RU2390741C1 - Device to calibrate pressure metres - Google Patents

Abstract

FIELD: instruments making.

SUBSTANCE: proposed device comprises assembly to produce pressure including flywheel, working fluid pump, assembly to set pressure and surplus pressure system comprising reference pressure metre connected to said pump. Assembly to produce pressure represents a housing. Inner-thread hole, chamber communicated with working fluid chamber and chamber communicated with the former and surplus pressure chamber are consecutively arranged inside said housing. Said inner-thread hole accommodates rod with outer thread and smooth section. Flywheel is secured to said rod top part to be driven thereby. Sealing element is arranged between specified chambers to make pressure setting assembly with said rod.

EFFECT: higher reliability of direct comparison device.

2 dwg

Description

The invention relates to instrumentation, in particular to devices that create pressure of a liquid or gas, and can be used for metrological purposes for calibration or verification of means of control and measurement of pressure by comparison.

Known devices are sources of pressure generation indicated in the Metrological Equipment catalog, issue 6/2007 CJSC PG METRAN, p. 101, portable model press 2113, universal small-sized presses PUM 60, PUM 40 and PUM 6 manufactured by ZAO Manometer ”, Moscow, and others (hydraulic units for comparative calibration GUSK-60, GUSK-250, GUSK-600-Russia, pressure comparator Gauge Calxp-USA), designed to create overpressure or vacuum during calibration of pressure measuring instruments direct comparison Rendering the reference and verified (calibrated) pressure measuring means. They have a minimal typical set of basic units ensuring the operability of the device according to their functional purpose: a press with a cylinder and a piston, and a piston drive, screw or lever, to create pressure or vacuum in the system, capacity, in hydraulic devices, for working fluid, in quantity necessary for filling the system of the device of standard and verified means of measuring pressure, the valve for cutting off the container with the working fluid from the overpressure system for hydraulic devices and other gas from atmospheric pressure for pneumatic devices and smooth pressure relief from the system and working cavities of the standard and verified pressure measuring instruments, connecting fittings for standard and verified pressure measuring instruments.

More complex pressure generating devices have additional pumps for accelerated filling of the device’s hydraulic system and the creation of preliminary pressure, valves for cutting off the working fluid or gas pressure of the device’s system from the outlet ports, a press, as a fine-tuning unit, for precise setting of the liquid or gas pressure.

The disadvantage of these devices is that in the presence of a minimum set of nodes it is quite difficult to quickly create the necessary pressure in all volumes of the cavities of the device, reference and calibrated pressure measuring devices in connection with the small diameters of the press pistons, which allow small portions of liquid or gas to flow smoothly and with less effort approach the required pressure or vacuum value, as The function of the press is to accurately approach the point being checked. For this purpose, presses with helical drive kinematics are more often used in pressure generating devices. A quick change in pressure in the device system must be performed in large portions of the supplied or pumped liquid or gas, which suggests the presence of an additional unit in the device - a pump, which does not allow you to smoothly and accurately set the required pressure or vacuum. As a rule, pumps with lever kinematics of the piston drive are used for this.

The inclusion of additional nodes in the composition of the device complicates their design and work with devices, as well as additional elements of the unreliability of these devices — failures, failure of them — appear.

The closest in technical essence to the claimed is a device for checking oxygen pressure gauges PPKM-250, described in the passport for the device DDD 900.00.000 PS from 12/25/95, manufactured by the Donetsk experimental plant "Etalon", Ukraine, and selected as a prototype.

The known device (Figure 1, 2) contains: a pressure generating unit, which includes a press fixed to the plate, which, in turn, consists of a cylinder, a piston, a threaded screw, a flywheel, and a pump assembly; a container for the working fluid in the form of a funnel and pressure setting units that ensure the flow and shutoff of the fluid supply in the form of valves. The pumping of the working fluid into the system and the preliminary pressure in it are created by a hand pump. After the appearance of the preliminary pressure, the valve of the pump is closed, and the operating pressure in the system is provided by the flywheel of the press. In the funnel, which serves as a reservoir for the working fluid, there is a valve to relieve pressure in the system.

