JP6738375B2 - Heater unit - Google Patents

Description

The present invention relates to a heater unit in which a cartridge heater is inserted in a metal block.

In low-temperature equipment using a small refrigerator, a heater unit in which a heater is inserted in a metal block is often used to adjust the internal temperature, and the required output level and the temperature range to be changed (for example, -270°C to +200°C), construction environment (for example, required vacuum degree), shape of metal block, etc. It is under construction.

Examples of the type of heater used in such a heater unit include a film heater and a cartridge heater.
In order to improve the thermal contact with the metal block, the film heater is filled with a resin such as stycast as a filling material, or is filled with a soft metal plate such as grease or indium. However, when a high vacuum or higher is required or when the upper limit temperature for raising the temperature is high, the use of the resin or metal plate may be restricted. Further, when high output is required, it is necessary to increase the size of the film-shaped heater, which increases the difficulty in construction. Furthermore, the contact state between the film-shaped heater and the metal block may deteriorate during repeated temperature changes from extremely low temperature to high temperature.

Therefore, when the installation environment permits, a cartridge heater that is relatively reliable and easy to install is often used.
A heater unit using a cartridge heater can be used in the air or liquid without any problem by inserting the cartridge heater into the insertion hole formed in the metal block with the clearance recommended in the specifications. In addition, a filler such as grease or stycast is often used in the gap between the cartridge heater and the insertion hole to improve thermal contact.

For example, in Patent Document 1, when attaching the cartridge-type heater to the mold member, a long hole having a diameter slightly larger than that of the cartridge-type heater is bored in the mold member, and the cartridge-type heater is inserted into the long hole. A technique for filling a void formed around a heater in an elongated hole with a conductive material is disclosed.

Further, in the case where the filler cannot be used in the gap between the cartridge heater and the insertion hole, if the space allows, the heater is sandwiched between metal blocks and fixed by a screw so that the reliability is increased. However, if the structure that the cartridge heater cannot be sandwiched is not possible due to space restrictions, or if it is necessary to raise the temperature above the melting point of the filler to be inserted in the gap during installation, or depending on the required vacuum degree. In some cases, the filler cannot be used.
Therefore, a heater unit is used in which an insertion hole having a size as close to the diameter of the cartridge heater as possible is provided in the metal block, and the cartridge heater is inserted into the insertion hole without using a filler. ..

JP-A-58-185210

As described above, in a low-temperature device using a small refrigerator, a heater unit is often used to adjust the internal temperature, but the temperature control range may be as wide as -270°C to +200°C, Normally, the heater unit is installed in a vacuum, so if the heater unit is not installed properly, heat cannot be efficiently transferred to the heating target, and the temperature of the cartridge heater itself will rise excessively, leading to a long service life. There was a problem in quality control due to problems such as decrease in the amount of waste and burnout.

Such troubles have been caused by a phenomenon in which the cartridge heater is disconnected when the heater unit in which the cartridge heater is simply inserted into the insertion hole provided in the metal block is used for a long period of time. For example, even if the temperature for controlling the heater unit is set to 200° C. at the maximum and the cartridge heater is used at a temperature sufficiently lower than the recommended temperature (surface) of about 800° C., the above-mentioned event may occur. The cause of this is that when the cartridge heater is inserted into the insertion hole of the metal block, sufficient heat contact cannot be obtained between the cartridge heater and the metal block, and a heater wire (for example, a heating element of the cartridge heater when energized (for example, This is because the temperature of the Nichrome wire) became too high.

Therefore, even if the filling material is not used, sufficient heat contact is made between the cartridge heater and the metal block, and even if the cartridge heater is used for a long period of time in a vacuum environment, the temperature of the heating part of the cartridge heater is A proper heater unit was desired.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a heater unit capable of obtaining sufficient thermal contact between a cartridge heater and a metal block without using a filler. To aim.

