JP2018116803A - Electric heater, injection device and spacecraft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric heater capable of improving heating efficiency and reliability while restraining up-sizing.SOLUTION: An electric heater 40 includes a first electric heating member 41 generating heat by electrification, a second electric heating member 41 facing the first electric heating member 41, while forming a first flow path 51 therebetween, and generating heat by electrification, a third electric heating member 41 facing the second electric heating member 41, while forming a second flow path 51 communicating with the first flow path 51 therebetween, and generating heat by electrification, and a conduction member 42 for conducting the first electric heating member 41, the second electric heating member 41 and the third electric heating member 41 each other, where the first electric heating member 41, the second electric heating member 41 and the third electric heating member 41 are formed integrally.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electric heater, an injection device, and a spacecraft.

In spacecraft such as artificial satellites and planetary probes, thrusters are used for attitude control and orbit change. The thruster has a plurality of forms with different thrust power ratios and specific thrusts, and a resist jet is known as one form thereof. The resist jet is a kind of electrothermal acceleration type electric propulsion apparatus (injection apparatus) that injects a propellant heated by an electric heater. In the resist jet, the higher the temperature of the propellant, the higher the performance. Therefore, it is important to efficiently convert electric energy into the thermal energy of the propellant.
As a method of the electric heater, for example, as shown in Non-Patent Document 1 below, there are a Coil type, a Heated Wall type, a Conmomerate type, a Solid Body type, and the like (specific examples include, for example, Non-Patent Document 2 below) reference). Conventional resist jets are mainly of the coil type, and the propellant is heated by a heater in which fine wires are formed in a coil shape. For the coil used in the coil system, for example, a configuration described in Patent Document 1 below can be considered.
Moreover, the structure of the following patent document 2 is also known as another form of a resist jet. In this resist jet, a hollow portion is formed in the plug nozzle, and the nozzle is directly heated by using the hollow portion as a heating portion. In Patent Document 2 described below, such a resist jet realizes a temperature distribution suitable for heating the propellant without complicating the structure.

US Patent Application Publication No. 2010/0171411 International Publication No. 2006/093198

Robert G. Jahn, “Physics of Electric Propulsion”, (USA), McGraw-Hill Inc. 1968, p. 103-110 J. et al. A. DONOVAN, two others, “FABRICATION AND PRELIMINARY TESTING OF A 3kW HYDROGEN RESISTOJET”, AAAA Paper, (USA), American Aerospace Engineering Association (AIAA), April 1972, No. 72-449

In the coil type resist jet to which the coil as described in Patent Document 1 is applied, for example, when the thin wire forming the coil is made thin for the purpose of increasing the energy conversion efficiency and the electric resistance, the life is shortened. In addition, there are constant problems such as disconnection, and the reliability is low. On the other hand, the efficiency decreases when the fine wires are protected.
Further, the resist jet described in Patent Document 2 is accompanied by an increase in the size of the apparatus in order to increase the heating efficiency. Further, for example, when a heat conducting rib or the like is provided, the fluid flow path itself is complicated, heating unevenness occurs, and the strength against a strong impact is reduced.

  This invention is made | formed in view of the situation mentioned above, Comprising: It aims at providing the electric heater which can improve heating efficiency and reliability, suppressing an enlargement.

In order to solve the above problems, the present invention proposes the following means.
The electric heater according to the present invention is a first electric heating member that generates heat upon energization, and is opposed to the first electric heating member and forms a first flow path between the first electric heating member and energization. Forming a second flow path that communicates with the first flow path between the second electric heating member that generates heat due to the second electric heating member and facing the second electric heating member; A third electric heating member that generates heat by energization; and a conductive member that electrically connects the first electric heating member, the second electric heating member, and the third electric heating member, the first electric heating member, The second electric heating member and the third electric heating member are integrally formed.

  In the electric heater according to the present invention, the conducting member, the first electric heating member, the second electric heating member, and the third electric heating member are made of the same heat generating material and integrally formed. Also good.

  In the electric heater according to the present invention, the first electric heating member, the second electric heating member, and the third electric heating member may be cylindrical electric heating members arranged coaxially with each other.

  In the electric heater according to the present invention, the first flow path and the second flow path may communicate with each other through a communication hole penetrating the second electric heating member.

  In the electric heater according to the present invention, an uneven portion may be formed on at least one of the first electric heating member, the second electric heating member, and the third electric heating member.

  The injection device according to the present invention includes the electric heater, and a nozzle to which a fluid that has passed through a heating channel formed at least partially by the plurality of the first channel and the second channel, A container for housing the electric heater.

  The spacecraft according to the present invention includes a thruster formed by the jetting device.

According to the electric heater and the injection device according to the present invention, it is possible to improve heating efficiency and reliability while suppressing an increase in size.
Furthermore, when the electric heater and the injection device according to the present invention are used as a thruster, a high propulsive efficiency can be realized even at a high specific thrust. While achieving this, the transition period for moving the spacecraft to a predetermined orbit can be made significantly shorter than before.

It is sectional drawing of the injection apparatus which concerns on 1st Embodiment of this invention. It is a modification of the injection device concerning a 1st embodiment of the present invention, and is a sectional view showing the state where a part of electric heater was expanded. It is sectional drawing of the injection apparatus which concerns on 2nd Embodiment of this invention. It is a perspective view of the electric heater which comprises the injection apparatus shown in FIG. It is a schematic diagram which shows a part of spacecraft concerning 3rd Embodiment of this invention.

(First embodiment)
With reference to FIG. 1, the injection apparatus 10 which concerns on 1st Embodiment of this invention is demonstrated.

