Swivel joint and vacuum drying apparatus having the same

Abstract

To provide a swivel joint capable of suppressing an increase in weight and cost due to an increase in size, and a vacuum drying device including the same.SOLUTION: A cylindrical fixed portion and a cylindrical rotating portion fitted to the fixed portion so as to be rotatable about an axial center of the fixed portion, the fixed portion having a fixed-side first surface portion facing a direction of the axial center and a fixed-side second surface portion facing a radial direction with respect to the axial center, the rotating portion having a rotation-side first surface portion facing the direction of the axial center and a rotation-side second surface portion facing the radial direction with respect to the axial center, the fixed-side first surface portion and the rotation-side first surface portion facing each other, A plurality of rotors and one or more seal rings are provided between the fixed-side second surface part and the rotation-side second surface part that face each other, and a plurality of rotors and one or more seal rings are provided between the fixed-side second surface part and the rotation-side second surface part that face each other.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a swivel joint and a vacuum drying apparatus including the same. [Background technology]

[0002] Patent Document 1 discloses a conventional swivel joint in which one of an inlet pipe and an outlet pipe is rotatably mounted on the outer periphery of the other pipe, and a heat-resistant and pressure-resistant seal material, a radial bearing, and a thrust bearing are mounted between the two pipes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-213670 Summary of the Invention [Problem to be solved by the invention]

[0004] In a swivel joint such as that disclosed in Patent Document 1, the larger the diameter of the inlet pipe, the larger the diameter of the radial bearing and thrust bearing. Therefore, for example, a swivel joint connecting the rotating part and fixed part of a vacuum drying device whose drum diameter exceeds 1 meter inevitably becomes larger and heavier, resulting in increased costs.

[0005] SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a swivel joint and a vacuum drying apparatus equipped with the same. [Means for solving the problem]

[0006] The present invention provides a swivel joint comprising a cylindrical fixed portion and a cylindrical rotating portion fitted to the fixed portion so as to be rotatable around the axis of the fixed portion, wherein the fixed portion has a fixed-side first surface portion facing in the direction of the axis and a fixed-side second surface portion facing radially from the axis, and the rotating portion has a rotating-side first surface portion facing in the direction of the axis and a rotating-side second surface portion facing radially from the axis, wherein the fixed-side first surface portion and the rotating-side first surface portion face each other and the fixed-side second surface portion and the rotating-side second surface portion face each other, a plurality of rotors and one or more seal rings are provided between the fixed-side first surface portion and the rotating-side first surface portion which face each other, and a plurality of rotors and one or more seal rings are provided between the fixed-side second surface portion and the rotating-side second surface portion which face each other.

[0007] The present invention also provides a vacuum drying apparatus comprising: a rotating drum having one end in the direction of the rotation axis that is open and the other end that is closed; a drum section that includes the swivel joint connected to one end of the rotating drum and a fixed closing plate connected to the swivel joint so as to close the opening of the rotating drum; a support section that supports the drum section and allows the rotating drum to rotate; a rotation drive section that rotates the rotating drum; a decompression section that reduces the pressure inside the drum section; and a heating section that heats the material to be dried contained in the drum section. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a swivel joint that suppresses increases in weight and cost that accompany increases in size, and a vacuum drying apparatus equipped with the same. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a left side view illustrating the configuration of a vacuum drying device equipped with a swivel joint according to a first embodiment of the present invention. FIG. [Figure 2] 1 is a front view of a vacuum drying apparatus according to a first embodiment, viewed from the direction of a rotation axis. [Figure 3] 1 is a partial vertical cross-sectional view taken along the rotation axis direction of a swivel joint according to a first embodiment. FIG. [Figure 4]3 is a front view of a rotating part of a swivel joint in the vacuum drying apparatus of the first embodiment, viewed from the direction of the rotation axis. FIG. [Figure 5] FIG. 4 is a partial longitudinal cross-sectional view taken in the axial direction of a swivel joint according to a modified example of the first embodiment. [Figure 6] FIG. 10 is a partial longitudinal cross-sectional view taken along the axial direction of a swivel joint according to a second embodiment. [Figure 7] FIG. 10 is a partial longitudinal cross-sectional view taken along the axial direction of a swivel joint according to a third embodiment. [Figure 8] FIG. 10 is a partial longitudinal cross-sectional view taken along the axial direction of a swivel joint according to a fourth embodiment. [Figure 9] FIG. 10 is a configuration explanatory diagram of a vacuum drying device according to a fifth embodiment, viewed from the left side. [Figure 10] FIG. 10 is a configuration explanatory diagram of a vacuum drying device according to a sixth embodiment, viewed from the left side. [Figure 11] FIG. 13 is a configuration explanatory diagram of a vacuum drying apparatus according to a seventh embodiment, viewed from the left side. [Figure 12] FIG. 13 is a configuration explanatory diagram of a vacuum drying apparatus according to an eighth embodiment, viewed from the left side. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in more detail below with reference to the accompanying drawings. Note that the following description is illustrative in all respects and should not be construed as limiting the present invention.

[0011] (First embodiment) 1 is a left side explanatory diagram of the configuration of a vacuum drying apparatus 2 equipped with a swivel joint 1 according to a first embodiment of the present invention. The vacuum drying apparatus 2 of the first embodiment comprises a drum unit 4 having a rotary drum 3, a support unit 5 that supports the drum unit 4, a rotation drive unit 6 that rotates the rotary drum 3, a pressure reducing unit 7 that reduces the pressure inside the drum unit 4, and a heating unit 8 that heats the material to be dried housed in the drum unit 4.

[0012] This vacuum drying apparatus 2 dries the material to be dried by reducing the pressure inside the drum unit 4 to a pressure lower than atmospheric pressure to lower the boiling point of the water in the material to be dried stored in the drum unit 4, and then heating the material to be dried inside the drum unit 4 to evaporate the water in the material to be dried and discharge it to the outside. Alternatively, the material to be dried inside the drum unit 4 may be heated and then the pressure inside the drum unit 4 may be reduced, or heating and decompression may be repeated multiple times.

[0013] This vacuum dryer 2 can be used, for example, to ferment and dry organic waste to produce fertilizer or feed, and can also be used to dry food and laundry. In this case, for example, when the pressure inside the drum unit 4 is a low vacuum of approximately 3 kPa to 5 kPa, the boiling point of the moisture in the material to be dried inside the drum unit 4 is 25 to 30°C, enabling drying at a lower temperature and in a shorter time than drying at room temperature and pressure. The pressure inside the drum unit 4 and the heating temperature of the material to be dried by the vacuum dryer 2 are arbitrary and can be room temperature, and can be set appropriately depending on the weight, moisture content, and form (lump, granular) of the material to be dried. For example, when the pressure inside the drum unit 4 is a low vacuum of approximately 0.6 kPa to 0.9 kPa, the boiling point of the moisture in the material to be dried inside the drum unit 4 is approximately 0°C to 5°C. Therefore, if the temperature inside the drum unit 4 is room temperature (e.g., 20°C), heating the material to be dried using the heating unit 8 is not necessary.

[0014] Fig. 2 is a front view of the vacuum drying apparatus 2 of the first embodiment as seen from the direction of the rotation axis. As shown in Figs. 1 and 2, the drum unit 4 includes a rotating drum 3 that is open at one end 10 and closed at the other end 11 in the direction of the axis 9 of the drum unit 4, a swivel joint 1 connected to the one end 10 of the rotating drum 3, and a fixed closing plate 12 connected to the swivel joint 1 so as to close the opening of the rotating drum 3. The swivel joint 1 allows the rotating drum 3 to rotate around the axis 9 relative to the fixed closing plate 12.

