Expander and power generation system

Abstract

This makes it easier to assemble and disassemble the inflator, thereby improving work efficiency during the manufacturing and maintenance of the inflator. [Solution] The expander includes a generator within its housing that generates electricity using power produced by the expansion of a working medium. The generator has a shaft that rotates around a central axis extending vertically using the power, and a rotor positioned radially outside the shaft. The shaft has an inner shaft and an outer shaft positioned radially outside the inner shaft, through which the power is transmitted. The inner shaft is rotatably supported by the housing via a first bearing and is axially slidable with respect to the outer shaft and the first bearing. The outer shaft is fixed to the rotor and is rotatably supported by the housing via a second bearing.

Description

Technical Field

[0001] The present invention relates to an expander and a power generation system including the expander.

Background Art

[0002] Conventionally, a power generation system that generates power using waste heat generated in factories and the like has been proposed. In the power generation system, a working medium that has received waste heat and has become high-temperature and high-pressure expands in an expansion unit of an expander. The expansion energy generated during the expansion of the working medium is converted into the rotational force of the drive shaft (shaft) of the generator in the expander. When the shaft of the generator rotates, power generation is performed. An example of such an expander is disclosed as a waste heat utilization device in, for example, Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional generator built into an expander, a shaft, a rotor, and a bearing are integrated and assembled. Here, the rotor is fixed to the outer peripheral surface of the shaft and rotates together with the shaft. The bearing rotatably supports the shaft within the housing of the expander. When the generator is assembled as described above, it is difficult to disassemble the generator itself, so it becomes difficult to perform maintenance on the expander. Also, when assembling the expander, it is necessary to incorporate the assembled generator into the housing in a state including a long shaft. Therefore, there is a risk that the work of incorporating the generator will become difficult. That is, in the configuration of the conventional expander, there is a concern that the workability during manufacturing and maintenance of the expander will decrease.

[0005] The present invention was made to solve the above-mentioned problems, and its purpose is to provide an expander that is easier to assemble and disassemble, thereby improving workability during the manufacture and maintenance of the expander, and a power generation system equipped with the expander. [Means for solving the problem]

[0006] An expander according to one aspect of the present invention is an expander equipped with a generator in a housing that generates electricity by power generated by the expansion of a working medium, wherein the generator has a shaft that rotates about a central axis extending in the vertical direction by the power, and a rotor disposed radially outside the shaft, wherein the shaft has an inner shaft and an outer shaft disposed radially outside the inner shaft and to which the power is transmitted via the inner shaft, wherein the inner shaft is rotatably supported in the housing via a first bearing and is axially slidable with respect to the outer shaft and the first bearing, and the outer shaft is fixed to the rotor and is rotatably supported in the housing via a second bearing.

[0007] A power generation system according to another aspect of the present invention comprises the above-mentioned expander, a condenser for cooling the working medium discharged from the expander, and an evaporator for evaporating the working medium through heat exchange with waste heat from a heat source and supplying it to the expander. [Effects of the Invention]

[0008] This makes it easier to assemble and disassemble the inflator. This improves work efficiency during the manufacturing and maintenance of the inflator. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram illustrating the general configuration of a power generation system according to one embodiment of the present invention. [Figure 2] A perspective view showing the external appearance of the expander equipped in the above power generation system. [Figure 3] This is an exploded perspective view of the above-mentioned expansion machine, seen from an oblique angle above. [Figure 4] This is an exploded perspective view of the above-mentioned expander, seen from a diagonal downward angle. [Figure 5] This is a cross-sectional view showing the configuration of the above-mentioned expander. [Figure 6] This is a magnified cross-sectional view showing the area around the shaft included in the above-mentioned expander. [Figure 7] This is a cross-sectional view of the shaft shown above, cut perpendicular to its central axis. [Figure 8] This is a schematic perspective view showing the state before and after inserting the inner shaft, which constitutes the above-mentioned shaft, into the outer shaft. [Figure 9] This is a plan view of another configuration example of the shaft described above. [Figure 10] Figure 9 is a cross-sectional view showing the state before and after inserting the inner shaft, which constitutes the shaft, into the outer shaft. [Figure 11] This is a perspective view of the central case of the above-mentioned expansion machine, seen from diagonally above. [Figure 12] This is a cross-sectional view of the central case shown above. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings.

[0011] [1. Outline configuration of the power generation system] Figure 1 is a schematic diagram illustrating the general configuration of the power generation system 1 of this embodiment. The power generation system 1 is a system that generates electricity by utilizing the expansion energy generated when a working fluid expands. Water (steam) can be used as the working fluid, but in this embodiment, an organic fluid with a lower boiling point than water is used. By using an organic fluid, power generation can be efficiently performed by evaporating the organic fluid even at temperatures lower than the boiling point of water. As the organic solvent, for example, alternative fluorocarbon gases such as HFCs (hydrofluorocarbons) can be used. The power generation system 1, which uses an organic fluid as the working fluid and generates electricity by circulating the working fluid, is also called an Organic Rankine Cycle (ORC) system. The power generation system 1 of this embodiment will be described in detail below.

[0012] The power generation system 1 comprises an expander 2, a condenser 3, and an evaporator 4. The expander 2 generates electricity by expanding the working medium, which has been heated to a high temperature and pressure by the evaporator 4, thereby rotating the shaft 31 of the generator 30 (see Figure 4, etc.), which will be described later. Details of the configuration of the expander 2 will be described later.

[0013] The condenser 3 cools the working fluid discharged from the expander 2 by heat exchange. The cooling water used for heat exchange in the condenser 3 is supplied from a cooling source C0 by a cooling water pump 3a. The cooling source C0 can be a tank for holding cooling water, a heat exchanger for cooling the cooling water by air cooling, etc. The cooling water contained in the tank is not particularly limited and can be tap water, well water, groundwater, etc. The low-temperature working fluid cooled in the condenser 3 is supplied to the evaporator 4.

