JPH01228561A - Ventilation-controlled hot air thermostatic chamber - Google Patents

Abstract

PURPOSE:To make it possible to regulate directly and continuously the flow rate of air, adjusted at a specific temperature, to be fed to a test vessel, by setting differential pressure values on a differential pressure detector from the relationship between the differential pressure of a fan outlet and an air release cylinder and the air flow rate. CONSTITUTION:Heated air of specific temperature is fed to a test vessel 1 provided with an air feed port 3 and air release port 5, while a specific quantity of ventilation is conducted every predetermined time. A blower 18 is connected to the air feed port 3 through an air feed channel 14, while a differential pressure detector 23 to detect the differential pressure values corresponding to the air flow rate, depending on predetermined relationships between the differential pressure, i.e. of the outlet of the blower 18 and an air release cylinder 4, and the air flow rate, is connected to the air release cylinder 4 provided at an air release port 5. Further, a blower revolution regulator 24 to control the number of revolution of the blower 18 in response to the signal corresponding to the differential pressure value measured by the differential pressure detector 23 is provided between the blower 18 and the detector 23. As a result, the flow rate of air, adjusted at a specific temperature, to be fed to a test vessel can be controlled directly and continuously.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a ventilated hot air constant temperature chamber, and more specifically, the present invention relates to a hot air constant temperature chamber with controlled ventilation, and more specifically, for example, to control the air inside the hot air constant temperature chamber in a thermal aging test of samples such as rubber and plastic materials. This concerns ventilation adjustment.

[Conventional technology]

-i, in heat aging tests of samples of rubber, plastic materials, etc., the ventilation of the air in the tank is such that the air volume equivalent to the volume inside the test tank is ventilated at least once per hour, and the number of ventilations during the test is However, this difference in ventilation frequency causes large variations in test results and is a problem.

Conventionally, in the thermostatic chamber described above, there is a method of measuring the flow rate in the exhaust stack as a method of measuring the number of ventilations. but,
There is a problem with the durability of the flowmeter against temperature, and the number of ventilations is generally calculated by measuring the power consumption of the heater in accordance with the ASTM E 145 standard.

The measurement method is to close the ventilation holes of the test chamber to create a non-ventilated state, calculate the average power consumption of the heater required to maintain the test temperature at the same temperature, then open the ventilation holes to create a ventilated state. The average power consumption required to maintain the specified temperature is determined, and the ventilation frequency, which is a measure of the amount of air passing through the test chamber when the ventilation holes are open, is calculated from the difference in power consumption. ing.

In order to determine this amount of power consumption, the temperature inside the test chamber was set to 80±2° C. higher than the ambient temperature, and the temperature was raised to obtain a thermal equilibrium state, and then the amount of power consumed was measured.

[Problem that the invention seeks to solve]

The ventilation frequency determined in this way requires a long time to measure, and has the disadvantage that it becomes inaccurate due to changes in outside temperature, power supply voltage, wind speed, etc. The problem with internal samples is that they generate gases due to chemical reactions caused by high-temperature air, which can clog the exhaust stack and change the amount of ventilation air.

For example, it takes at least 30 minutes to measure the ventilation frequency after the temperature is raised to 80±2℃ higher than the specified ambient temperature, and it takes at least 30 minutes to reach a thermal equilibrium state, and it takes more than 30 minutes to measure the power consumption once. .

This measurement is carried out three times each with the test tank in an unventilated state and in a ventilated state, so it takes a long time. In addition, if there are power supply voltage fluctuations during measurement, it is difficult to obtain a thermal equilibrium state in the test chamber, and especially when the number of ventilations is low, less than 10 times per hour, the difference in power consumption between non-ventilated and ventilated states is small. Since it is a value, it takes more time and the calculated ventilation frequency is also inaccurate.

In addition, changes in ambient temperature change the heat radiation from the test chamber, causing a difference in the power consumption value, and even during the test, there is usually a large temperature difference between morning, noon, and night. If a temperature difference occurs, the test must be stopped and the measurement process to calculate the ventilation frequency must be restarted from the beginning. If you continue the test without performing this step, the power consumption in a non-ventilated state with the ventilation holes of the test chamber closed will be calculated based on the value originally measured, resulting in poor accuracy, especially when the ventilation frequency is low. If so, it will be inaccurate.

Furthermore, even if the ventilation frequency is set once, when a sample is placed in the test chamber and a test is performed under those conditions, gases, plasticizers, etc. emitted by the sample will gradually condense and adhere to the test tank exhaust stack, reduce the diameter, and be discharged. The amount of ventilation air changes over time, tending to increase the internal pressure of the test chamber.