[0015] An inlet 13 for the material to be dried and an opening / closing door 14 for the inlet 13 are provided on the upper part of the fixed closing plate 12, and an outlet 15 for removing the material to be dried (the dried material to be dried) and an opening / closing door 16 for the outlet 15 are provided on the lower part of the fixed closing plate 12. Furthermore, lock levers (not shown) are provided on the outer surface 12a of the fixed closing plate 12 near each of the upper and lower opening / closing doors 14, 16, and the lock levers can be locked to keep the opening / closing doors 14, 16 closed, and the lock levers can be unlocked to open the opening / closing doors 14, 16. Seal rings 30 (see FIG. 3) are provided around the inlet 13 and the opening / closing door 15 on the outer surface of the fixed closing plate 12, and when the opening / closing doors 14, 16 are closed, the inside of the drum unit 4 can be maintained as an airtight space.

[0016] In this embodiment, the heating unit 8 is a panel-type explosion-proof heater and is provided on the inner surface 12b of the fixed closure plate 12 between the upper and lower open / close doors 14, 16. The decompression unit 7 is a suction device such as a vacuum pump or an electric suction fan, and is connected via a gas flow passage 17 to a first through-hole 12c provided between the inlet 13 in the fixed closure plate 12 and the heating unit 8. A three-way valve (not shown) may be provided in the gas flow passage 17, and a dry air supply device (not shown) may be connected to the three-way valve. In this way, low-humidity dry air from the dry air supply device may be supplied via the gas flow passage 17 into the drum unit 4 after reduced-pressure drying, and the pressure inside the drum unit 4 may be returned to atmospheric pressure while the dry air comes into contact with the dried material.

[0017] The support unit 5 includes a base 18, a support stand 19 that supports the swivel joint 1 and fixed closure plate 12 of the drum unit 4, and a pair of support rollers 20 that support the rotating drum 3 of the drum unit 4. In this embodiment, the support unit 5 also includes three weight measuring devices 21 provided between the base 18 and the support stand 19 and between the base 18 and the pair of support rollers 20. The rotation drive unit 6 is an electric motor with a reducer that can rotate forward and backward and is connected to the outer surface of the end wall 29 on the other end 11 side of the rotating drum 3, and can rotate the rotating drum 3 about the axis 9 in a first rotation direction (the direction of arrow A) or a second rotation direction (the direction opposite to the direction of arrow A).

[0018] As shown in FIG. 1 , the inner peripheral surface of the rotating drum 3 is provided with a plurality of agitating blades 22 and a plurality of transferring blades 23 that agitate the material to be dried when the rotating drum 3 rotates. The plurality of agitating blades 22 are long blades extending from one end 10 to the other end 11 of the rotating drum 3 in the direction of the axis 9, and are arranged at equal intervals in the circumferential direction around the axis 9. The plurality of transferring blades 23 are short blades extending in the circumferential direction around the axis 9, and have a shape that is slightly curved or inclined with respect to the direction perpendicular to the axis 9 when viewed from a direction perpendicular to the axis 9. In the region between two adjacent agitating blades 22, a plurality of transferring blades 23 are arranged at equal intervals in the direction of the axis 9. One transferring blade 23 is offset from another transferring blade 23 adjacent to it in the circumferential direction in the direction of the axis 9.

[0019] When the rotating drum 3 rotates in the first rotation direction, the material to be dried inside the rotating drum 3 is lifted circumferentially to a certain height by the rotating agitator blades 22 and then dropped, thereby being agitated. During this time, the material to be dried inside the rotating drum 3 is transferred from one end 10 to the other end 11 by the rotating transfer blades 23. When the rotating drum 3 rotates in the second rotation direction, the material to be dried inside the rotating drum 3 is transferred from the other end 11 to the one end 10 by the rotating transfer blades 23 while being agitated by the rotating agitator blades 22. When the dried material to be dried is removed from the drum section 4, the lower opening / closing door 16 is opened while the rotating drum 3 is rotating in the second rotation direction, and the dried material is automatically discharged to the outside through the outlet 15. The rotating drum 3 rotates at a rotation speed of approximately 2 rpm to 20 rpm.

[0020] FIG. 3 is a partial longitudinal cross-sectional view of the swivel joint 1 of the first embodiment, taken along the axis 9. FIG. 4 is a front view of the rotating portion of the swivel joint 1 in the vacuum drying apparatus 2 of the first embodiment, viewed along the axis 9. The swivel joint 1 includes a fixed portion 31 connected to a fixed closure plate 12, a rotating portion 32 fitted to the fixed portion 31 so as to be rotatable about the axis 9, and a plurality of first rotors 33a, a plurality of second rotors 33b, a first seal ring 34a, and a second seal ring 34b, which are provided between the fixed portion 31 and the rotating portion 32. The fixed portion 31 is formed concave, and the rotating portion 32 is formed convex, with the convex rotating portion 32 rotatably fitted into the concave fixed portion 31. The rotating portion 32 of the swivel joint 1 is connected to the rotating drum 3 so as to rotate integrally with the rotating drum 3.

[0021] As shown in FIG. 3, the fixed portion 31 of the swivel joint 1 has a short cylindrical appearance, and the vertical cross section of the thick portion of the cylinder is approximately L-shaped. The fixed portion 31 has two fixed-side first surfaces 35a, 35b facing the axis 9 and a fixed-side second surface 36 facing radially relative to the axis 9 and provided between the two fixed-side first surfaces 35a, 35b. One fixed-side first surface 35a is provided closer to the rotating drum 3 and radially outward than the other fixed-side first surface 35b. In other words, the other fixed-side first surface 35b is provided closer to the fixed closure plate 12 and radially inward than the one fixed-side first surface 35a.

[0022] The rotating part 32 of the swivel joint 1 has a short cylindrical appearance, and the vertical cross section of the thick part of the cylinder is approximately L-shaped. This rotating part 32 has two rotation-side first surfaces 37a, 37b facing the axis 9, and a rotation-side second surface 38 facing radially relative to the axis 9 and provided between the two rotation-side first surfaces 37a, 37b. One rotation-side first surface 37a is provided closer to the rotating drum 3 and further outward in the radial direction than the other rotation-side first surface 37b. In other words, the other rotation-side first surface 37b is provided closer to the fixed closure plate 12 and further inward in the radial direction than the one rotation-side first surface 37a.

[0023] In this swivel joint 1, one fixed-side first surface portion 35a faces one rotation-side first surface portion 37a, the fixed-side second surface portion 36 faces one rotation-side second surface portion 38, the other fixed-side first surface portion 35b faces the other rotation-side first surface portion 37b, and the fixed-side second surface portion 36 is disposed radially outward of the rotation-side second surface portion 38. A first seal ring 34a is provided between one fixed-side first surface portion 35a and one rotation-side first surface portion 37a that face each other, a plurality of first rotors 33a and second seal rings 34b are provided between the fixed-side second surface portion 36 and rotation-side second surface portion 38 that face each other, and a plurality of second rotors 33b are provided between the other fixed-side first surface portion 35b and the other rotation-side first surface portion 37b that face each other. As shown in FIG. 3, the first seal ring 34a, the plurality of first rotors 33a, the second seal ring 34b, and the plurality of second rotors 33b are alternately arranged from the outside to the inside in the radial direction.

