JPH0968520A - Oven for gas-chromatograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oven for gas-chromatograph which can be heated and cooled efficiently. SOLUTION: A fan 14 rotating in an internal space of a housing 12 formed from four side walls 15, front wall 15, and rear wall 16 is pivotally supported by a rotary shaft 22 furnished as penetrating the rear wall 16, and a heater 13 is installed around the fan 14, and a column 11 housed in the housing 12 is heated and cooled by turning-on and -off of the heater 13 and opening/closing of an air suction hole 33 and exhaust hole 32. Thus, an oven for gas chromatograph is constructed, wherein the angle α of blades of the fan 14 is varied so as to be small when the internal temp. of housing 12 is high, for example α=25deg., and large when the temp. is low, for example 30deg. To vary the blade angle α in compliance with the temp., the blades of the fan 14 are made, for example from a shape memory alloy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas chromatograph oven in which a column of a gas chromatograph is housed in its internal space for temperature control in order to perform chromatography under a condition of a predetermined temperature or a predetermined temperature program.

[0002]

2. Description of the Related Art In a conventional gas chromatograph oven, a heater and a fan are provided in an inner space of a housing for accommodating a column. To heat (heat) the column, the heater is energized and the fan is rotated. Due to
Air having a high temperature is supplied to the column from around, and the temperature inside the oven is controlled by controlling the energization amount of the heater and the opening of the intake port and the exhaust port. On the other hand, when cooling the inside of the oven, the intake port and the exhaust port are fully opened and the fan is rotated.

[0003]

In the conventional gas chromatograph oven, an AC motor is used to rotate the fan, and the fan rotation speed is the same when the oven is heated and when it is cooled. Since the shape of the fan was also constant, increasing the fan rotation speed or increasing the air volume by using a fan with a large blade angle to increase the internal pressure of the oven caused the intake port and exhaust port to be fully opened (when cooling). ), The ventilation efficiency is high and the cooling rate is high, but even if the intake port and the exhaust port are closed (at the time of temperature increase), the gap from the inside of the housing, for example, the sample vaporization chamber, the detector mounting port, the front door, etc. The leak affects
The heating rate does not increase easily. Conversely, if the fan rotation speed is reduced, or if the air flow rate is reduced by using a fan with a small blade angle, the internal pressure of the oven is reduced, leakage from the gap in the housing is reduced and the temperature rise rate is increased, but the intake port , Even if the exhaust port is fully opened, the ventilation efficiency is low and the cooling rate does not increase. There was a problem.

It is an object of the present invention to obtain a gas chromatograph oven capable of efficiently heating and cooling the oven.

[0005]

In order to achieve the above object, in a gas chromatograph oven of the present invention, a fan that rotates in an inner space of a housing formed by four side walls and front and rear walls is provided. It is rotatably supported by a rotary shaft that penetrates through the rear wall, and a heater is arranged around this fan. By turning on / off the heater and opening / closing the intake port and exhaust port provided in the housing, the inside space of the housing is set. An oven for a gas chromatograph that heats and cools a column housed therein, and is variable so that the blade angle of a fan blade is small when the internal temperature of the housing is high and is large when the internal temperature is low.

That is, when the rotation speed of the fan is constant, when the blade angle α of the fan blade is large (see FIG. 6), the internal pressure of the oven is high, the rate of temperature increase is slow, and the rate of cooling is fast (see FIG. 3). Conversely, when the blade angle α of the fan blades is small, the oven internal pressure tends to be low, the rate of temperature increase is fast, and the rate of cooling is low (see FIG. 4). Since it is desirable that the internal pressure of the oven is high when cooling the low temperature region (see FIG. 5), it is efficient to make the blade angle α of the fan blade small at high temperature and large at low temperature.

In order to make the blade angle α of the blade variable depending on the temperature as described above, the blade of the fan can be made of, for example, a shape memory alloy.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A gas chromatograph oven according to the present invention will be described below with reference to the drawings.
In FIG. 2, the oven 10 has a housing 12 formed of four side walls, a door 15 to be a front wall, and a rear wall 16 to which a motor 17 is fixed on the outside. The column 11 of the graph (see FIG. 2), the fan 14, the heater 13 arranged on the outer periphery of the fan 14, and the protective cover 23 are housed.

The fan 14 has a blade blade angle α (see FIG. 6) formed at a predetermined angle so as to allow air to be blown in the radial direction, and also the blade blade angle α of the blade.
Is small at high temperature, for example, 25 °, and large at low temperature, for example, 30 °.