(1) A heater unit according to the present invention comprises a cartridge heater having a heating portion in which a heating element is covered with a metal tube, and a metal block into which the heating portion of the cartridge heater is inserted and heated. Then, the metal block has a heater insertion portion into which the heating portion is inserted, and a pressing member insertion portion into which a heater pressing member that presses the heating portion inserted into the heater insertion portion against an inner wall is inserted. The heater pressing member is provided with a hole portion, and the heater pressing member has at least one cutout portion formed by cutting out a peripheral wall to expand the diameter, and a cylindrical wedge member inserted into the cylindrical wedge member. A wedge diameter expanding member for expanding the diameter of the cylinder, the wedge diameter expanding member being inserted into the cylindrical wedge to expand the diameter of the cylindrical wedge, and the expanded diameter cylindrical wedge presses the heat generating portion. However, the heat generating portion is pressed against the inner wall of the hole.

(2) In the structure described in (1) above, the heat generating portion and the cylindrical wedge have arcuate surface portions on their outer peripheral surfaces, and the heater inserting portion and the pressing member inserting portion include the heat generating portion and the heat generating portion. A curved surface portion is formed along the arcuate surface portion of the cylindrical wedge.

(3) In the structure described in (1) or (2) above, the cylindrical wedge has an internal thread portion having an internal thread formed on an inner surface thereof, and a flat portion provided at a portion for pressing the heat generating portion. The wedge diameter enlarging member includes a male screw portion that is screwed into a female screw portion of the cylindrical wedge to expand the diameter of the cylindrical wedge, and the hole portion inserts the heat generating portion and the cylindrical wedge. Then, when the male screw portion of the wedge expanding member is screwed into the female screw portion of the tubular wedge, the flat portion is brought into contact with the heat generating portion and the diameter of the hole is set to prevent the tubular wedge from rotating. It is characterized by being present.

(4) In the structure described in (3), the cylindrical wedge has a stepped portion with a recessed surface on the insertion start end side of the flat surface portion into which the wedge expanding member is inserted, and the stepped portion The heat generating portion and the tubular wedge are inserted into the hole, and the heat generating portion is inserted in a state in which the wedge expanding member is screwed only on the insertion start end side of the tubular wedge. It is characterized in that it is formed so as not to be pressed.

(5) In the structure described in (3) or (4) above, the wedge-diameter expanding member has a reduced-diameter portion on the tip side, and only the reduced-diameter portion is screwed into the cylindrical wedge. In this state, the cylindrical wedge is not expanded in diameter.

(6) In any one of the above (1) to (5), it is used in a vacuum environment.

In the present invention, the cartridge heater and the metal block can be sufficiently brought into thermal contact without using a filling material, and an excessive temperature rise of the cartridge heater can be suppressed.

It is a figure explaining the structure of the heater unit which concerns on embodiment of this invention ((a) top view, (b) sectional view, (c) cylindrical wedge). In the heater unit according to the embodiment of the present invention, the diameter of the heating portion of the cartridge heater, the diameter of the tubular wedge, and the hole diameter of the hole provided in the metal block is a diagram illustrating a desirable relationship. ((A) Heat generating part, (b) Cylindrical wedge, (c) Hole). It is a figure explaining the other aspect of a structure of the heater unit which concerns on embodiment of this invention ((a) top view, (b) sectional view). It is a figure which illustrates the arrangement of the cartridge heater and the shape of the cylindrical wedge in the heater unit according to the embodiment of the present invention. It is a figure explaining the heater unit which concerns on the comparative example made into the comparison object of this invention. It is a figure which shows the apparatus structure of the experiment which concerns on the Example of this invention. It is a graph which shows the heater resistance of the cartridge heater used in the Example of this invention, and the relationship of temperature. It is a figure which shows the shape of the copper block used for the heater unit which concerns on Example 1 of this invention ((a) top view, (b) AA sectional view). It is a figure which shows the shape of the cylindrical wedge used for the heater unit which concerns on Example 1 of this invention ((a) top view, (b) AA sectional drawing, (c) perspective view). It is a graph which shows the heater resistance value and the temperature change of the copper block obtained by the experiment using the heater unit which concerns on Example 1 of this invention, and the comparative example. It is a figure which shows the shape of the copper block used as a metal block in the heater unit which concerns on Example 1 of this invention ((a) top view, (b) AA sectional drawing). It is a figure explaining the apparatus used in Example 3 of this invention.

