JPH0627693B2 - 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, a liquid specific gravity measuring device of the present invention is a cylinder having an eccentric shaft eccentric in parallel with a central axis and having a channel formed concentrically with the eccentric shaft. -Shaped float is supported by the eccentric shaft and accommodated in the housing, and the fluid to be measured is caused to flow in the flow passage, and the fluid to be measured is guided from a part of the flow passage into the housing. It is characterized in that the float is immersed in the fluid to be measured, a sensor capable of detecting the moment of the float around the eccentric axis is arranged, and the specific gravity of the fluid to be measured is measured from the detection output of this sensor.

[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.

Further, a flow path is formed concentrically with the eccentric shaft of the float, and the main flow of the fluid to be measured is made to flow through this flow path, and a part of the fluid to be measured is guided to the housing so that the float is immersed in the fluid to be measured. Therefore, the specific gravity of the flowing fluid can be accurately measured without disturbing the float.

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

FIG. 1 is a sectional view of a fluid specific gravity measuring apparatus according to an embodiment of the present invention seen from above, and FIG. 2 is a side sectional view of this apparatus.

In FIG. 1 and FIG. 2, a central axis C passing through the center of gravity C
In order to form an eccentric axis (Z axis) Q parallel to the central axis C by a predetermined distance S, a projecting shaft 2 concentric with the eccentric axis Q on the left side surface and a small diameter concentric with the eccentric axis Q on the right side surface. A cylindrical portion 3 is provided. A bearing 4 is tightly fitted to the tip end of the protruding shaft 2, and an outer ring of the bearing 4 is tightly fitted to a bearing fitting recess 6 provided in a fixed housing 5. A bearing 7 is tightly fitted to the tip of the small-diameter cylindrical portion 3.
The outer ring is tightly fitted in the bearing fitting recess 9 provided at the base end of the fitting recess 8 of the housing 5 into which the small-diameter cylindrical portion 3 is fitted.

As a result, the cylindrical float 1 has the eccentric shaft (Z axis).
It is rotatable around Q.

A channel 10 is formed inside the eccentric shaft (Z-axis) Q concentrically with the small-diameter cylindrical portion 3, the float 1, and the protruding shaft 2 in series.

Further, the cylindrical portion 11 of the housing 5 surrounding the outer periphery of the float 1, the side plate portion 12 having the bearing fitting recessed portion 6 formed therein and fixed in contact with the cylindrical portion 10, the fitting recessed portion 8 and the cylindrical portion 11 are provided.
The continuous portion 13 between them forms a float chamber 14 that surrounds the float 1.

A plurality of communication holes 39 that communicate the flow passage 10 and the float chamber 14 are formed at the base end of the protruding shaft 2. A plurality of communication holes 40 that communicate the flow passage 10 and the float chamber 14 are also formed at the base end of the small diameter cylindrical portion 3. These communication holes 3
A part of the liquid to be measured flowing in the flow path 10 is guided to the float chamber 14 by 9,40, and the float 1 is immersed in the liquid to be measured.

Further, a pipe portion 15 is integrally formed so as to project from the base end portion of the fitting concave portion 8, and the flow passage 16 of the pipe portion 15 is continuous with the flow passage 10 in the small diameter cylindrical portion 3. A pipe portion 17 is integrally formed on the outer surface of the side plate portion 12 so as to project.
The flow path 18 of 17 is continuous with the flow path 10 in the protruding shaft 2.

Further, the inner rings of the bearings 19, 19 are tightly fitted to the pipe portion 15, and the inner rings of the rotor 20 which rotates the outer circumference of the fitting recess 8 are tightly fitted to the outer rings of the bearings 19, 19. It is fitted.