  As shown in FIG. 1, the injection device 10 heats and injects the fluid F supplied from the outside. For example, when this injection device 10 is used as a thruster of a spacecraft, a propellant is applied to the fluid F. Various fluids can be adopted as the propellant regardless of liquid or gas. Examples of the propellant include hydrazine, hydrogen, ammonia, helium, nitrogen, xenon, hydrocarbon, chlorofluorocarbon, and nitrous oxide. When hydrazine or the like is employed as the propellant, the propellant can be heated by heat generated by the catalytic reaction. Moreover, as a propellant, a low-toxic high-performance propellant such as HAN or ADN can be employed.

The injection device 10 includes an electric heater 40, a nozzle 11, a pair of electrodes 12 and 13, an insulator 14, an elastic seal 15, a container 16, and a power source 17.
The electric heater 40 converts electric energy into heat energy, heats the fluid F, and supplies it to the nozzle 11. The electric heater 40 includes three or more electric heating wall members 41 (hereinafter referred to as “a plurality of electric heating wall members 41”), a conduction member 42, and a closing member 43. The electric heating wall member 41 is an electric heating member in the present invention.

  The plurality of heating wall members 41 are juxtaposed at intervals and are electrically connected to each other. Each electric heating wall member 41 generates heat when energized. The plurality of electric heating wall members 41 are formed in a cylindrical shape arranged coaxially with each other. Thereby, the electric heater 40 is formed in the multiple cylinder shape. Hereinafter, the axial direction of the electric heater 40 is referred to as an axial direction D, the radial direction of the electric heater 40 is simply referred to as a radial direction, and the circumferential direction of the electric heater 40 is simply referred to as a circumferential direction.

  In the present embodiment, six heating wall members 41 are provided as the plurality of heating wall members 41. As the heating wall member 41, the first heating wall member 41a, the second heating wall member 41b, the third heating wall member 41c, the fourth heating wall member 41d, and the fifth heating wall are sequentially arranged from the outer side to the inner side in the radial direction. A member 41e and a sixth electric heating wall member 41f are provided. An inter-member flow path 51 is formed between the heating wall members 41 facing each other. The inter-member flow path 51 is a flow path in the present invention. As the inter-member flow path 51, the first inter-member flow path 51a, the second inter-member flow path 51b, the third inter-member flow path 51c, and the fourth inter-member flow path 51d are sequentially arranged from the outer side to the inner side in the radial direction. And a fifth inter-member flow path 51e.

  The first inter-member flow path 51a is formed between the first electric heating wall member 41a and the second electric heating wall member 41b. The flow path 51b between the second members is formed between the second heating wall member 41b and the third heating wall member 41c. The third inter-member flow path 51c is formed between the third electric heating wall member 41c and the fourth electric heating wall member 41d. The fourth inter-member flow path 51d is formed between the fourth electric heating wall member 41d and the fifth electric heating wall member 41e. The fifth inter-member flow path 51e is formed between the fifth electric heating wall member 41e and the sixth electric heating wall member 41f.

  The conducting member 42 conducts the heating wall members 41 facing each other. The conductive member 42 continuously connects the electrically heated wall members 41 facing each other over the entire circumference in the circumferential direction. The conducting member 42 closes the inter-member flow path 51 in the axial direction D. In this embodiment, as the conducting member 42, the first conducting member 42a, the second conducting member 42b, the third conducting member 42c, the fourth conducting member 42d, and the fifth conducting member 42e are sequentially arranged from the outside in the radial direction toward the inside. Is provided.

  The first conduction member 42a connects the first heating wall member 41a and the second heating wall member 41b, and closes the first inter-member flow path 51a. The 2nd conduction member 42b connects the 2nd heating wall member 41b and the 3rd heating wall member 41c, and obstructs channel 2b between the 2nd members. The third conducting member 42c connects the third electric heating wall member 41c and the fourth electric heating wall member 41d, and closes the inter-third member channel 51c. The fourth conducting member 42d connects the fourth electric heating wall member 41d and the fifth electric heating wall member 41e, and closes the fourth inter-member flow path 51d. The fifth conducting member 42e connects the fifth electric heating wall member 41e and the sixth electric heating wall member 41f, and closes the fifth inter-member flow path 51e.

  Each conducting member 42 connects ends in the axial direction D of the electrically heated wall members 41 facing each other. The first conducting member 42a, the third conducting member 42c, and the fifth conducting member 42e connect the ends of one side D1 in the axial direction D, and the second conducting member 42b and the fourth conducting member 42d are in the axial direction D. The ends of the other side D2 are connected to each other. As a result, in this embodiment, the conducting member 42 (the first conducting member 42a, the third conducting member 42c, and the fifth conducting member 42e) located on the one side D1 in the axial direction D and the conducting member located on the other side D2. 42 (second conducting member 42b and fourth conducting member 42d) are alternately arranged in the radial direction. The first conducting member 42a, the third conducting member 42c, and the fifth conducting member 42e are respectively connected to the first inter-member passage 51a, the third inter-member passage 51c, and the fifth inter-member passage 51e in the axial direction D. The second conducting member 42b and the fourth conducting member 42d close the second inter-member flow path 51b and the fourth inter-member flow path 51d from the other side D2 in the axial direction D, respectively. In the illustrated example, the sixth heating wall member 41f is also closed from the one side D1 in the axial direction D.

  The closing member 43 closes some of the inter-member flow paths 51 among the plurality of inter-member flow paths 51. In the present embodiment, two (plural) closing members 43 are provided so as to close the second inter-member flow path 51b and the fourth inter-member flow path 51d. The closing member 43 includes a second closing member 43b that closes the second inter-member flow path 51b, and a fourth closing member 43d that closes the fourth inter-member flow path 51d.

