Piezoelectric pulse valve device used at front end of Laval nozzle and used for generating ultra-low-temperature uniform molecular flow

Abstract

The invention relates to the field of simulating an extremely low temperature interstellar environment in a laboratory, in particular to a piezoelectric pulse valve device used at the front end of a Laval nozzle to generate an extremely low temperature uniform molecular flow. The device comprises a mechanically assembled micrometer head, stacked piezoelectric ceramics, a piezoelectric ceramic fixing piece, a metal piston, a pre-expansion gas chamber and a flow guide plate. The piezoelectric ceramic is fixed on the annular Teflon block and is connected with the front end of the pre-expansion gas chamber through a plurality of screws, and the guide plate is connected with the rear end of the pre-expansion gas chamber through a plurality of screws. The micrometer head is fixedly connected to the front end of the piezoelectric ceramic, and the metal piston is fixedly connected to the rear end of the piezoelectric ceramic and transversely penetrates through the pre-expansion gas chamber. According to the device, the gas disturbance at the front end of the Laval nozzle can be reduced, meanwhile, large-air-volume gas inlet is realized, a stable and pulse-width-adjustable gas pressure platform is formed, and the device is used for solving the problems that in the continuous uniform flow technology, the gas sample consumption is too large, and the requirement for a pump is too high.

Description

Technical Field

[0001] The present invention relates to the field of simulating extremely low temperature interstellar environment in a laboratory, and in particular to a piezoelectric pulse valve device used at the front end of a Laval nozzle to generate an extremely low temperature uniform molecular flow. Background Art

[0002] There are about 300 species of molecules that have been discovered in the interstellar medium, most of which have been detected in extremely low temperature environments (such as between planets). In order to explain the origin of these molecules, it is necessary to establish relevant low-temperature reaction models. And the establishment of these models often requires detailed information on chemical reactions, such as reaction efficiency (reaction rate constant) and reaction product information. The earliest researchers usually tried to use the Arrhenius formula to predict the reaction or generation rate information of these species, but due to factors such as the quantum tunneling effect of chemical reactions under low temperature conditions, the low-temperature reaction rate coefficients predicted by this formula are usually quite different from the actual ones. Therefore, it is necessary to simulate the interstellar low-temperature environment in the laboratory to provide key information such as the rate and products of molecular reactions.

[0003] Ultrasonic uniform flow technology based on Rafale nozzle is a uniform flow technology based on isentropic diffusion. This uniform flow has strong unidirectionality and can usually last for tens of centimeters in space. Various physical parameters in this uniform flow are uniform and stable, which can help us simulate the interstellar low temperature environment in the laboratory. At present, some foreign colleagues in related fields still use continuous beams, which are continuous beams that connect pre-expanded gas to the front end of the Rafale nozzle. The beam quality of the continuous beam is relatively high, but it consumes a lot of carrier gas. And because the gas flow is continuously injected into the cavity, in order to maintain the vacuum condition of the cavity, the demand for the vacuum pump system is also very large. In order to solve this problem, it is necessary to use some method to convert the continuous beam into a pulse beam. The commonly used means at present is mainly to use electromagnetic pulse valves. The electromagnetic pulse valve uses electromagnetic effect combined with springs to realize gas pulses, but its gas flux is low, and the nozzle front end pressure that can be achieved is also low. The uniform flow temperature generated is correspondingly high, which cannot meet the conditions of interstellar ultra-low temperature (<50K). If we simply consider directly introducing a large amount of gas into the vacuum at the front end of the nozzle, the instability of the gas will be directly transmitted to the nozzle, and this instability will interfere with the generated beam state, and even make the generated beam no longer a uniform flow state. Therefore, it is necessary to design a high gas flux steady-flow pulse valve to optimize the above process and produce a stable gas pressure platform with a suitable pulse width. Summary of the invention

[0004] In view of the shortcomings of the above technologies, the purpose of the present invention is to provide a piezoelectric pulse valve device for the front end of the Rafale nozzle to generate an extremely low temperature uniform molecular flow, so as to solve the problems of large gas and vacuum pump consumption in the prior art, or insufficient gas flux and unstable gas flow while reducing gas consumption. The present invention can also be used to prepare high-density and high-flux molecular beams in the gas phase for reaction research and industrial production.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A piezoelectric pulse valve device used at the front end of a Rafale nozzle to generate an extremely low temperature uniform molecular flow comprises a differential head 1-1, a piezoelectric ceramic 2-3, a pre-expansion gas chamber, a piston 3-3 and a guide plate.