Here, an inner magnet is provided inside the small-diameter cylindrical portion 3.
21 and 21 are fixed. Outer magnets 22, 22 are attached to the rotor 20 at positions facing the inner magnets 21, 21 with screws 24 via support members 23, 23. The outer magnets 22, 22 are adapted to attract the inner magnets 21, 21 and form a magnet coupling 25. With this magnet coupling 25, the eccentric shaft (Z
The moment about the axis Q is transmitted to the rotor 20 side.

A mounting plate 27 is fixed to the rotor 20 with screws 26, and one end of a sensor support 28 is fixed to the mounting plate 27. A stress sensor 29 such as a strain gauge that does not generate displacement is attached to the small diameter portion of the sensor support 28. The stress sensor 29 is made of a nickel alloy such as manganin or constantan whose resistance changes according to a compressive force and a tension.

Further, on the left side of the rotor 20, a ring-shaped board body 30 that is tightly fitted in the pipe portion 15 is provided. This board 30 is a screw
Attaching plate to the fitting recess 8 of the flange 6 by 31,32,33
Fixed through 34. This board 30 constitutes a stator. The board 30 is also used as a bearing stop for the bearing 19. The rotor 20 is formed with an elongated hole 35 that allows the head 32a of the screw 32 to escape. Above board 30
A mounting plate 36 is fixed to the mounting plate 36 by a screw 37, and the other end of the sensor support 23 is fixed to the mounting plate 36.

As a result, one end of the stress sensor 29 has an eccentric shaft (Z axis).
Magnet coupling 25 on the float 1 that rotates with Q
, And the other end is indirectly fixed to the housing 5.

At this time, the extension line XX ′ of the stress sensor 29 is eccentric (Z
Float 1 and rotor so that it passes through axis Q and center line C
20 is magnetically coupled with magnets 21 and 22.

The rotor 20, the sensor 29 and the like are covered by the cylindrical cover 38 of the housing 5.

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 29 such as a strain gauge that does not generate the stress is used.

In order to actually measure the specific gravity of the liquid to be measured using the above-mentioned specific gravity measuring device, the device is arranged so that the XX ′ line is horizontal, and the measured fluid is fed from the flow channel 16 to the flow channel 10 side. Let it flow. At this time, a part of the liquid to be measured is introduced into the float chamber 14 through the communication holes 39 and 40, and the float 1 is immersed in the liquid to be measured.

Since the change in the specific gravity of the liquid to be measured appears as a change in the resistance of the stress sensor 29, the change in resistance is detected,
The specific gravity ρ of the liquid to be measured can be obtained by calculation 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.

In addition, the liquid to be measured is made to pass through the flow path provided concentrically with the eccentric shaft of the float, and a part of the liquid to be measured is guided around the float. Specific gravity can be measured without causing it.

[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 ... Projection shaft 3 ... Small-diameter cylindrical portion, 4, 7, 19 ... Bearing 6, 9 ... Bearing fitting recess 8 ... Fitting recess, 10, 16, 18 ... … Flow path 11 …… Cylinder part, 12 …… Side plate part 13 …… Continuous part, 14 …… Float chamber 15,17 …… Piping part, 20 …… Rotor 21 …… Inner magnet 22 …… Outer magnet 23 …… Support material 24,26,31,32,33,37 …… Screw 25 …… Magnet coupling 27, 36 …… Mounting plate, 28 …… Sensor support 29 …… Stress sensor, 30 …… Board 34 …… Mounting plate, 35 ... Oval hole 38 ... Cylinder cover, 39,40 ... Communication hole

Claims (1)

[Claims] 1. A cylindrical float having an eccentric shaft eccentric to the central axis and having a flow path formed concentrically with the eccentric shaft is supported by the eccentric shaft and accommodated in a housing.
While flowing the fluid to be measured in the flow channel, the fluid to be measured is guided from a part of the flow channel into the housing to immerse the float in the fluid to be measured, and the moment about the eccentric axis of the float. A specific gravity measuring device for a fluid, which is provided with a sensor capable of detecting the specific gravity, and measures the specific gravity of the fluid to be measured from the detection output of the sensor.