Flexible heating assembly suitable for aircraft hyperbolic air inlet sewing and embroidering structure

Abstract

The utility model discloses a flexible heating assembly suitable for an aircraft hyperbolic air inlet channel sewing and embroidering structure, and belongs to the technical field of aviation ice prevention and removal. The first composite structure layer (1), the electric heating fabric layer (2), the honeycomb reinforcing structure layer (3) and the second composite structure layer (4) are sequentially stacked. The electric heating fabric layer (2) comprises a base fabric, an electric heating wire and insulating fibers, and the electric heating wire is fixedly sewn on the base fabric through the insulating fibers to form a heating element (5). The utility model has the characteristics that the bearing performance is good, the heating rate is high, the structure is not easy to layer, and the heat distribution is uniform.

Description

Technical Field

[0001] The utility model relates to the technical field of aviation anti-icing and de-icing, in particular to a flexible heating component suitable for a hyperbolic air inlet sewing structure of an aircraft. Background Art

[0002] Electric heating anti-icing is a common anti-icing method used for rotorcraft engine intake ducts, tail fins and windshields. The basic principle is to convert electrical energy into thermal energy through the heating elements on the inner surface of the anti-icing material, and transfer the heat to the surface of the component to increase the temperature to achieve the purpose of anti-icing. Although electric heating anti-icing technology is one of the most reliable anti-icing technologies, it still has defects such as easy stratification of heating components, poor follow-up performance, high power consumption, large thermal inertia, and repeated icing, and a series of key technical difficulties need to be overcome. Therefore, the current electric heating anti-icing structure has problems such as low load-bearing performance, low heating rate, easy stratification of structure, and uneven heat distribution. Utility Model Content

[0003] The purpose of the utility model is to provide a flexible heating component suitable for the hyperbolic air inlet sewing structure of an aircraft. The utility model has the characteristics of good load-bearing performance, fast heating rate, non-delamination structure and uniform heat distribution.

[0004] The technical solution of the utility model is: a flexible heating component suitable for the sewing structure of the hyperbolic air inlet of an aircraft, which is composed of a first composite structure layer, an electric heating fabric layer, a honeycomb reinforcement structure layer, and a second composite structure layer stacked in sequence; the electric heating fabric layer includes a base fabric, an electric heating wire and insulating fibers, and the base fabric is fixed with an electric heating wire through the insulating fiber sewing to form a heating element.

[0005] In the aforementioned flexible heating component suitable for the aircraft hyperbolic air inlet sewing structure, the base fabric is one of plain, twill and satin fabrics; the electric heating wire is one of nickel-chromium alloy wire, copper wire, and stainless steel wire; the insulating fiber is used as the textile surface thread and bottom thread, and is one of polyester yarn, aramid yarn, and ultra-high molecular weight polyethylene yarn.

[0006] In the aforementioned flexible heating assembly suitable for the sewing structure of the hyperbolic air inlet of an aircraft, the sewing is a sawtooth embroidery of a sewing machine.

[0007] In the aforementioned flexible heating assembly suitable for the hyperbolic air inlet stitching structure of an aircraft, an insulating adhesive film A is adhered to the surface of the heating element.

[0008] In the aforementioned flexible heating component suitable for the aircraft hyperbolic air inlet stitching structure, the first composite structure layer is composed of 2 layers of plain glass fiber epoxy prepreg or carbon fiber prepreg laid at a lay-up angle of 0° and 45°; the second composite structure layer is composed of 2 layers of plain glass fiber epoxy prepreg or carbon fiber prepreg laid at a lay-up angle of 45° and 0°.

[0009] In the aforementioned flexible heating component suitable for the stitching structure of the aircraft hyperbolic air inlet, the honeycomb reinforcement structure layer includes a paper honeycomb core, an insulating film B and a reinforcement layer; the insulating film B is laid on the lower surface of the paper honeycomb core, and the reinforcement layer is a square ring structure and is laid on the edge of the upper surface of the paper honeycomb core; the reinforcement layer is composed of a plain glass fiber epoxy prepreg or a carbon fiber prepreg.

