JPH0627691B2 - Fluid specific gravity measuring device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for measuring specific gravity of a fluid, and particularly to accurately measuring the specific gravity of a fluid by using a cylindrical float having an eccentric shaft deviated from a center of gravity. The present invention relates to a specific gravity measuring device for a fluid.

[Prior Art] Conventionally, for example, when measuring the specific gravity of a fluid,
As shown in FIG. 4, the glass tube hydrometer 16 is floated on the liquid 15 whose specific gravity is to be measured.
The glass tube pycnometer 16 rises and falls due to the difference in the liquid gravities of the liquids 15. Therefore, the specific gravity of the liquids 15 can be measured by measuring the displacement of the ups and downs.

The glass tube specific gravity meter 16 is provided with a weight 17 at the bottom thereof to form a float. Further, the elongated portion 18 on the upper portion is provided with a scale 19 for detecting the ups and downs of the pycnometer 16 due to the change in the liquid specific gravity to increase the specific gravity.

Further, in the conventional specific gravity measuring apparatus shown in FIG. 5, a member to be detected is attached to the tip of the bar 21 projecting above the hollow float 20.
22 is attached, and the ups and downs of the float 20 due to the difference in the liquid specific gravity of the liquid 15 are detected by the position detection sensors 23 provided on both sides of the detected member 22, and the specific gravity of the liquid 15 is measured. Here, the position detection sensors 23 attached to both sides of the housing 24 are made of a coil or the like, and the detected member 22 attached to the bar 21 slidable in the housing 24 is made of an iron piece or the like.

Therefore, when the float 20 in the liquid 15 rises and falls due to the difference in the specific gravity of the liquid 15, the iron piece of the detected member 22 moves up and down, and the inductance of the coil of the position detection sensor 23 changes. By doing so, the specific gravity of the liquid 15 can be measured.

[Problems to be Solved by the Invention] As described above, in the conventional fluid specific gravity measuring device, for example, by detecting the ups and downs due to the difference in the liquid specific gravities of the glass tube hydrometer 16 and the float 20 submerged in the liquid 15, The specific gravity of 15 was measured. By the way, in the specific gravity measuring apparatus used in the specific gravity measuring apparatus of FIG. 5, the bar 21 must be slidable in the housing 24, and the apparatus needs a movable part, which complicates the configuration of the apparatus. There is a problem.

Further, when dust adheres to the through hole 25 of the housing 24 due to long-term use or the like, the smooth vertical movement of the bar 21 is hindered, which causes a problem that the specific gravity of the liquid 15 cannot be accurately measured.

Furthermore, the glass tube specific gravity meter 16 and the specific gravity measuring device measure the specific gravity of the liquid 15 by converting the change in buoyancy due to the difference in the specific gravity of the liquid 15 into the vertical movement (change in position) of the specific gravity meter 16 and the float 20. Therefore, there is also a drawback that a measurement error is likely to occur.

When the liquid 15 is flowing, the hydrometer 16 or float
Since 20 is shaken, the specific gravity of the liquid 15 cannot be accurately measured.

Therefore, the present invention has been proposed in order to solve such a conventional problem, and can simplify the configuration of the specific gravity measuring device, measure the specific gravity with high accuracy, and the specific gravity of a flowing liquid. An object of the present invention is to provide a device for measuring the specific gravity of a fluid capable of measuring

[Means for Solving the Problems] In order to achieve this object, the fluid specific gravity measuring apparatus of the present invention is supported horizontally in the fluid to be measured in the housing on an eccentric axis that is eccentric in parallel with the central axis. A cylindrical float whose supporting shaft is supported by a housing, and one end of which is attached to an appropriate position of the float and the other end of which is fixed to the housing, and which is generated around the eccentric axis of the float by buoyancy of the float. The structure is provided with a stress sensor for detecting the moment.

[Operation] In the present invention, the moment about the eccentric axis is detected with the moment arm of the component perpendicular to the buoyancy direction kept constant. Therefore, since the specific gravity of the fluid is measured without causing displacement (rotation) around the eccentric axis of the float, no movable part is required and the structure of the device is simplified.

Moreover, since the specific gravity is measured without converting the change in the buoyancy force due to the difference in the specific gravity of the fluid to be measured into the change in the vertical movement position of the float, highly accurate measurement is possible.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view of a cylindrical float for explaining an embodiment of the present invention, and FIG. 2 is a side view of the float.

In FIG. 1, a cylindrical float 1 made of metal, for example, has a closed hollow structure. In addition, at the position eccentric to the central axis C passing through the center of gravity of the cylindrical float 1, both side surfaces are
Support shafts 3a and 3b, which are eccentric shafts parallel to the central axis C, are provided so as to protrude from the 2a and 2b. The support shafts 3a and 3b are separated from the central axis C by a predetermined distance S. This distance S
Is the amount of eccentricity (moment arm) of the support shafts 3a, 3b with respect to the central axis C. Here, the total length of the cylindrical float 1 is L, and the outer diameter of the float 1 is D.

The cylindrical float 1 thus formed is attached to the support shaft 3
It is supported by a and 3b, and it is embedded in the liquid whose specific gravity is to be measured so that the extension line XX 'connecting the support shaft 3a or 3b and the central axis C is horizontal to the liquid surface. For example, a moment M based on the specific gravity of the liquid to be measured is generated around the support shafts 3a and 3b. By measuring this moment M, the weight of the measured liquid can be measured.

