CN102705107A - Solid chemical micro-thruster - Google Patents

Abstract

The invention discloses a micro solid chemical propeller, which belongs to the field of micro propulsion technology and micro electromechanical system (MEMS). The silicon wafer and heat-resistant glass are bonded to form a micro-propeller, and the surface 2 of the upper silicon wafer 1 is concave to form the combustion chamber 4 and the nozzle 3; the throat at the connection between the combustion chamber 4 and the nozzle 3 is an arc with a radius of curvature R ; The lower glass sheet 7 is made up of heat-resistant glass 8 and the ignition circuit structure thereon. The beneficial effects of the invention are: the ignition groove is in the form of a straight line on the silicon surface, and under the same width and bonding area of the ignition groove, the linear ignition groove reduces the difficulty of silicon-glass bonding; the throat is an arc with a certain radius of curvature And make it tangent to the boundary of the air inlet and the air outlet, reduce the gas boundary layer, and increase the thrust of the device; the igniter adopting the design form of multiple resistors connected in parallel increases the contact area with the propellant, expands the heating area, The fuse of one igniter does not cause the function failure of the whole device, which improves the reliability of the igniter.

Description

micro solid chemical propulsion

Field:

The invention relates to a micro-solid chemical propulsion device, which is used for position maintenance, attitude control, gravitational compensation, orbit adjustment, etc. of a micro-space vehicle, and belongs to the fields of micro-propulsion technology and micro-electromechanical systems (MEMS).

Background technique:

The propulsion system is a key subsystem of most spacecraft, mainly used for position keeping, attitude control, gravitational compensation and orbit adjustment of the spacecraft. With the continuous maturity of micro-spacecraft, such as micro-satellites, nano-satellites, and pico-satellites, if micro-spacecraft are required to complete certain special tasks, such as satellite formation flight, these micro-spacecraft need to be equipped with propulsion systems. Because the traditional propulsion system is relatively large in size and mass, it cannot be applied to micro-spacecraft. Therefore, there is an urgent need for a micro-propulsion system suitable for micro-satellites with high reliability, low power consumption, micro-thrust, and micro-impulse.

The micro propeller based on MEMS technology has improved the traditional propeller in structure, combined with micro-nano and micro-processing technology in technology, and has the advantages of easy miniaturization, integration, low power consumption, etc., so it has become a micro propulsion An important research direction of the system. In "Development of a solid propellant microthruster with chamber and nozzle etched on a wafer surface" and "A MEMS-based solid propellant microthruster with Au/Ti igniter" reported by Zhang K L et al., see Figure 1 and Figure 2, a proposed Using DRIE technology, the micro-propeller is bonded by silicon and glass. The micro-propeller includes a silicon structure layer and a glass layer. The silicon structure layer has a nozzle 3, a combustion chamber 4, a lower wire groove 5, and an upper wire groove 6; glass The layer includes an igniter 9, an upper ignition wire 10, and a lower ignition wire 11. The propeller adopts a DRIE process to obtain a combustion chamber 4, a nozzle 3 and a wire groove 5, and adopts a metal sputtering and etching process to obtain an igniter 9 and an ignition wire. 10. The ignition groove of this thruster is in the form of a right angle on the silicon surface. When the bonding area of the silicon surface is constant, the larger the surface area of the ignition groove is, the more difficult it is to bond the glass and the silicon surface; the throat of the nozzle is in contact with the air inlet, The gas outlets intersect to form a sharp angle, which causes the boundary layer of the ejected gas to increase, making it difficult to generate greater thrust; while the ignition resistor on the glass plate adopts a single design form, and the igniter of the single design form is ignited after being energized. The heating temperature is the highest at the narrowest part of the line width of the device, which is prone to fusing and causes irreversible failure of the igniter. Therefore, the ignition groove structure of the propeller proposed by Zhang et al. thrust, low reliability of the igniter, etc.

Invention content:

The purpose of the present invention is: to overcome the shortcomings of the silicon-glass bonding process in the existing micro-propulsion technology that is difficult, the gas boundary layer is too large to increase the thrust and the reliability of the igniter is low. Heat-resistant glass is bonded to form the micro-propellers.

As shown in Fig. 3, the technical scheme that the present invention adopts is: miniature solid chemical propeller, comprises the upper layer silicon chip 1 of bonding and lower layer glass sheet 7; The nozzle 3; the throat at the connection between the combustion chamber 4 and the nozzle 3 is a circular arc with a radius of curvature R, and the throat width r satisfies: r=R; there are linear lower wire grooves 5 and upper wires on the opposite sides of the combustion chamber 4 Groove 6; The depth of the lower wire groove 5 and the upper wire groove 6 is less than the depth of the combustion chamber 4 and the nozzle 3; The igniter 9 at the corresponding position of the chamber 4, the igniter 9 is a plurality of parallel igniters; the two ends of the igniter 9 are respectively connected with the upper ignition wire 10 located in the lower wire groove 5 and the lower ignition wire located in the upper ignition groove 6 11. The upper ignition wire 10 and the lower ignition wire 11 are connected to the upper pad 12 and the lower pad 13 outside the corresponding area of the upper silicon chip 1; the thickness of the upper ignition wire 10 and the lower ignition wire 11 is smaller than that of the lower ignition groove 5 and the upper ignition The depth of the groove 6 makes the upper silicon chip 1 non-contact with the igniter 9 on the lower glass sheet 7, the upper ignition wire 10, the lower ignition wire 11, the upper pad 12 and the lower pad 13.

