JPH0810187B2 - Ventilation resistance measuring instrument - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a ventilation resistance measuring device for measuring the ventilation resistance of a sample such as a filter used for a cigarette.

[Conventional technology]

As shown in FIG. 4, a conventional ventilation resistance measuring device is provided with a collar portion 3 near both ends of an outer peripheral surface of an inner cylinder 2 having a plurality of suction small holes 1, and the collar portion 3 has an outer cylinder 4 with a collar portion 3a. The inner peripheral surface is airtightly fitted to form a double cylinder.

The outer cylinder 4 has a suction port 5 that opens to the outside, and an upper flange 6 and a lower flange 7 are provided at both upper and lower ends of the outer peripheral surface. The upper flange 6 has a hole at the center with a rubber packing 8 sandwiched therebetween. An upper holder 10 having a sample insertion port 11 is attached to the lower flange 7, and a lower holder 12 having a sample insertion port 11 is attached to the lower flange 7.

A latex tube 13 is coated on the inner peripheral surface of the inner cylinder 2, and both ends of the latex tube 13 are folded back outward and fixed to both ends of the outer peripheral surface of the inner cylinder 2 to hold a sample inside. A is constructed.

The latex tube 13 has elasticity, and when the inside of the double cylinder 14 composed of the inner cylinder 2 and the outer cylinder 4 becomes a vacuum pressure, the latex tube 13 adheres to the inner peripheral surface of the inner cylinder 2,
When the pressure inside the double cylinder increases, the latex tube 13 swells inside.

The hole 9 of the upper holder 10 is connected to the digital manometer 16 via the main measurement flow path 15, and the branch pipe 17 of the main measurement flow path 15 is connected to the first surge tank 21 via the filter 18, the flow rate controller 19 and the needle valve 20. To do.

 Reference numeral 22 is a vacuum gauge indicating the pressure of the branch pipe 17.

The latex tube suction passage 23 connected to the suction port 5 is connected to the three-way valve 24.

Reference numeral 25 is a vacuum gauge that indicates the pressure in the latex tube suction passage 23.

The three-way valve 24 is connected to the latex tube main suction passage 26 and the latex tube atmospheric pressure introduction passage 27, and when the command from the control unit 28 is turned on, the latex tube suction passage 23 is connected to the latex tube main suction passage 26 and the command is turned off. Then, the latex tube suction passage 23 is connected to the latex tube atmospheric pressure introduction passage 27.

The latex tube main suction passage 26 communicates with the first surge tank 21 via a needle valve 29.

The first surge tank 21 is provided with a pipe 32 connected to a pipe 30 that opens to the atmosphere and connected to a valve 31 that opens and closes according to a command from the control unit 28. The pipe 32 communicates with a vacuum pump 33. Road 34 connects.

In order to measure the air flow resistance of the rod-shaped sample S such as a filter plug with the air flow resistance measuring device configured as described above, first, the pressure in the first surge tank 21 is set to 200 to 300 TORR.
Adjust to a certain degree and turn on the three-way valve 24 to connect the latex main suction passage 26 and the latex tube suction passage 23,
The latex tube 13 adheres to the inner peripheral surface of the inner cylinder 2.

Next, when the sample S is inserted into the latex tube 13 and the three-way valve 24 is turned off, the latex tube suction path 2
3 communicates with the latex tube atmospheric pressure introducing passage 27, and the latex tube 13 receives the atmospheric pressure and bulges inward to closely hold the outer peripheral surface of the sample S.

Next, the needle valve 20 is opened to make the inside of the upper holder 10 a negative pressure, and a constant flow rate of air is supplied from the sample insertion port 11 to the sample S.
To the main measurement flow path 15 and the differential pressure between the main measurement flow path 15 and the atmosphere is measured by the digital manometer 16 to measure the ventilation resistance of the sample S.

[Problems to be Solved by the Invention] When the three-way valve 24 is turned off and the suction port 5 is set to the atmospheric pressure, the latex tube 13 is inflated inward and the outer peripheral surface of the sample S is airtightly held, As shown in the figure, the inside bulge amount of the latex tube 13 is increased above the sample S, and the main measurement flow path is narrowed, which causes a problem that accurate ventilation resistance measurement cannot be performed.

