Sealing structure of helicopter engine air inlet channel

Abstract

The invention provides a helicopter engine air inlet duct sealing structure which is used for an air inlet duct, the air inlet duct is composed of an upper air inlet duct body, a middle air inlet duct body and a lower air inlet duct body, the sealing structure comprises a middle sealing structure, a tensioning mechanism, a lower sealing structure and an engine sealing structure, and the upper air inlet duct body is fixedly installed on a firewall through an adjustable pull rod; the middle air inlet channel and the lower air inlet channel are fixed to the engine through the tensioning mechanism, the upper air inlet channel and the middle air inlet channel are sealed through the middle sealing structure, the V-shaped structure is arranged on the upper portion of the middle sealing structure, and due to the fact that the rigidity of the V-shaped structure is small, the required compression force is small under the same compression amount; therefore, the problem of large compression force of the P-type fireproof sealing rubber strip is solved; the middle air inlet channel and the lower air inlet channel are sealed through the lower sealing structure, the middle air inlet channel, the lower air inlet channel and the engine are sealed through the engine sealing structure, and the sealing requirement between the air inlet channels and the engine body structure can be met.

Description

Technical Field

[0001] The invention belongs to the field of helicopter structure design, and in particular relates to a sealing structure of an air inlet of a helicopter engine. Background Art

[0002] The helicopter air intake connects the engine air intake with the atmosphere outside the power cabin, supplying the air required by the engine. The air intake directly affects the working efficiency of the engine. It is an important component for whether the engine works normally and plays an important role in the performance of the helicopter.

[0003] When the engine is working, it will produce large thermal deformation and dynamic displacement. In order to prevent the deformation and displacement of the engine from affecting the body structure, a flexible connection is often used to seal the air intake duct fixed on the engine and the body structure. Usually, a P-type sealing rubber ring or a bellows structure is installed between the air intake duct and the body structure to ensure the seal; because the air intake duct sealing structure needs to meet fire protection requirements, the P-type fireproof sealing strip has a large compression force and it is difficult to meet the design requirements; and the space for the bellows to be installed is very large, and it is difficult to arrange the bellows under the requirement of small space in the engine compartment. Summary of the invention

[0004] In order to solve the sealing problem between the air inlet and the body structure, the present invention provides a sealing structure of the air inlet of a helicopter engine, and the technical solution is as follows:

[0005] In a first aspect, a sealing structure of a helicopter engine air inlet is provided, which is used for the air inlet. The air inlet is composed of an upper air inlet 1, a middle air inlet 2, and a lower air inlet 3. The sealing structure includes a middle sealing structure 5, a tensioning mechanism 6, a lower sealing structure 7, and an engine sealing structure 8. The upper air inlet 1 is fixed to a firewall 9 by an adjustable pull rod 4, the middle air inlet 2 and the lower air inlet 3 are fixed to the engine by a tensioning mechanism 6, the upper air inlet 1 and the middle air inlet 2 are sealed by an intermediate sealing structure 5, and a V-shaped structure is provided on the upper part of the middle sealing structure 5. Since the V-shaped structure has a small rigidity and the compression force required for the same compression amount is small, there is no problem of large compression force of the P-type fireproof sealing strip; the middle air inlet 2 and the lower air inlet 3 are sealed by the lower sealing structure 7, and the middle air inlet 2, the lower air inlet 3 and the engine are sealed by the engine sealing structure 8.

[0006] In the present invention, there is no problem of a large space for installing the bellows, because a V-shaped structure is provided on the upper part of the middle sealing structure 5, so there is no problem of a large compression force of the P-type fireproof sealing strip.

[0007] The air intake duct of the annular air intake engine needs to wrap around the engine air intake duct in a circular direction. In order to meet the installation requirements of the air intake duct and the engine, the air intake duct needs to be divided into multiple blocks. Reasonable design of the structural form of the sealing strip must meet the sealing requirements of both the air intake duct itself and the air intake duct and the engine. This is a key factor in ensuring that the air intake duct can provide the engine with sufficient intake flow.

