches the initial launch pressure, the large air chamber inflation electromagnetic valve 8.6 is closed, and after this stage, the large air chamber is in an energy storage state, and the air cannon is ready to launch,

[0030] Further, as shown in Figure 2 、 Figure 3 , the control module opens the small air chamber electromagnetic valve 8.6, the pressure in the small air chamber 8.3 drops rapidly, and the high-pressure gas in the large air chamber 8.4 drives the piston 8.2 to move backward under the driving of the pressure difference, the piston 8.2 moves away from the tail end of the launch pipe 8.1, and the launch pipe 8.1 is temporarily opened; the high-pressure gas stored in the large air chamber 8.4 is released through the launch pipe 8.1 to form a high-energy air pulse, and the air pulse propagates along the surface of the greenhouse film to loosen and shed the snow outside the film.

[0031] In this embodiment, in order to make the shock wave generated by the air cannon snow removal device just achieve the snow removal effect and not damage the film, formula derivation and calculation are performed, and the specific steps are as follows:

[0032] 1. Inflation stage:

[0033] According to the sealing mode of the air cannon piston and the cannon mouth seat, the left end face of the piston is in contact with the outside to form a seal, and the effective pressure receiving area is:

[0034] A L =πr l 2 =5.03×10 -3 m 2

[0035] Under the working condition that the working pressure of the large air chamber is 0.8 MPa, in order to ensure that the sealing surface still has sufficient compression force in the high-pressure impact and low-temperature environment, the average pressure p seal of the sealing contact surface is selected as 0.8 MPa in this embodiment. Thus, the minimum closing force required to maintain the seal is:

[0036] F min =p seal A L =4.0×10 3 N

[0037] That is, approximately 4 kN. This force value also includes the equivalent safety margin for guide friction, manufacturing deviations, and external disturbances, which can meet the sealing stability requirements of the air cannon under repeated loading.

[0038] The right side of the air cannon piston is formed by the combined action of a small air chamber and a large air chamber. The cross-sectional area of ​​the small air chamber is:

[0039] A s =πr s 2 =7.85×10 -3 m 2

[0040] The annular pressure area of ​​the atmospheric chamber is:

[0041] A o =πr b 2 -πr l 2 =3.46×10 -3 m 2

[0042] The condition for the piston to remain closed is:

[0043] p s A s +p b A o ≥F min

[0044] During the initial locking phase of the air cannon, only the small air chamber is filled with air, while the large air chamber is maintained at atmospheric pressure (p). b =0), at this point the closure condition can be simplified to:

[0045] p s A s ≥4000

[0046] Substitute area A s =7.85×10 -3 m 2 The minimum gauge pressure required to obtain the small air chamber is:

[0047]

[0048] 2. Launch Phase

[0049] After the large and small air chambers are fully inflated and the piston is tightly closed, the solenoid valve of the small air chamber is opened. The pressure in the small air chamber drops rapidly, causing the high-pressure gas in the large air chamber to push the piston backward. This instantly opens the launch pipe, allowing the high-pressure air to be rapidly discharged along the launch pipe. In this embodiment, the working pressure of the large air chamber is 0.8 MPa, and the inner diameter of the launch pipe is D = 80 mm, corresponding to a cross-sectional area of:

[0050]

[0051] At the moment when the piston is fully opened, the muzzle of the launching tube is in communication with the air in the shed, and the pressure at the outlet can be approximately regarded as 0. Therefore, under ideal conditions of neglecting the frictional resistance of the pipeline and the local contraction loss, the pressure energy in the air chamber can be regarded as being completely converted into the kinetic energy of the airflow at the nozzle, and the speed thereof can be estimated by the energy conservation relationship as follows:

[0052]

[0053] where p b = 0.8 MPa = 0.8 x 10 6 Pa, the air density is taken as p = 1.2 kg / m 3 .

[0054] Substituting the numerical values, the average flow speed of air at the nozzle is about:

[0055]

[0056] The above result is the theoretical upper limit speed under the condition that the piston is instantaneously fully opened and the pressure energy in the air chamber is completely converted into kinetic energy. At this speed level, the dynamic pressure at the nozzle can be represented as:

[0057]

[0058] Substituting v e = 1155 m / s and p = 1.2 kg / m 3 , we get:

[0059] q0 = 0.5 x 1.2 x 1155 2 ≈ 8.0 x 10 5 Pa = 0.80 MPa

[0060] It can be seen that under ideal conditions, the instantaneous dynamic pressure at the nozzle is basically consistent with the gage pressure in the air chamber, indicating that the pressure energy of high-pressure air can be fully manifested as kinetic energy impact effect at the nozzle, and the instantaneous impact force at the nozzle is:

[0061] F0 = q0A p ≈ 4000 N

[0062] 3. Decay stage

[0063] After the piston is opened, the compressed air in the air chamber is ejected through the launching tube to form a nearly circular free jet, which produces an impact on the shed film. In this embodiment, the inner diameter of the launching tube is D0 = 0.08 m, and the corresponding muzzle cross-sectional area is A0 = 5.03 x 10 - 3 m 2 .

[0064] The axial distance between the shed film and the muzzle is 4 m. Considering that the high-speed airflow will spread laterally during propagation, the jet can be regarded as a conical jet with a certain divergence angle. Assuming that the half divergence angle of the jet is a, the equivalent diameter of the jet at the shed film position can be approximately expressed as:

[0065] D m = D0 + 2Ltan a

[0066] where L = 4 m is the distance from the muzzle to the shed film. Taking the commonly used jet divergence half angle a = 6° as an example, substituting D0 = 0.08 m and L = 4 m, we get D m = 0.92 m.

