Full-automatic small air pressure setter
(1) technical field
The utility model belongs to electromechanical integration technology, especially a kind of online minute-pressure calibrating installation that is applied to pressure transducer calibration, electron scanning pressure-measuring system.
(2) background technology
In the pressure measurement technology field, in order to obtain force value accurately, need calibrate used pressure transducer in measuring, these calibrating installations can be divided into active pressure calibration device and passive pressure calibration device.
Active pressure calibration device has manually and automatic two kinds.Manual have ball pneumatic dead wieght tester or a piston manometer; Electric variable valve and high-precision pressure standard are arranged automatically.More than two kinds of devices all must be equipped with positive and negative pressure source, i.e. nitrogen cylinder and vacuum pumps.
For example, the patent No. is that " the pressure transducer calibration equipment that connects microcomputer " of ZL 01251353.9 just must be equipped with air pump, and can't provide accurate, stable slight pressure.
Passive pressure calibration device has the device that adopts corrugated tube or piston to regulate pressure.Be hand-operated pressure regulation appliance (annex etc. is regulated in the additional minute-pressure as hand-rail type corrugated tube minute-pressure regulator, piston manometer).Though these devices do not need to be equipped with the positive and negative pressure source, can not be online, need the manual read to get force value.Inconvenience is used for the automatic on-line calibration of pressure-measuring system.
For example, the patent No. is that " a kind of pressure-generating device that is used for pressure calibration " of ZL 98202705.2 is exactly to move with piston to produce pressure, its structure more complicated, and processing and manufacturing is time-consuming takes a lot of work.And can not in time provide force value accurately.
Even current state-of-the-art " electron scanning pressure-measuring system " also still need carry out on-line calibration at the pressure survey scene.Need adopt corresponding pressure calibration device during on-line calibration, provide and corresponding, the stable base measuring pressure of pressure transducer range.Obviously, above-mentioned calibrating installation can not satisfy the requirement of electron scanning pressure-measuring system.
At present, the electron scanning pressure-measuring system has only the ScaniValve company of the U.S. and PSI company to provide, and in the pressure calibration device of these systems, all adopts pressure regulator valve control, regulates, provide needed base measuring pressure at last, all need to dispose high-pressure air source and vacuum pump.Simultaneously, the stable base measuring pressure that these calibrating installations provide generally all greater than 1 ft lbf/square inch (psi), promptly is about the 700mm water column.For the littler pressure transducer of range, for example range is a 250mm water column or lower, just is difficult to provide stable base measuring pressure with pressure regulator valve.
(3) summary of the invention
Can not provide the defective of stablizing small base measuring pressure in order to overcome prior art, the utility model provides the small air pressure setter of a kind of small-sized, digitizing, robotization, the principle that the utility model is inversely proportional to according to gas volume in closed container and gaseous tension, utilize electromechanical integration technology, by the volume of digital control change closed container, obtain small gaseous tension.
The utility model comprises corrugated tube 1, leading screw 3, stepper motor 4, driver 5, I/O card 6, pressure criteria 8, buffer tank 9, speed reduction unit 11, absolute type encoder 12 and zero-bit solenoid valve 13.Wherein corrugated tube 1 is the core component that can realize changing volume, and its end matches by fixing nut 2 and leading screw 3; The other end connects zero-bit solenoid valve 13, buffer tank 9 respectively by pipe adapter 10 and by the school sensor, and buffer tank 9 is a kind of closed containers that have two pipe nipples, the other end connects the pressure criteria 8 that has communication interface, pressure criteria 8 is a kind of high-precision pressure sensors with communication interface, can directly be associated on the computing machine 7, as pressure control.Have stepper motor 4 one ends that twin shaft stretches and be connected with leading screw 3 by shaft coupling, the other end connects scramblers 12 by speed reduction unit 11, and scrambler 12 is electrically connected with I/O card 6, as the position control of corrugated tube.Stepper motor 4 is electrically connected by driver 5 and I/O card 6.I/O card 6 is inserted in the expansion slot of computing machine 7.
During work, the numerical control program of computing machine 7 drives leading screw 3 corresponding rotations by the forward or reverse of I/O card 6, driver 5 control step motors 4, nut 2 is moved, corrugated tube 1 phase strain stretch or compression along leading screw 3.Produce negative pressure or malleation in the chamber.This force value can be detected by pressure criteria 8, feeds back to computing machine 7, and compares with setting value.
For guarantee corrugated tube 1 can be in elastic range trouble free service, scrambler 12 described in the utility model adopts absolute type encoder, it is characterized in that after the power down position memory function being arranged, utilize this feature, set the initial code and the maximum code of absolute type encoder 12, the stretching of corresponding corrugated tube 1 or the extreme position of compression, the intermediate code of setting absolute type encoder 12, the zero-pressure position of corresponding corrugated tube 1.