[0008] Optionally, the upper air inlet duct 1, the middle air inlet duct 2, and the lower air inlet duct 3 are all composite honeycomb sandwich structures;

[0009] The upper air inlet 1 is fixed to the firewall 9 by means of hexagonal bolts 13, with a peelable gasket 12 installed in the middle. By adjusting the thickness of the peelable gasket 12, the position of the sealing strip sliding pressure plate 56 in the heading can be adjusted.

[0010] Optionally, the adjustable tie rod 4 is a tie rod with adjustable axial length, which is used to offset the installation error of the air intake duct; the lower end of the adjustable tie rod 4 is connected to the firewall 9, and the upper end is connected to the upper air intake duct 1. A composite material tie rod mounting seat 10 is riveted on the outer surface of the upper air intake duct 1, and its outer surface is designed to be a plane. The mounting joint of the adjustable tie rod 4 is fixed on the tie rod mounting seat 10.

[0011] Optionally, the middle sealing structure 5 is composed of a middle sealing strip 51, a sealing strip clamping plate 52, a sealing strip sliding pressure plate 56, and a fault-proof baffle 57.

[0012] The upper part of the middle sealing strip 51 is a V-shaped surface 511.

[0013] The sealing strip sliding pressure plate 56 is installed on the upper air inlet duct 1 by countersunk screws, and the lower part is pressed on the upper V-shaped surface 511 of the middle sealing strip 51; the sealing strip sliding pressure plate 56 has a C-shaped cross section, and its inner circle boundary is smaller than the inner boundary of the middle sealing strip 51, and the outer circle boundary is larger than the inner boundary of the middle sealing strip 51, so that the middle sealing strip 51 can be wrapped in the middle;

[0014] A peelable gasket 54 and a wedge-shaped gasket 55 are installed between the sealing strip sliding plate 56 and the upper air inlet duct 1. By adjusting the number of the peelable gaskets 54 and the number of the wedge-shaped gaskets 55, the parallelism and gap between the inner surface of the sealing strip sliding plate 56 and the upper surface of the middle air inlet duct 2 can be ensured, thereby ensuring the sealing performance of the middle sealing structure 5;

[0015] The fault-prevention baffle 57 is riveted to the lower air inlet duct 2 by countersunk rivets 58, and has a C-shaped cross-section. It is a functional component for preventing faults. The dimension A of the fault-prevention baffle 57 is smaller than the dimension B of the middle sealing strip 51 in the fully extended state. After the adjustable tie rod 4 is damaged and fails, it can ensure that the upper air inlet duct 1 and the middle air inlet duct 2 are not separated, thereby ensuring the sealing of the middle sealing structure 5.

[0016] The cross section of the middle sealing strip 51 consists of three shapes, namely, an upper V-shaped cross section 511, a middle O-shaped cross section 512 and a lower Ω-shaped cross section 513; the upper V-shaped cross section 511 and the middle O-shaped cross section 512 are compressible sealing areas, and the dimensions are designed according to the compression height and compression force required by the design; the lower Ω-shaped cross section 513 is the installation area;

[0017] The middle sealing strip 51 and the sealing strip sliding plate 56 are slidable, and the distance between the inner boundary and the edge of the V-shaped cross section 511 is L, and the dimension L is greater than the displacement of the engine in the heading and lateral directions;

[0018] A plurality of vent holes 514 are provided at the bottom of the middle sealing strip 51, and vent holes 21 are arranged at corresponding positions on the sealing strip card plate 52 and the middle air inlet 2 to ensure smooth flow of the middle sealing strip 51 with the outside air when it is compressed and stretched;

[0019] The sealing strip clamping plate 52 is riveted to the lower air inlet duct 2 by countersunk rivets 53 to fix the middle sealing strip 51. Its cross-section is C-shaped and matches the lower Ω-shaped cross-section 513 of the middle sealing strip 51 to fix the sealing strip.