As follows from the description in the passport of the operating procedure (item 7, sheet 8) with the device, first use a manual pump to pump the working fluid into the system, create a preliminary pressure and close the pump valve (Figure 1 and 3). Then provide the operating pressure in the system by rotating the press flywheel (Figure 1). It is provided that the valve for depressurizing the system, which is located in the funnel serving as a reservoir for the working fluid, must be closed. This is specified in the description of possible malfunctions and methods for their elimination (paragraph 9, table 1, sheet 9) in the column of methods for eliminating malfunctions of pressure inconsistencies.

After the calibration of the oxygen manometer is completed, according to the method for calibrating pressure gauges, vacuum gauges, etc. MI 2124-90, it is necessary to unload the system of the device for checking oxygen pressure gauges PPKM-250 from pressure in the reverse order by rotating the press flywheel to lower the pressure, and then slowly discharge of residual pressure in the system by opening the discharge valve, draining the working fluid into the funnel.

A disadvantage of the known device is its insufficiently high reliability, due to the fact that setting the required working pressure in the PPKM-250 device system during calibration of oxygen manometers provides for manipulations with a large number of components in a certain sequence: a discharge valve, a pump and a press, which is a quantitative indicator device failure. At the same time, work with the pump valve is not considered - it serves to cut off the pump from the device system, the standard and the device to be verified to prevent pressure drop due to leaks through the exhaust valve, preloaded only by the spring, as well as to protect the pump exhaust valve from jamming and failure when high excess pressure in the system. This is a design feature of this device.

So, in the valves of the same type used on the device (Figure 3), as well as in the relief valve, a metal-metal seal is used, based on the implementation of elastic deformation in the contact of the seat and shut-off valve. Careful machining of the sealing surfaces is necessary to ensure the tightness of such valve seals. This increases the complexity of manufacturing valves and, in particular, a discharge valve. Intense wear of the rubbing surfaces of the seal contact determines a small resource of the valve and, as a result, loss of system tightness and failure of the device.

A large number of controls involves a complex combination of sequential actions with them to create pressure during calibration of pressure measuring instruments, thereby reducing the life of the instrument and significantly increasing the time it takes to calibrate pressure measuring instruments.

The purpose of the proposed technical solution is to increase the reliability of devices used for calibration of pressure measuring instruments by direct comparison.

This goal is achieved by the fact that in the device for calibrating pressure measuring devices containing a pressure generating unit including a flywheel, a pump for pumping a working fluid, a unit for setting pressure by shutting off and supplying a working fluid to a container for it and an overpressure system including a standard means of measuring pressure, which is connected to the pump, ACCORDING TO THE INVENTION, the pressure generating unit is made in the form of a housing, along the longitudinal axis of which there is a successive opening with an internal a cavity and a cavity connected to it and with an overpressure system connected to the reservoir for the working fluid, while a rod with an external thread and a smooth part is placed in the hole with an internal thread, the flywheel is attached to its upper part to allow its movement, and between the cavities there is a sealing element forming, together with the rod, a unit for setting the pressure.

The implementation of the node to create pressure in the form of a housing, along the longitudinal axis of which there is sequentially an opening with an internal thread, a cavity and a cavity communicating with it and with an overpressure system connected to the reservoir for the working fluid, when placed in the hole with an internal thread of a rod with an external thread and a smooth part, to the upper part of which a flywheel is attached to enable its movement, in conjunction with the location between the cavities of the sealing element, forming together with the rod l to set the pressure, allows you to reduce the number of individual controls for setting the pressure in the device, to simplify the combination of sequential actions with them to create pressure during calibration of pressure measuring instruments and thereby increase the service life of the device and significantly reduce the time of calibration of pressure measuring instruments, providing overall improved device reliability.

The technical result is an increase in the reliability of a device for checking means for measuring excess pressure and vacuum.

The inventive device for checking pressure measuring instruments has a novelty in comparison with the prototype, differing from it by the presence of such essential features as the implementation of the pressure generating unit in the form of a housing, along the longitudinal axis of which there is a hole with an internal thread connected to the cavity and cavity connected to the reservoir for the working fluid communicating with it and with the overpressure system, placement in the hole with an internal thread of the stem with an external thread and a smooth part, to the upper part of which is attached En a flywheel to ensure the possibility of its movement, the location between the cavities of the sealing element, which together with the rod forms a node for setting pressure, which together ensure the achievement of a given result.

The applicant is not aware of technical solutions containing the indicated distinctive features, which together ensure the achievement of a given result, as in the claimed object, therefore, he considers that the claimed technical solution meets the criterion of "inventive step".