  The second closing member 43b is disposed on the opposite side of the second conduction member 42b with the second inter-member flow path 51b sandwiched in the axial direction D, and the second inter-member flow path 51b is closed from the one side D1 in the axial direction D. doing. The fourth closing member 43d is disposed on the opposite side of the fourth conducting member 42d with the fourth inter-member flow path 51d sandwiched in the axial direction D, and the fourth inter-member flow path 51d is closed from the one side D1 in the axial direction D. doing. Each blocking member 43 is disposed on the opposite side of the conducting member 42 with the corresponding inter-member flow path 51 sandwiched in the axial direction D.

  The second closing member 43b is connected to the second heating wall member 41b, and the fourth closing member 43d is connected to the fourth heating wall member 41d. The conduction member 42 connects the heating wall members 41 facing each other as described above, whereas the closing member 43 does not connect the heating wall members 41 facing each other.

  All the electric heating wall members 41, the conducting members 42, and the closing members 43 are integrally formed. In the present embodiment, being integrally formed means that the target product is formed by an integrally molded product. In other words, being formed integrally means that the product is integrally formed at the same time as joining the members without using secondary bonding or mechanical joining. That is, in this embodiment, all the heating wall members 41 are formed of an integrally formed product, and all the heating wall members 41 are simultaneously joined to all the heating wall members 41 without using secondary bonding or mechanical bonding. 41 is integrally formed. In the present embodiment, the entire electric heater 40 is integrally formed by a three-dimensional modeling technique (so-called 3D printer).

  All the electric heating wall members 41, the conducting members 42, and the closing members 43 are made of the same heat generating material and are integrally formed. As the heat generating material, a material having high-temperature resistance is preferable. For example, tungsten or ruthenium, molybdenum, tantalum, platinum, titanium, nickel, niobium, indium, or an alloy containing at least one of them (for example, nickel And various metal materials such as Inconel 718 (registered trademark), which is an alloy containing carbon, and the like. In addition to high temperature resistance, the heat generating material is required to have high electrical resistivity and suitability according to the type of fluid F (propellant). Therefore, it is preferable that the heat generating material is appropriately selected according to the application and use environment of the electric heater 40. For example, Inconel 718 (registered trademark) has characteristics such as easy three-dimensional modeling, being a heat-resistant alloy, and being easy to handle because the temperature dependence of the electrical resistance value is almost constant, and these characteristics generate heat. When required for the material, Inconel 718 (registered trademark) can be suitably employed as the heat generating material.

Various product performances such as the mass, cost, size, and heating efficiency of the electric heater 40 are the total number of the electric heating wall members 41, the surface shape of each electric heating wall member 41, the length in the axial direction D, and the thickness (wall thickness). ), By adjusting the diameter and the like, it can be designed appropriately.
For example, each heating wall member 41 is desirably thin from the viewpoint of securing electric resistance. The thickness of each electric heating wall member 41 is determined by, for example, modeling feasibility or required rigidity, and can be set to about 0.1 mm to 0.5 mm as an example.

  Here, the thickness (wall thickness) of the sixth electric heating wall member 41f (electric heating member located on the innermost side in the radial direction) is the thickness (wall thickness) of the other electric heating wall members 41a, 41b, 41c, 41d, and 41e. Larger than (thick). Since the circumference of the sixth electric heating wall member 41f is smaller than the circumferences of the other electric heating wall members 41a, 41b, 41c, 41d, 41e, the thickness of the sixth electric heating wall member 41f is the other electric heating wall member 41a, When the thickness is equal to the thickness of 41b, 41c, 41d, 41e, the electrical resistance in the sixth heating wall member 41f is higher than the electrical resistance in the other heating wall members 41a, 41b, 41c, 41d, 41e, and the sixth heating Joule heat generation in the wall member 41f increases. By making the sixth electric heating wall member 41f thicker than the other electric heating wall members 41a, 41b, 41c, 41d, and 41e, an excessive increase in heat in the sixth electric heating wall member 41f can be suppressed. Further, since the second electrode 13 is joined to the sixth heating wall member 41f as will be described later, it is also possible to secure the strength of the sixth heating wall member 41f by increasing the thickness of the sixth heating wall member 41f. It is desired. However, if the sixth heating wall member 41f is made too thick, the electrical resistance in the sixth heating wall member 41f is lowered and Joule heat generation becomes too small, and heat energy can be transferred from the fluid F to the sixth heating wall member 41f. Therefore, it is desirable to adjust the wall thickness of the sixth electric heating wall member 41f as appropriate.