[0020] Optionally, the lower sealing structure 7 includes a lower sealing strip 71, a lower sealing strip slot 72 and a lower sealing strip mounting plate 73.

[0021] The lower sealing strip 71 is bonded to the lower sealing strip mounting plate 73 by means of structural adhesive, and the lower sealing strip mounting plate 73 is fixed to the lower air inlet duct 3 by means of rivets;

[0022] The middle air inlet duct 2 is provided with a lower sealing strip slot 72, and the inner shape of the lower sealing strip slot 72 is the same as the outer shape of the lower sealing strip 71. By inserting the lower sealing strip 71 into the lower sealing strip slot 72, not only can the sealing of the lower sealing structure 7 be met, but also the middle air inlet duct 2 and the lower air inlet duct 3 can be connected.

[0023] Optionally, the engine sealing structure 8 includes a front sealing strip 81, a front sealing strip mounting groove 82, an engine sealing boss 83, a rear sealing strip 84, a rear sealing strip mounting plate 85 and an engine sealing surface 86.

[0024] The front sealing strip 81 is divided into two sections, upper and lower, both of which have a U-shaped cross section;

[0025] A front sealing strip installation groove 82 is designed at the front of the middle air inlet duct 2 and the lower air inlet duct 3. The inner surface of the front sealing strip installation groove 82 is U-shaped, which is the same as the front sealing strip 81. The front sealing strip 81 is glued into the front sealing strip installation groove 82 of the middle air inlet duct 2 and the lower air inlet duct 3.

[0026] An engine sealing boss 83 is provided on the engine, and the outer shape of the engine sealing boss 83 is the same as the inner shape of the front sealing strip 81;

[0027] The front sealing strip installation grooves 82 of the middle air inlet duct 2 and the lower air inlet duct 3 are inserted into the engine sealing boss 83 to achieve sealing of the front of the engine sealing structure 8;

[0028] The rear sealing strip 84 is divided into two sections, the upper and lower sections, and the cross-sectional shape is H-shaped. The upper U-shaped structure of the cross-sectional shape of the rear sealing strip 84 is the sealing surface, and the wall thickness is relatively thin. Under the premise of meeting the fire protection and sealing requirements, the compression force of the strip is reduced as much as possible. The lower U-shaped structure serves as a mounting structure and is stuck on the lower air inlet duct 3 mounting plate 85.

[0029] Optionally, the tensioning mechanism 6 is composed of an upper bracket 61, an upper connecting plate 62, a peelable gasket 63, a lower connecting plate 64, and a lower bracket 65;

[0030] The upper bracket 61 is connected to the middle air intake duct 2 by bolts, the lower bracket 65 is connected to the lower air intake duct 3 by bolts, the upper connecting plate 62 is connected to the upper bracket 61 by bolts, and the lower connecting plate 64 is connected to the lower bracket 65 by bolts; the bolts 66 connect the upper connecting plate 62 and the lower connecting plate 64 together, and the sealing of the lower sealing structure 7 and the engine sealing structure 8 is ensured by adjusting the thickness of the middle gasket 63.

[0031] Optionally, the middle sealing strip 51 is made of a composite of fluorosilicone rubber and fabric to facilitate fire resistance and high temperature resistance.

[0032] The beneficial effects of the present invention are at least:

[0033] 1. The design of multiple cross sections of the middle sealing strip 51 satisfies the sealing of the upper air inlet 1 and the lower air inlet 2 when the engine has a large displacement in the up-down direction, and also satisfies the requirements of compression volume and compression force;

[0034] 2. The design of the margin L of the sealing strip sliding pressure plate 56 ensures the sealing of the upper air inlet duct 1 and the lower air inlet duct 2 when the engine has a large displacement in the front-to-back direction and the left-to-right direction;

