JP3525090B2 - Ablator structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ablator structure for covering an outer surface of a body such as a spacecraft.

[0002]

2. Description of the Related Art A spacecraft or the like that is launched into space orbit, recovered after performing experiments, etc., has a very high temperature due to friction with air when reentering the atmosphere. The outer surface of the airframe is covered with an ablator in order to protect the airframe from the high temperature at the time of re-entry.

The ablator is roughly classified into a sublimation ablator, a fusion ablator and a carbonized ablator according to the heat insulating mechanism, and the present invention belongs to the carbonized ablator. The carbonized ablator is made of, for example, a phenol resin, a reinforced fiber, and a microballoon, and when heated at a high temperature, the resin undergoes thermal decomposition and is carbonized to form a carbonized layer, a thermal decomposition layer and a virgin layer from the heated surface.
The carbonized ablator generally has a heat insulating mechanism mainly composed of the following elements. -Endothermic due to thermal decomposition of resin-Heat transfer due to thermal decomposition gas passing through and flowing out of carbonized layer-Heat cutoff due to thermal decomposition gas flowing out from surface of carbonized layer-Radiation cooling of surface of carbonized layer As a conventional technique, Japanese Patent No. 269
There is 6648 publication.

In order to insulate the body of the spacecraft, the outer surface of the shell structure is covered with a heat insulating material, and the outer surface of the heat insulating material is further covered with an ablator. When it re-enters the atmosphere, it becomes extremely hot and receives great pressure. Since the heat insulating material is made of, for example, a flexible heat insulating material and has no mechanical strength, it is necessary to increase the mechanical strength in order for the ablator to withstand high pressure.

However, in general, the mechanical strength of an ablator decreases significantly when carbonized. Therefore, in order to give the ablator a mechanical strength when re-entry, the ablator should have a large thickness and should not be carbonized inside. There is a need to. By providing the non-carbonized layer in this manner, the ablator can have mechanical strength.

[0006]

However, if the thickness of the ablator is increased, the weight of the ablator will increase. It is necessary to make the weight of the spacecraft as light as possible, and avoid increasing the weight of the ablator.

It is an object of the present invention to provide an ablator structure that is lightweight and has mechanical strength.

[0008]

The present invention according to claim 1 is made of a resin containing reinforcing fibers, and in an ablator structure for covering the outer surface of the airframe and thermally protecting the airframe by carbonizing, a long continuous reinforcement is provided. An inner layer portion made of a resin containing fibers, and an outer layer portion made of a resin containing short and discontinuous reinforcing fibers and covering the inner layer portion, and both the inner layer portion and the outer layer portion are carbonized when heated at a high temperature. Is an ablator structure.

According to the invention, the outer layer portion of the ablator is
Contains short, discontinuous reinforcing fibers. Since the reinforcing fibers are short and discontinuous, there are relatively many gaps compared to long reinforcing fibers, so the permeability of the pyrolysis gas is high, and the pyrolysis gas is easy to spout from the surface of the carbonized layer, which provides thermal protection. It is high, and delamination is unlikely to occur. On the other hand, since the inner layer portion has long continuous reinforcing fibers, gas is less likely to be emitted and heat protection is inferior because the gap is smaller than that of the outer layer portion, but the long reinforcing fibers are used even after carbonization of the resin. Since the load is transmitted, it has sufficient mechanical strength even after carbonization.

As described above, in the ablator of the present invention, both the outer layer portion and the inner layer portion are carbonized. That is, the ablator is thin and lightweight. In addition, the ablator has a two-layer structure, and the outer layer part is mainly responsible for heat protection, while the inner layer part is responsible for heat protection and mechanical strength. You can have it.

The outer layer portion of the present invention according to claim 2 is formed by randomly attaching rectangular prepregs in which reinforcing fibers are impregnated with resin and hot pressing the inner layer portion in a predetermined direction. A cloth-like prepreg obtained by impregnating oriented reinforcing fibers with a resin is laminated on the inner surface of the outer layer portion.

According to the present invention, the rectangular prepreg is randomly (irregularly) attached to the inner surface of the mold and hot pressed to easily form the outer layer portion containing the short reinforcing fibers. Also, by laminating the cloth-like prepreg on the inner surface of the outer layer portion, the inner layer portion having long fibers can be easily formed.

[0013]

1 is a sectional view showing a spacecraft 1 using the ablator structure of the present invention. The spacecraft 1 is a self-contained return-type capsule that is launched into space orbit and after various experiments are performed, it re-enters the atmosphere and is recovered. The spacecraft 1 has a substantially bell shape, a diameter of about 1.5 m, and a height of about 1.3 m. The outer surface of this spacecraft 1 is an ablator 2 for heat protection during re-entry into the atmosphere.
Covered with.

FIG. 2 is a sectional view showing the outer wall portion of the spacecraft 2. Reference numeral 3 is a shell of the spacecraft 1, and a flexible heat insulating material 4 is provided so as to cover the entire outer surface of the shell 3, and an ablator 2 is provided so as to cover the entire outer surface of the heat insulating material 4.

