KR20000027175A - Apparatus for measuring dropping distance of noncontact piston of poise pressure gauge - Google Patents

Abstract

PURPOSE: An apparatus for measuring dropping distance of noncontact piston of poise pressure gauge is provided to accurately measure a real moving distance of a piston by sensing a position movement of a core ring and displaying a current position, a dropping rate and a dropping distance on a digital display. CONSTITUTION: A pressure adjusting device(2) in which a handle(2a) is installed is formed to a face of one side of a frame(1). A poise providing bell(3) in which a cylinder and a piston are inserted is formed to one side of a upper surface of the frame(1). A certain number of poises(4) are formed on a peripheral surface of the poise providing bell(3). A measuring object pressure gauge(5) is coupled on a pressure gauge installing nipple(6) in the other side of the upper surface of the frame(1). A core ring(10) is inserted into a peripheral surface of a piston(9). A coil(13) having primary and secondary coils is installed on an inner circumference of a supporting nut(12). A display(15) is installed to an upper surface of one side of the frame(1).

Description

Non-contact piston drop distance measuring device of deadweight tester

The present invention relates to a piston drop distance measuring apparatus of a deadweight type pressure gauge, and more particularly, to combine a core ring with a high throwing ratio around the piston, and to move the piston by winding a coil around a certain distance from the outer peripheral surface of the core ring. A non-contact piston drop distance measuring apparatus for a deadweight tester configured to display the current position, drop rate, and drop distance of a piston on a digital display by sensing the positional movement of the core ring.

Deadweight testers are so-called primary pressure gauges that measure pressure directly based on the principle of pressure, that is, the magnitude of the force acting on a unit area.The basic principle is simple, repeatability and long term Due to its excellent stability, it has been widely used as a reference or standard for secondary pressure gauges used in laboratories and industrial sites.

These deadweight testers are classified into hydraulic and pneumatic types according to the type of fluid used. The main components are piston / cylinder devices, pressure generating devices, pressure control devices and weights.

Figure 1 is a perspective view showing the overall structure of a general deadweight tester, as shown in the deadweight pressure gauge is a pressure regulator (2) is provided with a handle (2a) on one side of the frame (1) made of a rectangular enclosure Is mounted, one side of the upper surface of the frame (1) is a cylindrical weighting bell (3) having a cylinder and a piston built therein is formed to be able to move up and down with the piston, the outer peripheral surface of the weight applying bell (3) The weight 4 is mounted in multiple stages, and on the other side of the upper surface of the frame 1, the pressure gauge 5 to be measured is coupled to the pressure gauge mounting nipple 6. In the figure, reference numeral 7 is a bar engraved with a scale for detecting the piston position.

The pressure measurement process in a deadweight tester having such a structure is as follows. First, the handle 2a of the pressure regulating device 2 is rotated so that the fluid stored in the fluid reservoir (not shown) is exerted with a predetermined hydraulic pressure through a fluid pipe connected to the lower end of the piston and the pressure gauge mounting nipple 6. .

When the hydraulic pressure is applied to the lower part of the piston in this way, the piston rises vertically upward, and together with the weight-applying bell (3) on which the weight is raised, the hydraulic force and weight of the weight acting on the underside of the piston When is equilibrated, the piston will stop at a position above the original position. At this time, the pressure of the same pressure as the pressure applied to the piston is also transmitted through the pressure gauge mounting nipple 6 to which the measurement target pressure gauge 5 is coupled.

On the other hand, the pressure of the deadweight tester is determined by the weight (4) mounted on the weight application bell (3) or by the weight of the weight divided by the cross-sectional area of the piston. The pressure value indicated by the indicator of the pressure gauge 5 is compared, and the pressure gauge 5 is corrected.

These deadweight testers must be equipped with a device to observe and determine the vertical position of the piston within the operating range of the piston during pressure measurement. According to the International Recommendation on the Piston Drop Rate of Pressure Gauges, the piston drop rate should be in accordance with the manufacturer's specifications, but without the specification, the piston drop rate should not exceed the values given in Table 1 below.

Table 1

Pressure transfer medium Upper limit of measurement range (Mpa) Descent rate for accuracy class (mm / min) 0.005 0.01 0.02 0.05 0.1 0.2 Gas gas liquid 0.1 to 1 or less 1 to 0.6 to 6 or more 6 or more to 500 or less 1 1 1 2 2 -2 2 2 3 3 -0.4 0.4 0.4 1 2 31.5 1.5 1.5 1.5 3 3

Therefore, in order to accurately measure the pressure in a deadweight tester, a device for detecting the position of the piston and monitoring the state of movement of the piston is required. The same three kinds are known.