[0007] The interface end of the differential head 1-1 is fixedly connected to the front end of the piezoelectric ceramic 2-3 through the adapter 1-3; the rear end of the piezoelectric ceramic 2-3 is fixedly connected to the top end of the piston 3-3, and the outer periphery of the piezoelectric ceramic 2-3 is sleeved with a piezoelectric ceramic assembly fixed shell 2-2, and the two are fixedly connected through a fixed block 2-4, and the top of the piezoelectric ceramic assembly fixed shell 2-2 is provided with a differential head fixed cover plate 1-2; the piezoelectric ceramic electric control connector 2-1 is connected to the stacking sheet inside the piezoelectric ceramic 2-3; a sealing ring is fixed at the bottom end of the piston 3-3; when the piston rod of the piston 3-3 is at the maximum stroke, the sealing ring is sealed and connected to the pre-expansion gas chamber sealing lower cover plate 3-6;

[0008] The pre-expansion gas chamber is formed by the pre-expansion gas chamber sealing upper cover plate 3-5, the valve body adapter flange 3-2, and the pre-expansion gas chamber sealing lower cover plate 3-6 from top to bottom. The secondary sealing cover plate 3-4 is fixed above the pre-expansion gas chamber sealing upper cover plate 3-5. The centers of the secondary sealing cover plate 3-4 and the pre-expansion gas chamber sealing upper cover plate 3-5 are always sealed with the side of the piston 3-3. The center of the valve body adapter flange 3-2 does not contact the side of the piston 3-3. The pre-expansion gas chamber sealing lower cover plate 3-6 is arranged on the lower surface of the valve body adapter flange 3-2. A leakage hole is opened on the pre-expansion gas chamber sealing lower cover plate 3-6. The position and size of the leakage hole are adapted to the sealing ring at the bottom end of the piston 3-3. An air inlet is opened on the side of the valve body adapter flange 3-2 and is connected to the air inlet interface 3-1.

[0009] The guide plate is sealed and fixed below the pre-expanded gas chamber, and is formed by the upper flange cover plate 4-1 on the guide plate and the lower flange cover plate 4-2 of the guide plate. The flange cover plate 4-1 on the guide plate is sealed and fixed to the lower cover plate 3-6 of the pre-expanded gas chamber; a guide plate air inlet 4-7 is provided on the flange cover plate 4-1 on the guide plate, and the guide plate air inlet 4-7 is coaxially connected with the leakage hole on the lower cover plate 3-6 of the pre-expanded gas chamber seal; an inner guide groove 4-8 of the guide plate is provided between the flange cover plate 4-1 on the guide plate and the lower flange cover plate 4-2 of the guide plate, and the inner guide groove 4-8 of the guide plate is connected to the air inlet 4-7 upstream, and the bottom surface of the inner guide groove 4-8 of the guide plate is perpendicular to the axis of the piston 3-3; the sealing groove 4-6 is used to realize the sealing connection between the valve body adapter flange 3-2 and the flange cover plate 4-1 on the guide plate;

[0010] A sealed observation window 4-3 is provided on the flange cover 4-1 on the guide plate;

[0011] The gas sensor reserved interface A4-4 and the gas sensor reserved interface B4-5 are both connected to a gas pressure sensor; the gas sensor reserved interface A4-4 is set downstream of the guide groove 4-8 in the guide plate, and the gas sensor reserved interface B4-5 is set upstream of the guide groove 4-8 in the guide plate; the guide plate outlet 4-9 is opened on the guide plate lower flange cover 4-2, and is located downstream of the guide groove 4-8 in the guide plate. The other end of the guide plate outlet 4-9 can be sealed and connected with the Rafale nozzle through a fluoro rubber ring and a number of screws.

[0012] Furthermore, the fixing blocks 2-4 are made of Teflon;

[0013] Furthermore, the piezoelectric ceramics 2-3 are of stacked type;

[0014] Furthermore, the guide plate air outlet 4-9 is communicated with the sealed observation window 4-3 and is coaxial with each other.

[0015] Beneficial effects of the present invention: The combination of the differential head and the piezoelectric ceramics in the present invention can realize the coarse and fine adjustment of the uniaxial displacement. The multi-stage seal adopted in the upper cover plate of the pre-expansion gas chamber in the present invention can ensure dynamic sealing and static sealing. The present invention is an oil-free vacuum air intake method, which eliminates the pollution of vacuum caused by oil evaporation. The present invention is a pulse air intake with adjustable pulse width, and the pulse width can be adjusted to cover the range of microseconds to hundreds of milliseconds. The present invention can ensure the intake of large gas flux in practical applications while greatly reducing the consumption of sample gas and the demand for vacuum pumps. The introduction of the guide plate in the present invention can greatly eliminate the gas disturbance and instability during pulse jetting, thereby producing a stable air pressure platform with a suitable pulse width. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1The present invention is a schematic diagram of the three-dimensional structure of a piezoelectric pulse valve device used at the front end of a Rafale nozzle to generate an extremely low temperature uniform molecular flow.