However, in the past, there was no means to detect this, and there was a problem in that the ventilation frequency gradually changed as the test progressed, and before long it had a large impact on the test results.

[Summary of the invention]

This invention was devised by focusing on such conventional problems, and its purpose is to detect the differential pressure value using a differential pressure detector based on the relationship between the pressure difference between the blower outlet and the exhaust stack and the air volume. By setting this to The present invention provides a ventilated hot air constant temperature chamber that can output an abnormality alarm when a change occurs, protect the sample, obtain reproducible test results, and eliminate the need for measuring the number of ventilations.

[Means for solving problems]

This invention was developed in order to solve the above-mentioned problems.A blower is connected to the air supply port of the test chamber via an air supply path, while a blower is connected to the exhaust pipe provided at the air exhaust port. , a differential pressure detector that determines in advance the relationship between the pressure difference between the outlet of the blower and the exhaust stack and the air volume and detects a differential pressure value corresponding to the air volume is connected, and the air supply port and the blower are connected. A throttle control valve whose opening degree is switched and controlled according to the airflow rate of the blower is provided in the path, and a signal output corresponding to the differential pressure value measured by the differential pressure detector is provided between the blower and the differential pressure detector. The gist of the present invention is to provide a blower rotation speed regulator for controlling the rotation speed of the blower, thereby controlling the air volume based on the differential pressure value without being affected by the ambient temperature.

[For production]

In this invention, the outside air supplied to the test chamber through the filter, heating section, and throttle control valve is preheated to a temperature higher than the ambient temperature throughout the year in order to eliminate the influence of the ambient temperature. The air volume is controlled to be constant and supplied to the test chamber.

In order to control the preheated air and manage the number of ventilations as described above, a differential pressure value is set on the differential pressure detector based on the relationship between the air volume corresponding to the number of ventilations and the differential pressure value, and the differential pressure value is set on the differential pressure detector. The blower rotation speed is controlled by the blower rotation speed regulator that receives the signal from the blower.

The throttle control valve switches the valve position depending on the number of ventilations, and adjusts the required air volume by controlling the rotation speed of the blower.

When the differential pressure value between the blower outlet and the exhaust stack changes, the blower rotation speed regulator is driven by a signal from the differential pressure detector to adjust the air volume to the required amount.

If the exhaust stack becomes clogged and the differential pressure value falls outside the range set by the differential pressure detector, the differential pressure will be detected and an alarm will be output.

〔Example〕

The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a schematic configuration diagram of a ventilated hot air constant temperature chamber according to the present invention. The test chamber 1 is formed into a hollow rectangular shape by a heat insulating partition wall 2, and has openings and closing doors (not shown) on the sides for loading and unloading samples. There is a door. A supply port 3 for air A is formed in the partition wall 2a at the bottom of the test tank 1, and an exhaust port 5 for the exhaust AI to which an exhaust pipe 4 is connected is provided in the upper part 2b of the partition wall.

A circulating air passage 8 is formed in the partitioned test tank 1 via a partition member 7 having a plurality of air ventilation holes 6, and a test tank heater 9 is arranged at the bottom of the circulating air passage 8. A circulating fan 10 is also provided at the center of the partition wall. Furthermore, a sample rotation frame (not shown) is provided at the top of the test chamber 1, and a plurality of samples to be subjected to a heat aging test are suspended therefrom.

The circulation fan 10 faces the outside of the partition wall member 7, has a rotating shaft 10a attached so that its axis coincides with the center line of the side partition wall, and sucks air in the test room by rotating it with a motor 11. It looks like this.

Here, the circulation blower fan 10 is surrounded by a hood 10b, and is designed to efficiently suck in the air in the test room without causing backflow.

In addition, a temperature detector 12 for measuring the temperature in the test chamber during the test is installed in the test chamber of the test chamber 1, and this temperature detector 12 is connected to a temperature controller 13 installed outside the test chamber 1. It is connected.

Next, the air supply path 14 connected to the supply port 3 of the test chamber 1 is supplied with a desired temperature, that is, a temperature higher than the atmospheric temperature outside the test chamber 1, according to a command from the temperature controller 13. A preheating means 15 such as a hot air box that preheats the air A and supplies it into the test chamber is provided, and a blower 18 is connected to an air passage 16 connected to the preheating means 15 via a throttle control valve 17. .

The temperature of the test tank heater 9 is also controlled by the temperature controller 13.
It is carried out according to instructions from.

A preheating device 20 including a temperature regulator 19 is connected to the blower 18, and an air purifier 22 including a dust filter 21 is connected to the preheating device 20.