First, as shown in the device of Fig. 1, the rod is vertically mounted around the piston on which the weight is lifted, and the position of the piston and the drop state are compared visually by comparing the scale and the horizontal position of the weight. Observation However, there is a disadvantage in that the minute distance change of the piston cannot be observed in the way of using a graduated rod.

In the second type, the rod is formed at the lower end of the weight application bell and the rod provided with a pointer (indicator) indicating the scale at one end is rotatably installed around the piston using the lever principle. A magnet is installed between the center of rotation and the pointer, the end of which is in contact with the metal ring, so that the rotation of the rod occurs according to the lifting movement of the weight application bell so that the scale indicated by the pointer provided at the end of the rod changes. .

However, in the method using the magnet and the lever principle, it is difficult to measure the sensitive behavior of the piston by applying a small force to the weight application bell.

The third type is equipped with a laser generator directly on top of the piston, and laser is measured on the upper surface of the piston from the laser generator to measure the distance of the piston movement through the distance measurement result between the laser generator and the upper surface of the piston. That's the way.

However, in this laser distance measuring method, the diffuse reflection of the laser irradiated to the upper surface of the piston is generated, so that the error of distance measurement is large and the installation cost of the laser measuring device is not only high but also needs to be separately installed outside the frame. It is pointed out that the complexity of the system is caused.

The present invention has been made in view of the above-mentioned disadvantages and problems pointed out in the piston drop distance measuring apparatus of the conventional deadweight tester, and combines a core ring with a high throwing ratio around the piston and has a constant distance from the outer circumferential surface of the core ring. Winding the primary and secondary coils based on the Linear Variable Differential Transformer (LVDT) principle away from each other to detect the displacement of the core ring moving with the piston to display the piston's current position, drop rate and drop distance on the digital display. An object of the present invention is to provide a non-contact piston drop distance measuring apparatus for a deadweight tester.

Another object of the present invention is to simplify the apparatus by installing the component for measuring the drop distance of the piston inside the weight application bell without being exposed to the outside of the apparatus, while at the same time measuring the current position, the drop rate and the drop sensitivity of the measured piston. The present invention provides a non-contact piston drop distance measuring apparatus for a deadweight tester that enables the measurement result to be displayed on a display mounted on a frame so that the measurement result can be easily recognized.

1 is a perspective view showing the overall structure of a general deadweight tester.

Figure 2 is a perspective view showing the overall structure of an embodiment deadweight tester of the present invention.

Figure 3 is a longitudinal sectional view of the main portion of the deadweight tester of the present invention.

((Description of the code for the main part of the drawing))

1. Frame 2. Pressure generator

3. Weight Approval Bell 4. Weight

8. Cylinder 9. Piston

10. Coring Ring 12. Support Nut

13. Coil 15. Display

The object of the present invention is a piston to which the pressure of the fluid is applied to the lower portion, a cylinder installed around the piston to guide the vertical lifting movement of the piston, a weight applying bell coupled to the upper portion of the piston to move with the piston, The position and drop rate of the piston are determined by the core ring fitted to the outer circumferential surface of the piston, the coil wound around the core ring to detect the secondary output by the displacement of the core ring, and the secondary output from the coil. It is achieved by the structure which consists of a display which displays the fall sensitivity etc.

In the piston drop distance measuring apparatus of the present invention, there is a technical feature that can measure minute distance changes of 0.1 mm or less in a non-contact manner through a core ring integrally formed with a piston and a coil installed at a fixed position around the core ring.

Details of the object and technical configuration of the present invention and the resulting effects thereof will be clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of the present invention.

First, Figure 2 is a perspective view showing the overall structure of an embodiment of the deadweight tester of the present invention, Figure 3 is a longitudinal sectional view of the main portion of the deadweight tester of the present invention. In the drawings, the same parts as in the prior art are given the same reference numerals as in FIG.

As shown, the deadweight type pressure gauge according to the present invention is provided with a pressure regulating device (2) equipped with a handle (2a) on one side front of the frame (1) made of a rectangular box, on one side of the upper surface of the frame (1) Cylindrical weight applying bell (3) having a cylinder and a piston inside therein is formed to be able to move up and down with a piston, and a predetermined number of weights (4) are mounted on the outer circumferential surface of the weight applying bell (3) in multiple stages. In addition, on the other side of the upper surface of the frame 1, in the deadweight type pressure gauge in which the measurement target pressure gauge 5 is coupled on the pressure gauge mounting nipple 6, the vertical lifting movement is guided by the cylinder 8, and the pressure is adjusted on the lower end. The core ring 10 having a high projection rate is extrapolated to the outer circumferential surface of the piston 9 on which the hydraulic pressure generated by the device 2 acts, and the nut is coupled to the upper portion of the main pressure housing 11 supporting the cylinder 8. On the inner circumferential surface of the supporting nut 12 The display unit 15 is mounted with a coil 13 composed of primary and secondary coils on one side of the frame 1, and receives an output from the coil 13 on the upper surface of the frame 1 to display a moving distance and a drop rate of the piston. The structure is made up.

