CN203385466U - Electric drive symmetrical plunger type gas micro flow standard device - Google Patents

Abstract

The utility model discloses an electrically driven symmetrical plunger type gas micro-flow standard device. The right cylinder is fixed between the right bracket and the transmission end plate, and the left cylinder is fixed between the transmission bracket and the buffer tank; the plunger is installed coaxially with the left and right cylinders horizontally, and the right cylinder communicates with the left cylinder through a two-way flow indicator; the transmission end plate A ball screw is installed between the drive bracket and the plunger; the plunger is connected with the T-shaped connecting block, and the shoulder of the T-shaped connecting block matches the linear guide rails on the top surface of both sides of the transmission bracket; its lower part is fixedly connected with the screw nut; with an encoder The stepper motor is connected to the right end of the ball screw through the reducer and the diaphragm coupling, the temperature transmitter is installed on the top side of the buffer tank, the inlet of the flowmeter to be tested is connected to the buffer tank, and the flow controller is installed on the top of the flowmeter to be tested. of the exit. The utility model reduces the fluctuation of gas temperature and pressure in the cylinder during verification through the complete complementary symmetry of the volume changes in the left and right cylinders when the plunger moves, and realizes micro flow measurement and high pressure measurement at the same time.

Description

An electric-driven symmetrical plunger type gas micro-flow standard device

technical field

The utility model relates to a flow metering device, in particular to an electrically driven symmetrical plunger type gas minute flow standard device.

Background technique

In recent years, the application of small gas flow measurement and control in semiconductor manufacturing, medical chemical industry, food hygiene, bioengineering, high-tech and other fields has become more and more common. The verification and calibration of small flow related instruments has become one of the important branches of the current flow measurement field. First, generally, the range of micro flow is defined below 10mL/min.

At present, there are mainly the following types of micro gas flow measurement technologies: soap film device method, pressure volume temperature time (PVTt) method, mass time (mt) method, constant pressure type, variable volume method (such as piston type), etc. With the development of electromechanical technology, the variable volume method has developed rapidly, among which the piston type is the most typical.

The traditional piston-type standard device is driven by a power mechanism to move a piston or plunger smoothly, and a stable flow is generated by space extrusion. When performing micro-flow measurement, on the one hand, the squeeze of the space will change the state of the gas, which will reduce the measurement accuracy. On the other hand, if the measuring instrument is under high pressure, the power mechanism will have a huge load, which is difficult to achieve.

Contents of the invention

In order to solve the problems in the background technology, the purpose of this utility model is to provide an electrically driven symmetrical plunger-type gas micro-flow standard device, which can be used for measurement and calibration of micro-gas flow instruments.

In order to achieve the above object, the technical scheme that the utility model adopts is:

The right bracket, transmission end plate, transmission bracket, buffer tank, detected flow meter, flow controller, pressure transmitter and motor bracket of the utility model are respectively fixed on the base plate; the right cylinder is fixed between the right bracket and the transmission end plate. Between the right bracket, there is an air inlet connected with the right cylinder; the left cylinder is fixed between the transmission bracket and the buffer tank, and the buffer tank is connected with the gas outlet of the left cylinder; the plunger is installed horizontally with the left cylinder and the right cylinder, and respectively Through two O-ring dynamic seals, the two O-rings of the left cylinder are close to the transmission bracket, and the two O-rings of the right cylinder are close to the transmission end plate; the air outlet of the right cylinder is connected with the air inlet of the left cylinder through a two-way flow indicator , where the air outlet of the right cylinder is close to the right side of the O-ring, and the air inlet of the left cylinder is close to the left side of the O-ring; a ball screw is installed between the transmission end plate and the transmission bracket, and the ball screw is located directly below the plunger There is a groove in the middle of the plunger axis, a through hole is opened in the upper part of the T-shaped connecting block, and a plane groove connected with the through hole is opened on the top of the T-shaped connecting block, and the plunger passes through the through hole in the upper part of the T-shaped connecting block , the locking block is fastened in the plane groove of the T-shaped connecting block, and the bottom is pressed into the groove of the plunger to realize the rigid connection between the plunger and the T-shaped connecting block; slide blocks are respectively installed on the lower sides of the front and rear shoulders of the T-shaped connecting block , the slider is matched with the linear guide rail corresponding to the top surface of the front and rear sides of the transmission bracket; the screw nut matched with the ball screw is fixed at the lower part of the T-shaped connecting block; the stepper motor is connected with the reducer and diaphragm coupling The right end of the ball screw is connected, the encoder is installed on the right side of the stepping motor, the reducer and the diaphragm coupling are respectively fixed on the right side and left side of the motor bracket; the temperature transmitter is installed on the top side of the buffer tank, and the pressure transmitter The transmitter is installed on the right side of the buffer tank, the inlet of the checked flowmeter is connected with the buffer tank, and the flow controller is installed at the outlet of the checked flowmeter.