[0035] 3. The uniformity of the gap between the sealing strip sliding plate 56 and the sealing strip clamping plate 52 is ensured by the adjustable pull rod 4 and the wedge-shaped washer 55, thereby ensuring the sealing of the upper air inlet duct 1 and the lower air inlet duct 2;

[0036] 4. The middle sealing strip 51 and the sealing strip clamping plate 52 are installed without fasteners, making the middle sealing strip 51 more convenient to disassemble and assemble;

[0037] 5. The design of the fault-proof baffle 57 further reduces the probability of sealing failure in the air intake duct;

[0038] 6. The peelable gasket 54 ensures the vertical position of the sealing strip sliding plate 4, and the peelable gasket 12 ensures the directional position of the sealing strip sliding plate 4.

[0039] 7. The lower sealing structure 7 has the functions of sealing and fixing the middle air inlet duct 2 and the lower air inlet duct 3;

[0040] 8. The tensioning mechanism 6 can not only reasonably adjust the compression amount of the sealing strips of the lower sealing structure 7 and the engine sealing structure 8, but also ensure that the middle air intake duct 2, the lower air intake duct 3 and the engine are firmly connected;

[0041] 9. The engine sealing structure 8 has the functions of sealing and fixing the middle air intake duct 2, the lower air intake duct 3 and the engine, and also eliminates the influence of the thermal deformation and dynamic displacement of the engine on the air intake duct. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the air intake duct sealing structure;

[0043] Figure 2 It is a cross-sectional schematic diagram of the fireproof sealing structure;

[0044] Figure 3 It is a schematic diagram of the cross section of the fireproof sealing strip;

[0045] Figure 4 A schematic diagram of the cross section of a fault-proof baffle;

[0046] Figure 5-1 is a schematic diagram of a wedge washer;

[0047] Figure 5-2 Schematic diagram of the cross section of a wedge washer

[0048] Figure 6 is a cross-sectional view of the vent hole;

[0049] Figure 7 It is the connection diagram of the adjustable tie rod and the air intake duct;

[0050] Figure 8 This is the connection diagram between the upper air intake and the firewall;

[0051] Fig. 9 It is a schematic diagram of the lower sealing structure;

[0052] Figure 10-1 It is a schematic diagram of the engine sealing structure;

[0053] Figure 10-2 It is a partial schematic diagram of the engine sealing structure;

[0054] Figure 10-3 It is a partial schematic diagram of the engine sealing structure;

[0055] Fig.11 Schematic diagram of the tensioning mechanism.

[0056] Among them, 1-upper air inlet, 2-middle air inlet, 3-lower air inlet, 4-adjustable tie rod, 5-middle sealing structure, 6-tensioning mechanism, 7-lower sealing structure, 8-engine sealing structure, 9-firewall, 10-tie rod mounting seat, 12-peelable gasket 13-hexagonal head bolt, 51-middle sealing strip, 52-sealing strip card plate, 53-countersunk rivet, 55-wedge washer, 54-peelable gasket, 56-sealing strip sliding plate, 511-upper V-section 512-middle O-section 513-lower Ω-section Surface, 57-failure-proof baffle 58-countersunk rivet, 514-middle sealing ring vent 21-middle air inlet vent, 71-lower sealing strip 72-lower sealing strip slot, 73-lower sealing strip mounting plate, 81-front sealing strip, 82-front sealing strip mounting slot, 83-engine sealing boss, 84-rear sealing strip, 85-rear sealing strip mounting plate, 86-engine sealing surface, 61-upper bracket, 62-upper connecting plate, 63-peelable gasket, 64-lower connecting plate, 65-lower bracket, 66 bolts. DETAILED DESCRIPTION

[0057] The present invention is further described in detail below through specific implementation modes and drawings.

[0058] See also Figure 1 An intake duct sealing structure provided by one embodiment of the present invention includes an upper intake duct 1, a middle intake duct 2, a lower intake duct 3, an adjustable pull rod 4, a middle sealing structure 5, a tensioning mechanism 6, a lower sealing structure 7, an engine sealing structure 8 and a firewall 9.