  Further, for example, in the present embodiment, the shape of each heating wall member 41 is a smooth shape. However, as shown in FIG. 2, for example, an uneven portion 44 may be formed on the heating wall member 41. The shape of 41 may be uneven. As the uneven portion 44, for example, a wavy uneven portion 44a as shown in FIG. 2A, a saw-like uneven portion 44b as shown in FIG. 2B, or a stepped shape as shown in FIG. The uneven portion 44c can be employed. In these concavo-convex portions 44a, 44b, and 44c, the concave portion and the convex portion are arranged in the axial direction D, but the concave portion and the convex portion are arranged in the circumferential direction like the concavo-convex portion 44d shown in FIG. May be lined up. In the heating wall member 41 shown in FIG. 2D, the thick portions 46 and the thin portions 47 are alternately arranged in the circumferential direction. In the illustrated example, the thick portions 46 and the thin portions 47 are alternately repeated with the same length in the circumferential direction, but the present invention is not limited thereto. For example, in order to increase the electric resistance while maintaining the required rigidity of the electric heating wall member 41, it is desirable that the thin portion 47 be as long as possible in the circumferential direction. The thick portion 46 has a thickness about twice that of the thin portion 47 in the radial direction. The thick portion 46 protrudes toward both the inside and outside in the radial direction with respect to the thin portion 47 to form a convex rib. Thereby, the uneven | corrugated | grooved part 44d is formed in the both sides of the inner peripheral surface and outer peripheral surface in the heating wall member 41. As shown in FIG. The uneven portion 44d extends continuously over the entire circumference in the circumferential direction. In this case, for example, the uneven portion 44d is not formed on the heating wall member 41, and the heating efficiency is improved and the strength (rigidity) of the heating wall member 41 is improved as compared with the case where the heating wall member 41 has a smooth shape. Can be improved. For example, by improving the strength of the electric heating wall member 41, the amount of use of the entire material is suppressed, and the electric cross section of the electric heating wall member 41 in a cross-sectional view perpendicular to the axis (hereinafter referred to as “transverse cross-sectional view”) is reduced. It is possible to increase the electric resistance in the heating wall member 41 and increase the heat generation efficiency (heating efficiency). Furthermore, it is possible to increase the surface area of the heating wall member 41 by the uneven portion 44d, and the heat transfer efficiency (heating efficiency) in the heating wall member 41 can be increased. In addition, it is expected that the heat transfer rate is improved by disturbing the flow of the fluid F due to the uneven portions 44a, 44b, 44c, and 44d.

  As shown in FIG. 1, the nozzle 11 ejects a fluid F. The nozzle 11 extends in the axial direction D and ejects the fluid F from the one side D1 in the axial direction D toward the other side D2. A throat 18 having a minimum flow path cross-sectional area is formed at an intermediate portion in the axial direction D of the nozzle 11. The nozzle 11 is formed in a cylindrical shape arranged coaxially with the electric heater 40 (electric heating wall member 41). At least a part of the nozzle 11 is made of the same heat generating material as the electric heater 40 and is integrally formed. The nozzle 11 is connected to an end portion on the other side D2 in the axial direction D of the sixth electric heating wall member 41f, and protrudes from the end portion toward the other side D2.

The pair of electrodes 12 and 13 are electrically connected to the electric heater 40. The pair of electrodes 12 and 13 includes a first electrode 12 and a second electrode 13.
The first electrode 12 is directly connected to the electric heater 40. The first electrode 12 is formed in an annular shape coaxial with the electric heater 40. The first electrode 12 protrudes outward in the radial direction from the first heating wall member 41a. The 1st electrode 12 is connected with the edge part of the other side D2 of the axial direction D of the 1st heating wall member 41a. The first electrode 12 is made of the same heat generating material as the electric heater 40 and is integrally formed.

  The second electrode 13 is indirectly connected to the electric heater 40. The second electrode 13 is electrically connected to the electric heater 40 through the nozzle 11. The second electrode 13 is formed in an annular shape coaxial with the nozzle 11. The second electrode 13 protrudes outward from the nozzle 11 in the radial direction. The second electrode 13 is connected to the end of the other side D <b> 2 of the nozzle 11 in the axial direction D. The second electrode 13 is not formed integrally with the nozzle 11. The second electrode 13 is formed separately from the nozzle 11 and then joined to the nozzle 11 by welding, fitting, screwing, or the like. The first electrode 12 and the second electrode 13 are opposed to each other with an interval in the axial direction D.

  The insulator 14 is sandwiched between the pair of electrodes 12 and 13. The insulator 14 electrically insulates the pair of electrodes 12 and 13 from each other. The insulator 14 is formed in an annular shape coaxial with the electric heater 40 (nozzle 11). The insulator 14 hits the edge in the axial direction D of the at least one heating wall member 41 of the plurality of heating wall members 41, and at least one of the plurality of member flow paths 51 among the plurality of member flow paths 51. It is closed from the axial direction D. In the present embodiment, the insulator 14 abuts against the edge of the other side D2 in the axial direction D of all the heating wall members 41. The insulator 14 blocks the first inter-member flow path 51a, the third inter-member flow path 51c, and the fifth inter-member flow path 51e from the other side D2 in the axial direction D among the plurality of inter-member flow paths 51. doing.

  The elastic seal 15 is disposed between the insulator 14 and the electric heater 40 or the pair of electrodes 12 and 13. The insulator 14 is abutted against the electric heating wall member 41 and the pair of electrodes 12 and 13 via the elastic seal 15. In the illustrated example, the elastic seal 15 is not disposed in a portion of the insulator 14 that closes the inter-member flow path 51. The elastic seal 15 may be fixed to the insulator 14 by, for example, fitting into a groove formed in the insulator 14.

  The container 16 accommodates the electric heater 40. The container 16 is formed in a cylindrical shape extending in the axial direction D, and is arranged coaxially with the electric heater 40 in this embodiment. The end of one side D1 in the axial direction D of the container 16 is closed, and the end of the other side D2 is open. The end of the other side D2 is in contact with the first electrode 12. An outer flow path 53 is formed between the container 16 and the electric heater 40. The outer flow path 53 is closed from the other side D2 in the axial direction D by the first electrode 12.

  In addition, when utilizing the injection apparatus 10 as a thruster, in order to obtain high propulsion efficiency, it is possible to raise the pressure of the fluid F. FIG. Even in such a case, in the injection device 10 according to the present embodiment, the container 16 is not subjected to a pressure load on the electric heating wall member 41 that should be thin from the viewpoint of electrical resistance (heat generation efficiency). The pressure in the heating channel 50 can be borne with the two electrodes 13 (flange). Therefore, in the injection device 10, the fluid F can be set to a high pressure as described above and high propulsion efficiency can be obtained.