[0014] The evaporator 4 evaporates the working medium by heat exchange with the waste heat of the heat source H0 and supplies it to the expander 2. The heat exchange in the evaporator 4 is performed, for example, via hot water. That is, when water is heated by the waste heat of the heat source H0, the heated water (hot water) is supplied to the evaporator 4 by the hot water pump 4a. In the evaporator 4, the low-temperature working medium is heated by the heat of the hot water and evaporates. Here, as the heat source H0, for example, heat source equipment such as factories, incineration facilities, hot springs, biomass boilers, cogeneration (combined heat and power) facilities, etc. can be considered. The above waste heat refers to the heat utilized as regenerative heat energy and is distinguished from the heat (exhaust heat) that is discarded without being reused.

[0015] The above working medium circulates in the order of the expander 2, the condenser 3, and the evaporator 4 by the drive of the circulation pump 5. By such circulation of the working medium, a power generation system 1 (ORC system) that performs power generation using the waste heat of the heat source H0 is realized. The equipment including the above-described power generation system 1, heat source H0, cooling source C0, cooling water pump 3a, and hot water pump 4a is also called the power generation equipment 100.

[0016] 〔2. Details of the Expander〕 Next, the details of the above-described expander 2 will be described. Fig. 2 is a perspective view showing the appearance of the expander 2. Figs. 3 and 4 are exploded perspective views of the expander 2. However, Fig. 3 is a view when the expander 2 is viewed obliquely from above. Fig. 4 is a view when the expander 2 is viewed obliquely from below. Fig. 5 is a cross-sectional view of the expander 2. Fig. 6 is an enlarged cross-sectional view showing the vicinity of the shaft 31 included in the expander 2 of Fig. 5.

[0017] Here, in this specification, direction is defined as follows. First, the direction in which the central axis CA of the shaft 31 of the generator 30 shown in Figure 5 extends is defined as the "axial direction." Then, one side of the axial direction is defined as "up," and the other side as "down." Therefore, the axial direction in which the central axis CA extends is the up-down direction. Note that the central axis CA of the shaft 31 refers to the axis that serves as the rotation center of the inner shaft 311 and the outer shaft 312, which will be described later. Furthermore, the direction perpendicular to the central axis CA is defined as the "radial direction." In the radial direction, the side approaching the central axis CA is defined as the radially inward side, and the side moving away from the central axis CA is defined as the radially outward side. In addition, the direction along the arc drawn with the central axis CA as the center, when viewed from the axial direction, is defined as the "circumferential direction." Note that Figures 5 and 6 correspond to cross-sectional views of the expander 2 when viewed from the opposite side of the outlet 10b (see Figure 2, etc.), which will be described later, with respect to the central axis CA.

[0018] (2-1. Enclosure) The expander 2 has a housing 10. Inside the housing 10 are the expansion unit 20 and the generator 30, which will be described later. The housing 10 is sealed except for the inlet 10a and outlet 10b of the working medium. The inlet 10a of the working medium is connected to the evaporator 4 shown in Figure 1 via piping. The outlet 10b of the working medium is connected to the condenser 3 shown in Figure 1 via piping.

[0019] The housing 10 comprises a central case 11, an upper case 12, and a lower case 13. The central case 11 is an open case at the top and bottom, housing a generator 30 and the like inside. The outlet 10b is provided by passing radially through the side wall 11a of the central case 11. On the side wall 11a of the central case 11, a connector 10c (see Figure 2) is provided on the side opposite to the outlet 10b with respect to the central axis CA, to which wiring such as harnesses are connected. The power (alternating current) generated by the generator 30 is taken out to the outside via the connector 10c. A bearing plate 37 (see Figure 4) is fastened to the lower part of the central case 11 using fastening members such as bolts. The bearing plate 37 is provided to support the second bearing 35 and the third bearing 36 (both see Figure 4), which will be described later.

[0020] The upper case 12 is fastened to the upper part of the central case 11 using fastening members such as bolts. The upper case 12 has a lid shape with an open bottom and covers the expansion unit 20 housed inside from above. The inlet 10a is provided by penetrating the center of the upper wall portion 12a of the upper case 12 in the axial direction.

[0021] The lower case 13 is fastened to the lower part of the central case 11 via a bearing plate 37 using fastening members such as bolts. In other words, the lower case 13 is located at the bottom of the housing 10. The lower case 13 has a lid shape with an open top and has an oil storage chamber 131 inside. The oil storage chamber 131 contains lubricating oil OL. The oil OL in the oil storage chamber 131 is discharged upward by the discharge pump 132 (pumped up) and supplied to various parts of the housing 10 through the inside of the shaft 31 (particularly the inner shaft 311), which will be described later. The discharge pump 132 is supported by a pump support plate 133 and driven by the rotation of the shaft 31. The pump support plate 133 is fastened from below to the bearing plate 37 using fastening members such as bolts.

[0022] Thus, the housing 10 has an oil storage chamber 131 located at the bottom (lower case 13). Inside the housing 10, there is a discharge pump 132 that is driven by the rotation of the shaft 31 of the generator 30 and discharges the oil OL stored in the oil storage chamber 131.

[0023] (2-2. Expansion Unit) The expansion unit 20 is an expansion mechanism that expands the working medium introduced into the housing 10 through the inlet 10a. In this embodiment, the expansion unit 20 is composed of a scroll-type expansion mechanism. Specifically, the expansion unit 20 has a fixed scroll 21 and a rotating scroll 22.

[0024] The fixed scroll 21 has a spiral-shaped fixing wrap 21a. The fixing wrap 21a is fixed to the lower surface of the upper wall portion 12a of the upper case 12. In other words, the fixing wrap 21a is positioned to protrude downward from the upper wall portion 12a of the upper case 12. The radial center of the fixing wrap 21a is in communication with the inlet 10a.