[0024] More specifically, in this embodiment, a circumferential groove having a rectangular cross section is provided around the entire circumference on each of the fixed-side first surface portion 35a and the fixed-side second surface portion 36, and X-rings serving as first and second seal rings 34a, 34b are provided within these circumferential grooves. The first seal ring 34a is in close contact with the rotating-side first surface portion 37a, and the second seal ring 34b is in close contact with the rotating-side second surface portion 38. In this embodiment, the fixed-side second surface portion 36 and the rotating-side second surface portion 38 face each other. The rotating-side second surface portion 38 is provided with a circumferential groove having a semicircular cross section around the entire circumference, and the fixed-side second surface portion 36 is provided with a circumferential groove having a rectangular cross section around the entire circumference. A plurality of first balls (e.g., made of stainless steel or ceramics) serving as first rotors 33a are provided between these circumferential grooves around the entire circumference. The plurality of first rotors 33a are arranged between the circumferential grooves. Note that circumferential grooves having a rectangular cross section or a semicircular cross section may be formed on both the fixed-side second surface portion 36 and the rotating-side second surface portion 38, and the inner end surface of the plug 39 on the first ball 33a side may be formed in a concave curve. Also, a circumferential groove having a semicircular cross section is provided around the entire circumference on the other fixed-side first surface portion 35b, and hemispherical recesses are provided at equal intervals in the circumferential direction on the other rotating-side first surface portion 37b, and a plurality of second balls (made of, for example, stainless steel or ceramics) serving as the second rotor 33b are provided between these multiple hemispherical recesses and circumferential grooves (see FIG. 4).

[0025] Furthermore, in this embodiment, a shallow notch is provided on the radially inner side of the other fixed-side first surface portion 35b of the fixed part 31, and a circumferential groove with a rectangular cross section is provided on the inner peripheral surface of the notch, extending in the circumferential direction, and an X-ring is provided in this circumferential groove as a third seal ring 34c (see FIG. 3). Also, an annular small protrusion 40 that fits into the shallow notch of the fixed part 31 is provided on the radially inner side of the rotation-side first surface portion 37b of the rotating part 32, and the third seal ring 34c is in close contact with this small protrusion 40. This third seal ring 34c prevents the material to be dried inside the drum part 4 from entering the gap between the fixed part 31 and the rotating part 32. Hereinafter, the first rotor 33a may be referred to as the first ball 33a, the second rotor 33b may be referred to as the second ball 33b, and the first, second and third seal rings 34a, 34b and 34c may be referred to as the first, second and third X rings 34a, 34b and 34c.

[0026] The plurality of first balls 33a between the opposing fixed-side second surface portion 36 and the opposing rotation-side second surface portion 38 receive a radial force, and the plurality of second balls 33b between the opposing fixed-side first surface portion 35b and the opposing rotation-side first surface portion 37b receive a force in the direction of the axis 9. For this reason, the diameters of the first balls 33a and the second balls 33b are set to a diameter such that an appropriate gap (for example, a gap of about 0.1 mm to 1.0 mm) is formed between one opposing fixed-side first surface portion 35a and one opposing rotation-side first surface portion 37a, between the opposing fixed-side second surface portion 36 and the opposing rotation-side second surface portion 38, and between the other opposing fixed-side first surface portion 35b and the other opposing rotation-side first surface portion 37b. In this embodiment, the diameter of the first ball 33a is approximately 15 mm to 19 mm, and the diameter of the second ball 33b is approximately 13 mm to 16 mm, so that the first ball 33a is larger than the second ball 33b. However, the second ball 33b may be larger than the first ball 33a, or the first ball 33a and the second ball 33b may be the same size.

[0027] When assembling the swivel joint 1, the rotating part 32 is positioned with the rotation-side first surface 37b facing upward, the second balls 33b are placed in the hemispherical recesses of the rotation-side first surface 37b, and the fixed part 31 is fitted to the rotating part 32 with the fixed-side first surface 35b facing the rotation-side first surface 37b. At this time, the first, second, and third X rings 34a, 34b, and 34c are already attached to the fixed part 31, and the exposed hemispherical portions of the second balls 33b fit into the circumferential grooves of the fixed part 31. Thereafter, the first balls 33a are inserted one by one through ball insertion holes that have been formed in advance to penetrate (connect) from the outer circumferential surface of the fixed part 31 to the circumferential groove of the fixed-side second surface 36, filling the circumferential groove with the first balls 33a, and the ball insertion holes are then plugged with plugs 39. The first and second balls 33a and 33b are coated with a lubricant (for example, grease) in advance.

[0028] When the pressure inside the drum unit 4 is reduced, atmospheric pressure presses the outer surface of the fixed unit 31 of the swivel joint 1 toward the rotating unit 32, with the first balls 33a receiving a radial force and the second balls 33b receiving a force in the direction of the axis 9. Therefore, even when the drum unit 4 is evacuated, the gap between one fixed-side first surface 35a and one rotating-side first surface 37a, the gap between the fixed-side second surface 36 and the rotating-side second surface 38, and the gap between the other fixed-side first surface 35b and the other rotating-side first surface 37b are each maintained at an appropriate gap dimension. As a result, when the rotating unit 32 rotates relative to the fixed unit 31, the first X ring 34a slides against the rotating-side first surface 37a with an appropriate contact force, and the second X ring 34b slides against the rotating-side second surface 38 with an appropriate contact force. This extends the lifespan of the first and second X rings 34a, 34b, reducing the frequency of replacement of the first and second X rings 34a, 34b. Furthermore, even if the inside of the drum unit 4 is evacuated, an increase in the torque of the rotating unit 32 relative to the fixed unit 31 can be suppressed, reducing the burden on the rotation drive unit 6 (see FIG. 1). When the rotating drum 3 rotates, the multiple first balls 33a roll (spin) in roughly fixed positions, but the multiple second balls 33b roll (spin) while rotating (revolving) around the axis 9 together with the rotating unit 32.

[0029] As described above, when assembling the swivel joint 1 of this embodiment, the second balls 33b are placed in each of the multiple hemispherical recesses arranged at equal intervals on the rotation-side first surface portion 37b of the rotating portion 32, and then the fixed portion 31 can be fitted to the rotating portion 32. This prevents the multiple second balls 33b from coming into close contact with each other, and furthermore, the weight of the rotating drum 3 is not applied to the multiple second balls 33b, which is advantageous for arranging the multiple second balls 33b at intervals (reducing the number of second balls 33b). In contrast, after the fixed portion 31 is fitted to the rotating portion 32, the first balls 33a are inserted one by one through the ball insertion holes of the fixed portion 31 and placed between the circumferential grooves of the fixed-side second surface portion 36 and the rotation-side second surface portion 38. Therefore, the multiple first balls 33a are in close contact with each other. However, because the rotating drum 3 rotates at a slow rotation speed of approximately 2 rpm to 20 rpm, the multiple first balls 33a are prevented from rubbing against each other and becoming easily worn. Furthermore, because the swivel joint 1 of this embodiment uses the fixed portion 31 and the rotating portion 32 to rotatably hold the multiple first balls 33a and the multiple second balls 33b, the number of parts can be reduced compared to when a swivel joint is manufactured using a typical radial bearing and thrust bearing, resulting in a simplified structure. In other words, the swivel joint 1 of this embodiment does not require the inner ring, outer ring, and ball cage that constitute the radial bearing, and the shaft washer, housing washer, and ball cage that constitute the thrust bearing, thereby simplifying the structure and suppressing increases in weight and cost. Note that, like the multiple first balls 33a, the multiple second balls 33b may be arranged in close contact with each other.