[0059] The upper air intake duct 1 is fixed to the front firewall 9 by bolts and an adjustable pull rod 4, and the middle air intake duct 2 and the lower air intake duct 3 are fixed to the engine by a tightening mechanism 6, wherein the upper air intake duct 1 and the middle air intake duct 2 are sealed by an intermediate sealing structure 5, the middle air intake duct 2 and the lower air intake duct 3 are sealed by a lower sealing structure 7, and the middle air intake duct 2, the lower air intake duct 3 and the engine are sealed by an engine sealing structure 8.

[0060] The upper air intake duct 1, the middle air intake duct 2, and the lower air intake duct 3 are all composite honeycomb sandwich structures. The composite honeycomb sandwich air intake duct is integrally formed with a smooth inner surface, which ensures the aerodynamic requirements of the air intake duct and is lighter in weight than a metal air intake duct.

[0061] The upper air inlet 1 is fixed to the firewall 9 by a hexagonal bolt 13, and a peelable gasket 12 is installed in the middle. By adjusting the thickness of the peelable gasket 12, the position of the sealing strip sliding plate 56 in the heading is adjusted, such as Figure 8 As shown;

[0062] The adjustable pull rod 4 is designed as a pull rod with adjustable axial length, such as Figure 1 As shown, it is used to offset the installation error of the air intake duct; the lower end of the adjustable tie rod 4 is connected to the firewall 9, and the upper end is connected to the upper air intake duct 1. A composite tie rod mounting seat 10 is riveted on the outer surface of the upper air intake duct 1, and its outer surface is designed as a plane. The mounting joint of the adjustable tie rod 4 is directly fixed to the tie rod mounting seat 10, as shown in FIG. Figure 7 As shown;

[0063] The middle sealing structure 5 is composed of a middle sealing strip 51, a sealing strip clamping plate 52, a countersunk rivet 53, a wedge-shaped washer 55, a peelable gasket 54, and a sealing strip sliding pressure plate 56. Figure 2 shown.

[0064] The sealing strip sliding pressure plate 56 is installed on the upper air inlet 1 by countersunk screws, and the lower part is pressed on the upper V-shaped surface 511 of the middle sealing strip 51. The sealing strip sliding pressure plate 56 has a C-shaped cross section, and its inner circle boundary is smaller than the inner boundary of the middle sealing strip 51, and the outer circle boundary is larger than the inner boundary of the middle sealing strip 51, so that the middle sealing strip 51 can be wrapped in the middle. Figure 2 shown.

[0065] A peelable gasket 54 and a wedge-shaped gasket 55 are installed between the sealing strip sliding pressure plate 56 and the upper air inlet duct 1. The parallelism and gap between the inner surface of the sealing strip sliding pressure plate 56 and the upper surface of the middle air inlet duct 2 are ensured by adjusting the number of peelable gaskets 54 and the number of wedge-shaped gaskets 55, thereby ensuring the sealing of the middle sealing structure 5.

[0066] The wedge-shaped washer 55 is an inclined washer, and the cross-sectional dimensions are shown in the figure. The installation angle of the sealing strip sliding plate 6 is adjusted by installing the wedge-shaped washer 55, as shown in Figure 5;

[0067] The fault-prevention baffle plate 57 is riveted to the lower air inlet duct (2) by countersunk rivets 58, and has a C-shaped cross-section. It is a functional component for preventing faults. The dimension A of the fault-prevention baffle plate 57 is smaller than the dimension B of the middle sealing strip 51 when it is in the full length state. After the adjustable tie rod 4 is damaged and fails, it ensures that the upper air inlet duct 1 and the middle air inlet duct 2 are not separated, thereby ensuring the sealing of the middle sealing structure 5. Figure 4 As shown;

[0068] The middle sealing strip 51 is made of fluorosilicone rubber and fabric composite, and is a fireproof and high temperature resistant strip. The cross section consists of three shapes, namely, an upper V-shaped cross section 511, a middle O-shaped cross section 512 and a lower Ω-shaped cross section 513; the upper V-shaped cross section 511 and the middle O-shaped cross section 512 are compressible sealing areas, and the size is designed according to the compression height and compression force required by the design; the lower Ω-shaped cross section 513 is the installation area, such as Figure 3 shown.