As shown in FIG. 1, the heater unit 1 according to the embodiment of the present invention includes two cartridge heaters 3 and a metal block 5, and the metal block 5 includes two cartridge heaters. The heater pressing member 11 has a cylindrical wedge 17 and a hole portion 15 having two heater inserting portions 9 into which the respective heat generating portions 7 of 3 are inserted and a pressing member inserting portion 13 into which the heater pressing member 11 is inserted. The wedge expanding member 19 is provided. Hereinafter, each of the above configurations will be described.

In this specification and the drawings, elements having substantially the same functions and configurations are designated by the same reference numerals, and duplicate description is omitted.
Further, in the drawings used in the following description, in order to make the features easy to understand, the features may be enlarged for convenience, but the dimensions and ratios of each component are the same as the actual ones. Not necessarily.

The cartridge heater 3 has a heating portion 7 whose heating element is covered with a metal tube, and a lead wire 21 is connected to an end of the heating portion 7. As the cartridge heater 3, for example, a heater using a nichrome wire as a heating element of the heating portion 7 can be used, and the heating portion 7 is heated by passing a current through the lead wire 21 to the nichrome wire.

The metal block 5 is heated by the cartridge heater 3, and a heater insertion portion 9 into which the heat generation portion 7 of the cartridge heater 3 is inserted and a heater that presses the heat generation portion 7 inserted into the heater insertion portion 9 against the inner wall. A hole portion 15 having a pressing member insertion portion 13 into which the pressing member 11 is inserted is provided.
The metal block 5 is preferably made of a metal material having excellent thermal conductivity, and is particularly preferably a copper block made of pure copper.

The heater pressing member 11 has a cylindrical cylindrical wedge 17 having a notch 17a formed by cutting out a peripheral wall and capable of expanding the diameter, and a wedge expanding member which is inserted into the cylindrical wedge 17 and expands the cylindrical wedge 17. The diameter member 19 is included in the pressing member insertion portion 13 of the metal block 5.

As shown in FIGS. 1(b) and (c), the cylindrical wedge 17 has an internal thread portion 17b having an internal thread formed on the inner surface thereof, and has a flat surface portion 17c at a portion for pressing the heat generating portion 7 of the cartridge heater 3. Be prepared.

Further, as shown in FIG. 1B, the wedge-diameter expanding member 19 is provided with a male screw portion 19a that is screwed into the female screw portion 17b of the cylindrical wedge 17 to enlarge the diameter of the cylindrical wedge 17.
The diameters of the female threaded portion 17b of the tubular wedge 17 and the male threaded portion 19a of the wedge diameter enlarging member 19 are such that the male threaded portion 19a is screwed into the female threaded portion 17b, and the tubular wedge 17 expands when screwed. Is set as appropriate.

As shown in FIG. 1C, the cylindrical wedge 17 has a stepped portion 17f whose surface is recessed radially inward on the insertion start end 17e side of the flat surface portion 17c into which the wedge expanding member 19 is inserted. The step portion 17f has the heat generating portion 7 and the tubular wedge 17 inserted into the hole 15, and the wedge expanding member 19 is screwed only on the insertion start end 17e side of the tubular wedge 17. The step portion 17f is formed so as not to press the heat generating portion 7.

Further, in the heater unit 1 according to the present embodiment, the heat generating portion 7 and the cylindrical wedge 17 respectively have the arcuate surface portion 7a and the arcuate surface portion 17d on the outer peripheral surface, as shown in FIG. The heater insertion portion 9 is formed with a curved surface portion 9a along the arcuate surface portion 7a of the heat generating portion 7, and the pressing member insertion portion 13 is formed with a curved surface portion 13a along the arcuate surface portion 17d of the cylindrical wedge 17. Has been formed.

As shown in FIGS. 1 and 2, the hole portion 15 in which the curved surface portion 9a and the curved surface portion 13a are formed has both the heater insertion portion 9 and the pressing member insertion portion 13 as round holes, and the heater insertion portion 9 The circular hole of the pressing member insertion portion 13 overlaps with a part of the circular hole, and the center of the heater insertion portion 9 and the center of the pressing member insertion portion 13 are arranged in a line.

