JPH0627692B2 - 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 trying to measure the specific gravity of a liquid,
As shown in FIG. 3, the glass tube hydrometer 51 is floated on the liquid 50 whose specific gravity is to be measured.
Since the glass tube pycnometer 51 rises and falls due to the difference in the liquid gravities of the liquid 50, the specific gravity of the liquid 50 can be measured by measuring the displacement of the ups and downs.

The glass tube pycnometer 51 is provided with a weight 52 at the bottom thereof to form a float. Further, the elongated portion 53 on the upper portion is provided with a scale 54 for detecting the ups and downs of the hydrometer 51 due to a change in the liquid specific gravity to increase the specific gravity.

Further, in the conventional specific gravity measuring device shown in FIG. 4, a member to be detected is attached to the tip of the bar 56 projecting above the hollow float 55.
57 is attached, and the ups and downs of the float 55 due to the difference in the liquid specific gravity of the liquid 50 are detected by the position detection sensors 58 provided on both sides of the detected member 57, and the specific gravity of the liquid 50 is measured. Here, the position detection sensors 58 attached to both sides of the housing 59 are made of a coil or the like, and the detected member 57 attached to the bar 56 slidable in the housing 59 is made of an iron piece or the like.

Therefore, if the float 55 in the liquid 50 rises and falls due to the difference in the specific gravity of the liquid 50, the iron piece of the member to be detected 57 moves up and down, and the inductance of the coil of the position detection sensor 58 changes. By doing so, the specific gravity of the liquid 50 can be measured.

[Problems to be Solved by the Invention] As described above, conventionally, for example, the specific gravity of the liquid 50 is measured by detecting ups and downs due to the difference in the liquid specific gravities of the glass tube hydrometer 51 and the float 55 submerged in the liquid 50. Was there.

By the way, in the specific gravity measuring apparatus of FIG. 4, the bar 56 has to be slidable in the housing 59, and the apparatus needs a movable part, which causes a problem that the configuration of the apparatus becomes complicated.

Further, when dust adheres to the through hole 60 of the housing 59 due to long-term use or the like, the smooth vertical movement of the bar 56 is impeded, which causes a problem that the specific gravity of the liquid 50 cannot be accurately measured.

Further, in the above-mentioned glass tube specific gravity meter 51 and the above specific gravity measuring device, the change in buoyancy due to the difference in the specific gravity of the liquid 50 is converted into the vertical movement (change in position) of the specific gravity meter 51 and the float 55 to measure the specific gravity of the liquid 50. Therefore, there is also a drawback that a measurement error is likely to occur.

If the liquid 50 is flowing, the hydrometer 51 or float
55 is shaken and the specific gravity of the liquid 50 cannot be measured accurately.

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 liquid specific gravity measuring apparatus of the present invention has a small-diameter cylindrical portion that is eccentric to the central axis and has an eccentric axis that is eccentric in parallel with the central axis. Is supported by being inserted into the recess of the housing, the inner magnet mounted inside the small-diameter cylindrical portion, and rotatable around the recess of the housing with the inner magnet interposed therebetween. An outer magnet attached to the magnet coupling attracts each other to form a pair, and one end is attached to the outer magnet side,
The other end is fixed to the housing side, and the structure is provided with a stress sensor that detects a moment generated around the axis of the small diameter cylindrical portion by the buoyancy of the float.

[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, when the specific gravity measuring apparatus is configured by using the present invention, the apparatus does not need any moving parts and the configuration of the apparatus is simple. Be converted.

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 sectional view of the fluid specific gravity measuring apparatus of the present invention seen from above, and FIG. 2 is a side sectional view of this apparatus.

In FIG. 1 and FIG. 2, for example, a cylindrical float 1 made of metal and having a closed hollow structure is displaced from the central axis C passing through the center of gravity by a predetermined distance S and is parallel to the central axis C. Bearing fitting recesses 2 and 3 for forming an eccentric shaft (Z axis in the drawing) Q are formed on the left side surface and the right end side. The bearings 4, 5 are tightly fitted in the bearing fitting recesses 2, 3. The protruding shafts 7 and 8 formed in the housing 6 and provided on the float 1 side are tightly fitted to the inner rings of the bearings 4 and 5. As a result, the cylindrical float 1 is rotatable about the eccentric axis (Z axis) Q with respect to the fixed housing 6.

Here, the housing 6 is provided with a flange 9 on the right side of the float 1 that abuts the outer wall of a storage tank that stores the liquid to be measured whose specific gravity is to be measured. A cover 10 surrounding the float 1 is integrally provided from the base end of the flange 9, and the cover 10 has a plurality of holes.
Float 1 with 11 formed and plugged into storage tank
Is soaked with the liquid to be measured. The protruding shaft 7 is formed on the float support 14 of the housing 6 which is integrally fitted to the left end of the cover 10.

Further, inner magnets 13, 13 are fixed to the inside of a small-diameter cylindrical portion 12 that is concentric with the eccentric axis Q and projects to the right side (flange 9 side) of the float 1. The bearing fitting recess 3 is formed on the right side surface of the small diameter cylindrical portion 12.

The housing 6 is formed with a fitting recess 15 that fits in the small-diameter cylindrical portion 12, and the protruding shaft 8 is provided on the inner surface side of the fitting recess 15. On the outer surface side of the fitting concave portion 15, a rotor protruding shaft 16 is integrally formed coaxially with the protruding shaft 8. Bearings 17, 17 are tightly fitted to the rotor protruding shaft 16. And these bearings 17, 17
The outer ring of the rotor rotates the outer periphery of the fitting recess 15
The inner circumference of 18 is closely fitted.