[0069] The middle sealing strip 51 and the sealing strip sliding plate 56 are slidable, and the distance between the inner boundary and the edge of the V-shaped cross section 511 is L, and the dimension L is greater than the displacement of the engine in this direction. Figure 3 As shown;

[0070] A plurality of vent holes 514 are provided at the bottom of the middle sealing strip 51, and vent holes 21 are arranged at corresponding positions on the sealing strip card plate 52 and the air inlet 2 to ensure smooth flow of the middle sealing strip 6 with the outside air when it is compressed and stretched. Figure 6 As shown;

[0071] The sealing strip clamping plate 52 is riveted to the lower air inlet duct 2 by countersunk rivets 53 to fix the middle sealing strip 3. Its cross-sectional shape is C-shaped, which is consistent with the lower Ω-shaped cross-sectional shape 513 of the middle sealing strip 51 and is used to fix the sealing strip. Figure 2 As shown;

[0072] The lower sealing structure 7 comprises a lower sealing strip 71, a lower sealing strip slot 72 and a lower sealing strip mounting plate 73. Fig. 9 shown.

[0073] A lower sealing strip mounting plate 73 is riveted on the lower air inlet duct 3, the lower sealing strip 71 is bonded to the lower sealing strip mounting plate 73 by structural adhesive, and the lower sealing strip mounting plate 73 is fixed to the lower air inlet duct 3 by rivets;

[0074] The middle air inlet 2 is designed with a lower sealing strip slot 72, the inner shape of the lower sealing strip slot 72 is the same as the outer shape of the lower sealing strip 71, and by inserting the lower sealing strip 71 into the lower sealing strip slot 72, not only can the sealing of the lower sealing structure 7 be met, but also the middle air inlet 2 and the lower air inlet 3 can be connected;

[0075] The engine sealing structure 8 comprises a front sealing strip 81, a front sealing strip mounting groove 82, an engine sealing boss 83, a rear sealing strip 84, a rear sealing strip mounting plate 85 and an engine sealing surface 86, as shown in FIG. 10 .

[0076] The front sealing strip 81 is divided into two sections, upper and lower, both of which have a U-shaped cross section. The figure shows the lower front sealing strip, and the upper front sealing strip has the same cross section as the lower front sealing strip.

[0077] A front sealing strip installation groove 82 is designed at the front of the middle air inlet duct 2 and the lower air inlet duct 3. The inner profile of the front sealing strip installation groove 82 is U-shaped, which is the same as the front sealing strip 81. The front sealing strip 81 is glued in the front sealing strip installation groove 82 of the middle air inlet duct 2 and the lower air inlet duct 3.

[0078] An engine sealing boss 83 is designed on the engine, and the shape of the engine sealing boss 83 is the same as the inner shape of the front sealing strip 81;

[0079] The front sealing strip installation grooves 82 of the middle air inlet duct 2 and the lower air inlet duct 3 are inserted into the engine sealing boss 83 to achieve sealing of the front of the engine sealing structure 8;

[0080] The rear sealing strip 84 is divided into two sections, the upper and lower sections, and the cross-sectional shape is H-shaped. The figure shows the lower rear sealing strip, and the upper rear sealing strip has the same cross-sectional shape as the lower rear sealing strip. The upper U-shaped structure in the cross-sectional shape of the rear sealing strip 84 is the sealing surface, and the wall thickness is relatively thin. Under the premise of meeting the fire protection and sealing requirements, the compression force of the strip is reduced as much as possible. The lower U-shaped structure serves as a mounting structure and is stuck on the lower air inlet duct 3 mounting plate 85.