[0025] The orbital scroll 22 has a spiral orbital wrap 22a and a disc-shaped base plate 22b. The orbital wrap 22a is fixed to the upper surface of the base plate 22b. The orbital scroll 22 is supported on the upper part of the central case 11 via an Oldham ring 23, with the spiral orbital wrap 21a and the spiral orbital wrap 22a interlocking.

[0026] In this configuration of the expansion unit 20, the high-pressure working medium introduced from the inlet 10a is supplied to the space between the fixed wrap 21a and the swirling wrap 22a (hereinafter also referred to as the expansion chamber) near the radial center. The pressure inside the expansion chamber is low relative to the high-pressure working medium. As a result, the high-pressure working medium supplied to the expansion chamber expands. This changes the volume of the expansion chamber, causing the swirling scroll 22 to swirl, and the working medium flows in a swirling pattern from the radial inside to the radial outside of the expansion chamber. The working medium that reaches the radial outside of the expansion chamber flows downward through the central case 11 and is finally discharged to the outside of the expander 2 (towards the condenser 3) via the outlet 10b.

[0027] Here, when we say that the orbiting scroll 22 orbits, we mean that the orbiting scroll 22 does not rotate on its own axis, but rather that the center of the orbiting scroll 22 moves circumferentially around the central axis CA of the shaft 31. This orbiting of the orbiting scroll 22 is achieved by using the Oldham ring 23 described above.

[0028] As shown in Figures 3 and 4, the Oldham ring 23 has a ring body 23a, two lower protrusions 23b, and two upper protrusions 23c. The ring body 23a is formed in a ring shape in the circumferential direction. The two lower protrusions 23b are provided at two points symmetrically on the circumferential direction of the ring body 23a. The two lower protrusions 23b are formed to protrude downward from the ring body 23a. Grooves 11d are formed on the upper part of the central case 11 at positions corresponding to the two lower protrusions 23b. Each groove 11d extends radially. For convenience, the radial direction on which each groove 11d extends is also referred to as the X direction. By fitting the two lower protrusions 23b into the grooves 11d from above, the Oldham ring 23 becomes slidable along the grooves 11d in the X direction. Therefore, the orbiting scroll 22, supported by the central case 11 via the Oldham ring 23, becomes slidable in the X direction integrally with the Oldham ring 23.

[0029] On the other hand, the two upper protrusions 23c are provided at two points symmetrical locations in the circumferential direction of the ring body 23a, and are positioned 90° offset from the two lower protrusions 23b in the circumferential direction. The two upper protrusions 23c are formed to protrude upward from the ring body 23a. On the lower surface of the bottom plate 22b of the orbiting scroll 22, recessed portions 22c are formed at positions corresponding to the two upper protrusions 23c. Each recessed portion 22c is formed to extend radially. Here, in a plane perpendicular to the central axis CA, the radial direction in which each recessed portion 22c extends is perpendicular to the radial direction in which each groove 11d extends, and is here also referred to as the Y direction. As the two upper protrusions 23c fit into the recess 22c from below, the orbiting scroll 22 becomes slidable in the Y direction relative to the Oldham ring 23 (especially the upper protrusions 23c) in which the recess 22c extends.

[0030] In this way, by supporting the orbital scroll 22 on the central case 11 via the Oldham ring 23, the direction of movement of the orbital scroll 22 in a plane perpendicular to the central axis CA can be limited to at least one of the X and Y directions. This makes it possible to move (orbit) the orbital scroll 22 around the central axis CA while preventing the orbital scroll 22 from rotating on its own axis, i.e., from rotating around the central axis CA.

[0031] A slewing bearing holder 24 is fixed to the lower surface of the bottom plate 22b of the slewing scroll 22. The outer ring of the slewing bearing 25 is fixed to the slewing bearing holder 24 by shrink fitting or the like. An eccentric shaft portion 315 is inserted into the inner ring of the slewing bearing 25 by clearance fitting. Therefore, the eccentric shaft portion 315 is not fixed to the inner ring of the slewing bearing 25. The eccentric shaft portion 315 is connected to the upper part of the shaft 31 (particularly the inner shaft 311) and extends upward. However, the eccentric shaft portion 315 is provided eccentrically (radially offset) with respect to the central axis CA of the shaft 31. Therefore, when the slewing scroll 22 rotates, the eccentric shaft portion 315 moves circumferentially around the central axis CA, and as a result, the shaft 31 rotates circumferentially about the central axis CA.

[0032] As described above, the expansion of the working fluid in the expansion unit 20 causes the shaft 31 of the generator 30 to rotate. This means that the expansion energy generated when the working fluid expands in the expansion unit 20 is converted into a driving force that rotates the shaft 31, and the shaft 31 rotates due to this driving force.

[0033] (2-3. Generators) The generator 30 generates electricity using the power produced by the expansion of the working fluid in the expansion unit 20 described above. Here, the power refers to the driving force produced by the expansion of the working fluid. The expander 2 of this embodiment includes the generator 30 inside the housing 10. As shown in Figures 5 and 6, the generator 30 has a shaft 31, a rotor 32, and a stator 33.

[0034] <2-3-1. Shaft> The shaft 31 is a crankshaft that rotates around a central axis CA extending vertically by the above-mentioned power. The shaft 31 has an inner shaft 311 and an outer shaft 312. The outer shaft 312 is positioned radially outward of the inner shaft 311. In other words, the outer shaft 312 is formed as a hollow cylindrical body, and the inner shaft 311 is positioned radially inward of the outer shaft 312. The inner shaft 311 may be a solid rod-shaped body, but in this embodiment, it is formed as a hollow cylindrical body. This is because the hollow portion of the inner shaft 311 is utilized as a supply passage for oil OL in the oil storage chamber 131.

