JPH07209171A - Air flow resistance measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain a compact measuring apparatus capable of accurately measuring the air flow resistance of a sample by making the flow rate of air sucked by the sample constant and measuring the differential pressure between the inflow and suction sides of the sample. CONSTITUTION:Chucking rubber tube 1a in a plug holder 1 is opened by a changeover valve 11 for fitting a sample and a calibrating reference plug is set to the rubber tube 1a. For example, in the case of a tobacco filter, air flow resistance is predetermined corresponding to a brand and a proper calibrating reference plug is selected according to an object to be measured. Next, suction is started with a vacuum pump 10 and an air flow rate is adjusted to a reference flow rate by a reference flow rate setting device 12. At this time, the flow rate of air is measured by a flowmeter 7 and a control valve 9 is continuously controlled through a valve control circuit 8 so as to become a set reference flow rate. After an air flow rate reaches the reference flow rate, the calibrating reference plug is detached and a filter S to be measured is set to the holder 1 and the differential pressure between the inflow and suction sides of the filter S is measured by a differential pressure sensor 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a cigarette and a filter.
The present invention relates to a device for measuring ventilation resistance using, for example, a sample.

[0002]

2. Description of the Prior Art Cigarette filters must have a constant ventilation resistance in each product. 2. Description of the Related Art Conventionally, as a device for measuring ventilation resistance, there is known a device such as a filter for measuring a pressure difference between an inlet and an outlet of a sample by performing suction from one end side of the sample at a constant reference flow rate. As shown in FIG. 2, Japanese Patent Publication No. 45135/1993 provides a multi-capillary element type sensor H and a control valve 9 between a sample S and a suction pump 10 in order to perform suction at a constant reference flow rate, and a suction path. The pressure difference is sensed by the multi-tube element type sensor H in 13 and converted into a flow velocity, which is then valve-controlled to be a set reference flow rate. That is, it is a device that measures the air permeability by the velocity of the flow of air with respect to the pressure difference passing through the sample per unit area of the sample.

[0003]

However, in such a device, in order to make the amount of air to be sucked into a predetermined amount, the multi-tube element type sensor H measures the differential pressure in the suction path, and this is used as the flow velocity. It is a mechanism that controls the opening of the control valve after conversion. Therefore, the control circuit becomes complicated, and since the flow rate of the sucked air is used as a reference, it is affected by pressure loss in the pipe, turbulent flow, or fluid temperature, which affects the measurement accuracy. An object of the present invention is to provide a compact measuring device capable of accurately measuring the ventilation resistance of a sample composed of a filling body such as a cigarette or a filter.

[0004]

The ventilation resistance measuring device of the present invention made to solve the above problems is a device for measuring the ventilation resistance of a gas passing through a rod-shaped sample, and one end of the sample is measured. Holding member for holding the sample so that the side is open to the atmosphere and the suction path for sucking gas is connected to the other end side, and a vacuum pump for sucking a constant flow rate of gas through the suction path. A reference flow rate setting means for setting the gas at a constant flow rate, a flow meter for measuring the flow rate of the gas in the suction passage, and a control connected between the flow meter and the vacuum pump. It has a valve and a differential pressure gauge for measuring the differential pressure between the sample inflow side and the suction side, and after the flow rate of the gas to be sucked is made constant by the control valve, the differential pressure between the sample inflow side and the suction side is set. It is characterized by measuring.

[0005]

The vacuum pump 10 starts suction, and the flow rate is measured by a flow meter. A control valve connected to the flow meter controls the set flow rate. At this time, since the mass flow rate is measured regardless of the flow velocity, the flow rate can be set accurately without being affected by the pressure loss in the pipe. Then, after reaching a predetermined gas flow rate, the differential pressure between the sample inflow side and the suction side is measured.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of the ventilation resistance measuring device of the present invention. Tobacco filter that is a sample
S is set in the plug holder-1 as a holding member, and at this time, one end of the filter-S is opened to the atmosphere,
The other end is sucked by the vacuum pump 10 through the suction passage 13. The inside of the plug holder-1 is designed to hold the sample by the rubber tube for chuck 1a, and the opening and closing thereof is performed by the sample mounting switching valve 11.

