JP2668115B2 - Calibrated gas pressure applicator - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to a device for providing a calibrated (calibrated) gas pressure. The device of the present invention can be used to provide other calibrated gas pressures such as calibrated nitrogen pressure, but preferably comprises a device that provides the most commonly needed calibrated air pressure. In a particularly preferred embodiment, the present invention relates to a device for providing a calibrated low air pressure, for example, a calibrated low air pressure source (close to atmospheric pressure) for calibrating a commercially used pressure transducer. But slightly higher pressures) are widely needed. For this reason, it is assumed that the present invention can be used with gases other than air and that it can be calibrated not only at slightly above atmospheric pressure but also at slightly below atmospheric pressure. Of the low air pressure source of. PRIOR ART AND PROBLEMS Conventionally, a number of means of providing calibrated air pressure have been provided, most of which are, for example, due to the difficulty in measuring the very small forces involved. With the problem of inaccuracies at very low pressures. The present invention provides an apparatus that provides a source of calibrated low pressure air that can be varied in pressure as desired and that can be accurately measured. This calibrated air pressure is applied to, for example, a commercially available pressure transducer and used to test the accuracy of that transducer. (Means for Solving the Problems) According to a first feature of the present invention, there is provided a device for providing a calibrated gas pressure, the device including a piston mounted in a cylinder, and the piston and the cylinder being adjacent to each other. A gap is provided between the walls and the cylinder is fully closed at one end to define a sealed chamber, which includes a gas outlet at calibrated pressure and a variable outlet valve, with the gas inlet at the piston. Provided on the wall of the adjacent cylinder, wherein the piston includes means for engaging the force measuring device, wherein in use gas is supplied to the gas inlet and passes into the chamber to provide a calibrated gas pressure in the chamber, An apparatus is provided in which the pressure is measured by a force measuring device. The piston may be mounted in the cylinder by means of suspension which keeps the piston in proper clearance between the piston and cylinder walls and allows the piston to move parallel to the axis of the cylinder. The suspension means may comprise parallel link interlocking means mounted at each axial end of the piston. The variable outlet valve may comprise a variable needle valve. The gas supply means is provided at a position adjacent to the midpoint of the height of the piston. If the gas comprises air, the piston end opposite the chamber is preferably opened to the atmosphere. Thus, in use, air is supplied to the air inlet and passes in a layered manner in both directions toward the end of the piston, which opens to the atmosphere, and toward the chamber through the gap between the piston and the cylinder, and enters the chamber. It flows in and escapes from the chamber via a variable outlet valve. The variable outlet valve is adjusted to provide the desired pressure in the chamber that can be measured by a force measuring device, such as a weight measuring device such as a balance, which is suitable for the purpose and sufficiently accurate. The balance can be connected directly to the piston by means described below and the pressure in the chamber can be measured from the known diameter of the piston and the apparent weight of the piston.
Because of the gap between the piston and the cylinder walls, the piston is free to move within the cylinder. As air passes in both directions through the gap, the resistance created by the movement of air toward the chamber to the piston is balanced by the resistance created by movement of air through the gap in the opposite direction to the outlet. According to a second aspect of the invention, there is provided a device for providing a calibrated gas pressure, comprising a piston mounted in a cylinder, wherein a gap is provided between adjacent walls of the piston and the cylinder, the cylinder comprising: A cylinder closed entirely at the end to define a sealed chamber, the sealed chamber including a gas outlet at a calibrated pressure and a variable inlet valve, wherein a gas outlet connected to the pressure reducing means has a cylinder adjacent to the piston. Means for engaging the force measuring device with the piston provided on the wall of
In use, a gas is provided to the variable inlet valve and passed into the chamber to provide a calibrated gas pressure within the chamber, the gas pressure being measured by a force measuring device. Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings. FIG. 1 of the accompanying drawings shows a device for providing calibrated (calibrated) low-pressure air, comprising a cylinder 10 having a circular cross section with a piston 11 mounted therein. . The piston 11 is mounted so as to be movable in the cylinder 10 by parallel link interlocking means 12 and 13 provided at both ends in the axial direction thereof. Link interlocking means 12, 13
Will be described in detail later. An annular gap of 0.05 mm is provided between the piston 11 and the cylinder 10. The upper end of cylinder 10 is closed by a top cover plate 14 to form a substantially sealed chamber 16. The cover plate 14 includes two ports, one port having a calibrated gas outlet through which a calibrated pressure air is supplied, and an outlet fitting 17 having a variable outlet in the form of a needle valve 18 at the other port. A valve is provided. Air inlet ports 19 are provided in the wall of the cylinder 10, these air inlet ports 19 are arranged at different positions along the circumference of the cylinder 10 and at the same time, they are located at substantially the exact ends between the axial ends of the piston 11. It is provided at an intermediate position. The end of the cylinder 10 on the side opposite to the chamber 16 is not sealed, and a series of air outlets 21 are provided.