[0030] (Modification 1 of the first embodiment) Figure 5 is a partial longitudinal cross-sectional view taken in the axial direction of a swivel joint according to a modification of the first embodiment. In Figure 5, elements similar to those in Figure 3 are designated by the same reference numerals. In the swivel joint 1 of the drum section 4 of the first embodiment, X-rings (see Figure 4) are used as the first, second, and third seal rings 34a, 34b, and 34c, respectively. However, as shown in Figure 5, in the swivel joint 51 of the drum section 50 of Modification 1, U-rings are used as the first, second, and third seal rings 52a, 52b, and 52c. The first, second, and third seal rings may alternatively be O-rings.

[0031] (Modification 2 of the first embodiment) The swivel joint 1 of the first embodiment (see FIG. 3) is configured so that the fixed portion 31 is fitted to the rotating portion 32 after the multiple second balls 33b are placed in multiple hemispherical recesses provided in the rotating portion 32, but the opposite configuration may also be used. That is, multiple hemispherical recesses may be provided on the other fixed-side first surface portion 35b of the fixed portion 31, and a circumferential groove may be provided around the entire circumference of the other rotation-side first surface portion 37b of the rotating portion 32, so that the multiple second balls 33b are placed in the multiple hemispherical recesses of the fixed portion 31 before the rotating portion 32 is fitted to the fixed portion 31. With this configuration, the multiple second balls 33b roll (spin) in fixed positions when the rotating drum 3 rotates.

[0032] (Modification 3 of the first embodiment) In the first embodiment, the case where balls are used as the first and second rotors 33a, 33b in the swivel joint 1 (see FIG. 3) has been exemplified, but rollers may be used instead of balls.

[0033] (Second embodiment) FIG. 6 is a partial longitudinal cross-sectional view of a swivel joint 61 of a second embodiment, cut in the direction of the rotation axis. In FIG. 6, elements similar to those in FIG. 3 are assigned the same reference numerals. Below, differences between the swivel joint 61 of the drum unit 60 of the second embodiment and the first embodiment will be mainly described. In the swivel joint 1 of the drum unit 4 of the first embodiment (see FIG. 3), the fixed portion 31 is formed concavely and the rotating portion 32 is formed convexly, with the convex rotating portion 32 rotatably fitted into the concave fixed portion 31. In contrast, in the swivel joint 61 of the drum unit 60 of the second embodiment shown in FIG. 6, the fixed portion 62 is formed convexly and the rotating portion 63 is formed concavely, with the concave rotating portion 63 rotatably fitted into the convex fixed portion 62.

[0034] As shown in FIG. 6, the fixed portion 62 of the swivel joint 61 has a short cylindrical appearance, and the vertical cross section of the thick portion of the cylinder is approximately L-shaped. The fixed portion 62 has two fixed-side first surfaces 64a, 64b facing the axis 9 and a fixed-side second surface 65 facing radially relative to the axis 9 and provided between the two fixed-side first surfaces 64a, 64b. One fixed-side first surface 64a is provided closer to the rotating drum 3 and more radially inward than the other fixed-side first surface 64b. In other words, the other fixed-side first surface 64b is provided closer to the fixed closure plate 12 and more radially outward than the one fixed-side first surface 64a.

[0035] The rotating portion 63 of the swivel joint 61 has a short cylindrical appearance, and the vertical cross section of the thick portion of the cylinder is approximately L-shaped. This rotating portion 63 has two rotation-side first surfaces 66a, 66b facing the axis 9 and a rotation-side second surface 67 facing radially relative to the axis 9 and provided between the two rotation-side first surfaces 66a, 66b. One rotation-side first surface 66a is provided closer to the rotating drum 3 and radially inward than the other rotation-side first surface 66b. In other words, the other rotation-side first surface 66b is provided closer to the fixed closure plate 12 and radially outward than the one rotation-side first surface 66a.

[0036] In this swivel joint 61, one fixed-side first surface portion 64a faces one rotation-side first surface portion 66a, the fixed-side second surface portion 65 faces one rotation-side second surface portion 67, the other fixed-side first surface portion 64b faces the other rotation-side first surface portion 66b, and the fixed-side second surface portion 65 is disposed radially inward of the rotation-side second surface portion 67. A first seal ring 68a is provided between the other fixed-side first surface portion 64b and the other rotation-side first surface portion 66b that face each other, a plurality of first rotors 69a and second seal rings 68b are provided between the fixed-side second surface portion 65 and the rotation-side second surface portion 67 that face each other, and a plurality of second first rotors 69b are provided between the one fixed-side first surface portion 64a and one rotation-side first surface portion 66a that face each other. As shown in Figure 6, between the fixed part 62 and the rotating part 63, from the radial outside to the radial inside, a first seal ring 68a, a plurality of first rotors 69a, a second seal ring 68b, and a plurality of second rotors 69b are arranged.

[0037] More specifically, in this embodiment, a circumferential groove having a rectangular cross section is provided around the entire circumference on each of the other fixed-side first surface portion 64b and the other fixed-side second surface portion 65, and X-rings serving as first and second seal rings 68a, 68b are provided within these circumferential grooves. The first seal ring 68a is in close contact with the other rotating-side first surface portion 66b, and the second seal ring 68b is in close contact with the rotating-side second surface portion 67. In this embodiment, of the opposing fixed-side second surface portion 65 and rotating-side second surface portion 67, the fixed-side second surface portion 65 is provided with a circumferential groove having a semicircular cross section around the entire circumference, and the rotating-side second surface portion 67 is provided with a circumferential groove having a rectangular cross section around the entire circumference. A plurality of first balls (e.g., made of stainless steel or ceramics) serving as first rotors 69a are provided between these circumferential grooves around the entire circumference. The plurality of first rotors 69a are arranged between the circumferential grooves. Alternatively, a circumferential groove having a rectangular cross section or a semicircular cross section may be formed on both the fixed-side second surface portion 65 and the rotating-side second surface portion 67, and the inner end surface of the plug 39 on the first ball 69a side may be formed concavely. Alternatively, a circumferential groove having a semicircular cross section may be formed around the entire circumference on one fixed-side first surface portion 64a, and hemispherical recesses may be formed at equal intervals in the circumferential direction on one rotating-side first surface portion 66a, with a plurality of second balls (made of, for example, stainless steel or ceramics) serving as second rotors 69b being provided between these multiple hemispherical recesses and circumferential grooves (see FIG. 6). In this case, too, it is possible to avoid a state in which the multiple second balls 69b are in close contact with each other.

[0038] Furthermore, in this embodiment, a circumferential groove with a rectangular cross section is provided around the entire circumference on the radially inner side of one of the fixed-side first surface portions 64a of the fixed portion 62, and an X-ring serving as a third seal ring 68c is provided within this circumferential groove. This third seal ring 68c prevents the material to be dried in the drum portion 4 from entering the gap between the fixed portion 62 and the rotating portion 63. Hereinafter, the first rotor 69a may be referred to as the first ball 69a, the second rotor 69b as the second ball 69b, and the first, second, and third seal rings 68a, 68b, and 68c as the first, second, and third X-rings 68a, 68b, and 68c. Note that a U-ring or an O-ring may be used instead of the X-ring.