The flow meter 7 provided in the suction passage 13 uses a mass flow sensor to measure the mass flow rate of the fluid. This is because two heating resistors are wound inside the sensor tube, and when a current is passed to heat the sensor, a temperature difference occurs between two points when gas flows, and this temperature change is regarded as a resistance value change, The flow rate is measured by utilizing the fact that these and the specific heat of gas have a functional relationship. The flow meter 7 is connected to the control valve 9, and the flow meter 7 and the control valve 9 control whether or not the flow rate set by the setter 12, which is the reference flow rate setting means, is flowing correctly. is there. At this time, since the flow rate is measured from the temperature change without converting the gas flow rate into the flow rate, the influence of turbulent flow and pressure loss in the pipe can be reduced, and accurate and responsive control can be achieved. In this embodiment, a thermal mass flow meter is used as the flow meter, but a rotor meter may be used.

Next, the measuring method will be described. The chuck mounting rubber tube 1a in the plug holder-1 is opened by the sample mounting switching valve 11, and the calibration reference plug is set therein. There are a plurality of calibration reference plugs for 300 mmAq, 600 mmAq and others, which are selected according to the standard of the sample. For example, in the case of a cigarette filter, the ventilation resistance is determined by each brand, and an appropriate calibration reference plug is selected according to the object to be measured. After setting the calibration reference plug, the chuck rubber tube 1a is brought into close contact with the plug.

Next, suction is started by the vacuum pump 10, and the reference flow rate setter 12 sets a reference flow rate of 17.5 cc.
Adjust to / sec. At this time, the flow rate is measured by the flow meter 7,
The control valve 9 continuously controls the valve control circuit 8 so that the set reference flow rate is achieved. After reaching the set reference flow rate, the calibration reference plug is removed, and the filter to be measured-S is set in the plug holder-1.

Then, the differential pressure sensor 2 measures the differential pressure between the inflow side and the suction side of the filter-S to be measured, and the differential pressure display 3 reads the differential pressure to determine whether or not it is a predetermined ventilation resistance value. Confirm.

[0011]

As described above, according to the ventilation resistance measuring device of the present invention, the setting control of the reference flow rate is performed by directly measuring the flow rate of the gas and continuously controlling by the control valve. The influence of turbulence and pressure loss can be reduced, and accurate and responsive control can be performed. In this way, the ventilation resistance can always be measured under a constant air flow rate. In addition, the valve control circuit is not complicated and the entire apparatus becomes compact.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a conventional ventilation resistance measuring device.

[Explanation of symbols]

S sample, 1 plug holder, 2 differential pressure gauge, 3 differential pressure display, 4 air filter, 5 flow control valve, 6 air filter, 7 flow meter, 8 valve control circuit, 9 control valve, 10 vacuum pump, 11 Sample mounting switching valve, 12 reference flow rate setter, 13 suction path, H
Multiple Capillary Element Sensor

Claims (1)

[Claims] 1. A device for measuring ventilation resistance of a gas passing through a rod-shaped sample, wherein one end of the sample is open to the atmosphere and a suction path for sucking gas is connected to the other end. A holding member for holding a sample, a vacuum pump for sucking a constant flow rate of gas through the suction passage, a reference flow rate setting means for setting the gas at a constant flow rate, and a suction passage in the suction passage. A flow meter for measuring the gas flow rate, a control valve connected to the flow meter and located between the vacuum pump, and a differential pressure gauge for measuring the differential pressure between the sample inflow side and the suction side. A ventilation resistance measuring device, characterized in that the differential pressure between the inflow side and the suction side of the sample is measured after the flow rate of the gas to be sucked is made constant by the control valve.