As described above, when the heater insertion portion 9 and the pressing member insertion portion 13 are round holes, the diameters of the holes may be set according to the diameters of the heat generating portion 7 and the cylindrical wedge 17, for example, the heat generating portion 7 The clearance between the heater insertion portion 9 and the heater insertion portion 9 may be the clearance recommended for the cartridge heater 3.

Further, in the heater unit 1 according to the present embodiment, the diameter D1 of the heat generating portion 7 inserted into the heater insertion portion 9 and the long diameter d1 of the cylindrical wedge 17 inserted into the pressing member insertion portion 13 (diameter at the arc surface portion 17d) ), the minor diameter d2 (diameter in the flat surface portion 17c), and the hole diameter A of the hole portion 15 are set so as to satisfy the following relationship (see FIG. 2).
2D1+d2<A
A<2D1+d1

Next, the function and effect of the heater unit 1 according to this embodiment will be described.
In the heater unit 1, the heating portion 7 of the cartridge heater 3 and the cylindrical wedge 17 of the heater pressing member 11 are inserted into the heater insertion portion 9 and the pressing member insertion portion 13 of the hole 15 of the metal block 5, respectively. ing.

Then, when the male screw portion 19a of the wedge expanding member 19 is screwed into the female screw portion 17b of the tubular wedge 17, the flat portion 17c abuts the heat generating portion 7 so that the tubular wedge 17 is prevented from rotating and is tubular. The wedge 17 expands in diameter. As a result, since the flat surface portion 17c presses the heat generating portion 7 and the heat generating portion 7 can be strongly pressed against the inner wall of the hole portion 15, the thermal contact between the heat generating portion 7 and the inner wall can be improved, and the cartridge heater 3 It is possible to prevent the temperature of the heat generating portion 7 from excessively rising.

As described above, the heater unit 1 can improve the thermal contact between the heat generating portion 7 and the metal block without using a filler such as grease in order to improve the thermal contact. In the present invention, the “vacuum environment” means a high vacuum from atmospheric pressure to about 10 ⁻⁵ Pa).

Further, in the heater unit 1, since the dimensions of the heat generating portion 7, the tubular wedge 17 and the hole 15 are appropriately set as described above (see FIG. 2), the flat portion 17c of the tubular wedge 17 causes the tubular shape. While preventing the wedge 17 from rotating, the wedge expanding member 19 can be screwed into the cylindrical wedge 17 to expand the diameter.

Further, the curved surface portion 9a and the curved surface portion 13a formed on the heater insertion portion 9 and the pressing member insertion portion 13, respectively, serve as a guide when the heat generating portion 7 and the cylindrical wedge 17 are inserted into the hole portion 15, and at predetermined positions. It can be easily inserted into the heater insertion portion 9 and the pressing member insertion portion 13.

Further, a step portion 17f is formed on the flat surface portion 17c of the cylindrical wedge member 17, and even in a state where the cylindrical wedge member 17 and the wedge expanding member 19 are screwed together, the screwed portion is engaged. Since the cylindrical wedge 17 can be prevented from expanding in diameter, the cylindrical wedge 17 can be taken out from the hole 15 while the wedge expanding member 19 is screwed into the cylindrical wedge 17.

Thereby, even when the heater unit 1 is installed in a narrow space, the cylindrical wedge 17 can be pulled out, and the cartridge heater 3 can be removed and replaced. Note that this point has been verified in Example 3 described later.

In the above description, the hole portion 15 has a shape in which the round hole of the pressing member insertion portion 13 overlaps a part of the round hole of the heater insertion portion 9. However, in the present invention, the shape of the hole portion is The shape is not limited to this, and the heat generating portion and the tubular wedge may be inserted, and the heat generating portion may be pressed against the inner wall of the hole due to the expansion of the diameter of the cylindrical wedge. It may have an elliptical shape.