[0035] The inner shaft 311 is formed to be longer vertically than the outer shaft 312. Furthermore, the inner shaft 311 extends upward above the outer shaft 312. The power (rotational driving force of the shaft 31) transmitted to the eccentric shaft portion 315 by the rotation of the orbiting scroll 22 of the expansion unit 20 is transmitted to the outer shaft 312 via the inner shaft 311. The specific structure for transmitting power from the inner shaft 311 to the outer shaft 312 will be described later.

[0036] A first balance weight 313, acting as a primary inertia body, is provided on the outer circumferential surface of the connection portion between the inner shaft 311 and the eccentric shaft portion 315. As the orbiting scroll 22 rotates, the shaft 31 rotates together with the first balance weight 313, thereby maintaining good rotational balance of the shaft 31 and suppressing wobble during rotation of the shaft 31. Furthermore, a second balance weight 314, acting as a secondary inertia body, is provided on the outer circumferential surface of the lower end of the inner shaft 311. This further improves the rotational balance of the shaft 31. The first balance weight 313 and the second balance weight 314 are fixed to the inner shaft 311, for example, by screw fastening.

[0037] Within the housing 10, the first bearing 34 is positioned above the outer shaft 312. The first bearing 34 is positioned above the second bearing 35, which will be described later. The housing 10 (particularly the central case 11) has a housing portion 14 inside. The first outer ring 34a, which is the outer ring of the first bearing 34, is fixed to the housing portion 14 by shrink fitting or the like. The inner shaft 311 is clearance fitted onto the first inner ring 34b, which is the inner ring of the first bearing 34. As a result, the inner shaft 311 is supported by the housing 10 via the first bearing 34 so that it can rotate about the central axis CA.

[0038] Thus, the first bearing 34 has a first outer ring 34a and a first inner ring 34b. As a result of the inner shaft 311 being clearance-fitted to the first inner ring 34b, the first inner ring 34b faces the first outer surface 311a, which is the outer surface of the inner shaft 311, with a gap between them.

[0039] Here, the housing portion 14 has a partition wall portion 141 and a bearing support portion 142. The partition wall portion 141 is a wall that extends in a direction intersecting the central axis CA of the shaft 31 and divides the inside of the housing 10 (particularly the central case 11) vertically. The radially outer end of the partition wall portion 141 is connected to the side wall 11a of the central case 11. The radially inner end of the partition wall portion 141 is connected to the bearing support portion 142. The upper end of the bearing support portion 142 is connected to the partition wall portion 141 and extends downward. The first outer ring 34a is fixed to the radially inner side of the bearing support portion 142 by shrink fitting or the like. In this way, the first outer ring 34a is fixed to the housing 10 (housing portion 14).

[0040] In this embodiment, two first bearings 34 are provided in the vertical direction. The first outer ring 34a of each first bearing 34 is fixed to the housing portion 14 (particularly the bearing support portion 142). Note that the number of first bearings 34 is not limited to the two described above; there may be one or three or more.

[0041] Furthermore, within the housing 10, a third bearing 36 is positioned below the outer shaft 312. The third bearing 36 is positioned below the second bearing 35. The aforementioned bearing plate 37 is attached to the lower part of the housing 10 (especially the central case 11). The third outer ring 36a, which is the outer ring of the third bearing 36, is fixed to the bearing plate 37 by shrink fitting or the like. Within the housing 10, the inner shaft 311 extends below the outer shaft 312. The inner shaft 311 is then clearance-fitted to the third inner ring 36b, which is the inner ring of the third bearing 36, below the outer shaft 312. As a result, the inner shaft 311 is supported by the housing 10 via the third bearing 36 so that it can rotate around the central axis CA.

[0042] In this embodiment, only one third bearing 36 is provided within the housing 10. However, the number of third bearings 36 is not limited to one. For example, two or more third bearings 36 may be arranged side by side in the vertical direction.

[0043] The outer shaft 312 is rotatably supported in the housing 10 via a second bearing 35. The second bearing 35 has a second outer ring 35a and a second inner ring 35b. The second outer ring 35a is fixed to the housing 10. More specifically, the second bearings 35 are positioned above and below the rotor 32 within the housing 10. The second outer ring 35a of the second bearing 35 positioned above the rotor 32 is fixed by shrink fitting or the like radially inward of the bearing support portion 142 of the housing portion 14 and below the position of the first bearing 34. On the other hand, the second outer ring 35a of the second bearing 35 positioned below the rotor 32 is fixed by shrink fitting or the like to the bearing plate 37 at a position above the third bearing 36. The second outer surface 312a, which is the outer surface of the outer shaft 312, is fixed to the second inner ring 35b of each second bearing 35 by welding or the like. As a result, the outer shaft 312 is supported by the housing 10 via the second bearing 35 so as to be rotatable about the central axis CA.

[0044] <2-3-2. Rotary> The rotor 32 is a rotor having a rotor core 321 and magnet pieces 322. Magnet mounting portions are arranged at equal intervals in the circumferential direction on the rotor core 321. The magnet mounting portions are formed, for example, by through holes in the vertical direction. The magnet pieces 322 are inserted into and fixed to the magnet mounting portions.

[0045] The rotor 32 is positioned radially outward of the shaft 31 (particularly the outer shaft 312). The rotor 32 is positioned between two second bearings 35 that are positioned vertically and is fixed to the second outer surface 312a of the outer shaft 312 by welding or other means. In other words, the outer shaft 312 is fixed to the rotor 32.

[0046] <2-3-3. Status> The stator 33 is a stator fixed to the housing 10. The stator 33 is positioned radially outward from the rotor 32 within the housing 10, and faces the rotor 32 with a gap in the radial direction between them. The stator 33 is constructed by winding coils around a stator core via an insulator.

[0047] In the above configuration, when the shaft 31 (inner shaft 311 and outer shaft 312) rotates about the central axis CA, the magnet piece 322 of the rotor 32 moves relative to the coil of the stator 33. This causes current to flow through the coil due to electromagnetic induction, and power is generated. The current generated by electromagnetic induction (e.g., alternating current) is taken out to the outside via the connector 10c of the housing 10 (see Figure 2), as described above.