[0039] The plurality of first balls 69a between the fixed-side second surface portion 65 and the rotation-side second surface portion 67 facing each other receive a radial force, and the plurality of second balls 69b between the fixed-side first surface portion 64a and the rotation-side first surface portion 66a facing each other receive a force in the direction of the axis 9. For this reason, the diameters of the first balls 69a and the second balls 69b are set to a diameter such that an appropriate gap (for example, a gap of about 0.1 mm to 1.0 mm) is formed between one of the fixed-side first surface portion 64a and one of the rotation-side first surface portion 66a facing each other, between the fixed-side second surface portion 65 and the rotation-side second surface portion 67 facing each other, and between the other of the fixed-side first surface portion 64b and the other of the rotation-side first surface portion 66b facing each other. In this embodiment, the diameter of the first ball 69a is approximately 15 mm to 19 mm, and the diameter of the second ball 69b is approximately 13 mm to 16 mm, with the first ball 69a being larger than the second ball 69b. However, the second ball 69b may be larger than the first ball 69a, or the first ball 69a and the second ball 69b may be the same size.

[0040] When assembling the swivel joint 61, the rotating part 63 is positioned with the rotation-side first surface 66a facing upward, the second balls 69b are placed in the hemispherical recesses of the rotation-side first surface 66a, and the fixed part 62 is fitted to the rotating part 63 with the fixed-side first surface 64a facing the rotation-side first surface 66a. At this time, the first, second, and third X rings 68a, 68b, and 68c are already attached to the fixed part 62, and the exposed hemispherical portions of the second balls 69b fit into the circumferential grooves of the fixed part 62. Thereafter, the first balls 69a are inserted one by one through ball insertion holes that are formed in advance to penetrate (communicate with) the outer circumferential surface of the rotating part 63 to the circumferential groove of the rotation-side second surface 67, filling the circumferential groove with the first balls 69a, and the ball insertion holes are then plugged. The first and second balls 69a, 69b are coated with a lubricant (for example, grease) in advance.

[0041] As with the swivel joint 1 of the first embodiment (see FIG. 3), in the swivel joint 61 of the second embodiment, when the pressure inside the drum portion 60 is reduced, the outer surface of the rotating portion 63 of the swivel joint 61 is pressed toward the fixed portion 62 by atmospheric pressure, but the first balls 69a are subjected to a radial force and the second balls 69b are subjected to a force in the direction of the axis 9. Therefore, even when the inside of the drum portion 60 is evacuated, the gap between one fixed-side first surface portion 64a and one rotating-side first surface portion 66a, the gap between the fixed-side second surface portion 65 and the rotating-side second surface portion 67, and the gap between the other fixed-side first surface portion 64b and the other rotating-side first surface portion 66b are each maintained at an appropriate gap dimension. As a result, when the rotating portion 63 rotates relative to the fixed portion 62, the first X ring 68a slides against the rotating-side first surface portion 66b with an appropriate contact force, and the second X ring 68b slides against the rotating-side second surface portion 67 with an appropriate contact force. This extends the life of the first and second X rings 68a, 68b, reducing the frequency of replacement of the first and second X rings 68a, 68b. Furthermore, even if the inside of the drum portion 60 is evacuated, an increase in the torque of the rotating portion 63 relative to the fixed portion 62 can be suppressed, reducing the burden on the rotation drive portion 6 (see FIG. 1). Note that, when the rotating drum 3 rotates, the multiple first balls 69a roll (rotate) in approximately fixed positions, while the multiple second balls 69b roll (rotate) while rotating (revolving) together with the rotating portion 63 around the axis 9.

[0042] The swivel joint 61 of the second embodiment also avoids a state in which the multiple second balls 69b come into close contact with one another, and furthermore, because the weight of the rotating drum 3 is not applied to the multiple second balls 69b, it is advantageous for arranging the multiple second balls 69b at intervals (for reducing the number of second balls 69b). In contrast, after the rotating part 63 is fitted into the fixed part 62, the first balls 69a are inserted one by one through the ball insertion hole of the rotating part 63 and are arranged between the circumferential groove of the fixed-side second surface part 65 and the circumferential groove of the rotating-side second surface part 67. Therefore, although the multiple first balls 69a come into close contact with one another, because the rotating drum 3 rotates at a slow rotation speed similar to that of the first embodiment, a situation in which the multiple first balls 69a rub against one another violently and become easily worn is suppressed. Furthermore, in the swivel joint 61 of this embodiment, the fixed portion 62 and the rotating portion 63 rotatably hold the plurality of first balls 69a and the plurality of second balls 69b, so the number of parts can be reduced compared to when a swivel joint is made using a general radial bearing and thrust bearing, and the structure can be simplified. In other words, the inner ring, outer ring, and ball cage that make up the radial bearing and the shaft washer, housing washer, and ball cage that make up the thrust bearing are not required in the swivel joint 61 of this embodiment, simplifying the structure and suppressing increases in weight and cost. Note that, like the plurality of first balls 69a, the plurality of second balls 69b may be arranged in close contact with each other.

[0043] (Modification 1 of the second embodiment) The swivel joint 61 of the second embodiment (see FIG. 6) is configured so that the fixed portion 62 is fitted to the rotating portion 63 after the multiple second balls 69b are placed in multiple hemispherical recesses provided in the rotating portion 63, but the reverse configuration may also be used. That is, multiple hemispherical recesses may be provided on one fixed-side first surface portion 64a of the fixed portion 62, and a circumferential groove may be provided around the entire circumference of one rotation-side first surface portion 66a of the rotating portion 63, so that the multiple second balls 69b are placed in the multiple hemispherical recesses of the fixed portion 62 after which the rotating portion 63 is fitted to the fixed portion 62. With this configuration, the multiple second balls 69b roll (spin) in fixed positions when the rotating drum 3 rotates.

[0044] (Third embodiment) FIG. 7 is a partial longitudinal cross-sectional view of a swivel joint 71 of the third embodiment, taken along the rotation axis. In FIG. 7, elements similar to those in FIG. 3 are designated by the same reference numerals. Below, differences between the swivel joint 71 of the drum unit 70 of the third embodiment and the first embodiment will be mainly described. In the swivel joint 71 of the third embodiment, the longitudinal cross-sectional shape of the thickness portion of the cylindrical fixed portion 72 is approximately L-shaped, while the longitudinal cross-sectional shape of the thickness portion of the cylindrical rotating portion 73 is approximately I-shaped. Therefore, in the swivel joint 71 of the third embodiment, one of the rotation-side first surfaces 37a of the swivel joint 1 of the first embodiment (see FIG. 3) is omitted, and a first X ring 34a and a second X ring 34b are provided on both sides of the fixed-side second surface 36 of the fixed portion 72, sandwiching the plurality of first balls 33a. The swivel joint 71 of the third embodiment may adopt the configuration of Modifications 1 or 2 of the first embodiment.

[0045] (Fourth embodiment) FIG. 8 is a partial longitudinal cross-sectional view of a swivel joint 81 of the fourth embodiment, taken along the rotation axis. In FIG. 8, elements similar to those in FIG. 6 are designated by the same reference numerals. Below, differences between the swivel joint 81 of the drum unit 80 of the fourth embodiment and the second embodiment will be mainly described. In the swivel joint 81 of the fourth embodiment, the longitudinal cross-sectional shape of the thickness portion of the cylindrical rotating unit 83 is approximately L-shaped, while the longitudinal cross-sectional shape of the thickness portion of the cylindrical fixed unit 82 is approximately I-shaped. Therefore, the swivel joint 81 of the fourth embodiment does not include the other fixed-side first surface 64b of the swivel joint 61 of the second embodiment (see FIG. 6). Instead, a first X ring 68a and a second X ring 68b are provided on both sides of the fixed-side second surface 65 of the fixed unit 82, sandwiching a plurality of first balls 69a. The swivel joint 81 of the fourth embodiment may be configured as modified examples 1 and 2 of the first embodiment.