Further, although the tubular wedge 17 does not expand the diameter at the step portion 17f even when the wedge expanding member 19 is screwed, the present invention is not limited to this. May have a reduced diameter portion (not shown) on the tip side thereof. In this case, in the state where only the reduced diameter portion is screwed to the insertion start end 17e side of the tubular wedge 17, the diameter of the reduced diameter portion may be formed so that the tubular wedge 17 does not expand. As a result, similarly to the case where the step portion 17f is provided on the flat surface portion 17c of the tubular wedge 17, the tubular wedge 17 is taken out from the hole portion 15 while the wedge expanding member 19 is screwed into the tubular wedge 17. You can

Further, although the above description is for the heater unit 1 that heats the metal block 5 by the two cartridge heaters 3, the present invention limits the number of cartridge heaters for heating the metal block. Not something to do. For example, one cartridge heater may be used (see FIG. 3) as shown in Example 1 described later, or three or more cartridge heaters may be used as shown in FIG. When a plurality of cartridge heaters are used, the load per cartridge heater when heating the metal block is small, so it is effective when high output is required while preventing overheating of the cartridge heater.

When the heat generating portions 7 of a plurality of cartridge heaters are inserted into the metal block 5, as shown in FIG. 4, the number and position of the notches 17a provided in the cylindrical wedge 17 are set appropriately. May be.

FIG. 4A shows a case where four heat generating portions 7 are arranged at positions corresponding to the four corners of a square, and a cylindrical wedge 27 is inserted in the center thereof. Two notches 27a are formed in the. Then, when the diameter of the cylindrical wedge 27 is expanded, each portion of the peripheral wall divided into two by the notch portion 27a presses the two heat generating portions 7.

Further, FIG. 4B shows a case where four heat generating portions 7 are arranged at positions corresponding to the four corners of a square, and the cylindrical wedge 29 is inserted in the center thereof, and the cylindrical wedge 29 has a peripheral wall. Four notches 29a are formed in the circumferential direction. Then, when the diameter of the cylindrical wedge 29 is expanded, each portion of the peripheral wall divided into four by the notch portion 29a presses one heat generating portion 7.

Further, FIG. 4C shows a case where the three heat generating portions 7 are arranged at positions corresponding to the vertices of an equilateral triangle, and the cylindrical wedge 31 is inserted in the center thereof, and the cylindrical wedge 31 has a peripheral wall. Has three notches 31a formed in the circumferential direction. Then, when the diameter of the tubular wedge 31 is expanded, each portion of the peripheral wall divided into three by the notch portion 31a presses one heat generating portion 7.

In this way, by setting the number and position of the notches provided on the peripheral wall of the tubular wedge according to the number and arrangement of the heat generating portions pressed by the tubular wedge, even with one tubular wedge It is possible to uniformly press the plurality of heat generating portions when the diameter of the heat generating element is increased.

However, the present invention is not limited to the one in which the heating portions of the plurality of cartridge heaters are pressed by one cylindrical wedge. For example, a cylindrical wedge may be installed for each of a plurality of cartridge heaters.

Further, in the case of forming one notch in the peripheral wall of the cylindrical wedge 17, as shown in FIG. 1C, at the end of the wedge expanding member 19 on the opposite side of the insertion start end 17e. The cutout portion 17a is not limited to the one in which the peripheral wall remains connected, and a cutout portion (not shown) cut out over the entire axial length of the tubular wedge may be formed.

Further, as shown in FIG. 4, a cylindrical wedge provided with two or more notches in the circumferential direction of the peripheral wall has a notch in which the end opposite to the insertion start end is connected. Alternatively, the notch portions may be formed alternately on the insertion start end side and the opposite end portion.

The material of the cylindrical wedge is preferably brass, copper alloy, aluminum alloy, or the like, which is harder than pure copper and relatively good in heat conduction. As a result, the heat transfer performance of the heat generating portion can be improved. Further, it is desirable that the diameter of the cylindrical wedge is approximately the same as the diameter of the heat generating portion of the cartridge heater.

Further, as the material of the wedge diameter expanding member, it is preferable to use an austenite type material such as SUS304 or SUS316. When the wedge diameter enlarging member is provided with the male screw portion, the male screw portion has a diameter smaller than the diameter of the cylindrical wedge by about several mm.