During work, the igniter 9 located in the combustion chamber 4 is energized through the upper pad 12, the lower pad 13, the upper ignition wire 10, and the lower ignition wire 11, and the temperature of the igniter 9 rises to reach the ignition temperature of the fuel in the combustion chamber 4 , the fuel is ignited, the pressure in the combustion chamber 4 increases, and the gas is ejected through the nozzle 3 to produce a propulsion effect.

The beneficial effects of the present invention are: the ignition groove is in the form of a straight line on the silicon surface, and under the same width and bonding area of the ignition groove, the linear ignition groove reduces the difficulty of silicon-glass bonding; the throat is processed to have a certain radius of curvature The arc is tangent to the boundary of the air inlet and the air outlet to reduce the gas boundary layer and improve the thrust of the device; the igniter with multiple resistors in parallel design increases the contact area with the propellant and expands the heating area, the entire device will not fail due to the fusing of one igniter, which improves the reliability of the igniter

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a structural schematic diagram of a combustion chamber and a nozzle of a MEMS thruster in the prior art;

Fig. 2 is a structural schematic diagram of the MEMS thruster ignition circuit in the prior art;

Fig. 3 is the structural representation of the miniature solid chemical propeller among the present invention;

Fig. 4 is a schematic diagram of the structure of the upper silicon chip in the embodiment;

Fig. 5 is a schematic structural view of the lower glass sheet in the embodiment;

Fig. 6 is the enlarged schematic view of the structure of the igniter in the embodiment;

In the figure, 1-upper silicon wafer, 2-surface, 3-nozzle, 4-combustion chamber, 5-lower wire groove, 6-upper wire groove, 7-lower glass sheet, 8-heat-resistant glass, 9-igniter , 10-upper ignition wire, 11-lower ignition wire, 12-upper pad, 13-lower pad.

Detailed ways:

Example 1:

Referring to Figures 3-6, the micro solid chemical propeller in this embodiment includes a bonded upper layer silicon chip 1 and a lower layer glass sheet 7; the surface 2 of the upper layer silicon chip 1 is recessed by 500 μm to form a combustion chamber 4 and a nozzle 3; The throat at the connection between the combustion chamber 4 and the nozzle 3 is a circular arc with a radius of curvature of 500 μm, and the throat width r is also 500 μm; the opposite sides of the combustion chamber 4 have linear lower wire grooves 5 and upper wire grooves 6 respectively; The depth of the groove 5 and the upper wire groove 6 is 1 μm; the lower glass sheet 7 is made up of heat-resistant glass 8 and the ignition circuit structure thereon, and the heat-resistant glass 8 is Pyrex7740 in this embodiment; the ignition circuit structure includes and burns The igniter 9 at the corresponding position of the chamber 4, the igniter 9 is two parallel snake-shaped folded metal chromium film resistors, the thickness is 200nm; and the lower ignition wire 11 located in the upper wire groove 6; the upper ignition wire 10 and the lower ignition wire 11 are connected to the upper pad 12 and the lower pad 13 outside the corresponding area of the upper silicon chip 1; the upper ignition wire 10, the lower ignition wire 11. The material of the upper pad 12 and the lower pad 13 is copper; the thickness of the upper ignition wire 10 and the lower ignition wire 11 is 200nm, so that the igniter 9 on the upper silicon chip 1 and the lower glass sheet 7, the upper ignition wire 10. The lower ignition wire 11, the upper pad 12 and the lower pad 13 are non-contact;

During work, the igniter 9 located in the combustion chamber 4 is energized through the upper pad 12, the lower pad 13, the upper ignition wire 10, and the lower ignition wire 11, and the temperature of the igniter 9 rises to reach the fuel HTPB/AP in the combustion chamber 4. The ignition temperature is 350°, the fuel is ignited, the pressure in the combustion chamber 4 increases, and the gas is ejected through the nozzle 3 to produce a propulsion effect.

Claims (1)

1. A micro solid chemical propeller, including a bonded upper layer of silicon (1) and a lower layer of glass (7), characterized in that: the surface (2) of the upper layer of silicon (1) is concave to form a combustion chamber (4) and the nozzle (3); the throat at the connection between the combustion chamber (4) and the nozzle (3) is a circular arc with a radius of curvature R, and the throat width r satisfies: r=R; there are straight lines on the opposite sides of the combustion chamber (4) Shaped lower wire groove (5) and upper wire groove (6); the depth of the lower wire groove (5) and the upper wire groove (6) is less than the depth of the combustion chamber (4) and the nozzle (3); the lower glass sheet (7) It consists of heat-resistant glass (8) and the ignition circuit structure on it. The ignition circuit structure includes an igniter (9) at a position corresponding to the combustion chamber (4), and the igniter (9) is a plurality of parallel igniters The two ends of the igniter (9) are respectively connected with the upper ignition wire (10) located in the lower wire slot (5) and the lower ignition wire (11) located in the upper ignition slot (6); the upper ignition wire (10) and The lower ignition wire (11) is connected to the upper pad (12) and the lower pad (13) outside the corresponding area of the upper silicon wafer (1); the thickness of the upper ignition wire (10) and the lower ignition wire (11) is smaller than that of the lower ignition wire The depth of the groove (5) and the upper ignition groove (6) makes the igniter (9), upper ignition wire (10), lower ignition wire (11), The upper pad (12) and the lower pad (13) are not in contact.

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