On the other hand, the exhaust pipe 4 connected to the exhaust port 5 of the test tank has an exhaust pressure P1 and an outlet pressure P of the blower 18.
A differential pressure detector 23 is connected to detect the differential pressure value between the two.

The setting of the differential pressure value of the differential pressure detector 23 is determined in advance from the relationship between the air volume corresponding to the number of ventilations of the test chamber 1 and the above-mentioned differential pressure value, and the differential pressure value corresponding to the number of ventilations is set to the differential pressure value. Detector 23
It is set to .

The function of the differential pressure detector 23 described above is to output a signal to the blower rotation speed regulator 24 provided in the circuit 25 connecting the differential pressure detector 23 and the blower 18 according to the setting of the differential pressure value. , the pressure difference between the outlet pressure P2 at the outlet of the blower I8 and the exhaust pressure P1 at the exhaust pipe section is detected, and when a change occurs in the set differential pressure value, the blower rotation speed regulator 24 is activated to turn the blower 18 on. The air volume is controlled to the required level, and when gases, plasticizers, etc. emitted by the sample condense and adhere to the exhaust stack 4 and the inner diameter becomes small, and the detected differential pressure value falls outside the initial setting range, an abnormal condition display means (not shown) issues an abnormal signal. (e.g. issue an alarm)
It has a function to output.

Blower rotation speed regulator 2 operated by a signal from differential pressure detector 23
4 is set to a frequency corresponding to a signal output based on the differential pressure value set in the differential pressure detector 23, and the rotation speed of the blower 18 is controlled by this frequency.

That is, when the differential pressure value decreases due to clogging in the exhaust pipe 4, the fan rotates and operates to increase the air volume to adjust to the required air volume.

Further, the configuration of the throttle control valve 17 is such that, as shown in FIG. 2, the throttle valve 17a is moved up and down by a drive motor 26.
The valve opening degree is configured so that it can be fixed at several levels (for example, three levels, X, Y, and Z).

The amount of air supplied to the test tank 1 is adjusted by controlling the rotational speed of the blower 18 and the valve position of the throttle control valve 17 in combination.

By switching the valve position of the throttle control valve 17, the number of ventilations can be changed, for example, by 1.
~10 times/hour, 11~loO times/hour, 101~20
There are 3 stages of 0 times/hour, and the throttle valve 17 is adjusted depending on the number of ventilations.
By switching the position of a, the air volume is adjusted more accurately and supplied to the test chamber 1.

To switch the valve position of the throttle control valve 17, the switch is switched to a position corresponding to the required number of ventilations, and the throttle valve 17a is moved up and down and fixed.

Next, the operation of this embodiment will be explained.

First, air A, which is supplied from outside air and is adjusted to a constant air volume, is supplied into the test chamber 1. Dust and dirt in the air are removed using a dustproof filter 21, and contaminated gases from the air are removed using an air purifying filter 22. After that, a preheating device 2° equipped with a temperature regulator 19 is heated to a temperature not affected by the ambient temperature, for example, 40°.
'C, the air volume is adjusted by an air blower 18 and a throttle valve 17, and the air is supplied to a preheating means 15 such as a hot air box through an air blowing path 16.

The supply air A supplied to the preheating means 15 is preheated to the test room temperature, and further passes through the preheating means 15 to the supply port 3.
The supply air A sent into the testing chamber heater 9 portion of the circulating ventilation path 8 is further preheated by a command from the temperature controller 13, and then passes from one side of the partition member 7 through the ventilation hole 6 into the testing chamber. enter.

The temperature in the test chamber is detected by the temperature detector 12 of the temperature controller 13 provided in the room, and the test chamber heater 9 is controlled according to the signal to adjust the temperature, and the preheating means 1
The air A passing through 5 is preheated to the test room temperature.

The air A supplied into the test chamber is sucked in by the rotation of the circulation fan 10 and is discharged from the exhaust port 5 to the exhaust stack 4 .

In this way, the test chamber air is circulated in a temperature-controlled state, and a certain amount of fresh outside air is supplied into the test chamber 1 by the blower 18 via the throttle control valve 17 and the preheating means 15, and the ventilation frequency is Accordingly, an amount of air corresponding to the amount of ventilation air per hour is discharged from the exhaust stack 4.

The blower 18 that adjusts the air volume is controlled by the differential pressure detector 2 based on the differential pressure value set in the differential pressure detector 23 as described above.
The blower rotation speed regulator 24 is driven by the signal from 3, and the rotation speed of the blower 18 is controlled by the signal 7.

For example, in a test tank with a capacity of v245β, the relationship between the number of ventilations, the air volume, and the differential pressure value is as shown in Table 1.