Outer magnets 19, 19 are attached to the rotor 18 at positions facing the inner magnets 13, 13 with screws 20 via support members 33, 33. The outer magnets 19, 19 are adapted to attract the inner magnets 13, 13 to form a magnet coupling 31. This magnet coupling 31 is configured. By this magnet coupling 31, the moment about the eccentric axis (Z axis) Q of the cylindrical float 1 is transmitted to the rotor 18 side.

A mounting plate 22 is fixed to the rotor 18 with screws 21, and one end of a sensor support 23 is fixed to the mounting plate 22. A stress sensor 30 such as a strain gauge that does not generate displacement is attached to the small diameter portion of the sensor support 23. The stress sensor 30 is made of a nickel alloy such as manganin or constantan, the resistance of which changes depending on the compressive force and the tension.

Also, the ring-shaped board 24 fitted into the bearing mounting portion 18a of the rotor 18 is fixed to the flange 6 by the screws 25 and 26.
It is fixed to the fitting recess 15 of. This board 24 constitutes a stator. The rotor 18 is formed with an elongated hole 27 that allows the head 25a of the screw 25 to escape. A mounting plate 28 is fixed to the board 24 with screws 29, and the other end of the sensor support 23 is fixed to the mounting plate 28.

As a result, one end of the stress sensor 30 has an eccentric shaft (Z axis).
Magnet coupling 31 on the float 1 that rotates with Q
, And the other end is indirectly fixed to the housing 6.

At this time, the extension line XX ′ of the stress sensor 30 is changed to the eccentric axis (Z
Float 1 and rotor so that it passes through axis Q and center line C
The magnets 18 and 19 are magnetically coupled to each other.

The rotor 18, the sensor 24, and the like are covered by the cylindrical cover 32 of the housing 6.

Next, the principle that the specific gravity of the liquid to be measured can be measured by the above-described specific gravity measuring device will be described.

When the float 1 is dipped in the liquid to be measured, the cylindrical float 1 has a moment M _w due to its own weight (Y ′ direction) and a buoyancy force for placing the float 1 in the liquid to be measured ( The moment M _F (direction opposite to the moment M _w ) due to the Y direction) acts as the moment M about the eccentric axis (Z axis) Q.

Here, if the diameter of the cylindrical float 1 is D, the total length is L, and the specific gravity is ρ _f , the moment M _w is Becomes S is the distance between the central axis C and the eccentric axis (Z axis), and is the amount of eccentricity (moment arm).

If the unknown specific gravity of the measured liquid is ρ, the moment M _F is Becomes

Therefore, the moment M about the eccentric axis (Z axis) Q 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 rotational displacement about the eccentric axis (Z axis) Q of the cylindrical float 1. The above-mentioned stress sensor 30 such as a strain gauge that does not generate the stress is used.

To actually measure the specific gravity of the liquid to be measured using the specific gravity measuring device, one part of the float is inserted into the storage tank from the side so that the XX ′ line is horizontal,
To be submerged by the liquid to be measured in the tank.
At this time, the flange 9 is in contact with the outer wall of the storage tank.

The change in the specific gravity of the liquid to be measured in the storage tank appears as a change in the resistance of the stress sensor 30. Therefore, the specific gravity ρ of the liquid to be measured can be obtained by detecting this resistance change and calculating it with a microprocessor or the like.

[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, the device does not need any moving parts, 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.

In addition, a direct means of detecting the moment around the eccentric axis instead of measuring the specific gravity by 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 float position (ups and downs) as in the past. Since the specific gravity of the fluid to be measured is measured by, high-precision measurement is possible.

[Brief description of drawings]

FIG. 1 is a sectional view of a fluid specific gravity measuring apparatus according to an embodiment of the present invention as seen from above, FIG. 2 is a side sectional view of the specific gravity measuring apparatus, and FIG. 3 is a front view of a conventional hydrometer. FIG. 4 is a sectional view of a conventional specific gravity measuring device. In the figure, 1 ... Cylindrical float 2, 3 ... Bearing fitting recess 4,5, 17 ... Bearing, 6 ... Housing 7, 8, 16 ... Projection shaft, 9 ... Flange 10 ... Cover, 11 ... … Hole 12 …… Small diameter cylindrical part 13 …… Inner magnet 14 …… Float support 15 …… Mating recess, 18 …… Rotor 18a …… Bearing mount 19 …… Outer magnet 20, 21, 25, 26, 29 ...... Screws 22, 28 …… Mounting plate, 24 …… Board 27 …… Slot, 30 …… Stress sensor 31 …… Magnet coupling 32 …… Cylindrical cover

Claims (3)

[Claims] 1. A cylindrical float supported by a small-diameter cylindrical portion projecting from a side surface being fitted into a recessed portion of a housing with an eccentric axis line that is eccentric parallel to the central axis as a central axis. 2. An inner magnet attached to the inside of the small diameter cylindrical portion and an outer magnet rotatably attached to the outer periphery of the concave portion of the housing sandwiching the concave portion of the housing attract each other to form a pair. Become a magnetic coupling 3. A fluid having a stress sensor, one end of which is attached to the outer magnet side, the other end of which is fixed to the housing side, and which detects a moment generated around the axis of the small diameter cylindrical portion by the buoyancy of the float. Specific gravity measuring device.