[0048] (2-4. Details about the shaft) In this embodiment, by configuring the inner shaft 311 and the outer shaft 312 as follows, the inner shaft 311 can be inserted into and removed from the outer shaft 312, while also enabling power transmission from the inner shaft 311 to the outer shaft 312.

[0049] Figure 7 is a cross-sectional view of the shaft 31 when it is cut perpendicular to the central axis CA. Figure 8 is a schematic perspective view showing the state before and after inserting the inner shaft 311 into the outer shaft 312. The outer circumferential surface (first outer circumferential surface 311a) of the inner shaft 311 is provided with recesses 41. The recesses 41 are composed of, for example, spline grooves 41a. The spline grooves 41a are recessed radially inward on the first outer circumferential surface 311a and extend along the central axis CA. The spline grooves 41a are provided at predetermined intervals in the circumferential direction on the first outer circumferential surface 311a. As a result, the first outer circumferential surface 311a has a shape in which the irregularities are continuous in the circumferential direction.

[0050] In this embodiment, the recess 41 (spline groove 41a) is provided on a part of the axial direction of the first outer peripheral surface 311a of the inner shaft 311, but it may also be provided along the entire axial direction. Here, the part of the axial direction refers to the portion of the first outer peripheral surface 311a of the inner shaft 311 that faces the inner peripheral surface 312b of the outer shaft 312 and the portion that protrudes downward from the above portion when the inner shaft 311 is inserted radially inward of the outer shaft 312 and assembled within the housing 10.

[0051] On the other hand, a protrusion 51 is provided on the inner circumferential surface 312b of the outer shaft 312. The protrusion 51 is a portion that fits into a recess 41 formed on the first outer circumferential surface 311a of the inner shaft 311 when the inner shaft 311 is inserted into the outer shaft 312. Such a protrusion 51 is composed of a spline projection 51a. The spline projection 51a protrudes radially inward from the inner circumferential surface 312b of the outer shaft 312 and extends along the central axis CA. The spline projections 51a are provided at predetermined intervals in the circumferential direction on the inner circumferential surface 312b. As a result, the inner circumferential surface 312b has a shape in which the irregularities are continuous in the circumferential direction.

[0052] By aligning the recess 41 on the first outer peripheral surface 311a of the inner shaft 311 with the protrusion 51 on the inner peripheral surface 312b of the outer shaft 312, the inner shaft 311 can be slid relative to the outer shaft 312 in the direction of the central axis CA (for example, from top to bottom within the housing 10) and fitted into place. Furthermore, when the inner shaft 311 is inserted radially inward into the outer shaft 312, the recess 41 and the protrusion 51 engage in the circumferential direction. This transmits the power generated when the inner shaft 311 rotates to the outer shaft 312 via the recess 41 and the protrusion 51, causing the outer shaft 312 to rotate. This allows the rotor 32, which is fixed to the second outer peripheral surface 312a of the outer shaft 312, to rotate. Conversely, by sliding the inner shaft 311 upward relative to the outer shaft 312, the inner shaft 311 can be easily removed from the outer shaft 312.

[0053] Thus, the configuration that allows the inner shaft 311 to be inserted into and removed from the outer shaft 312, while also enabling power transmission from the inner shaft 311 to the outer shaft 312, is not limited to the configuration of this embodiment described above. For example, the inner shaft 311 may be provided with a convex portion 51 (spline projection 51a) that protrudes radially outward on the first outer peripheral surface 311a, and the outer shaft 312 may be provided with a recess 41 (spline groove 41a) that is recessed radially outward on the inner peripheral surface 312b.

[0054] In other words, a recess 41 is provided on either the inner circumferential surface 312b of the outer shaft 312 or the first outer circumferential surface 311a of the inner shaft 311, and a protrusion 51 that fits into the recess 41 is provided on the other of the inner circumferential surface 312b or the first outer circumferential surface 311a.

[0055] In particular, from the viewpoint of achieving both insertion and removal of the inner shaft 311 from the outer shaft 312 and power transmission from the inner shaft 311 to the outer shaft 312, it is desirable to use spline fitting. In this respect, it is desirable that the recess 41 is a spline groove 41a and the protrusion 51 is a spline projection 51a.

[0056] Figure 9 is a plan view of the shaft 31 as seen from the direction of the central axis CA (for example, from above), showing another example of the shaft 31 configuration. Figure 10 is a cross-sectional view of the shaft 31 in Figure 9, showing the state before and after inserting the inner shaft 311 into the outer shaft 312. Note that the cross-sectional view in Figure 10 corresponds to the cross-sectional view along line AA in Figure 9. The recess 41 provided on the inner circumferential surface 312b of the outer shaft 312 may be a keyway 41b. Also, the protrusion 51 provided on the first outer circumferential surface 311a of the inner shaft 311 may be a key 51b that fits into the keyway 41b.

[0057] The key 51b is provided on a part of the circumferential surface 311a and protrudes radially outward. In the example shown in Figure 9, the key 51b is provided at two points symmetrically on the circumferential surface 311a, but there may be one key 51b or three or more. The keyway 41b is a groove that extends axially and has a shape corresponding to the shape of the key 51b. On the inner circumferential surface 312b, the keyway 41b extends from the insertion end of the inner shaft 311 to a predetermined position in the axial direction. The predetermined position is the position where the insertion of the inner shaft 311 into the outer shaft 312 is completed.