21 are arranged at different points along the circumference of the cylinder 10 adjacent to the end of the piston 11 opposite to the chamber 16. The piston 11 is located at the lower end in FIG.
It includes a means for connecting to a force measuring means, here a rod 22, which may be provided in the form of a weight measuring means. The weight measuring means may be of any suitable form, such as a zero balance (null balance) 20 with a digital readout. Zero scales are rods through which force and weight are applied to the scale.
25 is one that does not move or moves very little when weight or force is applied to it. Also,
This type of scale has the function of preloading the rod 25,
The scale's digital output can be zeroed to give a zero reading, and the scale only reads weight or force gains and losses. In use, the rod 22 is placed directly on the rod 25. In order to prevent the overload from being transmitted from the piston 11 to the scale 20, the rod 22 is not directly connected to the piston 11,
It is connected via a spring connection 23, whose details are shown in the figure. The device can be mounted on the scale 20 as follows. Scale
20 includes a metal ring 24 mounted on its top surface and surrounding a rod 25, and the device is attached to ring 24 by machine screws 26 which pass through ring 27 mounted around the outer surface of cylinder 10. Therefore, the device can be removed from the scale by simply loosening the machine screw 26, and vice versa. Next, the parallel link interlocking means 12, 13 will be described with reference to FIGS. A mounting plate 28 is provided in the chamber 16 on one side of the cylinder 10, and the mounting plate 28 supports a link as a rigid frame 31 extending transversely to the axis of the chamber 16 as a rigid frame 31. 29 is clamped. Another flexible spring plate 32 is mounted on the opposite side of the frame 31, and is clamped to the end surface of the piston 11 by a mounting plate 33. The link interlocking means 13 has the same structure and is parallel to the link interlocking means 12. In this way, the two link interlocking means 12 and 13 form a parallel arm link mechanism, and the axis of the piston 11 is always kept parallel to the axis of the cylinder 10. The axial movement of piston 11 is
Limited by a plate 36 mounted at each end of the ten. There is a small gap 15 (generally 0.05 mm) between both adjacent cylindrical walls of the cylinder 10 and piston 11, and link interlocking means
It will be appreciated that 12,13 also prevent slight deviations of the axial movement of the piston 11. Since the outlet fitting 17 is provided on the axis of the cylinder and piston and is attached to the top cover plate by screws,
Note that it can be easily removed. The top surface of the piston 11 located in the chamber 16 has a fitting 34 on the axis of the piston 11 which includes an internal thread coaxial with the axis of the piston 11. Other structural details of the device will be apparent from the drawings. All of the above components are made of stainless steel. The operation of the device of the present invention will be described below. In use, the device is coupled to the balance by machine screws 26 which engage a mounting plate 28. In this state, the rod 22 is placed on the rod 25 of the scale 20. The outlet fitting 17 is removed, and then air at a substantially constant pressure is supplied to the air inlet port 19. Air enters the inlet port 19, part of which goes upwards through the gap 15 into the chamber 16, part of which goes through the gap 15 and the air outlet 21.
Heading downward. Pressure at air outlet 21 and chamber 16
Since the pressure inside is the same, the proportion of air going in each direction is substantially the same. That is, the resistance between the air trying to move the piston and the piston is balanced by an equal flow of air in both directions. In any case, the flow of air is always kept low enough to be laminar without turbulence. The instrument can then be calibrated by screwing the weighing pan 30 through the hole in the top cover plate 14 after removing the outlet fitting 17 and engaging the female thread of the fitting 34. The weight is added to the weighing pan 30, and the scale reading is noted. Once the device has been checked for calibration, the weighing pan 30 is removed and the outlet fitting 17 is replaced and, if desired, reconnected to the pressure transducer 35 generally to be tested. Zero scale 20. The pressure in the chamber 16 can be changed by turning the variable needle valve 18 or changing the pressure of the air supplied to the air inlet port 19. The pressure in the closed chamber 16 gives a force applied to the upper surface of the piston 11, and this force is transmitted to the balance via the piston 11 and the rod 22. That is, the pressure in the chamber, and thus the calibrated air pressure supplied through the outlet fitting 17, can be measured based on the output readings of the scale, and the weight indicated by the scale is determined by the pressure in the chamber and the piston.