The ablator 2 has a two-layer structure having an inner layer portion 5 and an outer layer portion 6, and is made of a fiber reinforced composite material. As the resin for the ablator 2, a phenol resin is used,
Carbon fiber is used as the reinforcing fiber. Further, as the resin, besides this, a silicone resin or an epoxy resin can be used. In addition, silica fibers can be used as the reinforcing fibers.

The ablator 2 is formed of a cloth-like prepreg in which a reinforcing fiber is impregnated with a resin. In a prepreg, a plurality of continuous long reinforcing fibers are oriented in the longitudinal direction and the right angle direction. The diameter of the reinforcing fibers is about 6 μm, and the fiber content is about 50% by volume.

In the outer layer portion 6 of the ablator 2, first, the cloth-like prepreg is made to have a predetermined size, for example, width 1 cm × length 4
It is cut to about a cm to form a rectangular, so to speak, strip-shaped prepreg. This shortens long continuous fibers. Then, this strip-shaped prepreg is randomly attached to the inner surface of the press die so as to have a predetermined thickness, and hot pressed. In this way, the outer layer portion 6 having short discontinuous fibers can be formed. The thickness of the outer layer portion 6 is, for example, about 1 to 2 times the thickness of the inner layer portion.

The inner layer portion 5 is formed by laminating a plurality of cloth-like prepregs on the inner surface of the outer layer portion 6. At this time, in the first layer, cloth-like prepregs are uniformly arranged and attached to the inner surface of the outer layer portion 6 with the directions of the fibers aligned, without any gaps. Next, the second layer is pasted from above the first layer with a predetermined angle, for example 45 °, with respect to the direction of the fibers of the first layer. In this way, a plurality of layers of prepreg are laminated.
In this embodiment, the inner layer portion 5 of the nose portion 7 at the tip of the spacecraft 1 has, for example, 32 layers, and the thickness thereof is about 8 mm. The inner layer portion 5 of the body portion 8 is, for example, 20 layers and has a thickness of about 5 mm.

After the inner layer portion 5 and the outer layer portion 6 are formed in this manner, they are inserted into an autoclave and heated under pressure to cure the resin, thus completing the ablator 2.

Since the inner layer portion 5 of the ablator 2 is formed of a cloth-like prepreg and the reinforcing fibers are long, even if the resin of the inner layer portion 5 is carbonized at the time of re-entry, the load is transmitted by the reinforcing fibers, so that the mechanical strength is high. Have the desired strength.

The outer layer portion 6 of the ablator 2 is formed by randomly arranging strip-shaped prepregs and the reinforcing fibers are short, so the mechanical strength after carbonization is lower than that of the inner layer portion 5, but
Since the fibers are short, there are more gaps between the fibers than in the outer layer portion 5, and the gas permeability is high. As a result, the resin becomes a gas and easily blows out, and the heat protection can be enhanced. Further, since the strip-shaped prepregs are laminated at random, they exhibit plastic (pseudo-ductile) material properties, and no interlayer cracking due to high heating during re-entry occurs.
Further, since the reinforcing fiber holds the resin, it is possible to prevent the resin from peeling off when re-entering.

As described above, the inner layer portion 5 and the outer layer portion 6 are carbonized at the time of heating at a high temperature, and the outer layer portion 6 mainly shares the heat protection.
Further, the inner layer portion 5 has a temperature lower than that of the outer layer portion 6, and the load is transmitted by the long fibers, so that the mechanical strength of the ablator 2 is mainly shared. As a result, the thickness of the ablator 2 as a whole can be reduced, and the ablator 2 can be made lightweight.

[0023]

As described above, according to the present invention, the two-layer structure of the outer layer portion for sharing the heat protection and the inner layer portion for sharing the strength has a high mechanical strength and a lightweight ablator. Can be formed.

[Brief description of drawings]

FIG. 1 is a sectional view showing a spacecraft 1 using an ablator structure of the present invention.

FIG. 2 is a cross-sectional view showing an outer wall portion of the spacecraft 1.

[Explanation of symbols]

1 Spacecraft 2 Ablator 3 shell 4 Flexible insulation 5 Inner layer 6 Outer layer

Front page continuation (72) Inventor Shunichi Bando 1 Kawasaki-cho, Kakamigahara-shi, Gifu Kawasaki Heavy Industries, Ltd. Gifu factory (56) Reference JP-A-6-72398 (JP, A) JP-A-6-1659 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B64G 1/58 B29B 11/16 B32B 5/28 C08J 5/24 CEZ C08L 101: 00

Claims (2)

(57) [Claims] 1. An ablator structure which is made of a resin containing reinforcing fibers and which protects the airframe by covering the outer surface of the airframe and carbonizing it, and an inner layer portion made of a resin containing long continuous reinforcing fibers and a short discontinuity. An ablator structure which is made of a resin containing various reinforcing fibers, has an outer layer portion that covers the inner layer portion, and carbonizes both the inner layer portion and the outer layer portion when heated at a high temperature. 2. The outer layer portion is formed by randomly attaching rectangular prepregs obtained by impregnating reinforcing fibers with a resin and hot-pressing the inner layer portion. Cloth-like prepreg impregnated with
The ablator structure according to claim 1, wherein the ablator structure is formed by laminating on the inner surface of the outer layer portion.