  A heating flow path 50 is formed in the injection device 10. The fluid F that has passed through the heating flow path 50 is supplied to the nozzle 11. At least a part of the heating channel 50 is formed by a plurality of inter-member channels 51. In the present embodiment, the heating channel 50 is formed by the outer channel 53 and the plurality of inter-member channels 51. The inter-member flow path 51 and the outer flow path 53 communicate with each other through a communication hole 45 formed in each electric heating wall member 41.

  The communication hole 45 passes through each electric heating wall member 41. A plurality of communication holes 45 are formed in each electric heating wall member 41 in the circumferential direction. In this embodiment, as the communication hole 45, the 1st communication hole 45a formed in the 1st heating wall member 41a, the 2nd communication hole 45b formed in the 2nd heating wall member 41b, and the 3rd heating wall member 41c. The third communication hole 45c formed in the fourth electric heating wall member 41d, the fourth communication hole 45d formed in the fourth electric heating wall member 41d, the fifth communication hole 45e formed in the fifth electric heating wall member 41e, and the sixth electric heating wall member. And a sixth communication hole 45f formed in 41f.

  The first communication hole 45a communicates the outer flow path 53 and the first inter-member flow path 51a. The second communication hole 45b, the third communication hole 45c, the fourth communication hole 45d, and the fifth communication hole 45e communicate the adjacent member flow paths 51 with the electric heating wall member 41 formed with the respective communication holes 45 interposed therebetween. To do. The sixth communication hole 45f allows communication between the fifth inter-member flow path 51e and the sixth electric heating wall member 41f.

  In the communication holes 45 formed in the electrically heated wall members 41 facing each other, the positions in the axial direction D are different from each other. In the present embodiment, the first communication hole 45a, the third communication hole 45c, and the fifth communication hole 45e are located at the end of the other side D2 in the axial direction D of each electric heating wall member 41, and the second communication hole 45b, The fourth communication hole 45d and the sixth communication hole 45f are located at the end of one side D1 in the axial direction D of each electric heating wall member 41. As a result, in this embodiment, the communication hole 45 (second communication hole 45b, fourth communication hole 45d, and sixth communication hole 45f) located on one side D1 in the axial direction D and the communication hole located on the other side D2. 45 (first communication hole 45a, third communication hole 45c, and fifth communication hole 45e) are alternately arranged in the radial direction.

The fluid F is supplied to the heating channel 50 from the supply port 21. The supply port 21 is provided in the container 16. The supply port 21 communicates with the outer flow path 53. The supply port 21 is disposed at the end portion on the one side D <b> 1 in the axial direction D of the container 16.
The fluid F supplied from the supply port 21 to the heating flow path 50 has a plurality of inter-member flow paths 51 arranged between the inter-member flow paths 51 located outside in the radial direction and the inter-member flow paths located inside in the radial direction. Pass in turn toward 51. In the present embodiment, the fluid F supplied from the supply port 21 to the heating flow path 50 includes the outer flow path 53, the first communication hole 45a, the first inter-member flow path 51a, the second communication hole 45b, and the second member. Flow path 51b, third communication hole 45c, third member flow path 51c, fourth communication hole 45d, fourth member flow path 51d, fifth communication hole 45e, fifth member flow path 51e, fourth communication hole 45 d and the sixth heating wall member 41 f pass through the heating flow path 50 in this order, and are supplied into the nozzle 11. At this time, the flow direction of the fluid F is reversed in the channel 51 between the members adjacent to each other with the electric heating wall member 41 interposed therebetween, and the fluid F moves the channel 51 between the members to the one side D1 or the other side D2 in the axial direction D. Circulates alternately.

  The power source 17 applies a voltage to the electric heater 40 through the pair of electrodes 12 and 13 and energizes the electric heater 40. When the power source 17 energizes the electric heater 40, the electric current C is directed from the electric heating wall member 41 located on the radially outer side to the electric heating wall member 41 located on the inner side in the radial direction. It flows toward the electric heater 40 in order. In the present embodiment, the current C is applied to the first electrode 12, the first heating wall member 41a, the first conduction member 42a, the second heating wall member 41b, the second conduction member 42b, the third heating wall member 41c, and the third conduction. The member 42c, the fourth heating wall member 41d, the fourth conduction member 42d, the fifth heating wall member 41e, the fifth conduction member 42e, the sixth heating wall member 41f, the nozzle 11 and the second electrode 13 flow in this order. The electric heater 40 and the nozzle 11 form a series of electric circuits (closed circuit) together with the power source 17 and the pair of electrodes 12 and 13 when the power source 17 is connected to the pair of electrodes 12 and 13.

  In the ejection device 10, when the electric heating wall member 41 is energized when the fluid F passes through the inter-member flow channel 51 in the process of flowing through the heating flow channel 50, the fluid F that passes through the inter-member flow channel 51. Is heated by Joule heat generated from the electric heating wall member 41. In the injection device 10, the inter-member flow path 51 is formed between the heating wall members 41 facing each other, and the inter-member flow paths 51 adjacent to each other with the heating wall member 41 in communication with each other. For this reason, the fluid F is heated by each of the heating wall members 41 over a long section by passing through the inter-member passage 51 in the process of passing the heating passage 50 through the fluid F. Further, as in the present embodiment, when three or more inter-member flow paths 51 are laminated, a part of the inter-member flow paths 51 located in an intermediate region in the radial direction among the plurality of inter-member flow paths 51. The channel 51 is covered with another inter-member flow path 51, and in this part of the inter-member flow paths 51, the heat energy hardly escapes to the outside, and the fluid F is effectively heated. For example, it is possible to heat the fluid F in the other inter-member flow paths 51 adjacent to the some inter-member flow paths 51 by the thermal energy that is about to escape from the some inter-member flow paths 51. Thus, heat loss can be suppressed and the heating efficiency of the fluid F can be increased. Further, as in the present embodiment, in the case where the plurality of heating wall members 41 are formed in a cylindrical shape arranged coaxially with each other, among the plurality of inter-member flow paths 51, they are positioned on the inside in the radial direction. It becomes possible to suppress the leakage of thermal energy in the inter-member flow path 51, and the fluid F is heated more effectively.