[0010] In the aforementioned flexible heating assembly suitable for the aircraft hyperbolic air inlet stitching structure, the electric heating wire is connected to the electrode by spot welding, brazing or crimping, and the electrode passes through the direction of the honeycomb reinforcement structure layer and the second composite structure layer.

[0011] The utility model has the advantages that the electric heating film structure formed by weaving the electric heating wire and the insulating fiber of the utility model has the advantages of light weight and uniform heat distribution.

[0012] After the utility model is compounded with the electric heating fabric layer through the honeycomb sandwich structure, the heating element dissipates heat toward one end due to the heat insulation effect of the honeycomb structure, and the thermal efficiency is high.

[0013] The insulating adhesive film of the utility model has the same resin system as the first composite structure layer and the second composite structure layer, and has the same curing conditions, and is not easy to be delaminated after co-curing.

[0014] The utility model solves the shortcomings of the traditional heating element, such as uneven heating, easy stratification, high weight, poor hyperbolic followability, etc., and can also provide effective heating efficiency and balanced temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of the electrothermal composite material;

[0016] Figure 2 The figure is a flow chart of the preparation method. DETAILED DESCRIPTION

[0017] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0018] Example 1. A flexible heating assembly suitable for the stitching structure of a hyperbolic inlet of an aircraft, see Figure 1-2, which is composed of a first composite structure layer 1, an electric heating fabric layer 2, a honeycomb reinforcement structure layer 3, and a second composite structure layer 4 stacked in sequence; the electric heating fabric layer 2 includes a base fabric, an electric heating wire, and an insulating fiber, and the base fabric is fixed with an electric heating wire through the insulating fiber sewing to form a heating element 5. Traditional anti-icing composite materials are generally laminated structures without honeycomb structures, and the heating elements dissipate heat to both sides, resulting in large heat losses; while the utility model is provided with a honeycomb sandwich structure, and because the honeycomb structure has a heat-insulating effect, the heating element dissipates heat to one end, and has high thermal efficiency.

[0019] The base fabric is one of plain, twill and satin fabrics; the electric heating wire is one of nickel-chromium alloy wire, copper wire and stainless steel wire, with a diameter of 0.04mm to 0.08mm; the insulating fiber is used as the textile surface and bottom line, which is one of polyester yarn, aramid yarn and ultra-high molecular weight polyethylene yarn. The thickness of traditional polyimide film heating elements is usually greater than 0.1mm, and the surface density is generally greater than 400g / m 2 , and the heating is uneven, the adhesion with the composite material is poor, and it is easy to delaminate; and the electric heating fabric layer 2 of the utility model has a light weight (generally 150g / m 2 ~300g / m 2 ), thin thickness (0.05mm~0.1mm), and the electric heating fabric layer and the composite material have good bonding after co-curing and are not easy to delaminate.

[0020] The sewing embroidery is a sawtooth embroidery of a paving machine.

[0021] Traditional heating elements cannot be well adapted to the hyperbolic air inlet and wing shape due to the low elasticity and high tension of the polyimide protective film on the surface. The electric heating fabric of the utility model is woven from soft metal heating wires and insulating fibers, has a certain elasticity and good hyperbolic conformability, and can be completely attached to the complex hyperbolic air inlet structure. The electric heating fabric structure with this structure can be designed, and the shape and power density can be customized according to different needs. At the same time, the metal resistance heating wires and insulating fibers are evenly distributed, and the heat is more uniform than traditional heating elements.

[0022] The surface of the heating element 5 is adhered with an insulating adhesive film A6.