A drain hole is opened between the two O-rings of the right cylinder, and a drain hole is opened between the two O-rings of the left cylinder, and the differential pressure transmitter is connected to the two drain holes through a pipeline.

The beneficial effect that the utility model has is:

1. The upstream of the utility model supplies a certain pressure of gas to the inside of the two cylinders, and the flow adjustment is completed by the flow controller. When measuring, the fluctuation generated by the plunger movement can be compensated by the left and right cylinders, so the fluctuation of the gas state is small, and the small flow can be accurately achieved. Metering; when verifying the sonic nozzle, the system does not need to install a flow controller, and the system can directly verify the sonic nozzle.

2. In this utility model, the left and right cylinders are connected to each other, so that the front and rear pressures of the plunger are equal, and the load of the power mechanism is only the dynamic friction between the components, which can realize high-pressure gas metering.

3. The utility model can be used for rapid verification of sonic nozzles, mass flow meters, laminar flow meters, etc. with a flow range of (5-1000) mL/h.

4. The utility model has the characteristics of high precision, adjustable pressure, reliable operation, convenient operation and short verification time.

Description of drawings

Fig. 1 is the structural principle schematic diagram of the utility model.

Fig. 2 is a schematic diagram of the three-dimensional structure principle of the utility model.

In the figure: 1. Air inlet, 2. Right bracket, 3. Right cylinder, 4. O-ring, 5. Transmission end plate, 6. Plunger, 7. Locking block, 8. T-shaped connecting block, 9 , transmission bracket, 10, left cylinder, 11, temperature transmitter, 12, buffer tank, 13, tested flow meter, 14, flow controller, 15, pipeline, 16, pressure transmitter, 17, support bearing cover , 18, deep groove ball bearing, 19, lead screw nut, 20, ball screw, 21, angular contact ball bearing, 22, fixed bearing cover, 23, lock nut, 24, diaphragm coupling, 25, motor Bracket, 26, reducer, 27, stepper motor, 28, encoder, 29, base plate, 30, bidirectional flow indicator, 31, slide block, 32, differential pressure transmitter, 33, linear guide rail.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described further.

As shown in Figure 1 and Figure 2, the right bracket 2, the transmission end plate 5, the transmission bracket 9, the buffer tank 12, the tested flow meter 13, the flow controller 14, the pressure transmitter 16 and the motor bracket 25 are respectively fixed on the base plate 29 above; the right cylinder 3 is fixed between the right bracket 2 and the transmission end plate 5, and a rubber gasket is used to ensure the sealing between the connections. The right bracket 2 has an air inlet 1 connected with the right cylinder 3, and the pressure is stable and The adjustable gas source enters the inside of the right cylinder body 3 from the air inlet 1, and serves as a flow source for gas metering.

As shown in Figure 1 and Figure 2, the transmission end plate 5 is used as the connection object of the right cylinder 3 and the fixed side of the ball screw 20, the transmission end plate 5 is directly fastened on the transmission bracket 9, and the transmission end plate 5 and the transmission bracket 9 are composed Transmission mechanism: The left cylinder 10 is installed between the transmission bracket 9 and the buffer tank 12. The buffer tank 12 acts as a fixed bracket for the left cylinder 10 on the one hand, mainly to further alleviate the fluctuation of the gas inside the system, and on the other hand it is a temperature transmitter. The installation of 11 and pressure transmitter 16 provides space; the plunger 6 is installed horizontally and coaxially in the middle of the left and right cylinders, and the coaxiality requirements of the three are relatively high, and the parallelism with the axis of the ball screw 20 also has high precision requirements; Two O-rings 4 are used to realize the dynamic sealing between the plunger 6 and the inner wall of the left and right cylinder respectively. There is a drain hole between the two O-rings of the right cylinder, and a hole between the two O-rings of the left cylinder. Measuring the leakage hole, the differential pressure transmitter 32 is connected with the two measuring leakage holes through a pipeline; the right cylinder has an air outlet near the right side of the O-ring, the left cylinder has an air inlet near the left side of the O-ring, and the right cylinder has an air inlet on the left side of the O-ring. The air outlet and the air inlet of the left cylinder are respectively connected to the two ends of the two-way flow indicator.