Furthermore, in the above description, the diameter of the cylindrical wedge is expanded by screwing the male screw portion provided on the wedge diameter expanding member into the female screw portion of the cylindrical wedge. However, even if a rod-shaped wedge expanding member that gradually expands from the tip end toward the proximal side is inserted into the cylindrical wedge to expand the cylindrical wedge, heat is generated by the expanded cylindrical wedge. The part can be pressed and pressed against the inner wall of the hole. In this case, the tubular wedge does not have to have a female screw portion, and when the wedge expanding member has a male screw portion, the tubular wedge may have a female screw portion.

Further, in the above description, the cylindrical wedge 17 is provided with the flat surface portion 17c at the portion contacting the heat generating portion 7, but the present invention is in a state of being inserted into the pressing member insertion portion of the metal block. As long as the diameter of the cylindrical wedge can be expanded by inserting the wedge diameter expanding member, the heat generating portion may be pressed without providing the flat portion on the outer peripheral surface of the cylindrical wedge.

An experiment was conducted to confirm the action and effect of the heater unit according to the present invention. The result will be described below.

(Comparative example)
As a comparison target of the heater unit according to the present invention, an experiment was conducted using the heater unit 33 shown in FIG.
The heater unit 33 is a metal block having a diameter of 45 mm and a total length of 65 mm, and a copper block 35 having a diameter of 9.38 mm is formed as a heater insertion portion 37, and a cartridge heater 3 (heating element: nichrome wire, WATLOW) It was manufactured by inserting a fire rod cartridge heater (manufactured by the same company) and a heating portion 7 having a diameter of 9.35 mm.

The experiment was performed with the device configuration shown in FIG. First, a constant current (=2 A) is continuously applied to the cartridge heater 3 by the constant current power supply device 41 to change the resistance value of the nichrome wire which is a heating element (hereinafter, referred to as “heater resistance value”) and the copper-made product. The temperature of block 35 was determined. The heater resistance value was calculated from the voltage measured by the voltmeter 43 and the current applied to the heating element, and the temperature of the copper block 35 was measured by the temperature indicator 47 of the output of the temperature sensor 45 installed in the copper block 35. ..

The temperature measured by the temperature sensor 45 is the temperature of the copper block 35, which is different from the temperature of the heat generating portion 7. Further, as shown in FIG. 7, the heater resistance value of the heating portion 7 has a characteristic that it changes depending on the temperature of the nichrome wire itself, which is a heating element.

That is, as the temperature of the nichrome wire rises, the heater resistance value rises and reaches a maximum value in the vicinity of about 790K (about 500°C), and then the heater resistance value once decreases and rises again from about 1070K (about 800°C). .. Such temperature dependence of the heater resistance value is a characteristic of the nichrome wire itself, and it is considered that there is no difference between individual cartridge heaters.

Therefore, the temperature of the heat generating portion 7 was estimated from the relationship between the heater resistance value obtained by the experiment in the apparatus configuration shown in FIG. 6 and the heater resistance value and the nichrome wire temperature shown in FIG. The heater resistance value shown on the vertical axis in FIG. 7 is normalized by the maximum value.

(Example 1)
An experiment was conducted using the heater unit 23 shown in FIG. 3 as the heater unit according to the present invention.
As shown in FIG. 8, the heater unit 23 includes a cylindrical copper block 25 having a diameter of 45 mm and a total length of 65 mm, a circular hole having a diameter of 9.38 mm as the heater insertion portion 9 and a circular hole having a diameter of 6 mm as the pressing member insertion portion 13. The cartridge heater 3 (heating element: nichrome wire, fire rod cartridge heater manufactured by WATLOW, diameter φ9.35 mm) is inserted into the heater insertion portion 9, and the cylindrical wedge shown in FIG. 9 is inserted into the pressing member insertion portion 13. 17 is inserted, the cylindrical wedge 17 is expanded in diameter, and the heat generating portion 7 is wedged.