[0058] By aligning the keyway 41b and the key 51b, the inner shaft 311 can be slid relative to the outer shaft 312 in the direction of the central axis CA (for example, from top to bottom within the housing 10) and fitted into place. Furthermore, when the inner shaft 311 is fitted radially inward of the outer shaft 312, the keyway 41b and the key 51b engage in the circumferential direction. This allows the power generated when the inner shaft 311 rotates to be transmitted to the outer shaft 312 via the keyway 41b and the key 51b, thereby rotating the outer shaft 312 and the rotor 32. Conversely, by sliding the inner shaft 311 in the opposite direction relative to the outer shaft 312 (for example, upward), the engagement between the keyway 41b and the key 51b can be easily released, and the inner shaft 311 can be removed from the outer shaft 312.

[0059] Therefore, from the viewpoint of achieving both insertion and removal of the inner shaft 311 from the outer shaft 312 and power transmission from the inner shaft 311 to the outer shaft 312, a key fitting may be used. In other words, the recess 41 may be composed of a keyway 41b, and the protrusion 51 may be composed of a key 51b. Alternatively, a keyway 41b may be provided on the first outer circumferential surface 311a of the inner shaft 311, and a key 51b that fits into the keyway 41b may be provided on the inner circumferential surface 312b of the outer shaft 312.

[0060] In this embodiment, the inner shaft 311 is fitted into the first inner ring 34b of the first bearing 34 as described above. Therefore, within the housing 10, the inner shaft 311 is slidably positioned in the direction of the central axis CA relative to both the outer shaft 312 and the first bearing 34.

[0061] (2-5. Procedures for assembling and disassembling the inflator) The expander 2 with the above configuration can be assembled, for example, as follows. First, two first bearings 34 are inserted sequentially from above into the radially inward side of the housing portion 14 (bearing support portion 142) of the central case 11 and fixed in place. Methods such as shrink fitting and welding can be used to fix the first bearings 34 (the same applies to fixing the other bearings).

[0062] Next, the unit, which consists of two second bearings 35, an outer shaft 312, a rotor 32, a third bearing 36, and a bearing plate 37, is fixed to the central case 11. For example, one of the (upper) second bearings 35 is inserted from below into the radially inward side of the housing portion 14 (bearing support portion 142) of the central case 11 and fixed in place. Then, the bearing plate 37 is fixed to the lower part of the central case 11 with bolts or the like. This allows the unit to be fixed to the central case 11. The stator 33 is already fixed inside the central case 11. With the unit fixed to the central case 11, the rotor 32 is positioned radially inward of the stator 33.

[0063] Next, the inner shaft 311 is inserted downward from above the first bearing 34. The inner shaft 311 is positioned to pass sequentially through the first inner ring 34b of the first bearing 34, the radially inner side of the outer shaft 312, and the third inner ring 36b of the third bearing 36. The first balance weight 313 is assumed to be fixed to the upper part of the inner shaft 311 in advance, but it may be attached to the inner shaft 311 at a predetermined timing.

[0064] After screwing the second balance weight 314 to the lower end of the inner shaft 311 (the portion that protrudes downward from the third bearing 36), the pump support plate 133, to which the discharge pump 132 is fixed, is bolted to the bearing plate 37 from below. Then, the lower case 13 is bolted to the lower part of the central case 11 via the bearing plate 37.

[0065] Next, oil OL is injected into the central case 11. The injected oil OL moves downward inside the central case 11 and is contained in the oil storage chamber 131. Alternatively, with oil OL contained in the oil storage chamber 131, the lower case 13 may be bolted to the bottom of the central case 11.

[0066] Next, the orbital scroll 22 is positioned on the upper part of the central case 11 via the Oldham ring 23. At this time, the orbital bearing 25 is pre-fixed to the orbital bearing holder 24 on the lower surface of the orbital scroll 22. Then, when the orbital scroll 22 is positioned, the eccentric shaft portion 315, which is connected to the upper part of the inner shaft 311, is inserted into the inner ring of the orbital bearing 25.

[0067] Finally, the upper case 12, which has the fixed scroll 21, is bolted to the top of the central case 11. This completes the assembly of the expander 2.

[0068] On the other hand, when performing maintenance on the expander 2, maintenance can be performed by disassembling the expander 2 using the reverse procedure described above. For example, by removing the upper case 12 from the central case 11 and pulling the inner shaft 311 upward relative to the outer shaft 312, maintenance can be performed with the outer shaft 312 remaining on the housing 10 side along with the rotor 32 and the second bearing 35.

[0069] As described above, in this embodiment, the shaft 31 is configured to have an inner shaft 311 and an outer shaft 312. The inner shaft 311 is slidable relative to the outer shaft 312 in the direction of the central axis CA. With this configuration, when installing the generator 30 into the housing 10, the generator 30 can be installed separately, not all at once, by separating the inner shaft 311 from the other parts (outer shaft 312, rotor 32, etc.). For example, the elongated inner shaft 311 can be assembled after the other parts (outer shaft 312, etc.). This makes the assembly of the expander 2 easier. Also, when performing maintenance on the expander 2, a part of the generator 30 (inner shaft 311) can be removed first, and the other parts (outer shaft 312, etc.) can be left on the housing 10 side while maintenance of each part is performed. Therefore, maintenance of the expander 2 is also easier. In other words, compared to, for example, using an assembly in which the rotor and shaft etc. are integrated as a generator, the assembly and disassembly of the expander 2 are easier. As a result, the workability during the manufacturing and maintenance of the expander 2 can be improved.

[0070] Furthermore, the inner shaft 311 is configured to transmit power to the outer shaft 312 by spline fitting or the like. This allows the rotational power of the inner shaft 311 to be transmitted to the outer shaft 312 to rotate the rotor 32 and generate electricity, even if the inner shaft 311 is slidable relative to the outer shaft 312 in the direction of the central axis CA.

[0071] The inner shaft 311 is rotatably supported by the housing 10 by the first bearing 34. The first outer ring 34a of the first bearing 34 is fixed to the housing 10. This allows the inner shaft 311, which is inserted into the first inner ring 34b, to be rotatably supported relative to the housing 10. In addition, the first outer surface 311a of the inner shaft 311 faces the first inner ring 34b with a gap in between. This allows the inner shaft 311 to slide freely in the direction of the central axis CA relative to the first inner ring 34b. Therefore, it becomes easy to install and remove the inner shaft 311 on its own.