That is, the cylindrical float 1 pivotally supported by the Z-axis support shafts 3a, 3b has a moment M about the support shafts 3a, 3b.
Considering the above, the moment M _w due to the weight F ₂ (Y ′ direction) of the float 1 itself and the buoyancy F for placing the float 1 in the liquid to be measured in the opposite direction of this moment M _w.
The moment M _F due to ₁ (Y direction) will act.

If the known specific gravity of the cylindrical float 1 is ρf, the moment M _w is Given in.

If the unknown specific gravity of the measured liquid is ρ, the moment M _F is Given in.

Therefore, the moment M about the Z axis of the cylindrical float 1 is Becomes By detecting this moment M, the specific gravity ρ of the liquid to be measured in which the cylindrical float 1 is buried can be measured.

The specific gravity ρ of the measured liquid is Is required as.

Here, in order to satisfy the above equation for obtaining the moment M, it is necessary to prevent the rotational displacement of the cylindrical float 1 around the Z axis (support shafts 3a, 3b). For this reason,
To detect the moment M, a stress sensor such as a strain gauge that does not cause displacement is used. This stress sensor
It is made of a nickel alloy such as manganin or constantan whose resistance changes depending on the compressive force and tension.

In FIGS. 1 and 2, the stress sensor 4 is a cylindrical float 1.
The stress sensor 4 is fixed to a mount 11 provided on the side surface 2a of the stress sensor 4 via a support member 12, and the other end of the stress sensor 4 is fixed to one end of a support bar 5. The other end of the support bar 5 is fixed to a part of a housing (not shown) that supports the float 1 by eccentric shafts 3a and 3b.

The change in the specific gravity of the liquid to be measured appears as a change in the resistance of the stress sensor 4, and the specific gravity ρ is obtained by detecting this change in resistance and calculating it with a microprocessor or the like.

Next, another embodiment of the present invention will be described with reference to FIG.
FIG. 3 is a side view of the cylindrical float 6 viewed from one side surface 7. The cylindrical float 6 is provided with a support shaft 8, which is an eccentric shaft, at a position eccentric from the central axis C so as to be parallel to the central axis C and project from the side surface 7 side. Similarly, a support shaft is provided on the other side surface so as to protrude from the other side surface.

Further, a cylindrical flow path 9 is formed in the cylindrical float 6 concentrically with the support shaft 8 so as to penetrate the float 6. Here, the support shaft 8 is supported by the support member 10 in the cylindrical channel 9.

When measuring the specific gravity of the fluid to be measured using the float 6 as described above, the main flow of the fluid to be measured is passed through the cylindrical channel 9 and a part of the fluid to be measured is guided to the outer surface of the float 6. , The entire float 6 is immersed in the liquid to be measured. As a result, the specific gravity of the measured liquid flowing can be easily measured without shaking the float 6.

Here, the inner diameter of the cylindrical channel 9 can be appropriately selected. This is because the flow path 9 is concentric with the eccentric shaft and does not appear in the moment around the eccentric shaft.

By the way, in the above description, the case where the specific gravity of the liquid is measured has been described, but the specific gravity of the gas can be measured by reducing the weight of the floats 1 and 6 and making the inside of the floats 1 and 6 a vacuum. .

Further, the shapes of the floats 1 and 6 are not limited to the cylindrical shape,
Other shapes may be used.

[Effects of the Invention] As described above, according to the fluid specific gravity measuring apparatus of the present invention, the moment around the eccentric axis of the float is detected while the float arranged in the fluid to be measured is stationary, Since the specific gravity of the measurement fluid is measured, no moving parts are required, and the structure of the device can be simplified.

In addition, since there is no movable part, dust or the like does not interfere with the movement of the movable part, and a measurement error due to the inhibition of the movement of the movable part unlike the conventional case does not occur.

Also, instead of measuring the specific gravity by converting the change in buoyancy due to the difference in specific gravity of the fluid to be measured into the change in float position (ups and downs) as in the past, rather than detecting the moment around the eccentric axis, Since the specific gravity of the fluid to be measured is measured by the direct means of detecting the moment about the eccentric axis, highly accurate measurement is possible.

Furthermore, the specific gravity of the flowing fluid can be measured without causing the float to sway, unlike the conventional case.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a float constructed according to the present invention, FIG. 2 is a side view of the float, FIG. 3 is a side view of the float of another embodiment, and FIG. 4 is a conventional hydrometer. And FIG. 5 is a sectional view of a conventional specific gravity measuring apparatus. In the figure, 1 ... Cylindrical float, 3a, 3b ... Support shaft 4 ... Stress sensor, 5 ... Bar 6 ... Cylindrical float, 8 ... Support shaft 9 ... Cylindrical flow path, 10 ... Support material 11 ... … Mounting stand, 12 …… Supporting material

Claims (2)

[Claims] 1. A cylindrical float supported by a support shaft for horizontally supporting the fluid to be measured in a housing on an eccentric axis that is eccentric to the central axis. 2. Specific gravity measurement of a fluid having one end attached to a proper position of the float, the other end fixed to the housing, and a stress sensor for detecting a moment generated around the eccentric axis of the float by buoyancy of the float. apparatus.