As a measure against this, the length of the sample holder was changed according to the length of the sample, or the sample holders with different inner diameters were used according to the diameter of the sample, so it is necessary to prepare several types of latex tubes. In addition, the work of replacing the holder is complicated.

The present invention has been made to solve such problems.

[Means for solving the problem]

In order to achieve the above object, the inner peripheral surface of the inner cylinder of the double cylinder consisting of the inner cylinder and the outer cylinder having a suction small hole is covered with a latex tube, and the inner cylinder and the outer cylinder of the double cylinder. The latex tube adheres to the inner cylinder to allow the insertion of a rod-shaped sample when the space formed by the pressure is set to a predetermined negative pressure or lower, and the latex tube bulges inward at a predetermined pressure or higher to form a rod-shaped sample. Ventilation resistance to measure the ventilation resistance of the rod-shaped sample by having a sample holder that closely holds the sample and measuring the differential pressure between the upstream side and the downstream side of the rod-shaped sample by flowing a constant flow rate of gas into the rod-shaped sample. In the measuring device, a first surge tank adjusted to a pressure equal to or lower than the negative pressure and a second surge tank adjusted to a substantially minimum pressure within a pressure range capable of air-tightly holding the rod-shaped sample are provided via a three-way valve. Connect to the suction port of the sample holder. It was.

[Work]

When the three-way valve is switched and the second surge tank communicates with the suction port of the sample holder, the latex tube bulges inward and holds the sample airtight, but the pressure in the second surge tank holds the sample airtightly. Since the latex tube is adjusted to a substantially minimum pressure in the obtained pressure range, the amount of inward expansion of the latex tube is small and does not hinder the flow of air through the sample.

〔Example〕

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

 The same parts as those in the conventional example are designated by the same reference numerals.

FIG. 1 is a system diagram showing the relation of each device constituting the ventilation resistance measuring device. Instead of the conventional latex tube atmosphere introduction passage 27 connected to the three-way valve 24, the second surge tank 35 is shown.
And a pipe line 36 communicating with.

The second surge tank 35 has a pipe 39 connected to the atmospheric pressure introduction passage 38 via the needle valve 37, and the pipe 39 is a vacuum pump.
It is connected to a pipeline 41 communicating with 40.

 Others are the same as the conventional example.

Next, the measurement of the ventilation resistance of the sample S by the ventilation resistance measuring device configured as described above will be described based on the flowchart of FIG.

The control unit 28 is turned on (S ₀ ).

The valve 31 is closed according to a command from the control unit 28 (S ₁ ).

Next, the three-way valve 24 is turned off in response to a command from the control unit 28, and the suction port 5 of the sample holder A is set to the latex tube suction path 23.
And the second surge tank 35 via the pipe 36 (S ₂ ).

Reducing the pressure of the first surge tank 21 by operating the vacuum pump 33 (S _3).

Then to reduce the pressure of the second surge tank 35 by driving the vacuum pump 40 (S _4).

Open the needle valve 20 by adjusting the opening degree thereof to adjust the display pressure of the vacuum gauge 22 to a predetermined vacuum pressure (S _5).

Next, adjust the opening of the needle valve 37 to adjust the vacuum gauge.
After adjusting (S ₆₎ to 25 display the pressure a predetermined pressure (700 Torr), communicating (S ₇₎ the latex tube main suction passage 26 to the three-way valve 24 is turned ON and the latex tube suction passage 23, the needle valve 29 adjust the opening to adjust the display pressure vacuum gauge 25 to 200~300TORR with (S _8).

The above-mentioned pressure is transmitted to the latex tube 13 through the suction port 5 and the suction small hole 1, and the latex tube 13 is suction-adhered to the inner peripheral surface of the inner cylinder 2, and the inner diameter of the latex tube 13 is expanded to the diameter of the sample S or more. The sample S is ready for insertion.

Next, after inserting the sample S from the sample insertion hole 11 (S ₉ ), the three-way valve 24 is turned off (S ₁₀ ), the pipe line 36 and the latex tube suction line 23 communicate with each other, and the pressure in the sample holder A is increased. The pressure in the second surge tank gradually becomes 700 TORR.