As described above, according to the ejection device 10 according to the present embodiment, the fluid F can be heated by each of the heating wall members 41 over a long section, and the thermal energy in some of the inter-member flow paths 51 is obtained. Is difficult to escape to the outside. Therefore, heating efficiency can be improved.
Further, the plurality of electric heating wall members 41 are integrally formed. For example, the electric heating heater 40 can be formed as an integrally molded product using a three-dimensional modeling technique. Therefore, for example, compared with the case where the plurality of heating wall members 41 are separately molded and then combined, the reliability can be improved while reducing the cost and increasing the efficiency. That is, when combining the plurality of electric heating wall members 41 after being separately molded, for example, considering the assembling work and the accuracy of the assembly, the wall thickness of the electric heating wall member 41, the channel cross-sectional area of the channel 51 between members, etc. Restrictions may occur, which may affect the heating efficiency. Furthermore, when the plurality of heating wall members 41 are combined after being separately molded (when the number of parts is large), for example, vibration is generated in the injection device 10 such as when the fluid F is injected from the nozzle 11. In this case, the plurality of electric heating wall members 41 are relatively displaced, and the electric heater 40 may be damaged, resulting in a decrease in reliability.

  Moreover, all the heating wall members 41 and the conduction members 42 are made of the same heat generating material and are integrally formed. Therefore, it is not necessary to join between the electrically heated wall members 41 facing each other with an electrical insulator such as ceramic, and thermal design and accuracy management can be facilitated. That is, when the electrically heated wall members 41 facing each other are joined via a ceramic that is easily broken by thermal stress or the like, thermal design and accuracy management become difficult.

  Moreover, the some heating wall member 41 is formed in the cylinder shape arrange | positioned mutually coaxially. Therefore, it becomes possible to suppress the leakage of thermal energy in the inter-member flow path 51 located on the inner side in the radial direction among the plurality of inter-member flow paths 51, and the heating efficiency can be further increased. Further, as in the present embodiment, the fluid F moves the plurality of inter-member flow paths 51 from the inter-member flow paths 51 located on the radially outer side toward the inter-member flow paths 51 located on the radially inner side. After flowing in order, the hot fluid F can be supplied to the nozzle 11 by being supplied to the nozzle 11.

  Moreover, since the heating wall member 41 is formed in a cylindrical shape, the rigidity of the heating wall member 41 can be increased. Therefore, for example, even if the heating wall member 41 is thinned to increase the electrical resistance of the heating wall member 41, each heating wall member 41 can be formed larger (longer) in the axial direction D by the three-dimensional modeling technique. That is, although it is difficult to form a thin wall-like body with low rigidity for a long time with the three-dimensional modeling technique, the rigidity of the electric heating wall member 41 is increased, so even with the three-dimensional modeling technique, the electric heating The wall member 41 can be formed long.

Moreover, the electrically heated wall members 41 facing each other are continuously connected over the entire circumference. Therefore, it becomes possible to stabilize the relative positional relationship between the heating wall members 41 adjacent in the radial direction, and the reliability can be further improved.
The communication hole 45 communicates between the adjacent member flow paths 51 with the electric heating wall member 41 interposed therebetween. Therefore, for example, the heating efficiency can be optimized by appropriately changing the form (for example, the number, shape, position, etc.) of the communication hole 45. In addition to the form of the communication hole 45, the optimization of the heating efficiency is, for example, the total number of the heating wall members 41, the surface shape of each heating wall member 41, the length in the axial direction D, the thickness (wall thickness), and the diameter. It can be realized as appropriate by adjusting the above.

  Further, the nozzle 11 is formed integrally with the plurality of heating wall members 41. Therefore, for example, when the injection device 10 is manufactured, it becomes possible to eliminate the work of inserting the nozzle 11 along the axial direction D into the space located inside the electric heater 40 in the radial direction. Reliability can be further enhanced.

  Further, the insulator 14 hits the edge in the axial direction D of at least some of the heating wall members 41 among the plurality of heating wall members 41, and flows between at least some of the plurality of channel passages 51 between members. The path 51 is closed from the axial direction D. Therefore, it is possible to close at least some of the inter-member flow paths 51 among the plurality of inter-member flow paths 51 by using the insulator 14 that insulates the pair of electrodes 12 and 13 from each other. Can be reduced.

  The insulator 14 is abutted against the heating wall member 41 via the elastic seal 15. Therefore, it becomes possible to improve the sealing performance of the portion where the insulator 14 and the heating wall member 41 abut, and it is possible to suppress short circuit between the radially adjacent member flow paths 51 through the abutting portion. . Further, even if the electric heating wall member 41 generates heat and thermally expands in the axial direction D, the elastic seal 15 is elastically deformed, so that deformation based on the thermal expansion of the electric heating wall member 41 can be absorbed.

