JP2724976B2 - Sample heating device for thermal analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample heating device for a thermal analyzer, and more particularly to a sample heating device for heating a sample inside a protection tube from outside the protection tube.

[0002]

2. Description of the Related Art FIG. 6 is a front sectional view of a main part of a conventional sample heating device of a thermal analyzer. A sample is placed inside the protection tube 10 made of alumina, and a heater bobbin 14 made of alumina is placed around the protection tube 10. The heater wire 12 is wound around the heater bobbin 14. A heat insulating material 16 is arranged further outside the heater bobbin 14.

[0003]

The above-described conventional sample heating apparatus has the following problems. (1) Since a heater bobbin is required, there is a limit to downsizing of the heating device, and the temperature response is poor. (2) If the heater wires are wound at a constant pitch, the temperature in the central portion in the axial direction inside the protective tube becomes higher than those at both ends, and the temperature distribution in the axial direction is not uniform. (3) When a current is passed through the spiral heater wire, a magnetic field is induced by the current, and this induced magnetic field may adversely affect surrounding electronic circuits and the like. For each of these problems, countermeasures have been taken, but a new sample heating device that solves these problems at once is desired.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a sample heating apparatus which can be downsized and has good temperature response. Another object of the present invention is to provide a sample heating apparatus having good radial and axial temperature distribution inside a protective tube. Still another object of the present invention is to provide a sample heating apparatus in which an induction magnetic field is less generated by a heater wire.

[0005]

According to the present invention, there is provided a thermal analyzer which comprises a cylindrical protective tube defining a space around a sample, and heats the sample inside the protective tube from outside the protective tube. In one sample heating apparatus, one heater wire is folded in two, and this heater wire is placed on the outer peripheral surface of the protective tube by two.
It is wound spirally in a strip, and the winding pitch of the heater wire at the axially central portion of the protective tube is made larger than the winding pitch on both sides in the axial direction.

The present invention is not particularly limited with respect to the sample placed inside the protective tube and the method of measuring the sample. Can be used as

[0007]

The function of the sample heating device is as follows.
First, since the heater wire is wound directly around the protection tube,
A conventional heater bobbin is not required, and the sample heating device is reduced in size and the temperature response is improved. Second
Another effect of directly wrapping the heater wire around the protective tube is that the temperature distribution in the radial direction inside the protective tube becomes more uniform than in the conventional device. Third, since the heater wire is wound at a wide pitch at the center in the axial direction of the protective tube and at a narrow pitch on both sides, the temperature distribution in the axial direction inside the protective tube is more uniform than in the conventional device. Become. Fourth, since one heater wire is folded into two and wound in a two-strand spiral,
Induction magnetic fields are canceled by adjacent heater wires.
Most importantly, these functions are achieved at once by employing the configuration of the present invention. Further, if a pair of inclined grooves are formed in the flange of the protection tube and the bent portion of the heater wire is hooked on the groove, the winding start portion of the heater wire hardly comes off from the protection tube.

[0008]

FIG. 1 is a front sectional view of a sample heating apparatus according to one embodiment of the present invention. A sample for thermal analysis is arranged inside the cylindrical protection tube 20, and the heater wire 22 is spirally wound directly on the outer peripheral surface of the protection tube 20. Around the protective tube 20, a heat insulating material 24, a shield tube 26, an outer tube 28, and a casing 30 are arranged.

[0009] As shown in FIG.
Fig. 2 shows that one heater wire is folded in two,
(B), the protective tube 20 is spirally wound around the outer peripheral surface of the protective tube 20. Axial center part 3 of protection tube 20
In No. 2, the winding pitch of the heater wires 22 (center spacing between adjacent heater wires) is relatively wide, and both sides 34
In the figure, the winding pitch of the heater wire 22 is narrower than that of the central portion 32. In this embodiment, about 9
The two heater wires having a center interval of 1.7 mm make about one turn between the axial dimensions of 1 mm. On both sides 34 in the axial direction, two heater wires with a center interval of 1.7 mm are 1.7 mm.
It is wound at intervals. Two spiral grooves for accommodating the heater wire 22 are formed on the outer peripheral surface of the protection tube 20. The heater wire 22 is accommodated in this spiral groove,
After the heater wire 22 is wound, in order to prevent the heater wire 22 from shifting or coming off, the heater wire 2 is coated with alumina cement 35 at one location in the circumferential direction of the protective tube 20.
2 is adhered to the protection tube 20. In particular, when an iron-chromium-based heater wire having a large expansion and contraction is used, the bonding with the alumina cement 35 is effective. As a heater wire, a platinum / rhodium wire having a wire diameter of 0.5 mm or a wire diameter of 0.6 mm is used.
mm iron / chrome wire is used. In this embodiment, the inner diameter of the protection tube 20 is about 21 mm, and the outer diameter is about 23 mm.