As shown in Figure 1 and Figure 2, the screw nut 19 matched with the ball screw 20 is fixed on the lower part of the T-shaped connecting block 8, the plunger 6 passes through the through hole on the upper part of the T-shaped connecting block 8, and the plunger 6 is axially in the middle There is a groove, the top of the T-shaped connecting block 8 has a plane groove connected with the through hole, the locking block 7 is fastened in the plane groove of the T-shaped connecting block 8, and the bottom of the locking block 7 is pressed into the plunger 6 The groove realizes the rigid connection between the plunger 6 and the ball screw 20, and at the same time realizes the axial and radial positioning of the plunger 6; the lower sides of the front and rear shoulders of the T-shaped connecting block 8 are respectively equipped with sliders 31, which are in phase with the sliders 31. The matching linear guide rail 33 is installed on the top surface of the front and rear sides of the transmission bracket 9, and the cooperation between the slider 31 and the linear guide rail 33 reduces the radial vibration of the plunger 6 when it moves; the ball screw 20 adopts a fixed-support installation method, wherein , the fixed side is mainly composed of a pair of angular contact ball bearings 21, a fixed bearing cover 22 and a lock nut 23, wherein the outer ring of the angular contact ball bearing 21 is installed on the inner hole of the fixed bearing cover 22 with an interference fit, and the fixed bearing cover 22 The left end reaches the bottom surface of the mounting hole of the transmission end plate 5, and the right end is installed on the surface of the transmission end plate 5 through a flange. A lock nut 23 is installed on the ball screw 20 shaft behind the flange to realize the ball screw 20. Radial fixation; the supporting side of the ball screw 20 is composed of a deep groove ball bearing 18 and a supporting bearing cap 17, wherein the outer ring of the deep groove ball bearing 18 is installed in the inner hole of the supporting bearing cap 17 with an interference fit, and the supporting bearing cap 17 is installed on the transmission bracket 9 by its flange.

As shown in Figure 1 and Figure 2, the ball screw 20 and the reducer 26 are connected to each other through the diaphragm coupling 24, the reducer 26 is installed on the motor bracket 25, and the stepping motor 27 is installed through the flange On the reducer 26, the shafts of the stepper motor 27, the reducer 26, and the ball screw 20 are kept on the same horizontal axis as far as possible; the encoder 28 is installed on the right side of the stepper motor 27, and the position of the plunger is fed back to Control system; the stepper motor 27 is driven by the measurement and control system, given the specified control parameters, the stable movement of the corresponding speed of the plunger 6 can be realized, and the precise measurement of the gas flow can be realized in combination with the parameters of the device.

As shown in Figure 1 and Figure 2, the inlet of the flowmeter 13 to be tested is connected to the buffer tank 12 through a pipeline, the outlet is connected to the flow controller 14 through a pipeline 15, and the communication line of the flow controller 14 is connected to the measurement and control system, which can be written by the host computer. The input command completes the flow control of the whole system.

As shown in Figure 1 and Figure 2, the working principle of the present utility model is:

This invention uses plunger 6 as volume measurement standard. When the device is working, the upstream gas source continuously provides gas with stable pressure and adjustable pressure. The gas flows into the right cylinder 3 through the air inlet 1 of the right bracket 2, and enters the left cylinder 10 through the two-way flow indicator 30 until the entire system is filled. After entering the cylinder, the gas is quickly in pressure balance; the flow value of the flow controller 14 is adjusted by the host computer (assuming that the flow rate is Q ₀ ), since the gas pressure provided by the gas source is always higher than the outlet port of the flow controller, the pressure difference Under the action of , the system can generate the set flow Q ₀ of the flow controller; the computer controls the stepper motor 27 to drive the ball screw to rotate at a certain speed v (ie flow Q _s ), and the plunger 6 is driven by the ball screw 20 Perform translational movement below, the plunger 6 moves forward and enters the left cylinder 10, and at the same time pulls away from the right cylinder 3; the left and right cylinders of the plunger 6 have equal diameters d _k , and the flow rate discharged by the plunger is:

${\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}{{\mathrm{<span\; class="notranslate">\; d</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; v</span>}$

The movement of the plunger 6 causes the left cylinder 10 and the right cylinder 3 to produce flow values of Q _k1 and Q _k2 respectively, and the speed of the movement of the plunger 6 is determined by the rotation frequency f of the stepping motor 27 and the pitch s of the screw.