[0046] (Fifth embodiment) FIG. 9 is a left-side view of a vacuum drying apparatus 90 according to a fifth embodiment. In FIG. 9, elements similar to those in FIG. 1 are designated by the same reference numerals. Below, differences between the vacuum drying apparatus 90 according to the fifth embodiment and the first embodiment will be mainly described. While the vacuum drying apparatus 2 according to the first embodiment has a heating unit 8 (a panel-type explosion-proof heater) inside the drum unit 4, the vacuum drying apparatus 90 according to the fifth embodiment has a heating unit 92 outside the drum unit 4. More specifically, in the fifth embodiment, a panel-type heater is provided as the heating unit 92 on the base 18 of the support unit 5. The heating unit 92 heats the outer surface of the rotating drum 3, which is made of metal (e.g., stainless steel), thereby heating the material to be dried inside the drum unit 4. In the fifth embodiment, similar to the first embodiment, the heating unit 92 can heat the material to be dried and the decompression unit 7 can simultaneously reduce the pressure inside the drum unit 4. The vacuum drying apparatus 90 according to the fifth embodiment may be configured as any of the first to fourth embodiments and their modified examples.

[0047] (Sixth embodiment) FIG. 10 is a left-side view of the vacuum drying apparatus according to the sixth embodiment. In FIG. 10, elements similar to those in FIG. 1 are designated by the same reference numerals. Below, differences between the vacuum drying apparatus 100 according to the sixth embodiment and the first embodiment will be mainly described. The vacuum drying apparatus 100 according to the sixth embodiment includes a heating unit 102, which is a heated air supply device that supplies heated air into the drum unit 101 through the first through-hole 12c formed in the fixed closing plate 12. A sheathed heater, which is less susceptible to water droplets, can be used as the heat source for this heated air supply device. The heating unit 102 is connected to the first through-hole 12c of the fixed closing plate 12 via a heat medium supply passage 103. Furthermore, the vacuum drying apparatus 100 includes a moisture separation and discharge unit 104 and a switching valve 105.

[0048] The switching valve 105 is connected to the moisture separating and discharging section 104, the heating section 102, and the pressure reducing section 7. The pressure reducing section 7 is connected to the second through-hole 12d of the fixed closure plate 12 via the switching valve 105, the moisture separating and discharging section 104, and the gas discharge passage 106. The switching valve 105 is switchable between a first communication state in which the moisture separating and discharging section 104 communicates with the heating section 102 and a second communication state in which the moisture separating and discharging section 104 communicates with the pressure reducing section 7. When high-humidity air is introduced, the moisture separating and discharging section 104 separates moisture from the air and discharges it to the outside, and sends the reduced-humidity air to the switching valve 105. The moisture separating and discharging section 104 is a device that separates moisture from air using, for example, a separator type (baffle type) or a cyclone type (centrifugal separation type). The vacuum drying apparatus 100 of the sixth embodiment may be configured to employ the configurations of the first to fourth embodiments and their modified examples.

[0049] As an example of a drying process using this vacuum drying apparatus 100, first, a depressurization process is performed by switching to the second communication state and driving the depressurization unit 7 to depressurize the inside of the drum unit 101 to a predetermined pressure. Then, a heating process is performed by switching to the first communication state, rotating the rotating drum 3, and supplying heated air from the heating unit 102 into the drum unit 101. In the heating process, the objects to be dried are heated by the heated air supplied into the drum unit 101, thereby generating water vapor from the objects to be dried. Because the drum unit 101 is under vacuum, water vapor is generated before the temperature of the objects to be dried reaches 100°C. The air containing a large amount of water vapor flows from the drum unit 101 into the moisture separation and discharge unit 104 via the gas exhaust flow path 106, where moisture is removed. The reduced-humidity air is then circulated back to the heating unit 102 via the switching valve 105. The depressurization process and the heating process may be alternately repeated. Alternatively, the heating process may be performed first, followed by the depressurization process, and the heating and depressurization processes may be alternately repeated. Alternatively, an inert gas supply unit may be connected to the heating unit 102, and an inert gas (e.g., nitrogen gas) may be supplied to the heating unit 102 instead of air, and the material to be dried may be dried while circulating the heated inert gas. In this case, for example, if the material to be dried is food, the food can be dried while suppressing oxidation.

[0050] Seventh embodiment Figure 11 is an explanatory diagram of the configuration of a vacuum drying apparatus according to the seventh embodiment, viewed from the left side. In Figure 11, elements similar to those in Figure 10 are assigned the same reference numerals. Below, differences between the vacuum drying apparatus 110 of the seventh embodiment and the sixth embodiment will be mainly described. While the first to sixth embodiments illustrate configurations in which the heating unit and the decompression unit are provided on the fixed closing plate 12 side of the vacuum drying apparatus, the vacuum drying apparatus 110 of the seventh embodiment has the heating unit 102 and the decompression unit 7 on the rotating drum 3 side. Furthermore, the vacuum drying apparatus 110 of the seventh embodiment includes a rotary joint 111.

[0051] The rotary joint 111 includes a disk-shaped fixed sliding contact portion 112, a disk-shaped rotating sliding contact portion 113 that faces the fixed sliding contact portion 112, and a housing 114 that houses the fixed sliding contact portion 112 and the rotating sliding contact portion 113. The fixed sliding contact portion 112 has a fixed-side sliding surface and a fixed-side first flow path 112a and a fixed-side second flow path 112b that open onto the fixed-side sliding surface. The opening of the fixed-side first flow path 112a is a circular opening located on the axis of the fixed-side sliding surface. The opening of the fixed-side second flow path 112b is an annular opening (groove) located on the periphery of the fixed-side sliding surface (around the opening of the fixed-side first flow path 112a).

[0052] The rotary sliding contact portion 113 has a rotary-side sliding contact surface that is in sliding contact with the fixed-side sliding contact surface of the fixed sliding contact portion 112, a rotary-side first flow path 113a that opens on the rotary-side sliding contact surface and communicates with the fixed-side first flow path 112a, and a rotary-side second flow path 113b that opens on the rotary-side sliding contact surface and communicates with the fixed-side second flow path 112b. The opening of the rotary-side first flow path 113a is a circular opening located on the axis of the rotary-side sliding contact surface. The opening of the rotary-side second flow path 113b is an annular opening (groove) located in the peripheral portion of the rotary-side sliding contact surface (around the opening of the rotary-side first flow path 113a).

[0053] A through hole is provided in an end wall 29 on the other end 11 side of the axis 9 of the rotating drum 3. The outer surface of the rotary joint 111, opposite the rotation-side sliding contact surface of the rotary sliding contact part 113, is connected to the end wall 29 on the other end 11 side of the rotating drum 3, so that the first rotation-side flow path 113a and the second rotation-side flow path 113b of the rotary sliding contact part 113 communicate with the inside of the drum part 119.

