CN103406218B - Be applied to the sonic nozzle assembly that vacuum environment gas flow controls - Google Patents

Abstract

The invention discloses a kind of sonic nozzle assembly being applied to vacuum environment gas flow and controlling, include tracheae, thermometric mouth, pressure measurement mouth, steady air current pipe, sonic nozzle globe joint, cap nut, welding pressure inlet; Steady air current pipe one end is fixedly connected with into tracheae, the other end is fixedly connected with sonic nozzle globe joint, steady air current pipe is provided with thermometer hole and pressure tap, thermometric mouth, pressure measurement mouth are fixedly connected on thermometer hole, pressure tap respectively, the other end of sonic nozzle globe joint with weld pressure inlet and be fixedly connected with by cap nut.The present invention's entirety uses stainless steel material, sonic nozzle and the machine-shaping of globe joint one, more conventional sonic nozzle component process is simple, sealing surface quantity is reduced to 1 by 4, the sphere of globe joint forms linear sealing with the conical surface welding pressure inlet, reliability improves greatly, can under vacuum, low temperature environment continuous Long-Time Service.

Description

Be applied to the sonic nozzle assembly that vacuum environment gas flow controls

Technical field

The present invention relates to a kind of sonic nozzle assembly being applied to vacuum environment gas flow and controlling, belong to gas flow control technology field.

Background technology

Using sonic nozzle to control gas flow is that one is simple, reliability is high, respond method fast.When sonic nozzle throat gas flow rate reaches local velocity of sound, reach maximum by the flow of nozzle, and not by the impact of nozzle downstream pressure fluctuation.By formula calculate the flow by sonic nozzle.Wherein, q _maxfor flow; C _dfor discharge coefficient; k is specific heat ratio, and R is gas constant; p ^*for gas stagnation pressure before sonic nozzle; T ^*for gas stagnation temperature, A _tfor nozzle throat cross-sectional area.Generally, gas stagnation temperature T ^*, specific heat ratio k is constant, therefore, only need regulate and gas stagnation pressure p before measuring sonic nozzle ^*, the gas flow q under corresponding stagnation pressure can be obtained _max.

Be applied to the conventional sonic nozzle modular construction of atmospheric environment as shown in Figure 1, the removable sonic nozzle of general employing, reaches sealing effectiveness by the copper washer of annealing.Sealing means is face sealing, and has 4 sealing surfaces at least, and sealing effectiveness and reliability are not high.Under atmospheric environment, a small amount of gas leakage impact is little, but if be applied to vacuum environment, particularly in high vacuum, ultra-high vacuum environment, then can cause remarkable destruction to vacuum environment.Annealing red copper hardness is low, ductility good, and therefore conventional sonic nozzle assembly needs regularly to tighten sealing surface, ensures sealing effectiveness, if be applied to vacuum environment, then cannot accomplish that opening vacuum chamber at any time tightens sealing surface.If sonic nozzle assembly is placed in the pipeline portions of the outer atmospheric environment of vacuum chamber, although can use existing conventional sonic nozzle assembly, this layout, by making sonic nozzle long to the pipeline of vacuum chamber inner valve, causes flow-control low-response.

Summary of the invention

The object of the invention is to solve the problem that conventional sonic nozzle sealing effectiveness in vacuum environment is bad, reliability is not high, propose a kind of by sonic nozzle and globe joint one machine-shaping structure, use sphere-conical surface seal form to form reliable linear sealing, reduce sealing surface quantity; Overall use stainless steel material, improve processability and solderability, can under vacuum, low temperature environment continuous Long-Time Service.

Be applied to the sonic nozzle assembly that vacuum environment gas flow controls, include tracheae, thermometric mouth, pressure measurement mouth, steady air current pipe, sonic nozzle globe joint, cap nut, welding pressure inlet;

Steady air current pipe one end is fixedly connected with into tracheae, the other end is fixedly connected with sonic nozzle globe joint, steady air current pipe is provided with thermometer hole and pressure tap, thermometric mouth, pressure measurement mouth are fixedly connected on thermometer hole, pressure tap respectively, the other end of sonic nozzle globe joint with weld pressure inlet and be fixedly connected with by cap nut.

The invention has the advantages that:

(1) sonic nozzle and the machine-shaping of globe joint one, more conventional sonic nozzle component process is simple, and sealing surface quantity is reduced to 1 by 4, and reliability improves greatly;

(2) sphere of globe joint forms linear sealing with the conical surface welding pressure inlet, more more reliable than the face sealing of conventional sonic nozzle assembly annealing red copper;

(3) all parts all uses stainless steel processing and manufacturing, processability and weldability good, choose the suitable stainless steel trade mark, as 304 or 316L, material hardness is high, venting rate is low, it is little to be out of shape under cryogenic conditions, without the need to regularly tightening sealing surface, can under vacuum, low temperature environment continuous Long-Time Service.