Both the housing 12 and the door 15 are made of steel (stainless steel) and have a heat insulating material 16 between a front plate and a back plate.
It is formed by thick walls sandwiching 3 and the back plate (plate inside the oven) 161 of the rear wall 16 of the housing 12 has a rotation locus of the tip of the fan 14 around the drive shaft 22 of the central motor 17. Inner opening 3 for intake in the inside
0, and an internal opening 31 for exhaust is provided at the upper corner. On the other hand, a front plate (a plate outside the oven) 162 of the rear wall 16 of the housing 12 is provided with an exhaust external opening 32 at the same position as the exhaust internal opening 31, and the exhaust internal / external openings 31, 32 are provided. Rear wall 16
An external intake opening 33 is provided on the side wall adjacent to.

Since the exhaust inner opening 31 and the outer opening 32 are located at the same position, they are connected in a straight manner. However, since the inner opening 30 and the outer opening 33 for intake differ in position between the inner side and the outer side, both of them are rear parts. Communication is performed through a communication passage (duct) 34 provided inside the wall 16.

A common shaft driven by a stepping motor 38 is pivotally supported in a passage connecting the exhaust internal opening 31 and the external opening 32 and a passage connecting the intake internal opening 30 and the external opening 33. Doors 36 and 37 are provided,
The degree of opening is adjustable.

When the column 11 is heated by the oven 10, the heater 13 is energized and the fan 14 is rotated to supply high temperature air to the column 11 from the periphery, and the energization amount of the heater 13 and the intake passage. Also, the internal temperature of the oven 10 is controlled by controlling the opening degrees of the lids 36 and 37 of the exhaust passage. At this time, since the blade angle α of the blades of the fan 14 is made small to reduce the air volume to lower the internal pressure of the oven, the sample vaporization chamber in the housing, the detector mounting port (not shown), the front door 15, etc. The heat loss from the gap is reduced, the rate of temperature rise is increased, and energy is saved when holding in a high temperature region.

On the other hand, when the first heating or thermal history gas chromatography is finished and the second time gas chromatography is performed at a temperature lower than that, it is necessary to cool the inside of the oven 10, and the intake passage and The exhaust passage covers 36, 37 are fully opened, and the fan 14 is rotated. Since the blades of the fan 14 are set as described above, the air pressure in the rear center part of the fan 14 (inside the rotation locus of the tip of the fan 14) decreases, and in the peripheral part (than the rotation locus of the tip of the fan 14). The outside pressure is high. Therefore, the hot air inside the oven 10 is discharged from the exhaust passages 31 and 32 at the upper corner of the rear wall 16 and the exhaust passage 3
The outside air having a low temperature passes through the intake air passage 3 through the intake air outside opening 33 provided on the side wall of the surface different from the side walls 1 and 32.
Since it is sucked in from 0 and 34, the blade angle of the blade of the fan 14 becomes large, the air volume increases, and the internal pressure of the oven increases,
Ventilation efficiency is improved and rapid cooling is realized.

[0015]

Since the present invention is configured as described above, when the temperature inside the oven is raised or cooled, the cooling rate can be increased without sacrificing the rate of temperature rise. Alternatively, the heating rate can be increased without sacrificing the cooling rate, which is efficient.

[Brief description of drawings]

FIG. 1 is a perspective view including a partially transparent view of an oven for a gas chromatograph according to an embodiment of the present invention.

FIG. 2 is an upper cross-sectional view (a) and a lower cross-sectional view (b) of a gas chromatograph oven according to an embodiment of the present invention.

FIG. 3 is a curve showing a relationship with an oven temperature when a blade angle of a fan blade is large.

FIG. 4 is a curve showing the relationship with the oven temperature when the blade angle of the fan blades is small.

FIG. 5 is a curve showing the relationship with the oven temperature when the blade angle of the fan blades is variable (Example of the present invention).

FIG. 6 is a view showing a blade shape of a fan of a gas chromatograph oven.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Oven 12 ... Housing 13 ... Heater 14 ... Fan 15 ... Door (front wall) 16 ... Rear wall 17 ... Motor 30 ... Internal opening of intake passage 31 ... Internal opening of exhaust passage 32 ... External opening of exhaust passage 33 ... External opening of intake passage 34 ... Communication passage (duct) 36, 37 ... Lid of intake passage

Claims (1)

[Claims] 1. A fan rotating in an inner space of a housing formed by four side walls and front and rear walls is rotatably supported by a rotary shaft provided through a rear wall, and a heater is provided around the fan. In a gas chromatograph oven that heats and cools a gas chromatograph column housed in the housing interior by turning on / off the heater and opening / closing the intake port and the exhaust port provided in the housing, An oven for a gas chromatograph characterized in that the blade angle is variable so that it is small when the internal temperature of the housing is high and is large when the internal temperature is low.