  As described above, in the electric heater 40, the thermal stress is large because one side D1 in the axial direction D of each electric heating wall member 41 is fixed, but the other side D2 is free (not fixed). It is not a load. Furthermore, the pressure loss in the heating flow path 50 (for example, the first inter-member flow path 51a and the fifth inter-member flow path 51e is designed by appropriately designing the cross-sectional area of each inter-member flow path 51 in the electric heater 40. The pressure loss between the two can be kept small. As a result, the stress applied to the electric heater 40 is small. Therefore, the reliability of the electric heater 40 can be increased in combination with the rigidity of the electric heater 40 being increased by forming the electric heater 40 in a cylindrical shape.

(Second Embodiment)
With reference to FIG.3 and FIG.4, the injection apparatus 60 which concerns on 2nd Embodiment of this invention is demonstrated.
In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only different points will be described.

  As shown in FIG.3 and FIG.4, in the injection apparatus 60 which concerns on this embodiment, each heating wall member 41 except the 6th heating wall member 41f is provided with the inclination wall part 61 and the straight wall part 62. As shown in FIG. Yes. The inclined wall portion 61 is formed in a tapered shape (cone shape) whose diameter increases as it goes from one side D1 in the axial direction D to the other side D2. The straight wall portion 62 extends from the end portion on the other side D2 in the axial direction D of the inclined wall portion 61 toward the other side D2. The straight wall portion 62 is formed in a straight shape extending straight along the axial direction D. The sixth heating wall member 41f is formed in a straight shape extending straight along the axial direction D.

  The first conduction member 42a is formed in an annular shape disposed between the first heating wall member 41a and the second heating wall member 41b. The third conduction member 42c is formed in an annular shape disposed between the third heating wall member 41c and the fourth heating wall member 41d. The first conducting member 42a and the third conducting member 42c are arranged coaxially with the electric heater 40 (electric heating wall member 41). Both the first conducting member 42a and the third conducting member 42c connect the inclined wall portions 61 of the heating wall members 41 facing each other.

  The 2nd conduction member 42b is formed of the 2nd heating wall member 41b and the 3rd heating wall member 41c. The end of the other side D2 in the axial direction D of the second heating wall member 41b is reduced in diameter toward the other side D2, and the end of the other side D2 in the axial direction D of the third heating wall member 41c is the other side. The diameter increases as it goes to D2. The second conduction member 42b is connected to the edge of the second side D2 in the axial direction D of the second heating wall member 41b and the edge of the other side D2 of the third heating wall member 41c in the axial direction D. It is formed by.

  The fourth conducting member 42d is formed by a fourth heating wall member 41d and a fifth heating wall member 41e. The end of the other side D2 in the axial direction D of the fourth heating wall member 41d is reduced in diameter toward the other side D2, and the end of the other side D2 in the axial direction D of the fifth heating wall member 41e is the other side. The diameter increases as it goes to D2. The fourth conducting member 42d is connected to the edge on the other side D2 in the axial direction D of the fourth heating wall member 41d and the edge on the other side D2 in the axial direction D of the fifth heating wall member 41e. It is formed by.

  The fifth conduction member 42e is formed by a fifth heating wall member 41e and a sixth heating wall member 41f. The fifth conducting member 42e is formed by connecting an end edge on one side D1 in the axial direction D of the sixth electric heating wall member 41f to the inclined wall portion 61 of the fifth electric heating wall member 41e.

  The second closing member 43b is formed by a portion located on the one side D1 in the axial direction D with respect to the first conducting member 42a in the inclined wall portion 61 of each of the first heating wall member 41a and the second heating wall member 41b. Yes. In the illustrated example, the end of one side D1 in the axial direction D of the first heating wall member 41a is closed, while the end of the second heating wall member 41b has a through hole (hereinafter referred to as “first 2 through-holes 63b "). The second closing member 43b is hollow, and the inside of the second closing member 43b communicates with the second inter-member flow path 51b through the second through hole 63b.

  The fourth closing member 43d is formed by a portion located on one side D1 in the axial direction D from the third conducting member 42c in the inclined wall portion 61 of each of the third heating wall member 41c and the fourth heating wall member 41d. Yes. In the illustrated example, the end portion on one side D1 in the axial direction D of the third electric heating wall member 41c is closed, while the end portion of the fourth electric heating wall member 41d has a through hole (hereinafter referred to as “the 4 through-holes 63d "). The fourth closing member 43d is hollow, and the inside of the fourth closing member 43d communicates with the fourth inter-member flow path 51d through the fourth through hole 63d.

  According to the injection device 60 according to the present embodiment as described above, the same operational effects as those of the first embodiment can be obtained.

(Third embodiment)
A spacecraft 70 according to a third embodiment of the present invention will be described with reference to FIG.
The spacecraft 70 according to this embodiment includes a thruster 71 formed by the injection device 10 according to the first embodiment or the injection device 60 according to the second embodiment. In addition, in order to obtain high efficiency, it is also possible to cover the injection devices 10 and 60 with a heat insulating material (not shown).

  When the injection devices 10 and 60 are used as the thrusters 71, high propulsive efficiency can be realized even at high specific thrust, so that the spacecraft 70 can be moved to a predetermined orbit while achieving low fuel consumption with high specific thrust. It is possible to significantly shorten the transition period. That is, in order to achieve a high specific thrust, for example, when a light gas such as hydrogen or helium is used as the propellant (fluid F) and the propellant is heated to a high temperature of about 2500K, Heat loss tends to increase due to the low molecular weight gas and the propellant being heated to a high temperature. Therefore, the higher the specific thrust is, the more difficult it is to increase the propulsion efficiency. In the spacecraft 70 according to the present embodiment, even when such a high specific thrust is realized, the propulsion efficiency is improved by realizing a complicated flow path in the electric heater 40, for example, in the case of a stationary orbit injection In the past, the transition period, which conventionally required about 3 to 6 months after the rocket separation, can be significantly reduced to about 1 month.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, the elastic seal 15 may not be provided.