[0023] The first composite structure layer 1 is composed of two layers of plain glass fiber epoxy prepreg or carbon fiber prepreg laid at a lay-up angle of 0° and 45°; the second composite structure layer 4 is composed of two layers of plain glass fiber epoxy prepreg or carbon fiber prepreg laid at a lay-up angle of 45° and 0°.

[0024] The aforementioned honeycomb reinforcement structure layer 3 includes a paper honeycomb core 7, an insulating film B8 and a reinforcement layer 9; the insulating film B8 is laid on the lower surface of the paper honeycomb core 7, and the reinforcement layer 9 is a square ring structure, which is laid on the edge of the upper surface of the paper honeycomb core 7; the reinforcement layer 9 is composed of a plain glass fiber epoxy prepreg or a carbon fiber prepreg. With the development of more electric aircraft, the requirements for aircraft weight are getting higher and higher. Since the traditional polyimide film heating element heats unevenly, the hot spots are concentrated, and it is easy to delaminate, it is necessary to paste more than 4 layers of prepreg as a protective layer on the air inlet or wing skin surface, which greatly increases the weight of the body; while the utility model only has two layers of composite structure layers, which effectively reduces the weight.

[0025] The insulating adhesive film of the electric heating fabric layer 2 is a medium-high temperature structural insulating adhesive film, which is consistent with the resin system used by the first composite structure layer 1 and the second composite structure layer 4 and has the same curing conditions.

[0026] The aforementioned electric heating wire is connected to the electrode 10 by spot welding, brazing or crimping, and the electrode 10 is passed through the direction of the honeycomb reinforcement structure layer 3 and the second composite structure layer 4. The electrode connection method of the traditional heating element is lead-out, and under vibration conditions, the exposed root of the lead is easy to break, while the metal heating wire of the electric heating fabric is co-cured with the electrode and the composite material, and only a section of the terminal is exposed, and the structure is more solid.

[0027] The method for preparing the aforementioned flexible heating assembly comprises the following steps:

[0028] First, use a sewing machine to sew electrically heated fabrics. Design the arrangement of the electric heating wires on the CADV6.0 software and import it into the computer terminal of the NM-PC-1 sewing machine. Adjust the process parameters of the TFP technology on the NM-PC-1 sewing machine and set the embroidery mode. Install the upper thread and the lower thread, use a rope winding machine to wind the conductive metal wire to the swing rod position, and use a special clip for the embroidery frame to fix the backing paper and the base fabric on the embroidery frame together to keep the fabric surface flat. Before starting the machine, hold the reserved conductive metal wire to the presser foot, turn on the sewing machine, and let the continuous upper thread pass through the serrated lock needle with upper and lower threads to fix the electric heating wire to the surface of the base fabric.

[0029] The embroidery is completed. Pull the operating lever to the left to stop the embroidery, remove the special clamp frame, lay out the embroidered base fabric neatly, and use special scissors to cut off the unembroidered part to obtain the electrically heated fabric.

[0030] according to Figure 1The prepreg layering is performed according to the exploded diagram. The glass fiber epoxy prepreg or carbon fiber prepreg with a plain weave structure of 300×300mm and a thickness of 0.25mm is laid on the surface of the steel plate mold at a laying angle of 0° and 45°, followed by the laying of an insulating film with a thickness of 0.2mm with the same area. The lower surface of the electric heating fabric is close to the insulating film, and then a layer of insulating film is applied, followed by the laying of the honeycomb sandwich and the edge reinforcement layer, and then the insulating film and glass fiber epoxy prepreg or carbon fiber prepreg are symmetrically laid.

[0031] After the paving is completed, a multi-layer structure is formed, which is sealed with sealing strips and isolation films, and the multi-layer structure is connected to the conduit through the breathable felt and vacuum bag, and the multi-layer structure is vacuumed for 15 to 30 minutes at room temperature for pre-compaction, with a pressure of 0.07 to 0.1 MPa. Subsequently, vacuum compaction is performed again for 10 to 20 minutes.

