JPS6126913Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a tabletop density meter that can be used on a tabletop in a laboratory or laboratory.

As a conventionally known density meter, for example, the
As shown in Publication No. 26012, a fluid to be measured is introduced into a pipe vibrator formed in the shape of an acoustic pipe, and the density is determined from the transverse free frequency generated in this vibrator, or Tokuko Showa 51-16794
As shown in the above publication, there is a method in which a fluid to be measured is caused to flow inside and outside a cylindrical resonator, and the density is determined from the annular frequency of the cylindrical resonator.

The former requires a sampling pump, etc. to introduce the fluid to be measured into the pipe resonator, and the latter requires a cylindrical resonator to be installed in the pipe through which the fluid to be measured flows. The disadvantage is that it is difficult to install and operate. Furthermore, neither method is capable of measuring the density of a minute amount of fluid, such as a sample collected in a test tube.

Here, the present invention aims to realize a desk-top density meter that is easy to handle and capable of measuring the density of a minute amount of fluid.

FIG. 1 is a sectional view showing an example of a density meter according to the present invention, and FIG. 2 is a perspective view showing a partially sectional view. In these figures, 1 is a cylindrical resonator,
One end has a flange 11, and the other end has a flange 12.
and a bottom portion 13 that closes the other end. A through hole 14 is formed in the flange 12 on the other end side, through which the fluid to be measured that has entered through the opening on the one end side flows out. 2 is an excitation means for the cylindrical resonator 1 attached to the stepped portion of one flange 12, and 3 is a vibration detection means for the cylindrical resonator 1 also attached to the stepped portion of the flange 12. In this example, PZT is used in both cases. is shown as an example. 41 and 42 are covers with the same diameter, and the cover 41 has the flanges 1 at both ends.
1 and 12 to cover the outside of the cylindrical resonator 1,
Further, the cover 42 has one end connected to the flange 12 to form an elongated handle, and the excitation means 2
and a lead wire 2 connected to the vibration detection means 3
It covers 1,31. 5 is a temperature detection means attached to the bottom 13 of the cylindrical resonator 1, such as a thermistor.
A transistor is used to detect the temperature of the fluid to be measured that has flowed into the cylindrical resonator 1. This temperature detection means is used for temperature correction and is not necessarily required. cover 4
The chamber 15 formed between the resonator 1 and the cylindrical resonator 1 is filled with gas at atmospheric pressure or a constant pressure (including vacuum).

The device constructed in this way has an elongated rod shape as a whole, and as shown in FIG. 3, this device can be inserted into a sample taken in a test tube, for example, to measure the density. In addition, if the collected sample is hygroscopic or easily vaporized,
A stopper 6 is used between the handle and the test tube as shown. That is, the rod-shaped tip has the cylindrical resonator 1 attached thereto, and when this is inserted into the sample to be measured (fluid), the sample flows into the cylindrical resonator 1 from the tip opening as shown by arrow a. and through hole 14
The inside of the cylindrical resonator 1 is filled in such a way that it flows out from the cylindrical resonator 1. In this state, a self-excited oscillation loop (not shown) formed including the excitation means 2 and the vibration detection means 3 causes the cylindrical resonator 1 to vibrate in an annular manner.
Here, the resonant frequency of the cylindrical resonator 1 changes mainly in relation to the density D of the sample to be measured filled inside the cylindrical resonator 1. Note that the influence of the pressure difference between the inside and outside of the cylindrical resonator 1 can be eliminated by making the pressure of the sample to be measured equal to atmospheric pressure or maintaining it at a constant pressure. This can be ignored by making the material of the resonator 1 have a small coefficient of temperature elasticity, or by correcting it using the signal from the temperature detection means 5.

When the inside of the cylindrical resonator 1 is filled with a sample to be measured and subjected to circular vibration, its resonant frequency d
and the density D of the sample to be measured have a relationship as shown in the following equation.

However, o: resonance frequency at density 0 (in vacuum) K: constant determined by the diameter, thickness, etc. of the cylindrical resonator 1 According to the device configured in this way, the density detection section is a rod-shaped tip. Since it can be made into an elongated structure, it is easy to handle and can be inserted into even a minute amount of sample, and there is no need to install a sampling pump or the like. Further, the density detection section can be easily cleaned by supporting the handle part by hand and immersing the tip part in an organic solvent, for example.

4 to 6 are perspective views showing other examples of the density meter according to the present invention.

In FIG. 4, the cover 42 connected to the other flange of the cylindrical resonator 1 is constructed of a flexible tube, so that the density detection section at the tip can easily reach the inside of the curved sample. This example is effective, for example, when detecting fluid density at a specific location within the body of a human or animal.

In FIG. 5, the density detection section at the tip and the handle extending from this section are connected with different axes.

FIG. 6 shows a device in which the density detection section at the tip and the handle are connected to form a T-shape.

In each of the embodiments shown in FIGS. 5 and 6, the cylindrical resonator 1
has a structure with both ends open.

In each of the above embodiments, the cylindrical resonator 1
and a cover 42 for covering the lead wires.
However, they may have different diameters, and one end of the cover 42 may be connected to the cover 41 in addition to the flange portion 42 .

As explained above, according to the present invention, it is possible to realize a desktop densitometer that is easy to handle and can measure the density of a minute amount of fluid.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of the density meter according to the present invention, FIG. 2 is a partially cross-sectional view showing the structure, and FIG.
The figure is an explanatory diagram showing how the densitometer according to the present invention is used, and FIGS. 4 to 6 are perspective views showing other examples of the densitometer according to the present invention. DESCRIPTION OF SYMBOLS 1... Cylindrical resonator, 11, 12... Flange part, 2... Excitation means, 3... Vibration detection means, 4
1, 42...Cover, 5...Temperature detection means. 〓〓〓〓

Claims (1)

[Scope of utility model registration request] A cylindrical resonator having a structure in which each end has a flange portion and at least one end is open so that a fluid to be measured flows in therefrom and the fluid to be measured is filled inside the resonator; a cover that covers the outside of the cylindrical resonator; an excitation means that excites the cylindrical resonator; a detection means that detects the vibration of the cylindrical resonator; one end of which is coupled to at least one of the flange portions or the cover and which vibrates with the excitation means. The case is equipped with a case having an elongated handle that covers a cable connected to the detection means, and the chamber formed between the cylindrical resonator and the cover covering the cylindrical resonator is kept at atmospheric pressure or a constant pressure. A desktop density meter that encloses gas.