Then, similarly to the comparative example described above, an experiment was performed with the device configuration shown in FIG. 6, and the change in the heater resistance value when 2 A was continuously applied to the cartridge heater 3 by the constant current power supply device 41 and the copper block 25 The temperature was determined. Furthermore, the temperature of the heat generating part 7 was estimated from the obtained heater resistance value.

(Evaluation)
FIG. 10 shows the results of the temperature and the heater resistance value of the copper block obtained by the experiment using the heater unit 33 according to Comparative Example 1 and the heater unit 23 according to Example 1. In FIG. 10, the horizontal axis represents the elapsed time from the start of heating of the cartridge heater, the left axis represents the heater resistance value normalized by the maximum value, and the right axis represents the temperature of the copper block. Further, FIG. 10 shows the temperature of the heat generating portion when the heater resistance value is the maximum value and the minimum value.

As shown in FIG. 10, in Comparative Example 1 (a plot of ◯ and Δ in FIG. 10), the heater resistance value after passing a constant current through the cartridge heater 3 shows a maximum value, and The temperature was about 790K (about 520℃), while the temperature of the copper block was about 350K (about 80℃). Further, the heater resistance value decreased after showing the maximum value, became the minimum value, and then increased again. When the heater resistance value showed a minimum value, the temperature of the heat generating part was about 1070K (800°C), while the temperature of the copper block 35 was about 580K. As a result, a temperature difference of about 500 K occurs between the temperature of the heat generating part 7 and the temperature of the copper block 35, indicating that sufficient heat contact is not obtained between the heat generating part 7 and the copper block 35. ing.

On the other hand, in Example 1 (plotted with ● and ▲ in FIG. 10), the temperature of the heat generating portion was about 790K when the heater resistance value showed the maximum value, whereas the temperature of the copper block was about 550K. It was From this result, in the first embodiment, the cylindrical wedge 17 presses the heat generating portion 7 against the inner wall of the hole 15, so that the temperature difference between the heat generating portion 7 and the copper block 25 is reduced to about 250K, and the thermal contact is improved. You can see that

Further, from the results of Example 1 in FIG. 10, if the maximum current output applied to the cartridge heater 3 is set to 2 A and the temperature of the copper block 25 is controlled to be 500 K or less, the upper limit of the specified temperature of the cartridge heater 3 is obtained. It is suggested that the cartridge heater 3 can be used without exceeding (about 800° C.), and it is shown that the risk of disconnection of the cartridge heater 3 and the extension of life can be realized.

(Example 2)
In Example 2, an experiment was conducted using the heater unit 1 shown in FIG. Here, as the metal block 5 in the heater unit 1, the copper block 49 having the shape shown in FIG. 11 was used, and the heating portions 7 of the two cartridge heaters 3 were inserted into the two heater insertion portions 9, respectively. Further, as in the first embodiment, the cylindrical wedge 17 having the shape shown in FIG. 9 was inserted into the pressing member insertion portion 13.

The experiment was performed with the apparatus configuration shown in FIG. 6, and the temperature and the heater resistance value of the copper block 49 were obtained. As a result, even when two cartridge heaters 3 were inserted, the cylindrical wedge 17 improved the thermal contact between the heat generating portion and the metal block, and the same results as in Example 1 were obtained.

Further, in the heater unit 1 as well, it was shown that the copper block 49 can be heated without exceeding the upper limit of the specification temperature of the cartridge heater 3 by controlling the temperature of the copper block 49 to be 500K. As a result, the heater unit according to the present invention can reduce the risk of disconnection of the cartridge heater and extend the life thereof even when a plurality of cartridge heaters are inserted in the copper block.

(Example 3)
With the heater unit 1 according to Example 2 attached to the device 51 shown in FIG. 12, it was verified whether the cylindrical wedge 17 could be pulled out and the cartridge heater 3 could be replaced. The device 51 is used for a refrigerator, and has a bottomed outer tube 55 having a flange 53 provided on one end side, and a SUS304 product penetrating the flange 53 and inserted inside the outer tube 55. The holding pipe 57 has a double pipe structure, and the holding pipe 57 has the heater unit 1 installed at the bottom and a pipe 59 inserted inside.