Accompanying drawing explanation

Fig. 1: conventional sonic nozzle modular construction in prior art.

Fig. 2: the sonic nozzle modular construction being applied to the control of vacuum environment gas flow of the present invention's proposition.

In figure:

1-thermometric mouth 2-enters tracheae 3-pressure measurement mouth

4-steady air current pipe 5-sonic nozzle globe joint 6-cap nut

7-welds pressure inlet

Detailed description of the invention

Below in conjunction with drawings and Examples, the present invention is described in further detail.

The present invention is a kind of sonic nozzle assembly being applied to vacuum environment gas flow and controlling, and as shown in Figure 2, includes tracheae 2, thermometric mouth 1, pressure measurement mouth 3, steady air current pipe 4, sonic nozzle globe joint 5, cap nut 6, welding pressure inlet 7.

Steady air current pipe 4 one end is fixedly connected with into tracheae 2, the other end is fixedly connected with sonic nozzle globe joint 5, steady air current pipe 4 is provided with thermometer hole and pressure tap, thermometric mouth 1, pressure measurement mouth 3 are fixedly connected on thermometer hole, pressure tap respectively, measure the temperature and pressure of gas in steady air current pipe 4 respectively, the other end of sonic nozzle globe joint 5 with weld pressure inlet 7 and be fixedly connected with by cap nut 6.

Described enter tracheae 2, thermometric mouth 1, pressure measurement mouth 3, steady air current pipe 4, sonic nozzle globe joint 5 all adopt stainless steel material, after respective machine-shaping, form an entirety by the mode of welding.Before welding sonic nozzle globe joint 5, need cylindrical section cap nut 6 being inserted in sonic nozzle globe joint 5.

Described thermometric mouth 1 is for connecting temperature sensor, and pressure measurement mouth 3 is for Bonding pressure sensor, and the version of thermometric mouth 1, pressure measurement mouth 3 is determined according to selected temperature sensor and pressure sensor.

Described sonic nozzle globe joint 5 internal face is formed by connecting by cylindrical section, converging portion, venturi, expansion segment, outside wall surface is formed by connecting by cylindrical section, step, sphere, spherical face roughness Ra is better than (being less than or equal to) 0.8 μm, one end of cylindrical section is welded with steady air current pipe 4, one end and the taper-face contact welded in pressure inlet 7 of sphere.

The outside wall surface of one end of described welding pressure inlet 7 is provided with external screw thread, and internal face is formed by connecting by the conical surface, cylindrical section, and the conical surface contacts with the sphere of sonic nozzle globe joint 5, poppet surface roughness Ra is better than (being less than or equal to) 0.8 μm.

Described cap nut 6 inside is provided with internal thread, the step of sonic nozzle globe joint 5 outside wall surface is blocked in cap nut 6 one end, the internal thread of the other end coordinates with the external screw thread welding pressure inlet 7, cap nut 6 by sonic nozzle globe joint 5 with weld pressure inlet 7 fixing after, the welding conical surface of pressure inlet 7 and the sphere of sonic nozzle globe joint 5 compress and form linear sealing.Due to use stainless steel, can Assurance component bonding strength high, not yielding, can in vacuum, low temperature environment continuous Long-Time Service.

Described enter tracheae 2 internal face, steady air current pipe 4 internal face, the cylindrical section of sonic nozzle globe joint 5 internal face, welding pressure inlet 7 internal face cylindrical section diameter identical, diameter is chosen according to the flow of gas.

In described steady air current pipe 4, the length of thermometric, pressure tap distance sonic nozzle venturi, is greater than 5 times of steady air current pipe 4 internal diameter.

The diameter of described sonic nozzle globe joint 5 venturi is:

$d_t=\sqrt{\frac{4}{\mathrm{\π}{C}_{d}K}\·\frac{q\sqrt{T^{*}}}{p^{*}}}$

To d _tcarry out rounding process, obtain the diameter of sonic nozzle globe joint 5 venturi, wherein, C _dfor discharge coefficient, the complexity according to throat's processing can be taken as 0.85 ~ 0.95, k is specific heats of gases ratios, and R is gas constant, and q is the flow needing to regulate, p ^*for gas stagnation pressure before sonic nozzle, T ^*for gas stagnation temperature.

The described convergency of sonic nozzle globe joint 5 converging portion and the angle of flare of expansion segment, choose according to assembly internal diameter and sonic nozzle globe joint 5 throat diameter, and generally, get convergency and be less than 60 °, the angle of flare is less than 30 °, to reduce pitot loss.