As a preferred version of the present utility model, described speed reduction unit 11 adopts miniature gear speed reduction unit or worm type of reduction gearing.
As another preferred version of the present utility model, described zero-bit solenoid valve 13 adopts the 2/2-way normally open solenoid valve.
Original state of the present utility model is as follows: corrugated tube 1 is in the zero-pressure position, and 13 power down of zero-bit solenoid valve communicate with atmosphere, and absolute type encoder 12 is in intermediate code, and pressure criteria 8 monitors force value.
The given method of the utility model atmospheric pressure value is: computing machine 7 can be set three atmospheric pressure values, is respectively 1 of negative pressure, 1 of zero-pressure, 1 of malleation.Start numerical control program, I/O card 6 sends instruction, closes zero-bit solenoid valve 13, and drive stepping motor 4 is just being changeed, and leading screw 3 drives nut 2 stretching corrugated tubes 1, produces negative pressure in the chamber, after buffer tank 9 voltage stabilizings, records force value by pressure criteria 8.
I/O card 6 sends the counter-rotating instruction, drive stepping motor 4 counter-rotatings, and leading screw 3 drives nut 2 and recovers corrugated tube 1 zero-pressure position, opens zero-bit solenoid valve 13, through buffer tank 9, records the zero pressure value by pressure criteria 8.
I/O card 6 continues to send the counter-rotating instruction, closes zero-bit solenoid valve 13, drive stepping motor 4 counter-rotatings simultaneously, and leading screw 3 drives nut 2 compress bellows 1, produces malleation in the chamber, after buffer tank 9 voltage stabilizings, records force value by pressure criteria 8.
I/O card 6 sends just changes instruction, drive stepping motor 4 counter-rotatings, and leading screw 3 drives nut 2, makes corrugated tube turn back to the zero-pressure position, simultaneously, opens zero-bit solenoid valve 13, finishes for the pressure process.
The utility model energy is complete, effective and the electron scanning pressure-measuring system is supporting, and obtains well-content result.At range be ± the electron scanning pressure-measuring system of 1.0kPa in, utilize the utility model to carry out on-line calibration and accuracy test, the utility model can provide stable, small base measuring pressure and accuracy test pressure accurately for system.
(4) description of drawings
1, accompanying drawing 1 is a system chart of the present utility model.
(5) embodiment
The utility model adopts leading screw, nut, corrugated tube, buffer tank and the pressure criteria of different parameters, can make the small air pressure setter of different pressures range.
This example is an example with the electron scanning pressure-measuring system, and system's range of employing is ± 1.0kPa that the pressure measurement precision is ± 0.1%FS.Adopt the alignment unit of this small air pressure setter as system.
At this moment, the each several part parameter of this small air pressure setter is as follows:
The material of corrugated tube is a beryllium-bronze, and its external diameter is 50mm, and internal diameter is 37mm, and length is 50mm, its good springiness, corrosion resistivity are strong, can compress 20mm from free state, stretching 10mm, can not produce creep, corresponding corrugated tube internal pressure is ± 7.5kPa, and repeatability is fine.
The pitch of leading screw and nut is M12 * 1, and promptly leading screw circles, and nut drives corrugated tube stretching (or compression) 1mm, and the pressure that produces in the bellows chamber is about 0.3kPa.
Stepper motor is little moment of torsion, two-phase stepping motor, and supporting with it driver has the segmentation step function.Speed reduction unit is miniwatt, close-toothed two-stage spur gear speed reduction unit, and reduction gear ratio is 11: 1, its stepper motor of end connection just, and terminal connection precision is 10 a absolute type encoder.
What be connected with the corrugated tube other end is the four-way pipe nipple, and one connects corrugated tube, and two connect the zero-bit solenoid valve, and three connect the pressure transducer that is calibrated, and four-way connects buffer tank, and buffer tank links to each other with pressure criteria.This example adopts precision to be ± 0.02%FS, and range is ± 2.5kPa to have the high-precision pressure sensor of numeral output.As the control and the monitoring of bellows chamber internal pressure, conduct is calibrated the comparison standard of pressure transducer to this pressure criteria on the other hand on the one hand.
The digital input/output cards that the I/O card selects for use two 16 bit strips to have photoelectricity to isolate is inserted in the expansion slot of computing machine, accepts the control of computer numerical control program.
This example can carry out on-line calibration for the electron scanning pressure-measuring system provides a plurality of stable base measuring pressures arbitrarily.For example, ± 0.3kPa, ± 0.5kPa, ± 0.7kPa and ± 1.0kPa.