11 Given by multiplication with the known area of the top surface (generally 100 cm ² ). The output reading of the pressure transducer 35 may be calibrated against the digital reading of the scale 20. This provides a pneumatic source that can be accurately calibrated by the balance and used, for example, to calibrate pressure transducers. The present apparatus is not limited to the method described above, and can be used in another method. For example, if a gas other than air is passed through the inlet port 19, the gas pressure can be measured. It is also possible to measure air pressures below atmospheric pressure, which can be achieved, for example, by creating a partial vacuum at the air inlet port 19. In this case, the air is a needle valve
It flows through 18 to the inlet port 19 and creates a pressure in the chamber 16 slightly below atmospheric pressure. That is, the air flows from the needle valve 18 to the chamber 16 to the gap 15 to the air inlet port 19. In this sense, the needle valve 18 functions as a variable inlet valve and the air inlet port 19 functions as a gas outlet. A similar structure can be used to measure the pressure of other gases below atmospheric pressure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view of a calibrated low-pressure air application device according to the present invention, and FIG. 2 is a plan view of the device shown in FIG. 1 with the top cover removed. Explanation of symbols 10 …… Cylinder, 11 …… Piston 12,13 …… Suspension means (parallel link interlocking means) 15 …… Gap, 16 …… Closed chamber 17 …… Outlet fitting 18 …… Variable outlet or inlet valve (Variable needle valve) 19 …… Gas inlet or outlet 20 …… Force measuring device (scale) 22 …… Engagement means (rod)

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Henry Rosenberg               East Sussex, England               Istings, Canterbury Rise                 6                (56) References JP-A-55-30682 (JP, A)

Claims (1)

(57) [Claims] A piston mounted within the cylinder, wherein a gap is defined between adjacent two walls of the piston and the cylinder;
The cylinder is closed at one end to define a sealed chamber, the piston end opposite the sealed chamber is open to the atmosphere, the piston having means for engaging a force measuring device, and a gas in use. Is supplied to the gas inlet to enter the closed chamber, and the gas pressure supplied to the closed chamber is measured by the force measuring device via the piston to obtain a calibrated gas pressure applying device. Where the closed chamber comprises a calibrated gas pressure outlet for supplying the calibrated gas pressure and a variable outlet valve for adjusting the gas pressure in the closed chamber to obtain a desired calibrated gas pressure, Calibrated gas pressure applying device, wherein an inlet is provided in the cylinder wall portion adjacent to a side surface of the piston. 2. Suspension means for maintaining the piston at a predetermined clearance between both walls of the piston and the cylinder, and for allowing the piston to move parallel to the axis of the cylinder,
Apparatus according to claim 1, wherein the piston is mounted in a cylinder. 3. 3. A system according to claim 2, wherein said suspension means comprises parallel link movement means mounted on each axial end of said piston.
Item. 4. The device according to any one of claims 1 to 3, wherein the variable outlet valve comprises a variable needle valve. 5. The device according to any one of claims 1 to 4, wherein the gas inlet is provided at a position adjacent to an intermediate point of the height of the piston. 6. The piston according to any one of claims 1 to 5, wherein the force measuring device is directly coupled to the piston and the pressure in the closed chamber is measured from a known diameter of the piston and an apparent weight of the piston. Equipment. 7. A piston mounted within the cylinder, wherein a gap is defined between adjacent two walls of the piston and the cylinder;
The cylinder is closed at one end to define a sealed chamber, the piston end opposite the sealed chamber is open to the atmosphere, the piston having means for engaging a force measuring device, and a gas in use. Is supplied to a variable inlet valve into the closed chamber, and the gas pressure supplied into the closed chamber is measured by the force measuring device via the piston to obtain a calibrated gas pressure. The apparatus, wherein the closed chamber comprises a calibrated gas pressure outlet for providing a calibrated gas pressure, and a variable inlet valve for adjusting a gas pressure in the closed chamber to obtain a desired calibrated gas pressure. Calibrated gas pressure applicator, wherein a gas outlet connected to the means is provided in the cylinder wall adjacent to the side of the piston. 8. Suspension means for maintaining the piston at a predetermined clearance between both walls of the piston and the cylinder, and for allowing the piston to move parallel to the axis of the cylinder,
8. The device according to claim 7, wherein the piston is mounted in the cylinder. 9. The suspension means comprises parallel link movement means attached to each axial end of the piston.
Item. 10. 10. A device according to any one of claims 7-9, wherein the variable inlet valve comprises a variable needle valve. 11. The device according to any one of claims 7 to 10, wherein the gas outlet is provided at a position adjacent to an intermediate point of the height of the piston. 12. The force measuring device is directly connected to the piston,
12. A device according to any one of claims 7 to 11, wherein the pressure in the chamber is measured from the known diameter of the piston and the apparent weight of the piston.