${\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}}{{\mathrm{<span\; class="notranslate">\; d</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}$

When the gas flow Q _s of the left and right cylinders replaced by the plunger 6 is equal to the flow Q ₀ flowing through the measured flow meter, the indication value of the two-way flow indicator is equal to 0, and the internal pressure and temperature T of the cylinder are in a balanced state, and the control system records in real time Stepper motor step size and speed, plunger position, temperature, pressure, time and other parameters; if Q _s is not equal to Q ₀ , that is, the indication value of the bidirectional flow indicator is not zero, the feedback system will adjust the plunger movement speed according to the parameters v, so that it finally reaches an equilibrium state. Due to the complete compensation of the left and right cylinders, the adjustment of the plunger movement will not affect the flow rate of the tested flowmeter; finally, read the indication value of the two-way flow indicator, and calculate it according to the final operating parameters of the stepping motor and device structure parameters. The flow rate generated by the plunger movement is used to calculate the standard flow rate of the flow meter to be checked, and to verify and calibrate the flow meter to be checked.

Claims (2)

1. an electricity drives symmetric plunger formula gas tiny flow quantity standard set-up, and it is characterized in that: right support (2), transmission end plate (5), transmission bracket (9), surge tank (12), tested flowmeter (13), flow controller (14), pressure unit (16) and electric machine support (25) are separately fixed on substrate (29); Right cylinder (3) is fixed between right support (2) and transmission end plate (5), and right support (2) has air intake opening (1) and is communicated with right cylinder (3); Left cylinder (10) is fixed between transmission bracket (9) and surge tank (12), and surge tank (12) is communicated with left cylinder (10) gas outlet; Plunger (6) is coaxially installed with left cylinder (10) and right cylinder (3) level, and respectively by twice O type circle (4) motive seal, the twice O type circle of left cylinder (10) is near transmission bracket (9), and the twice O type circle of right cylinder (2) is near transmission end plate (5); Right cylinder (3) gas outlet is communicated with left cylinder (10) air intake opening through bidirectional traffics indicator (30), and its right cylinder (3) gas outlet is near its O type circle right side, and left cylinder (10) air intake opening is near its O type circle left side; Between transmission end plate (5) and transmission bracket (9), ball-screw (20) is installed, ball-screw (20) be positioned at plunger (6) under; Plunger (6) axially middle part has groove, T-shaped contiguous block (8) top has through hole, and T-shaped contiguous block (8) top has the plane groove be communicated with through hole, plunger (6) is through the through hole on T-shaped contiguous block (8) top, latch segment (7) is fastened in the plane groove of T-shaped contiguous block (8), bottom is pressed into plunger (6) groove, realizes being rigidly connected of plunger (6) and T-shaped contiguous block (8); Before and after T-shaped contiguous block (8), the shoulder downside is installed respectively slide block (31), and slide block (31) matches with the line slideway (33) that before and after transmission bracket (9), the both sides end face is corresponding; The feed screw nut (19) coordinated with ball-screw (20) is fixed on the bottom of T-shaped contiguous block (8); The stepper motor (27) of band scrambler (28) is connected with ball-screw (20) right-hand member with diaphragm coupling (24) through reductor (26), and reductor (26) and diaphragm coupling (24) are separately fixed at right side and the left side of electric machine support (25); Temperature transmitter (11) is arranged on surge tank (12) top side, pressure unit (16) is arranged on the right side of surge tank (12), tested flowmeter (13) entrance is communicated with surge tank (12), and flow controller (14) is arranged on the exit of tested flowmeter (13).

2. symmetric plunger formula gas tiny flow quantity standard set-up according to claim 1, it is characterized in that: have between described right cylinder (3) twice O type circle to survey and let out hole, have between left cylinder (10) twice O type circle to survey and let out hole, differential pressure transmitter (32) is let out hole by pipeline with two surveys and is connected.

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