[0067] Therefore, the equivalent action area of the jet cross section at the shed film is:

[0068]

[0069] Compared with the muzzle area A0 ≈ 5.03 × 10 -3 m 2 , the action area is enlarged by about 130 times, which is beneficial to forming a certain range of planar impact on the shed film.

[0070] Considering the viscous loss of the jet during propagation and the mixing with the surrounding air, the jet attenuation coefficient η ∈ (0, 1) is introduced to represent the momentum and energy loss within the 4 m distance from the muzzle to the shed film. Then the equivalent dynamic pressure at the shed film can be expressed as:

[0071]

[0072] Correspondingly, the total aerodynamic force on the shed film is:

[0073]

[0074] Substituting into the above formula, we get:

[0075]

[0076] It can be seen that the total impact force at the shed film under this model is independent of the geometric divergence of the jet, and mainly depends on the initial impact force at the nozzle and the jet attenuation coefficient η. According to the typical attenuation characteristics of free jet, η = 0.3 is taken for estimation in this embodiment, and the equivalent impact force at the shed film is about:

[0077] F m = 0.3 × F0 = 1.2 × 10 3 N

[0078] 4. Theoretical verification stage

[0079] Taking the working pressure of 0.8 MPa and the barrel diameter of 80 mm in the embodiment as an example, the equivalent action area of the jet flow at the shed film is about A m = 0.67 m 2 The corresponding equivalent aerodynamic force F m is 1.2 kN, and the average pressure p

[0080]

[0081] Taking the snow thickness of 0.10 m and the snow density of 300 kg / m 3 , the self-weight of the snow in the above area is about 200 N. The air cannon can provide a transient impact force of about 6 times the self-weight of the snow in a single injection, which can effectively destroy the adhesion between the snow and the shed film and induce the snow to slide along the arched shed film, thereby realizing the rapid snow removal of the greenhouse shed film.

[0082] In the embodiment, the thickened polyethylene (PO) shed film commonly used in northern regions is selected as the analysis object, and its typical engineering parameters include: thickness of 0.18 mm, tensile strength σ a = 28 MPa, elastic modulus of 1.0-1.5 GPa, and the curvature radius of the arched structure is about 5 m. According to the simplified model of the film structure under pressure, the maximum equivalent external pressure that the shed film can withstand is:

[0083]

[0084] Considering that the actual breaking strength of the shed film is usually higher than the nominal tensile strength, its ultimate bearing capacity can reach about 1.6 kPa. According to the aforementioned free jet decay model, the equivalent impact force F m of the shed film is: m = 1.79 kPa. As can be seen, the transient impact pressure of the air cannon acting on the shed film is lower than the ultimate bearing capacity of the shed film material, and considering that the impact time is extremely short and the load is distributed in a planar manner, the shed film can recover to its original state after transient elastic deformation without breaking or structural damage. Under this impact pressure, the adhesion of the snow layer is effectively destroyed and slips, thereby realizing safe and effective shed film snow removal.

[0085] The above is a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A mobile air cannon snow removal device for use inside a greenhouse, characterized in that, The device comprises a slide rail arranged inside a greenhouse, a moving platform moving along the slide rail, an azimuth platform arranged on the moving platform, an air storage tank, and a pitching platform connected with the azimuth platform, wherein an air cannon body is installed on the pitching platform; the air cannon body comprises an atmosphere chamber, a small air chamber, a piston, a solenoid valve, and a launching pipeline, the atmosphere chamber and the small air chamber are communicated with the air storage tank through a pipeline during use; the piston is arranged between the atmosphere chamber and the launching pipeline, and is used for plugging or opening the launching pipeline under the pressure of the small air chamber; during launching, the small air chamber pressure is rapidly released, so that the high-pressure gas in the atmosphere chamber pushes the piston to open the launching pipeline, and an air pulse is sprayed through a spraying end to remove the accumulated snow outside the greenhouse film.

2. The apparatus of claim 1, wherein, The slide rail is a linear slide rail or an arc-shaped slide rail, and the moving platform moves by cooperating with the slide rail through a roller.

3. The apparatus of claim 1, wherein, A driving mechanism is arranged on the moving platform, and comprises a motor and a transmission assembly, which are used for actively moving the moving platform.

4. The apparatus of claim 1, wherein, The azimuth platform is a rotatable mounting seat, which can be rotated in a horizontal direction to realize rotation adjustment in a range of 0-360°.

5. The apparatus of claim 1, wherein, The pitching platform comprises a fixing frame, a rotating shaft, and an angle adjusting mechanism, which can realize pitching adjustment in a range of 0-90° in a vertical direction.

6. The apparatus of claim 1, wherein, The small air chamber is provided with a small air chamber solenoid valve for establishing and rapidly releasing the small air chamber pressure.

7. The apparatus of claim 1, wherein, The atmosphere chamber is provided with an atmosphere chamber solenoid valve for injecting compressed air into the atmosphere chamber to establish the launching pressure.

8. The apparatus of claim 1, wherein, The small air chamber is provided with a small air chamber pressure sensor for monitoring the small air chamber pressure.

9. The apparatus of claim 1, wherein, The atmosphere chamber is provided with an atmosphere chamber pressure sensor for monitoring the atmosphere chamber pressure.

10. The apparatus of claim 1, wherein, The device is provided with a control module, which controls the small air chamber solenoid valve, the atmosphere chamber solenoid valve, the moving platform motor, the azimuth platform motor, and the pitching platform motor, and is used for positioning process, air charging process, and launching process.

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