[0081] The tensioning mechanism 6 is composed of an upper bracket 61, an upper connecting plate 62, a peelable gasket 63, a lower connecting plate 64, and a lower bracket 65. The sealing strip is compressed by the tensioning action of the tensioning mechanism to ensure the sealing of the lower sealing structure 7 and the engine sealing structure 8. The entire intake duct is arranged with 4 sets of tensioning mechanisms 6, such as Fig.11 shown.

[0082] The upper bracket 61 is connected to the middle air intake duct 2 by bolts, the lower bracket 65 is connected to the lower air intake duct 3 by bolts, the upper connecting plate 62 is connected to the upper bracket 61 by bolts, and the lower connecting plate 64 is connected to the lower bracket 65 by bolts; the bolts 66 connect the upper connecting plate 62 and the lower connecting plate 64 together, and the sealing of the lower sealing structure 7 and the engine sealing structure 8 is ensured by adjusting the thickness of the middle gasket 63.

[0083] The above only expresses the implementation mode of the present invention, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. In addition, the parts not detailed in the present invention are all conventional technologies.

Claims

1. A sealing structure for an air inlet of a helicopter engine, characterized in that: Used for an air intake duct, the air intake duct is composed of an upper air intake duct (1), a middle air intake duct (2), and a lower air intake duct (3); the sealing structure comprises a middle sealing structure (5), a tensioning mechanism (6), a lower sealing structure (7), and an engine sealing structure (8); the upper air intake duct (1) is fixed to a firewall (9) via an adjustable pull rod (4); the middle air intake duct (2) and the lower air intake duct (3) are fixed to the engine via a tensioning mechanism (6); the upper air intake duct (1) and the middle air intake duct (2) are sealed via an intermediate sealing structure (5); a V-shaped structure is provided on the upper part of the middle sealing structure (5); the middle air intake duct (2) and the lower air intake duct (3) are sealed via a lower sealing structure (7); and the middle air intake duct (2), the lower air intake duct (3) and the engine are sealed via an engine sealing structure (8).

2. The sealing structure according to claim 1, characterized in that: The upper air inlet (1), the middle air inlet (2) and the lower air inlet (3) are all composite honeycomb sandwich structures; The upper air inlet (1) is fixed to the fire wall (9) by means of hexagonal bolts (13), with a peelable gasket (12) installed in between.

3. The sealing structure according to claim 1, characterized in that: The adjustable tie rod (4) is a tie rod with adjustable axial length; the lower end of the adjustable tie rod (4) is connected to the firewall (9), and the upper end is connected to the upper air intake duct (1); a tie rod mounting seat (10) made of a composite material is riveted on the outer surface of the upper air intake duct (1), and its outer surface is designed as a plane; the mounting joint of the adjustable tie rod (4) is fixed on the tie rod mounting seat (10).