[0032] The vacuum multilayer structure is placed in an autoclave using a sealed vacuum bag and heated and cured. The specific conditions are as follows: the autoclave is evacuated at room temperature to maintain a vacuum degree of less than -0.097 MPa, the temperature is raised to 180°C at a rate of 30°C / hour during heating, and the temperature is kept for 4 hours. The temperature and pressure are then stopped and the temperature is lowered along with the furnace. When the temperature is lowered to below 60°C, the autoclave is removed from the mold to obtain an electrothermal composite material based on a sewing structure.

[0033] In the utility model, the electric heating composite material electric heating fabric layer comprises electric heating wire, insulating fiber, base fabric and insulating films on the upper and lower surfaces. The electric heating wire can be one of nickel-chromium alloy wire, copper wire and stainless steel wire, the insulating fiber can be one of polyester yarn, aramid yarn and ultra-high molecular weight polyethylene yarn, and the base fabric can be one of plain weave, twill and satin fabric.

[0034] In the utility model, the metal resistance wire is embroidered in a zigzag manner on the base fabric by using insulating fibers in the form of sewing, and the sewing machine is used to embroider the electrically heated fabric.

[0035] In the utility model, the electric heating fabric is heated by applying current to the reserved nickel-chromium alloy wire top electrode, the current generates Joule heat, the surface temperature of the fabric changes, and finally the electric heating fabric layer of the electric heating composite material can be heated evenly.

Claims

1. A flexible heating assembly suitable for the sewing structure of a hyperbolic inlet of an aircraft, characterized in that: The invention is composed of a first composite structure layer (1), an electric heating fabric layer (2), a honeycomb reinforcement structure layer (3), and a second composite structure layer (4) which are stacked in sequence; the electric heating fabric layer (2) comprises a base fabric, electric heating wires, and insulating fibers, and the base fabric is fixed with electric heating wires by sewing the insulating fibers to form a heating element (5); the honeycomb reinforcement structure layer (3) comprises a paper honeycomb core (7), an insulating film B (8), and a reinforcement layer (9); the insulating film B (8) is paved on the lower surface of the paper honeycomb core (7), and the reinforcement layer (9) is in a square ring structure and is paved on the edge of the upper surface of the paper honeycomb core (7); the reinforcement layer (9) is composed of a plain glass fiber epoxy prepreg or a carbon fiber prepreg.

2. The flexible heating assembly suitable for the aircraft hyperbolic air inlet sewing structure according to claim 1 is characterized in that: The base fabric is one of plain, twill and satin fabrics; the electric heating wire is one of nickel-chromium alloy wire, copper wire and stainless steel wire; the insulating fiber used as the textile surface thread and bottom thread is one of polyester yarn, aramid yarn and ultra-high molecular weight polyethylene yarn.

3. The flexible heating assembly suitable for the aircraft hyperbolic air inlet sewing structure according to claim 1 is characterized in that: The sewing embroidery is a sawtooth embroidery of a paving machine.

4. The flexible heating assembly suitable for the aircraft hyperbolic air inlet sewing structure according to claim 1 is characterized in that: The surface of the heating element (5) is adhered with an insulating adhesive film A (6).

5. The flexible heating assembly suitable for the aircraft hyperbolic air inlet sewing structure according to claim 1 is characterized in that: The first composite structure layer (1) is composed of two layers of plain glass fiber epoxy prepreg or carbon fiber prepreg laid at ply angles of 0° and 45°; the second composite structure layer (4) is composed of two layers of plain glass fiber epoxy prepreg or carbon fiber prepreg laid at ply angles of 45° and 0°.

6. The flexible heating assembly suitable for the aircraft hyperbolic air inlet sewing structure according to claim 1, characterized in that: The electric heating wire is connected to the electrode (10) by spot welding, brazing or crimping, and the electrode (10) passes through the direction of the honeycomb reinforcement structure layer (3) and the second composite structure layer (4).

Images