Before using, needing connects sonic nozzle assembly with proving flowmeter carries out flow calibration.By flow formula due to sonic nozzle machine-shaping, so flow coefficient C _dwith throat's cross-sectional area A _tconstant, and for the gas determined, generally, stagnation temperature T ^*, specific heat ratio k is constant, therefore, for the sonic nozzle assembly of a certain machine-shaping, stagnation pressure p before the flow passed through and sonic nozzle ^*linear, flow formula can be reduced to q=Ap ^*+ B, A, B are obtained by the method for demarcation linear regression.

Claims (10)

1. be applied to the sonic nozzle assembly that vacuum environment gas flow controls, include tracheae (2), thermometric mouth (1), pressure measurement mouth (3), steady air current pipe (4), sonic nozzle globe joint (5), cap nut (6), welding pressure inlet (7);

Steady air current pipe (4) one end is fixedly connected with into tracheae (2), the other end is fixedly connected with sonic nozzle globe joint (5), steady air current pipe (4) is provided with thermometer hole and pressure tap, thermometric mouth (1), pressure measurement mouth (3) are fixedly connected on thermometer hole, pressure tap respectively, the other end of sonic nozzle globe joint (5) with weld pressure inlet (7) and be fixedly connected with by cap nut (6).

2. a kind of sonic nozzle assembly being applied to vacuum environment gas flow and controlling according to claim 1, described enter tracheae (2), thermometric mouth (1), pressure measurement mouth (3), steady air current pipe (4), sonic nozzle globe joint (5) all adopt stainless steel material, after respective machine-shaping, form an entirety by the mode of welding.

3. a kind of sonic nozzle assembly being applied to vacuum environment gas flow and controlling according to claim 1, described thermometric mouth (1) is for connecting temperature sensor, pressure measurement mouth (3) is for Bonding pressure sensor, and the version of thermometric mouth (1), pressure measurement mouth (3) is determined according to selected temperature sensor and pressure sensor.

4. a kind of sonic nozzle assembly being applied to vacuum environment gas flow and controlling according to claim 1, described sonic nozzle globe joint (5) internal face is formed by connecting by cylindrical section, converging portion, venturi, expansion segment, outside wall surface is formed by connecting by cylindrical section, step, sphere, spherical face roughness Ra is better than 0.8 μm, one end of cylindrical section is welded with steady air current pipe (4), one end and the taper-face contact welded in pressure inlet 7 of sphere.

5. a kind of sonic nozzle assembly being applied to vacuum environment gas flow and controlling according to claim 1, the outside wall surface of one end of described welding pressure inlet (7) is provided with external screw thread, internal face is formed by connecting by the conical surface, cylindrical section, the conical surface contacts with the sphere of sonic nozzle globe joint (5), and poppet surface roughness Ra is better than 0.8 μm.

6. a kind of sonic nozzle assembly being applied to vacuum environment gas flow and controlling according to claim 1, described cap nut (6) inside is provided with internal thread, the step of sonic nozzle globe joint (5) outside wall surface is blocked in cap nut (6) one end, the internal thread of the other end coordinates with the external screw thread welding pressure inlet (7), cap nut (6) by sonic nozzle globe joint (5) with weld pressure inlet (7) fixing after, the conical surface of welding pressure inlet (7) and the sphere of sonic nozzle globe joint (5) compress and form linear sealing.

7. a kind of sonic nozzle assembly being applied to vacuum environment gas flow and controlling according to claim 1, described enter tracheae (2) internal face, steady air current pipe (4) internal face, the cylindrical section of sonic nozzle globe joint (5) internal face, welding pressure inlet (7) internal face cylindrical section diameter identical, diameter is chosen according to the flow of gas.

8. a kind of sonic nozzle assembly being applied to vacuum environment gas flow and controlling according to claim 1, in described steady air current pipe (4), the length of thermometer hole, pressure tap distance sonic nozzle venturi, is greater than 5 times of steady air current pipe (4) internal diameter.

9. a kind of sonic nozzle assembly being applied to vacuum environment gas flow and controlling according to claim 1, the diameter of described sonic nozzle globe joint (5) venturi is:

$d_t=\sqrt{\frac{4}{{\mathrm{\πC}}_{d}K}\·\frac{q\sqrt{T^{*}}}{p^{*}}}$

To d _tcarry out rounding process, obtain the diameter of sonic nozzle globe joint (5) venturi, wherein, C _dfor discharge coefficient, k is specific heats of gases ratios, and R is gas constant, and q is the flow needing to regulate, p ^*for gas stagnation pressure before sonic nozzle, T ^*for gas stagnation temperature.

10. a kind of sonic nozzle assembly being applied to vacuum environment gas flow and controlling according to claim 1, the convergency of described sonic nozzle globe joint (5) converging portion is less than 60 °, and the angle of flare of converging portion is less than 30 °.