4. The sealing structure according to claim 1, characterized in that: The middle sealing structure (5) is composed of a middle sealing rubber strip (51), a sealing rubber strip clamping plate (52), a sealing rubber strip sliding pressure plate (56), and a fault prevention baffle (57). The upper part of the middle sealing strip (51) is a V-shaped surface (511). The sealing strip sliding pressure plate (56) is installed on the upper air inlet duct (1) by means of countersunk screws, and the lower part is pressed on the upper V-shaped surface (511) of the middle sealing strip (51); the sealing strip sliding pressure plate (56) has a C-shaped cross section, the inner circle boundary of which is smaller than the inner circle boundary of the middle sealing strip (51), and the outer circle boundary is larger than the inner circle boundary of the middle sealing strip (51), so that the middle sealing strip (51) can be wrapped in the middle; A peelable gasket (54) and a wedge-shaped gasket (55) are installed between the sealing strip sliding pressure plate (56) and the upper air inlet duct (1); The fault-prevention baffle (57) is riveted to the lower air inlet (2) by countersunk rivets (58), and has a C-shaped cross-section; the dimension A of the fault-prevention baffle (57) is smaller than the dimension B of the middle sealing strip (51) in a fully extended state; The cross section of the middle sealing strip (51) consists of three shapes, namely an upper V-shaped cross section (511), a middle O-shaped cross section (512) and a lower Ω-shaped cross section (513); the upper V-shaped cross section (511) and the middle O-shaped cross section (512) are compressible sealing areas; the lower Ω-shaped cross section (513) is an installation area; The middle sealing strip (51) and the sealing strip sliding plate (56) are slidable, and the distance between the inner boundary and the edge of the V-shaped cross section (511) is L, and the dimension L is greater than the displacement of the engine in the heading and lateral directions; A plurality of ventilation holes (514) are provided at the bottom of the middle sealing strip (51), and ventilation holes (21) are arranged at corresponding positions on the sealing strip card plate (52) and the middle air inlet duct (2); The sealing strip clamping plate (52) is riveted to the lower air inlet duct (2) by means of countersunk rivets (53) and is used to fix the middle sealing strip (51). Its cross-section is C-shaped and matches the lower Ω-shaped cross-section (513) of the middle sealing strip (51) to fix the sealing strip.

5. The sealing structure according to claim 1, characterized in that: The lower sealing structure (7) comprises a lower sealing strip (71), a lower sealing strip slot (72) and a lower sealing strip mounting plate (73). The lower sealing strip (71) is bonded to the lower sealing strip mounting plate (73) by means of structural adhesive, and the lower sealing strip mounting plate (73) is fixed to the lower air inlet duct (3) by means of rivets; The middle air inlet (2) is provided with a lower sealing strip slot (72), the inner shape of the lower sealing strip slot (72) is the same as the outer shape of the lower sealing strip (71), and the lower sealing strip (71) is inserted into the lower sealing strip slot (72).

6. The sealing structure according to claim 1, characterized in that: The engine sealing structure (8) comprises a front sealing strip (81), a front sealing strip mounting groove (82), an engine sealing boss (83), a rear sealing strip (84), a rear sealing strip mounting plate (85) and an engine sealing surface (86). The front sealing strip (81) is divided into two sections, upper and lower sections, both of which have U-shaped cross-sections; A front sealing strip installation groove (82) is designed at the front of the middle air inlet duct (2) and the lower air inlet duct (3); the inner surface of the front sealing strip installation groove (82) is U-shaped and has the same shape as the front sealing strip (81); the front sealing strip (81) is glued into the front sealing strip installation groove (82) of the middle air inlet duct (2) and the lower air inlet duct (3); An engine sealing boss (83) is provided on the engine, and the outer shape of the engine sealing boss (83) is the same as the inner shape of the front sealing strip (81); By inserting the front sealing strip mounting grooves (82) of the middle air inlet duct (2) and the lower air inlet duct (3) into the engine sealing boss (83); The rear sealing strip (84) is divided into two sections, the upper section and the lower section, and has an H-shaped cross section. The upper U-shaped structure of the rear sealing strip (84) serves as a sealing surface, and the lower U-shaped structure serves as a mounting structure and is clamped on the mounting plate (85) of the lower air inlet duct (3).

7. The sealing structure according to claim 1, characterized in that: The tensioning mechanism (6) is composed of an upper bracket (61), an upper connecting plate (62), a peelable gasket (63), a lower connecting plate (64), and a lower bracket (65); The upper bracket (61) is connected to the middle air inlet (2) by bolts, the lower bracket (65) is connected to the lower air inlet (3) by bolts, the upper connecting plate (62) is connected to the upper bracket (61) by bolts, and the lower connecting plate (64) is connected to the lower bracket (65) by bolts; bolts (66) connect the upper connecting plate (62) and the lower connecting plate (64) together.

8. The sealing structure according to claim 4, characterized in that: The middle sealing rubber strip (51) is composited from fluorosilicone rubber and fabric.

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