  The nozzle 11 and the electric heater 40 may be formed as separate bodies, and the nozzle 11 may not be formed integrally with the electric heater 40. For example, in the injection device 10 shown in FIG. 1, the sixth electric heating wall member 41f is extended to the other side D2 in the axial direction D, and the nozzle 11 formed separately from the electric heating heater 40 is fitted in this extended portion. You may do it.

  The heating wall members 41 facing each other may not be continuously connected over the entire circumference. Further, the inter-member flow paths 51 adjacent to each other with the electric heating wall member 41 interposed therebetween may not communicate with each other through the communication hole 45. For example, the electrically heated wall members 41 facing each other may be intermittently connected over the entire circumference of each other, and the adjacent member flow paths 51 may be communicated with each other with the electrically heated wall member 41 interposed therebetween.

In the embodiment, all the six heating wall members 41 are integrally formed, but the present invention is not limited to this. Of the six electric heating wall members 41, the three electric heating wall members 41 arranged side by side can be appropriately changed to another form in which they are integrally formed.
For example, the form in which the 1st heating wall member 41a, the 2nd heating wall member 41b, and the 3rd heating wall member 41c were integrally formed is employable. In this case, the first electric heating wall member 41a, the second electric heating wall member 41b, and the third electric heating wall member 41c are used as the first electric heating member, the second electric heating member, and the third electric heating member in the present invention, respectively. The inter-member flow path 51a and the second inter-member flow path 51b can be used as the first flow path and the second flow path in the present invention, respectively. In this embodiment, some or all of the fourth electric heating wall member 41d, the fifth electric heating wall member 41e, and the sixth electric heating wall member 41f are formed by the first electric heating wall member 41a, the second electric heating wall member 41b, and the third electric heating member. It may be formed integrally with the wall member 41c.
Further, for example, a form in which the fourth electric heating wall member 41d, the fifth electric heating wall member 41e, and the sixth electric heating wall member 41f are integrally formed may be employed. In this case, the fourth electric heating wall member 41d, the fifth electric heating wall member 41e, and the sixth electric heating wall member 41f are used as the first electric heating member, the second electric heating member, and the third electric heating member in the present invention, respectively. The inter-member flow path 51d and the fifth inter-member flow path 51e can be used as the first flow path and the second flow path in the present invention, respectively. In this embodiment, some or all of the first heating wall member 41a, the second heating wall member 41b, and the third heating wall member 41c are used as the fourth heating wall member 41d, the fifth heating wall member 41e, and the sixth heating wall. It may be formed integrally with the wall member 41f.

  The plurality of heating wall members 41 can be formed in various cylindrical shapes such as a cylindrical shape (for example, a true cylindrical shape or an elliptical cylindrical shape) or a square cylindrical shape (for example, a rectangular cylindrical shape). Furthermore, the several heating wall member 41 does not need to be formed in the cylinder shape, for example, may be formed in flat form.

  In the said injection apparatuses 10 and 60, all the six heating wall members 41 are provided, but this invention is not limited to this. It is possible to appropriately change to another configuration in which three or more electric heating wall members 41 are provided. In addition, when the heating wall member 41 is cylindrical, among the heating wall members 41, the heating wall member 41 positioned on the outer side in the radial direction has a larger cross-sectional area and lowers electric resistance. Therefore, the heating efficiency tends to decrease. It is possible to design the total number of the electric heating wall members 41 in consideration of such heating efficiency and the weight and size of the electric heater 40 (the injection devices 10 and 60).

  The injection devices 10 and 60 can be applied to devices other than the thruster 71. For example, the ejection devices 10 and 60 can be applied to an inkjet printer or the like.

  In addition, it is possible to appropriately replace the constituent elements in the embodiment with known constituent elements without departing from the spirit of the present invention, and the above-described modified examples may be appropriately combined.

10, 60 Injection device 11 Nozzle 16 Container 40 Electric heater 41 Electric heating wall member (electric heating member)
42 Conducting member 44 Concavity and convexity 45 Communication hole 50 Heating channel 51 Channel between members (channel)
70 Spacecraft 71 Thruster D Axial F Fluid

Claims (7)

A first electrothermal member that generates heat when energized;
A second electric heating member facing the first electric heating member, forming a first flow path between the first electric heating member and generating heat by energization;
A third electric heating member facing the second electric heating member and forming a second flow channel communicating with the first flow channel between the second electric heating member and generating heat by energization; ,
A conductive member that conducts the first electric heating member, the second electric heating member, and the third electric heating member, and
An electric heater in which the first electric heating member, the second electric heating member, and the third electric heating member are integrally formed.   2. The electric heater according to claim 1, wherein the conducting member, the first electric heating member, the second electric heating member, and the third electric heating member are made of the same heat generating material and integrally formed. .   The electric heater according to claim 1 or 2, wherein the first electric heating member, the second electric heating member, and the third electric heating member are cylindrical electric heating members arranged coaxially with each other.   The electric heater according to any one of claims 1 to 3, wherein the first flow path and the second flow path communicate with each other through a communication hole that penetrates the second electric heating member.   The electric heater according to any one of claims 1 to 4, wherein an uneven portion is formed on at least one of the first electric heating member, the second electric heating member, and the third electric heating member. The electric heater according to any one of claims 1 to 5,
A nozzle to which a fluid having passed through a heating channel formed at least in part by the first channel and the second channel;
And a container for housing the electric heater.   A spacecraft having a thruster formed by the injection device according to claim 6.

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