At this time, the core ring 10 is a cylindrical material made of a material having a large throw ratio, for example, pure iron, and fixed in an extrapolated state to the piston 9, and is provided inside the support nut 12 outside the core ring 10. Although not shown in the figure, the coil 13 to be installed is connected to the display 15 through a lead wire and configured to apply an output value to the display 15.

The lower portion of the piston (9) is inserted into the center of the main pressure housing 12, the hydraulic passage 16 for communicating with the hydraulic generating device 2 to apply hydraulic pressure to the piston (9) is provided, the main pressure housing ( In the space between the 12 and the weight application bell (3) is provided a drive sleeve 18, the roller pin 17 is protruded on one side.

At this time, as shown in FIG. 2, the pulley 18a is integrally formed at the lower portion of the drive sleeve 18 so that the drive sleeve 18 is rotated by a rotation driving force transmitted from a motor (not shown). The rotational force of the driving sleeve 18 is transmitted to the contact pin 20 fixed on the carrier 19 coupled to the upper portion of the weight application bell 3 through the roller pin 17 and thus the weight 4 It is configured to rotate the weight application bell (3) on which is mounted.

As such, the reason for rotating the weight application bell 3 on which the weight 4 is mounted is to keep the piston 9 in a rotational state when the piston 9 is injured, so that the frictional portion between the two members is not motion friction but static friction. This is to reduce the error caused by friction by maintaining the state.

The upper end of the piston (9) is inserted into the through hole formed perpendicular to the center of the carrier 19, and fixed in contact with the lower end of the T bolt 21 is fastened from the top of the through hole, the carrier 19 Sleeve 22 and stopper 23 are mounted on the lower outer circumferential surface and the lower end of the pad, respectively, and a bearing 25 supported by the bearing holder 24 is provided on the upper outer side of the sleeve 22.

Accordingly, the vertical lifting movement distance of the piston 9 is determined by "D", and when the piston 9 is moving up and down, the core ring 10, the carrier 19, the T bolt 21, and the weight are coupled thereto. The bell 3 and the weight 4 are moved up and down together, and these components are maintained in a rotational state at a constant rotational speed by the rotation of the drive sleeve 18.

In this way, the components including the piston (9) is installed so as to be able to move up and down and rotational state, the main pressure housing 11, the support nut 12, the coil 13, the bearing including the cylinder (8) The holder 24 and the bearing 15 are always kept in a fixed position.

The piston falling distance measuring process of the piston falling distance measuring device of the present invention deadweight pressure gauge made as described above is as follows.

First, when the hydraulic pressure is applied through the hydraulic passage 16 under the piston 9 by the driving of the hydraulic generator 2 or when the piston 9 is raised by the hydraulic pressure and the time elapses, the piston 9 ) Moves up or down, and as the piston 9 moves, the core ring 10 coupled thereto is also moved.

When the core ring 10 is moved in this manner, a relative position change between the coil 13 and the core ring 13 installed around the core ring 13 occurs, thereby causing a change in induced electromotive force.

This change in induced electromotive force is transmitted to the display 15 installed on the frame 1 and displayed on the display as a result value of the position of the piston, the drop rate, the drop sensitivity, and the like.

As described above, in the piston drop distance measuring apparatus of the deadweight tester according to the present invention, a core ring having a high throwing ratio is fitted to the piston, and the first and second coils are wound on the outside by LVDT principle. As it is a non-contact structure that detects the output of the vehicle and displays the position, drop rate, and drop sensitivity on the display, the actual moving distance of the piston can be measured very precisely (less than 0.1mm). It has the advantage of being.

In addition, the device of the present invention also has the advantage that as the core ring and coil is mounted inside the weight application bell can simplify the device itself and reduce the manufacturing cost.

Claims (1)

In a deadweight type pressure gauge, a coil and a core ring consisting of a cylindrical core ring having a high projection rate extrapolated around a piston, and a primary and secondary coil fixedly installed at a constant interval from the core ring around the core ring. Non-contact piston drop distance measuring apparatus of the deadweight type pressure gauge, characterized in that the display is displayed by receiving the output generated from the coil by the movement of the piston.