[0054] In the seventh embodiment, a rotary drive unit 115 is provided on a base 18 below the rotary drum 3 in the support unit 5, a gear 116 is provided circumferentially on the outer circumferential surface of the rotary drum 3, and an output gear provided on the output shaft of the rotary drive unit 115 meshes with the gear 116 of the rotary drum 3. When the rotary drive unit 115 is driven, the rotary drum 3 and the rotary sliding contact part 113 of the rotary joint 111 rotate in a first rotation direction (the direction of arrow A) or a second rotation direction (the direction opposite to the direction of arrow A). At this time, the rotating side sliding contact surface of the rotary sliding contact part 113 of the rotary joint 111 rotates while sliding against the fixed side sliding contact surface of the fixed sliding contact part 112. When the rotary sliding contact portion 113 rotates, a communication state is maintained between the rotary-side first flow path 113a of the rotary sliding contact portion 113 and the fixed-side first flow path 112a of the fixed sliding contact portion 112, and a communication state is maintained between the rotary-side second flow path 113b of the rotary sliding contact portion 113 and the fixed-side second flow path 112b of the fixed sliding contact portion 112. Note that the vacuum drying apparatus 110 of the seventh embodiment may be applied with the configurations of the first to fourth embodiments and their modified examples.

[0055] Similar to the sixth embodiment, this vacuum drying apparatus 110 includes a water separating and discharging section 104 and a switching valve 105. The switching valve 105 is connected to the water separating and discharging section 104, the heating section 102, and the pressure reducing section 7. The switching valve 105 is switchable between a first communication state in which the water separating and discharging section 104 and the heating section 102 are connected to each other, and a second communication state in which the water separating and discharging section 104 and the pressure reducing section 7 are connected to each other. The water separating and discharging section 104 is connected to a fixed-side second flow path 112b of a fixed sliding contact section 112 of a rotary joint 111 via a gas discharge flow path 106, and the heating section 102 is connected to a fixed-side first flow path 112a of the fixed sliding contact section 112 via a heat medium supply flow path 103. Alternatively, the moisture separating and discharging section 104 may be connected to the fixed-side first flow path 112a via the gas discharge flow path 106, and the heating section 102 may be connected to the fixed-side second flow path 112b via the heat medium supply flow path 103.

[0056] The vacuum drying apparatus 110 of the seventh embodiment can perform the same drying process as in the sixth embodiment. In this case, the pressure reducing section 7 and the heating section 102 are not provided on the fixed closing plate 12 side of the drum section 119, and there are no pipes connecting the pressure reducing section 7 and the heating section 102 to the fixed closing plate 12. Therefore, it is easy to open the door 14 to put the material to be dried into the drum section 119 and open the door 16 to remove the material from the drum section 119 after the drying process.

[0057] (Eighth embodiment) Figure 12 is an explanatory diagram of the configuration of a vacuum drying apparatus according to the eighth embodiment, viewed from the left side. In Figure 12, elements that are the same as those in Figure 11 are given the same reference numerals. Below, differences between the vacuum drying apparatus 120 of the eighth embodiment and the seventh embodiment will be mainly described. In the vacuum drying apparatus 110 of the eighth embodiment, the rotating drum 123 of the drum unit 122 has a double-wall structure, and the decompression unit 7 and the heating unit 102 are directly connected to a rotary joint 121 that is connected to the rotating drum 123.

[0058] The rotating drum 123 includes a cylindrical inner cylinder 125 having an end wall 125a on the other end 124 side, a cylindrical outer cylinder 126 having an end wall 126a on the other end 124 side, and a plurality of spacers (not shown) provided between the inner cylinder 125 and the outer cylinder 126. The outer cylinder 126 is supported by a support 5. In the rotating drum 123, gaps 127 are provided between the peripheral wall of the inner cylinder 125 and the peripheral wall of the outer cylinder 126, and between the end wall 125a of the inner cylinder 125 and the end wall 126a of the outer cylinder 126, and steam or heated air as a heat medium flows into these gaps 127. Note that one end of the inner cylinder 125 and the outer cylinder 126 opposite the other end 124 is connected to a swivel joint 1, and one end of the gap 127 is closed.

[0059] In the rotary drum 123, an end wall 125a of the inner cylindrical portion 125 and an end wall 126a of the outer cylindrical portion 126 each have a through hole formed on the axis 9. The rotary joint 121 of the eighth embodiment is configured generally similarly to the rotary joint 111 of the seventh embodiment (see FIG. 11 ). However, in the rotary joint 121 of the eighth embodiment, a first rotation-side flow path 129a of the rotary sliding contact portion 129 communicates with the inside of the drum portion 122 via a through hole in the inner cylindrical portion 125, and a second rotation-side flow path 129b of the rotary sliding contact portion 129 communicates with the gap 127 via a through hole in the outer cylindrical portion 126. In addition, the pressure reducing portion 7 communicates with a first fixed-side flow path 112a of the fixed sliding contact portion 112 of the rotary joint 121 via a gas exhaust flow path 106, and the heating portion 102 communicates with a second fixed-side flow path 112b of the fixed sliding contact portion 112 via a heat medium supply flow path 103. The vacuum drying device 120 of the eighth embodiment may have the configurations of the first to fourth embodiments and their modified examples.

[0060] As an example of a drying process using this vacuum drying apparatus 120, first, a depressurization step is performed in which the pressure inside the drum section 122 is reduced to a predetermined pressure by driving the depressurization unit 7. Then, a heating step is performed in which the rotating drum 3 is rotated and steam from the heating unit 102 is supplied to the gap 127 of the drum section 101. In this case, the heating unit 102 is a boiler. In the heating step, the material to be dried is heated by the steam supplied into the gap 127 of the drum section 122, thereby generating water vapor from the material to be dried. The depressurization step may be performed continuously or intermittently during the heating step. Because the drum section 122 is in a vacuum, water vapor is generated before the temperature of the material to be dried reaches 100°C. The air containing a large amount of water vapor is discharged from the drum section 122 to the outside via the gas exhaust passage 106 and the depressurization unit 7. A drain pipe section 130 is provided on one end side (swivel joint 1 side) of the outer cylinder section 126 of the rotating drum 123, and water condensed as the steam supplied to the gap 127 cools is discharged to the outside from the drain pipe section 130. It is also possible to supply heated air from the heating section 102 to the gap 127 of the drum section 122.

[0061] Preferred aspects of the present invention also include any combination of the above-described aspects. In addition to the above-described embodiments, various modifications of the present invention are possible. These modifications should not be interpreted as not falling within the scope of the present invention. The present invention should include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0062] 1, 51, 61, 71, 81: Swivel joint, 2, 90, 100, 110, 120: Vacuum drying device, 3, 123: Rotating drum, 4, 50, 60, 70, 80, 101, 112, 122: Drum section, 5: Support section, 6, 115: Rotation drive section, 7: Pressure reduction section, 8, 92, 102: Heating section, 9: Shaft center, 10: One end, 11, 124: Other end, 12: Fixed closure plate, 12a: Outer surface, 12b: Inner surface, 12c: First through hole, 12d: Second through hole, 13: Inlet, 14, 16: Opening and closing door, 15: Outlet, 17: Gas flow passage, 18: Base, 19: Support stand, 20: Support roller, 21: Weight measuring device, 22: Agitating blade, 23: Transfer blade, 29: End wall, 31, 62, 72, 82: Fixed portion, 32, 63, 73, 83: Rotating portion, 33a, 69a: First rotor (first ball), 33b, 69b: Second rotor (second ball), 30: Seal ring (X ring), 34a, 52a, 68a: First seal ring (first X ring), 34b, 52b, 68b: Second seal ring (second X ring), 34c, 52c, 68c: Third seal ring (third X ring), 35a, 35b, 64a, 64b: Fixed side first surface portion, 36, 65: Fixed side second surface portion, 37a, 37b, 66a, 66b: Rotating side first surface portion, 38, 67: Rotation side second surface portion, 39: Plug, 40: Small protrusion, 102: Heating portion (heated air supply device), 103: Heat medium supply passage, 104: Moisture separation and discharge portion, 105: Switching valve, 106: Gas discharge passage, 111, 121: Rotary joint, 112: Fixed sliding contact portion, 112a: Fixed side first passage, 112b: Fixed side second passage, 113, 129: Rotation sliding contact portion, 113a, 129a: Rotation side first passage, 113b, 129b: Rotation side second passage, 114: Housing, 116: Gear, 125: Inner cylinder portion, 126: Outer cylinder portion, 126a: Drain pipe portion, 130: Drain pipe portion