This pressure causes the latex tube 13 to come into airtight contact with the sample S as shown in FIG. 2, but the amount of inward bulging of the latex tube 13 in the portion without the sample S (upper part of the sample S) becomes smaller. This is the pressure and does not hinder the measurement of the ventilation resistance of the sample S.

The air flows from the sample insertion port 11 through the sample S toward the hole 9 of the upper holder 10, and again passes through the filter 18, the flow rate controller 19 and the needle valve 20, and then the first surge tank 21.
Flows into.

The flow rate of this air is limited to a fixed amount by the flow rate controller 19, and the ventilation resistance of the sample S can be measured by a digital manometer that measures the differential pressure from the atmosphere.

After switching (S ₁₀₎ the three-way valve 24 to OFF, after a predetermined time elapses (S _11), read the indicated value of the digital manometer (S _12).

When the measurement of the ventilation resistance is completed, the three-way valve 24 is turned on to communicate the suction port 5 of the sample holder A with the first surge tank 21 (S
₁₃ ), and put the latex tube 13 into close contact with the inner surface of the inner cylinder 2.

Next, the sample S is taken out from the sample holder A and the measurement of the sample S is completed (S ₁₄ ).

Finishes measuring the predetermined number (S ₁₅₎ Then, the power is turned OFF in the controller 28 (S _16).

In addition, in the present embodiment, the first surge tank 21 is connected to the branch pipe 17 of the main measurement flow path 15 and is used for measuring the ventilation resistance of the sample. It is also possible to use another tank for measuring the ventilation resistance of the sample.

〔The invention's effect〕

Since the present invention is configured as described above,
The inward bulging of the latex tube, which is airtightly held in the sample, has been reduced, and samples with different lengths and diameters can be measured correctly.

Therefore, unlike the conventional method, it is not necessary to change the length of the sample holder according to the length of the sample or change the diameter of the sample holder according to the diameter of the sample. It has become possible to continuously measure several types of specimens with different values.

[Brief description of drawings]

1 to 3 show an embodiment of the present invention, FIG. 1 is a systematic diagram of equipment constituting a ventilation resistance measuring device, FIG. 2 is a vertical sectional view of a sample holder, and FIG. 3 is a flow chart diagram. FIG. 4 is a system diagram of components of a ventilation resistance measuring instrument in a conventional example, and FIG. 5 is a vertical sectional view of a sample holder in the conventional example. A ... Sample holder, S ... Sample, 1 ... Suction small hole,
2 ... Inner cylinder, 4 ... Outer cylinder, 5 ... Suction port, 9 ... Hole, 11
…… Sample insertion port, 13 …… Latex tube, 15 …… Main measurement flow path, 16 …… Manometer, 19 …… Flow controller, 20
…… Needle valve, 21 …… First surge tank, 22 ……
Vacuum gauge, 23 …… Latex tube suction path, 24 ……
Three-way valve, 25 …… vacuum gauge, 26 …… latex tube main suction passage, 28 …… control unit, 29 …… needle valve, 31…
… Valve, 33 …… vacuum pump, 35 …… second surge tank, 37 …… needle valve, 40 …… vacuum pump.

Claims (1)

[Claims] 1. A double cylinder comprising an inner cylinder having a small hole for suction and an outer cylinder having a suction port, wherein the inner peripheral surface of the inner cylinder is covered with a latex tube to form an inner cylinder and an outer cylinder of the double cylinder. When the space formed by the cylinder is set to a predetermined negative pressure or less, the latex tube comes into close contact with the inner cylinder to allow the insertion of a rod-shaped sample, and the latex tube bulges inward at a predetermined pressure or more. Ventilation to measure the ventilation resistance of the rod-shaped sample by having a sample holder that closely holds the rod-shaped sample and flowing a constant flow rate of gas through the rod-shaped sample to measure the differential pressure between the upstream side and the downstream side of the rod-shaped sample. In the resistance measuring device, a first surge tank adjusted to a pressure equal to or lower than the negative pressure and a second surge tank adjusted to a substantially minimum pressure in a pressure range capable of air-tightly holding the rod-shaped sample are provided via a three-way valve. Connect to the suction port of the sample holder. Ventilation resistance measuring instrument, characterized in that the.