[0017] Figure 2 The present invention is a schematic diagram of a three-dimensional cross-sectional structure of a piezoelectric pulse valve device used at the front end of a Rafale nozzle to generate an extremely low-temperature uniform molecular flow.

[0018] Figure 3 It is a schematic diagram of the three-dimensional structure of the guide plate of the present invention.

[0019] Figure 4 It is a schematic diagram of the three-dimensional cross-sectional structure of the guide plate of the present invention.

[0020] Figure 5 This is a jet pressure test diagram of a piezoelectric pulse valve device used at the front end of a Rafale nozzle to generate an extremely low temperature uniform molecular flow as described in the present invention.

[0021] In the figure, 1-1 is a differential head, 1-2 is a fixed cover plate of the differential head, 1-3 is an adapter, 2-1 is a piezoelectric ceramic electric control connector, 2-2 is a piezoelectric ceramic assembly fixed shell, 2-3 is a piezoelectric ceramic, 2-4 is a fixed block, 3-1 is an air inlet interface, 3-2 is a valve body adapter flange, 3-3 is a piston, 3-4 is a secondary sealing cover plate, 3-5 is a pre-expansion gas chamber sealing upper cover plate, 3-6 is a pre-expansion gas chamber sealing lower cover plate, 4-1 is a flange cover plate on the guide plate, 4-2 is a flange cover plate under the guide plate, 4-3 is a sealed observation window, 4-4 is a gas sensor reserved interface A, 4-5 is a gas sensor reserved interface B, 4-6 is a sealing groove, 4-7 is a guide plate air inlet, 4-8 is a guide groove inside the guide plate, and 4-9 is a guide plate outlet DETAILED DESCRIPTION

[0022] Combination Figure 1 , Figure 2 , Figure 3 and Figure 4 The present invention consists of a differential head 1-1, a differential head fixed cover plate 1-2, an adapter 1-3, a piezoelectric ceramic electric control connector 2-1, a piezoelectric ceramic assembly fixed shell 2-2, a stacked piezoelectric ceramic 2-3, a Teflon fixed block 2-4, an air inlet interface 3-1, a valve body adapter flange 3-2, a piston 3-3, a secondary sealing cover plate 3-4, a pre-expansion gas chamber sealing upper cover plate 3-5, a pre-expansion gas chamber sealing lower cover plate 3-6, a guide plate upper flange cover plate 4-1, a guide plate lower flange cover plate 4-2, a sealed observation window 4-3, a gas sensor reserved interface A4-4, a gas sensor reserved interface B4-5, a sealing groove 4-6, a guide plate air inlet 4-7, a guide plate inner guide groove 4-8 and a guide plate air outlet 4-9.

[0023] The interface end of the differential head 1-1 is fixedly connected to the front end of the piezoelectric ceramic 2-3 through the adapter 1-3; the rear end of the piezoelectric ceramic 2-3 is fixedly connected to the top end of the piston 3-3, and the outer periphery of the piezoelectric ceramic 2-3 is sleeved with a piezoelectric ceramic assembly fixed shell 2-2, and the two are fixedly connected through a fixed block 2-4, and the top of the piezoelectric ceramic assembly fixed shell 2-2 is provided with a differential head fixed cover plate 1-2; the piezoelectric ceramic electric control connector 2-1 is connected to the stacking sheet inside the piezoelectric ceramic 2-3; the bottom end of the piston 3-3 is processed with a conical groove, and a fluororubber ring is placed in the conical groove for sealing; when the piston rod of the piston 3-3 is at the maximum stroke, the fluororubber ring is sealed and connected to the pre-expansion gas chamber sealing lower cover plate 3-6;

[0024] The pre-expansion gas chamber is formed by the pre-expansion gas chamber sealing upper cover plate 3-5, the valve body adapter flange 3-2, and the pre-expansion gas chamber sealing lower cover plate 3-6 from top to bottom. The secondary sealing cover plate 3-4 is fixed above the pre-expansion gas chamber sealing upper cover plate 3-5. The piston 3-3 runs through the pre-expansion gas chamber. A groove is provided in the center of the secondary sealing cover plate 3-4 and the pre-expansion gas chamber sealing upper cover plate 3-5. A fluororubber ring is installed in the groove for always sealing with the side of the piston 3-3. The center of the valve body adapter flange 3-2 does not contact the side of the piston 3-3. The pre-expansion gas chamber sealing lower cover plate 3-6 is arranged on the lower surface of the valve body adapter flange 3-2. A leakage hole is provided on the pre-expansion gas chamber sealing lower cover plate 3-6. The position and size of the leakage hole are adapted to the sealing ring at the bottom end of the piston 3-3. An air inlet is provided on the side of the valve body adapter flange 3-2 and is connected to the air inlet interface 3-1.