In such a device 51, it is necessary to mount the heater unit 1 in a narrow space. However, in the heater unit 1, the wedge expanding member 19 that expands the cylindrical wedge 17 inserted into the copper block 49 is screwed only at a portion corresponding to the step portion 17f of the cylindrical wedge 17. By doing so, the pressing of the tubular wedge 17 against the heat generating portion 7 was reduced, the tubular wedge 17 could be pulled out, and the cartridge heater 3 could be replaced.
From the above, it was demonstrated that, in the heater unit according to the present invention, the cylindrical wedge can be pulled out and the cartridge heater can be replaced even when it is attached to a narrow place where it cannot be reached.

DESCRIPTION OF SYMBOLS 1 heater unit 3 cartridge heater 5 metal block 7 heating part 7a arcuate surface part 9 heater insertion part 9a curved surface part 11 heater pressing member 13 pressing member insertion part 13a curved surface part 15 hole part 17 tubular wedge 17a notch part 17b female screw part 17c Flat part 17d Arc-shaped surface part 17e Insertion start end 17f Step part 19 Wedge expanding member 19a Male screw part 21 Lead wire 23 Heater unit 25 Copper block 27 Cylindrical wedge 27a Notch part 29 Cylindrical wedge 29a Notch part 31 Cylindrical wedge 31a Notch 33 Heater unit 35 Copper block 37 Heater insert 41 Constant current power supply device 43 Voltmeter 45 Temperature sensor 47 Temperature indicator 49 Copper block 51 Device 53 Flange 55 Outer pipe 57 Holding pipe 59 Piping

Claims (6)

A heater unit comprising: a cartridge heater having a heating portion in which a heating element is covered with a metal tube; and a metal block into which the heating portion of the cartridge heater is inserted and heated.
The metal block has a hole portion having a heater insertion portion into which the heat generating portion is inserted, and a pressing member insertion portion into which a heater pressing member that presses the heat generating portion inserted into the heater insertion portion against an inner wall is inserted. Prepare,
The heater pressing member is provided with at least one notch formed by cutting out a peripheral wall and has a cylindrical tubular wedge that can be expanded in diameter, and a wedge that is inserted into the cylindrical wedge and expands the cylindrical wedge. And an expanding member,
The wedge expanding member is inserted into the cylindrical wedge to expand the cylindrical wedge, the expanded cylindrical wedge presses the heat generating portion, and the heat generating portion is pressed against the inner wall of the hole. The heater unit is characterized by The heat generating portion and the tubular wedge have arcuate surface portions on their outer peripheral surfaces, and the heater insertion portion and the pressing member insertion portion are formed with curved surface portions along the arc surface portions of the heat generating portion and the cylindrical wedge. The heater unit according to claim 1, wherein: The tubular wedge has an internal thread portion having an internal thread formed on the inner surface thereof, and a flat portion is provided at a portion for pressing the heat generating portion,
The wedge diameter enlarging member includes a male screw portion that is screwed into a female screw portion of the cylindrical wedge to expand the diameter of the cylindrical wedge.
The flat portion contacts the heat generating portion when the heat generating portion and the cylindrical wedge are inserted and the male screw portion of the wedge expanding member is screwed into the female screw portion of the cylindrical wedge. 3. The heater unit according to claim 1, wherein the cylindrical wedge is set to have a hole diameter that prevents the cylindrical wedge from rotating. The cylindrical wedge has a stepped portion with a concave surface on the insertion start end side of the flat surface portion into which the wedge expanding member is inserted,
The step portion generates heat when the heat generating portion and the tubular wedge are inserted into the hole and the wedge expanding member is screwed only on the insertion start end side of the tubular wedge. The heater unit according to claim 3, wherein the heater unit is formed so as not to press the portion. The diameter expansion part of the wedge has a diameter reduction part at the tip side, and the diameter of the cylindrical wedge is not expanded in a state where only the diameter reduction part is screwed into the cylindrical wedge. Item 3. The heater unit according to Item 3 or 4. The heater unit according to any one of claims 1 to 5, which is used in a vacuum environment.