[0072] The outer shaft 312, to which the rotor 32 is fixed, is rotatably supported in the housing 10 by a second bearing 35. The second outer ring 35a of the second bearing 35 is fixed to the housing 10. The second outer surface 312a of the outer shaft 312 is fixed to the second inner ring 35b. This easily realizes a configuration in which the outer shaft 312 is supported in the housing 10 so as to be rotatable together with the rotor 32.

[0073] In this embodiment, the first bearing 34 is positioned above the second bearing 35. The inner shaft 311 extends above the outer shaft 312. This ensures that the inner shaft 311 is rotatably supported by the housing 10 via the first bearing 34, and the outer shaft 312 is rotatably supported by the housing 10 via the second bearing 35.

[0074] [3. Regarding the partition walls of the enclosure] Next, we will provide further explanation regarding the partition wall portion 141 of the housing portion 14 of the enclosure 10 described above. Figure 11 is a perspective view of the central case 11 of the enclosure 10 when viewed from diagonally above. Figure 12 is a cross-sectional view of the central case 11 shown in Figure 11 when it is cut along a cross section including the central axis CA and BB line. The partition wall portion 141 has a first through hole 141a and a second through hole 141b.

[0075] The first through-hole 141a is a hole through which the working medium discharged from the expansion unit 20 passes. The first through-hole 141a is provided penetrating the partition wall 141 in the vertical direction. The first through-holes 141a are arranged in a row of three on each side of the second through-hole 141b (a total of six) in the circumferential direction of the partition wall 141. Note that the number of first through-holes 141a is not limited to the above six; there may be one or more than six.

[0076] As shown in Figure 5, the expansion unit 20 that expands the working fluid is located above the partition wall 141 within the housing 10. On the other hand, the aforementioned outlet 10b (see Figure 2), which is located on the side wall 11a of the central case 11, is located below the partition wall 141. Therefore, the expanded (high-temperature, low-pressure) working fluid discharged from the expansion unit 20 flows from top to bottom within the housing 10 through the first through-hole 141a of the partition wall 141, and is then discharged to the outside of the housing 10 through the outlet 10b.

[0077] The second through-hole 141b is a hole through which the oil OL, which has been pumped up above the partition wall 141 by the discharge pump 132, passes (as it subsequently flows downward). The second through-hole 141b is also provided to penetrate the partition wall 141 in the vertical direction. Only one second through-hole 141b is provided in the partition wall 141, but multiple holes may be provided.

[0078] In this embodiment, the inner shaft 311, which is located inside the housing 10, is formed as a hollow cylindrical body, i.e., a hollow shaft, as described above. The discharge pump 132 is driven by the rotation of the inner shaft 311 and discharges oil OL into the interior of the inner shaft 311. The oil OL is pumped upward inside the inner shaft 311. A portion of the oil OL moves radially outward during the pumping process and is supplied to the first bearing 34, the second bearing 35, and the third bearing 36, etc. The remainder of the oil OL is pumped further upward above the partition wall 141 and supplied to the expansion unit 20 and the swivel bearing 25, etc. After that, the oil OL moves downward due to gravity and passes through the second through hole 141b from top to bottom.

[0079] A filter section 141c is provided at the bottom of the second through-hole 141b. Therefore, when the oil OL that has passed through the second through-hole 141b passes through the filter section 141c, any foreign matter contained in the oil OL is captured by the filter section 141c. After passing through the second through-hole 141b and the filter section 141c in sequence, the oil OL then passes through the housing 10 (for example, between the rotor 32 and stator 33 of the generator 30) and is returned to the oil storage chamber 131.

[0080] Thus, by providing multiple holes (first through-hole 141a, second through-hole 141b) in the partition wall 141, the flow path for the working medium and the flow path for the oil OL can be separated. Therefore, compared to a configuration in which, for example, a separate member (a wall member that forms a flow path) is installed inside the housing 10 to separate the flow path for the working medium and the flow path for the oil, the expander 2 can be constructed with fewer parts because the separate member is not required.

[0081] Furthermore, by using a hollow shaft as the inner shaft 311, the discharge pump 132 can drive oil OL through the inside of the inner shaft 311 to a location above the partition wall 141. This allows oil OL to be used as a lubricant for the sliding parts of the expansion unit 20 located above the partition wall 141 (for example, the sliding parts between the fixed scroll 21 and the orbiting scroll 22).

[0082] In this embodiment, as shown in Figure 12, the partition wall 141 is positioned at an inclination with respect to the central axis CA. The inclination angle θ(°) of the partition wall 141 with respect to the central axis CA can be set to an appropriate angle other than 90°.

[0083] There is an affinity between the working fluid and the oil OL. Therefore, the working fluid and the oil OL mix easily within the housing 10. However, it is known that the slower the flow velocity of the oil OL, the less likely the working fluid and the oil OL are to mix (they become more likely to separate). When the partition wall 141 is inclined with respect to the central axis CA, the oil OL flows along the inclination of the upper surface 141U of the partition wall 141, so the flow velocity of the oil OL becomes slower compared to, for example, when the oil OL is in free fall. As a result, the working fluid and the oil OL become less likely to mix.

[0084] The second through-hole 141b described above may be provided at any position in the circumferential direction of the partition wall 141. However, as described above, in a configuration in which the partition wall 141 is inclined with respect to the central axis CA, it is desirable that the second through-hole 141b penetrates the lowest end 141UL on the upper surface 141U of the inclined partition wall 141. This is for the following reasons. That is, in a configuration in which the partition wall 141 is inclined, the oil OL supplied from above to the upper surface 141U of the partition wall 141 flows along the upper surface 141U toward the lower end 141UL. As a result, the oil OL is efficiently collected at the end 141UL and efficiently discharged downward from the second through-hole 141b located at the end 141UL. Furthermore, the accumulation of oil OL on the upper surface 141U of the partition wall 141 is also reduced.