Claims

1. a cylindrical fixed portion and a cylindrical rotating portion fitted to the fixed portion so as to be rotatable about an axis of the fixed portion; the fixed portion has a fixed-side first surface portion facing in the direction of the axis and a fixed-side second surface portion facing in a radial direction relative to the axis, the rotating portion has a first rotating surface portion facing the direction of the axis and a second rotating surface portion facing in a radial direction relative to the axis, the fixed-side first surface portion and the rotating-side first surface portion face each other, and the fixed-side second surface portion and the rotating-side second surface portion face each other, A swivel joint in which a plurality of rotors and one or more seal rings are provided between the fixed side first surface portion and the rotating side first surface portion which face each other, and a plurality of rotors and one or more seal rings are provided between the fixed side second surface portion and the rotating side second surface portion which face each other.

2. The swivel joint according to claim 1 , wherein the fixed-side second surface portion is disposed radially outward of the rotating-side second surface portion.

3. The swivel joint according to claim 1 , wherein the fixed-side second surface portion is disposed radially inward relative to the rotating-side second surface portion.

4. the fixed portion has the fixed-side first surface portions on both sides of the fixed-side second surface portion in the direction of the axis, The swivel joint according to claim 1 , wherein the rotating portion has the rotation-side first surface portion on both sides of the rotation-side second surface portion in the direction of the axis.

5. the plurality of rotors provided between the fixed-side second surface portion and the rotating-side second surface portion that face each other are a plurality of balls, a circumferential groove in which the plurality of balls are disposed is provided on each of the fixed-side second surface portion and the rotating-side second surface portion; The swivel joint according to any one of claims 1 to 4, wherein the radial ball insertion hole communicating with the circumferential groove of the fixed portion or the circumferential groove of the rotating portion is provided in the fixed portion or the rotating portion.

6. the plurality of rotors provided between the fixed-side first surface portion and the rotating-side first surface portion that face each other are a plurality of balls, a plurality of hemispherical recesses are provided at equal intervals in the circumferential direction on one of the fixed-side first surface portion and the rotating-side first surface portion; a circumferential groove is provided on the other of the fixed-side first surface portion and the rotating-side first surface portion; 5. The swivel joint according to claim 1, wherein the plurality of balls are disposed between the plurality of hemispherical recesses and the circumferential groove.

7. The swivel joint according to any one of claims 1 to 4, wherein the rotor is a ball or a roller.

8. The swivel joint according to any one of claims 1 to 4, wherein the seal ring is an X-ring, a U-ring or an O-ring.

9. a drum section including a rotary drum having one end in a rotation axis direction that is open and the other end that is closed, a swivel joint according to any one of claims 1 to 4 that is connected to the one end of the rotary drum, and a fixed closing plate that is connected to the swivel joint so as to close the opening of the rotary drum; a support portion that supports the drum portion so as to be rotatable; a rotation drive unit that rotates the rotary drum; a pressure reducing section that reduces the pressure inside the drum section; a heating section for heating the material to be dried contained in the drum section; A vacuum drying apparatus comprising:

10. The vacuum drying apparatus according to claim 9 , wherein the heating unit is a heater provided on the inner surface of the fixed closing plate inside the drum unit.

11. The vacuum drying apparatus according to claim 9 , wherein the heating unit is a heater that heats the outer surface of the rotating drum.

12. the pressure reducing unit is a suction device that sucks gas from inside the drum unit through a first through hole provided in the fixed closing plate, The vacuum drying apparatus according to claim 9 , wherein the heating unit is a heated air supply device that supplies heated air into the drum unit through a second through-hole provided in the fixed closing plate.

13. Further comprising a water separation and discharge part and a switching valve, the switching valve is connected to the water separation and discharge unit, the heating unit, and the pressure reducing unit; the pressure reducing section is connected to the first through-hole via the switching valve, the water separating and discharging section, and the gas discharging path; the heating unit is connected to the second through-hole via a heat medium supply path, 13. The vacuum drying apparatus according to claim 12, wherein the switching valve is switchable between a first communication state that connects the water separating and discharging unit with the heating unit and a second communication state that connects the water separating and discharging unit with the pressure reducing unit.

14. Further comprising a rotary joint, the rotary joint includes a disk-shaped fixed sliding contact portion and a disk-shaped rotary sliding contact portion facing the fixed sliding contact portion, the fixed sliding contact portion has a fixed-side sliding surface, and a fixed-side first flow path and a fixed-side second flow path that open to the fixed-side sliding surface, the rotary sliding contact portion has a rotary-side sliding contact surface that is in sliding contact with the fixed-side sliding contact surface, a rotary-side first flow path that opens at the rotary-side sliding contact surface and communicates with the fixed-side first flow path, and a rotary-side second flow path that opens at the rotary-side sliding contact surface and communicates with the fixed-side second flow path, the heating unit is connected to a heat medium supply flow path that is connected to the fixed-side first flow path, and is capable of supplying a heating fluid into the drum unit via the heat medium supply flow path, the fixed-side first flow path, and the rotation-side first flow path; The vacuum drying device according to claim 9, wherein the pressure reducing section is connected to a gas exhaust flow path that is connected to the fixed side second flow path, and gas within the drum section can be exhausted to the outside via the rotating side second flow path, the fixed side second flow path, and the gas exhaust flow path.

15. Further comprising a water separation and discharge part and a switching valve, the switching valve is connected to the water separation and discharge unit, the heating unit, and the pressure reducing unit; the pressure reducing unit is connected to the gas discharge flow path via the switching valve and the water separating and discharging unit, 15. The vacuum drying apparatus according to claim 14, wherein the switching valve is switchable between a first communication state that connects the water separating and discharging unit with the heating unit and a second communication state that connects the water separating and discharging unit with the pressure reducing unit.

16. The vacuum drying apparatus according to claim 15, wherein the heating unit is a heated air supply device that supplies heated air into the drum unit.

17. the rotating drum has an outer cylindrical portion supported by the support portion, and an inner cylindrical portion provided inside the outer cylindrical portion with a gap between it and the inner surface of the outer cylindrical portion, The vacuum drying apparatus according to claim 14 , wherein the first rotation-side flow path communicates with the interior of the inner cylindrical portion, and the second rotation-side flow path communicates with the gap.

18. The vacuum drying apparatus according to claim 17, wherein the heating unit is a boiler that supplies steam into the gap or a heated air supply device that supplies heated air.

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