[0025] The guide plate is sealed and fixed below the pre-expansion gas chamber 3-2, and is formed by the upper flange cover plate 4-1 on the guide plate and the lower flange cover plate 4-2 of the guide plate. The flange cover plate 4-1 on the guide plate is sealed and fixed to the lower cover plate 3-6 of the pre-expansion gas chamber; a circular guide plate air inlet 4-7 is provided on the flange cover plate 4-1 on the guide plate, and the guide plate air inlet 4-7 is coaxially connected with the leakage hole on the lower cover plate 3-6 of the pre-expansion gas chamber seal; a square guide plate inner guide groove 4-8 is provided between the upper flange cover plate 4-1 on the guide plate and the lower flange cover plate 4-2 of the guide plate, and the guide plate inner guide groove 4-8 is connected to the guide plate air inlet 4-7 upstream, and the bottom surface of the guide plate inner guide groove 4-8 is perpendicular to the axis (jet direction) of the piston 3-3. This design can greatly eliminate the instability caused by the instantaneous switch of the gas; the sealing groove 4-6 is used to realize the sealing connection between the valve body adapter flange 3-2;

[0026] The upper flange cover plate 4-1 of the guide plate and the lower flange cover plate 4-2 of the guide plate are both made of stainless steel;

[0027] A sealed observation window 4-3 is provided on the flange cover plate 4-1 on the guide plate; the sealed observation window 4-3 and the flange cover plate 4-1 on the guide plate are sealed via a knife edge and an oxygen-free copper ring.

[0028] The gas sensor reserved interface A4-4 and the gas sensor reserved interface B4-5 are both connected to a gas pressure sensor; the gas sensor reserved interface A4-4 is arranged downstream of the guide groove 4-8 in the guide plate, and the gas sensor reserved interface B4-5 is arranged upstream of the guide groove 4-8 in the guide plate; the guide plate gas outlet 4-9 is arranged on the guide plate lower flange cover 4-2, and is located downstream of the guide groove 4-8 in the guide plate. The guide plate gas outlet 4-9 is communicated with the sealed observation window 4-3 and is coaxial.

[0029] Other sealed connections are sealed with fluoro rubber rings and several screws.

[0030] In normal use, the stacked piezoelectric ceramic 2-3 is connected to the external electric control via the piezoelectric ceramic electric control connector 2-1. The external electric control can adjust the power supply voltage of the piezoelectric ceramic 2-3 and realize the control of the power supply time window at the same time, that is to say, the displacement and intake time window of the piezoelectric ceramic 2-3 in this device can be precisely controlled. At the maximum voltage (i.e., maximum stroke) of the piezoelectric ceramic 2-3, adjust the differential head 1-1 so that the sealing ring at the end of the piston 3-3 is exactly connected to the sealing lower cover plate 3-6 of the pre-expansion gas chamber. At this time, the gas is sealed in the pre-expansion gas chamber and cannot flow out from the leaking hole in the sealing lower cover plate 3-6 of the pre-expansion gas chamber. When the power supply voltage is zero (i.e., no displacement), the stacked piezoelectric ceramic 2-3 drives the piston 3-3 to contract. Due to the existence of the internal and external pressure difference (vacuum outside), the gas flows out from the leaking hole in the sealing lower cover plate 3-6 of the pre-expansion gas chamber. For ease of understanding, the maximum voltage (i.e., maximum stroke) of the piezoelectric ceramic 2-3 is defined as the valve is closed, and the supply voltage is zero (i.e., no displacement) is defined as the valve is open. Connect the pressure sensor at the reserved interface A4-4 of the gas sensor to the oscilloscope, and the pressure change at the outlet of the guide plate can be clearly observed when the valve is open ( Figure 5 ). By extending the valve opening time, a stable pressure platform can be seen in a certain period of time (millisecond width) ( Figure 5 This pressure platform can lay the foundation for generating extremely low temperature uniform molecular flow.