FIG. 3 is an enlarged cross-sectional view of a part of the protection tube 20. The left side from the center line is a cross-sectional view, and the right side is a front view. A heater wire 22 is accommodated in a spiral groove formed in the protection tube 20. The heater wire 22 is formed by folding one heater wire in two and then wound so as to form a double spiral. The matching heater wires have currents in opposite directions. As a result, the induced magnetic field induced by the current flowing through the heater wire is canceled by the adjacent heater wires. Therefore, the influence of the induced magnetic field on electronic circuits and the like is reduced. The current flowing through the heater wire may be alternating current or direct current. In this embodiment, an alternating current having a commercial frequency is used.

Next, the structure of the portion at the beginning of winding of the heater wire will be described. FIG. 4 is an enlarged perspective view of the lower end of the protective tube 20 arranged as shown in FIG. 1 when viewed from below. Protection tube 2
Numeral 0 is made of alumina, and an annular flange 38 is integrally formed at a portion near the end. This flange 38
Are formed with a pair of grooves 40, 41, into which the two-folded portion 42 of the heater wire 22 can be hooked. The grooves 40 and 41 pass through the protection tube 20 in the axial direction. On the other hand, the winding end portion of the heater wire 22 serves as a pair of terminals and is connected to a heating power supply.

FIG. 5 is a plan view of the flange 38 of the protection tube. Characteristically, the pair of grooves 40 and 41 described above are inclined with respect to the radial direction. That is, in each groove, the opposing wall surfaces 44 and 45 are inclined by the angle α with respect to the radial direction 46 of the protective tube. In this embodiment, the inclination angle α is about 30 degrees. The reason why the inclination is provided is that the winding start of the heater wire 22 is formed in the grooves 40 and 4.
This is so as not to deviate from 1. That is, the groove 4
If the heater wire 22 is wound in the opposite direction to the inclination of 0 and 41, the heater wire 22 will not easily come off due to the inclination of the grooves 40 and 41. To explain this, in FIGS. 4 and 5, the grooves 40 and 41 are inclined to the left, so if the heater wire 22 is hooked on the groove and wound around the right,
The heater wire 22 is less likely to come off.

[0013]

The sample heating apparatus of the present invention has the following advantages. First, since the heater wire is directly wound around the protective tube, a heater bobbin as in the related art is not required, so that the sample heating apparatus is reduced in size and the temperature response is improved. Secondly, as another effect of directly wrapping the heater wire around the protection tube, the temperature distribution in the radial direction inside the protection tube becomes more uniform than in the conventional device. Third, since the heater wire is wound at a wide pitch at the center in the axial direction of the protective tube and at a narrow pitch on both sides, the temperature distribution in the axial direction inside the protective tube is more uniform than in the conventional device. Become. Fourth, since one heater wire is bent into two and wound in two spirals, the induced magnetic fields are offset by adjacent heater wires. Fifth, a pair of inclined grooves are formed in the flange of the protection tube, and the bent portion of the heater wire is hooked on the groove, so that the winding start portion of the heater wire does not easily come off the protection tube.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a sample heating apparatus according to an embodiment of the present invention.

FIG. 2 is a front view of a heater wire and a protection tube.

FIG. 3 is an enlarged sectional view of a part of the protection tube.

FIG. 4 is an enlarged perspective view of the lower end of the protection tube when viewed from below.

FIG. 5 is a plan view of a flange of the protection tube.

FIG. 6 is a front sectional view of a main part of a conventional sample heating apparatus.

[Explanation of symbols]

 Reference Signs List 20 protection tube 22 heater wire 32 central part in axial direction 34 both sides in axial direction 38 flange 42 folded part

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takashi Akiyama 3-9-1, Matsubara-cho, Akishima-shi, Tokyo Inside Rigaku Denki Co., Ltd. (56) References JP-A 5-2004 (JP, A) 58-132861 (JP, U)

Claims (3)

(57) [Claims] 1. A sample heating apparatus for a thermal analyzer, comprising: a cylindrical protective tube defining a space around a sample; and heating a sample inside the protective tube from outside the protective tube. The heater wire is wound in two spirals on the outer peripheral surface of the protective tube, and the winding pitch of the heater wire at the axial center portion of the protective tube is changed to the winding pitch on both sides in the axial direction. A sample heating device characterized by being larger than the above. 2. An annular flange is integrally formed on the outer peripheral surface of the protective tube, and a pair of grooves penetrating in the axial direction of the protective tube are formed on the flange, and the opposing wall surfaces are protected in each groove. 2. The sample heating apparatus according to claim 1, wherein the heater wire is hooked on the pair of grooves so as to be inclined with respect to the radial direction of the tube. 3. The protective wire according to claim 1, wherein a spiral wire groove for accommodating the heater wire is formed on the outer peripheral surface of the protective tube, and the heater wire is wound in the spiral groove. Sample heating device.