The differential pressure detector 23 detects the pressure difference between the pressure P2 at the outlet of the blower and the pressure f)1 at the exhaust pipe section, and when a change occurs in the set differential pressure value, the blower rotation speed regulator 24 2 to control the required wind speed.

If the gas released by the sample or the sacrificial agent etc. condenses in the exhaust pipe 4 and the inner diameter becomes small and the detected differential pressure value falls outside the initial setting range, an abnormality (, No. 1 will be output. ,
By issuing an alarm signal, the sample is protected, and test accuracy and reliability are significantly improved (7), thereby significantly improving test performance and test efficiency.

Further, the air volume adjustment is performed by a combination of the fan 180 rotation speed control and the valve position of the throttle control valve 17 as described above, and switching the valve position of the throttle control valve 17 changes the number of ventilations, for example from 1 to 10 times/'. Time, 11~100 times/hour, 101~
The airflow is supplied to the test tank 1 in three stages of 200 times/hour, and the valve position is changed depending on the number of ventilations to more accurately adjust the air volume.

〔Effect of the invention〕

As described above, the present invention connects the blower to the air supply port of the test tank via the air supply path 7, and connects the blower outlet and the exhaust pipe to the exhaust pipe provided at the air exhaust port. The relationship between the pressure difference and the air volume is determined in advance, and the wind foot 1. A differential pressure detector for detecting the corresponding differential pressure value is connected, and a throttle control valve is provided in the circulating air passage connecting the air supply port and the blower, the opening degree of which is controlled by switching according to the air volume of the blower; A blower rotation speed regulator is provided between the blower and the differential pressure detector to control the rotation speed of the blower by outputting a signal corresponding to the differential pressure value measured by the differential pressure detector. By constantly detecting the differential pressure value between the pipe and the exhaust stack and adjusting the air volume to a constant level, the air volume can be adjusted without being affected by the ambient temperature, and constant ventilation is possible. It has the effect of keeping the test conditions constant, and by constantly detecting the differential pressure value, it is possible to notify the public of exhaust stack clogging, which protects the sample and significantly increases test accuracy and reliability. This has the effect of significantly improving test performance and test efficiency.

For example, Table 2 below shows the changes in the air ventilation rate of the test tank in the example and the changes after the change yξ.

Before the improvements, the ventilation rate gradually decreased by 38% over six months due to exhaust stack clogging, and testing continued unnoticed, reducing the reliability of test results. However, after the improvement, there is no such decrease, and if the decrease exceeds the controllable range, it will be notified, so always test at the correct ventilation rate by cleaning the exhaust stack and rechecking the ventilation rate. I can do things.

(Margin below) Table 2

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a ventilation-controlled hot air constant temperature chamber in which the present invention is implemented, and FIG. 2 is an enlarged explanatory diagram of a throttle control valve. 1... Test tank, 3... Supply port, 4... Exhaust stack, 5
...Exhaust port, 14...Air supply route, 16...Blower route, 17... Throttle control valve, 18...Blower, 2
3...Differential pressure detector, 24...Blower rotation speed regulator.

Claims (1)

[Scope of Claims] 1. In a ventilated hot air constant temperature chamber that supplies heated air at a constant temperature to a test chamber equipped with an air supply port and an air exhaust port, and also ventilates a fixed amount of air at predetermined time intervals, A blower is connected to the air supply port of the test tank via an air supply path, while the relationship between the pressure difference between the blower outlet and the exhaust pipe and the air volume is determined in advance at the exhaust pipe provided at the air exhaust port. hand,
Connect a differential pressure detector that detects the differential pressure value corresponding to the air volume,
A ventilation-controlled hot air constant temperature controller is provided between the blower and the differential pressure detector to control the rotation speed of the blower by outputting a signal corresponding to the differential pressure value measured by the differential pressure detector. Tank. 2. In addition to installing a temperature controller in the test chamber via a temperature detector, the air supply path connecting the air supply port of the test chamber and the throttle control valve is provided with a temperature controller connected to the outside of the test chamber via the temperature regulator. The ventilated hot air constant temperature bath according to claim 1, further comprising a preheating means for preheating the air to a temperature higher than the air temperature. 3. In the ventilation path connecting the air supply port and the blower,
The ventilation controlled hot air constant temperature bath according to claim 1, further comprising a throttle control valve whose opening degree is switched and controlled depending on the air volume of the blower. 4. Claim 1 or Claim 2, wherein the differential pressure detector is provided with an abnormal state display means for informing that an abnormal state exists when the differential pressure value measured by the differential pressure detector is out of a set value range. Ventilation-adjusted hot air constant temperature bath described in .