Claims

1. A piezoelectric pulse valve device for the front end of a Rafale nozzle to generate an extremely low temperature uniform molecular flow, characterized in that: It comprises a differential head (1-1), piezoelectric ceramics (2-3), a pre-expansion gas chamber, a piston (3-3) and a guide plate; The interface end of the differential head (1-1) is fixedly connected to the front end of the piezoelectric ceramic (2-3) via an adapter (1-3); the rear end of the piezoelectric ceramic (2-3) is fixedly connected to the top end of the piston (3-3); a piezoelectric ceramic assembly fixed shell (2-2) is sleeved on the outer periphery of the piezoelectric ceramic (2-3), and the two are fixedly connected via a fixed block (2-4); a differential head fixed cover plate (1-2) is arranged at the top end of the piezoelectric ceramic assembly fixed shell (2-2); the piezoelectric ceramic electric control connector (2-1) is connected to the stacking sheet inside the piezoelectric ceramic (2-3); a sealing ring is fixed to the bottom end of the piston (3-3); when the piston rod of the piston (3-3) is at the maximum stroke, the sealing ring is sealed and connected to the pre-expansion gas chamber sealing lower cover plate (3-6); The pre-expansion gas chamber is formed by a pre-expansion gas chamber sealing upper cover plate (3-5), a valve body adapter flange (3-2), and a pre-expansion gas chamber sealing lower cover plate (3-6) from top to bottom; a secondary sealing cover plate (3-4) is fixed above the pre-expansion gas chamber sealing upper cover plate (3-5); the centers of the secondary sealing cover plate (3-4) and the pre-expansion gas chamber sealing upper cover plate (3-5) are always sealed with the side of the piston (3-3); the center of the valve body adapter flange (3-2) does not contact the side of the piston (3-3); the pre-expansion gas chamber sealing lower cover plate (3-6) is arranged on the lower surface of the valve body adapter flange (3-2); a leakage hole is provided on the pre-expansion gas chamber sealing lower cover plate (3-6); the position and size of the leakage hole are adapted to the sealing ring at the bottom end of the piston (3-3); an air inlet is provided on the side of the valve body adapter flange (3-2) and is connected to the air inlet interface (3-1); The guide plate is sealed and fixed below the pre-expansion gas chamber, and is formed by sealing the guide plate upper flange cover (4-1) and the guide plate lower flange cover (4-2). The guide plate flange cover (4-1) is sealed and fixed to the pre-expansion gas chamber sealing lower cover (3-6); the guide plate upper flange cover (4-1) is provided with a guide plate air inlet (4-7), and the guide plate air inlet (4-7) is coaxially connected with the air leakage hole on the pre-expansion gas chamber sealing lower cover (3-6); the guide plate flange cover (4-1) is provided with a guide plate air inlet (4-7) and the air leakage hole on the pre-expansion gas chamber sealing lower cover (3-6); -1) and the flange cover plate (4-2) below the guide plate, an inner guide groove (4-8) of the guide plate is provided, the inner guide groove (4-8) of the guide plate is connected to the air inlet (4-7) of the guide plate upstream, and the bottom surface of the inner guide groove (4-8) of the guide plate is perpendicular to the axis of the piston (3-3); the sealing groove (4-6) is used to realize the sealing connection between the valve body adapter flange (3-2) and the flange cover plate (4-1) on the guide plate; and a sealing observation window (4-3) is provided on the flange cover plate (4-1) on the guide plate; A gas sensor reserved interface A (4-4) and a gas sensor reserved interface B (4-5) are both connected to a gas pressure sensor; the gas sensor reserved interface A (4-4) is arranged downstream of a guide groove (4-8) in a guide plate, and the gas sensor reserved interface B (4-5) is arranged upstream of the guide groove (4-8) in the guide plate; the guide plate air outlet (4-9) is arranged on a flange cover plate (4-2) below the guide plate, and is located downstream of the guide groove (4-8) in the guide plate; the other end of the guide plate air outlet (4-9) can be sealed and connected to a Rafale nozzle through a fluoro rubber ring and a plurality of screws.

2. A piezoelectric pulse valve device for generating a very low temperature uniform molecular flow at the front end of a Rafale nozzle according to claim 1, characterized in that: The fixing block (2-4) is made of Teflon material.

3. A piezoelectric pulse valve device for generating ultra-low temperature uniform molecular flow at the front end of a Rafale nozzle according to claim 1, characterized in that: The piezoelectric ceramics (2-3) are of stacked type.

4. A piezoelectric pulse valve device for generating a very low temperature uniform molecular flow at the front end of a Rafale nozzle according to claim 1, characterized in that: The air outlet (4-9) of the guide plate is in communication with the sealed observation window (4-3) and is coaxial with the air outlet (4-9).

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