The inventive device for calibration of pressure measuring instruments can be widely used in industry in the manufacture of pressure and vacuum measuring instruments, their calibration and verification and therefore meets the criterion of "industrial applicability".

The invention is illustrated by drawings, which represent:

- figure 1 - diagram of a device for checking means for measuring excess pressure in the closed state;

- figure 2 is a diagram of a device for checking means for measuring excess pressure in the open state.

A device for checking pressure measuring devices consists of a pressure generating unit 1 connected to a pump 2 connected to a working fluid reservoir 3. The node 1 is made in the form of a housing 4, along the longitudinal axis of which there is a successive hole 5 with an internal thread 6, a cavity 7 connected to the working fluid reservoir 3, and a cavity 8 communicating with it and with the overpressure system 9. At the same time, a hole 10 with an external thread 11 and a smooth part 12 is placed in the hole 5 with an internal thread 6, to the upper part of which a flywheel 13 is attached to enable its movement. Between the cavities 7 and 8 there is a sealing element 14, which together with the rod 10 forms a unit for setting pressure by shutting off and supplying the working fluid from the reservoir 3. The pump 2 is made, in particular, with lever kinematics of the piston drive and is included in the overpressure system 9, which also includes a reference 15 and calibrated 16 pressure measuring means associated therewith. In this case, the pump 2 is connected by means of connecting fittings 17 and 18 to the reference and verifiable means 15 and 16, and also communicated with the capacity 3 for supplying the working fluid in the amount necessary to fill the device system, reference and verifiable means 15 and 16 for measuring pressure, and with a cavity 8. In this case, the sealing element 14 can be made elastic.

A device for checking pressure measuring devices works as follows. To the fittings 17 and 18 connect the reference 15 and calibrated 16 means of measuring pressure. Before starting to create pressure, the device for calibrating pressure measuring devices must first, by rotating the flywheel 13 together with the stem 10 with the external thread 11 and the smooth part 12 along the internal thread 6 of the hole 5 of the housing 4, enter the smooth part 12 of the rod 10 into contact with the sealing element 14. The sealing element 14 together with the housing 4 and the smooth part 12 of the rod 10 forms a reliable tight connection. Thus, there is a cut-off of the tank 3 with the working fluid from the system 9 of the overpressure of the device and the reference 15 and calibrated 16 means of measuring pressure. Next, the pump 2 in the device system creates a preliminary pressure close to the calibration point of the reference means 15 of the measurement. Then, continuing the rotation of the flywheel 13 along the internal thread 6 of the hole 5 of the housing 4 by moving along the axis of the pressure rod assembly 10 with the external thread 11 and the smooth part 12, a change (increase or decrease) in the volume of the cavity 8 with the smooth part 12 is made and thereby achieve the required value pressure test point. Direct comparisons compare the readings of the reference 15 and calibrated 16 pressure measuring instruments.

To relieve excess pressure from the system of the device by turning the flywheel 13 in the direction opposite to the direction of rotation when creating pressure, the internal part 6 of the opening 5 of the housing 4 is moved along the axis of the pressure generating unit 10 with the external thread 11 and smooth part 12, the smooth part 12 is output the rod 10 from contact with the sealing element 14. Thus, the tight connection of the sealing element 14, the housing 4 and the smooth part 12 of the rod 10, and the working fluid from the system of the device through the cavity 8 and 7 p retekaet in the container 3 and decreasing the fluid pressure in the system device 9 excessive pressure.

Compared with the prototype of the inventive device for checking pressure measuring instruments is more reliable.

Claims (1)

A device for calibrating pressure measuring devices, comprising a pressure generating unit including a flywheel, a pump for pumping a working fluid, a unit for setting pressure by shutting off and supplying a working fluid to a container for it, and an overpressure system including reference pressure measuring means, which is connected to the pump, characterized in that in it the pressure generating unit is made in the form of a housing, along the longitudinal axis of which there is a hole with a female thread connected in series with For the working fluid, there is a cavity and a cavity communicating with it and with the overpressure system, while a rod with an external thread and a smooth part is placed in the hole with an internal thread, the flywheel is attached to the upper part to allow its movement, and there is a sealing between the cavities an element forming, together with the rod, a unit for setting pressure.

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