[0085] As shown in Figure 11, the partition wall portion 141 has a stepped portion 141d. The stepped portion 141d is a projection that protrudes upward from the upper surface 141U of the partition wall portion 141. The height of the stepped portion 141d relative to the upper surface 141U can be set to be appropriate or not. The stepped portion 141d is provided on a part of the upper surface 141U in the radial direction. Specifically, the stepped portion 141d is provided on the upper surface 141U towards the radially outer side. As a result, the upper surface 141U is exposed upward on the radially inner side of the stepped portion 141d. In Figure 11, the exposed portion of the upper surface 141U on the radially inner side of the stepped portion 141d is indicated by reference numeral 141Ue. The first through hole 141a described above is provided by penetrating the stepped portion 141d (in the vertical direction).

[0086] The stepped portion 141d may be provided on the upper surface 141U closer to the radially inward side. In this case, the upper surface 141U is exposed upward on the radially outward side of the stepped portion 141d. Therefore, it can be said that the upper surface 141U of the partition wall portion 141 only needs to be exposed (upward) on the radially lateral side of the stepped portion 141d.

[0087] By providing an upwardly projecting stepped portion 141d on the upper surface 141U of the partition wall portion 141, it becomes difficult for the oil OL flowing along the upper surface 141U of the partition wall portion 141 to overcome the step (height) of the stepped portion 141d and enter the first through-hole 141a. This makes it easy to allow only the working medium to pass through the first through-hole 141a. In other words, it becomes easy to reliably separate the flow path of the working medium from the flow path of the oil OL.

[0088] Furthermore, the upper surface 141U is exposed on the radial side of the stepped portion 141d. Therefore, the oil OL flowing along the upper surface 141U can be guided to the second through-hole 141b via the exposed portion 141Ue on the radial side of the stepped portion 141d. Thus, even with a configuration in which the stepped portion 141d is provided on the upper surface 141U, a flow path for the oil OL flowing toward the second through-hole 141b can be reliably secured on the upper surface 141U.

[0089] [4. Supplement] In this embodiment, an example in which a scroll-type expansion unit is used as the expansion unit 20 has been described. The scroll-type expansion unit 20 has a fixed scroll 21 and an orbiting scroll 22. The orbiting scroll 22 rotates relative to the fixed scroll 21 due to the expansion of the working medium, thereby rotating the shaft 31 of the expander 2. In this case, the power generated by the rotation of the orbiting scroll 22 can be used to rotate the shaft 31 and generate electricity.

[0090] However, the expansion unit 20 is not limited to a scroll-type expansion unit. For example, it is also possible to configure an expansion unit that expands the working medium using a method employed in various types of compressors. Examples of the above-mentioned types of compressors include reciprocating compressors, diaphragm compressors, rotary compressors, screw compressors, vane compressors, and claw compressors.

[0091] [5. Addendum] The expander 2 and power generation system 1 described in this embodiment can also be expressed as follows.

[0092] The inflator in Appendix (1) is An expander equipped with a generator that generates electricity using power produced by the expansion of a working medium, The aforementioned generator is The aforementioned power causes a shaft to rotate around a central axis extending in the vertical direction, The shaft comprises a rotor positioned radially outward from the shaft, The aforementioned shaft is The inner shaft and The system includes an outer shaft positioned radially outward from the inner shaft, through which the power is transmitted, The inner shaft is rotatably supported by the housing via a first bearing and is axially slidable with respect to the outer shaft and the first bearing. The outer shaft is fixed to the rotor and is rotatably supported by the housing via a second bearing.

[0093] The inflator in Appendix (2) is the same as the inflator described in Appendix (1), The first bearing is, A first outer ring fixed to the aforementioned housing, It has a first inner ring that faces the first outer surface, which is the outer surface of the inner shaft, with a gap between them.

[0094] The inflator in Appendix (3) is the same as the inflator described in Appendix (2), The second bearing is, A second outer ring fixed to the aforementioned housing, The system includes a second inner ring to which the second outer surface, which is the outer surface of the outer shaft, is fixed.

[0095] The inflator in Appendix (4) is the same as the inflator described in Appendix (3), The first bearing is positioned above the second bearing. The inner shaft extends upward more than the outer shaft.

[0096] The inflator in Appendix (5) is the inflator described in any of Appendix (2) to (4), A recess is provided on either the inner circumferential surface of the outer shaft or the first outer circumferential surface of the inner shaft. A protrusion that fits into the recess is provided on the other of the inner circumferential surface of the outer shaft and the first outer circumferential surface of the inner shaft.

[0097] The inflator in Appendix (6) is the inflator described in Appendix (5), The recess is a spline groove extending along the central axis, The aforementioned protrusion is a spline projection extending along the central axis.

[0098] The inflator in Appendix (7) is the same as the inflator described in Appendix (5), The recess is a keyway, The aforementioned protrusion is a key that fits into the keyway.

[0099] The inflator in Appendix (8) is the inflator described in any of Appendix (2) to (7), The aforementioned enclosure is The housing portion to which the first outer ring of the first bearing is fixed, It has an oil storage chamber located at the bottom, The housing portion has partition walls that extend in a direction intersecting the central axis of the shaft and divide the inside of the housing vertically. Inside the aforementioned enclosure, An expansion unit is positioned above the aforementioned partition wall and expands the working medium, A discharge pump is provided, which is driven by the rotation of the shaft of the generator and discharges the oil stored in the oil storage chamber. The aforementioned partition wall portion is A first through-hole through which the working medium discharged from the expansion unit passes, It has a second through-hole through which the oil, after being pumped up above the partition wall by the discharge pump, passes.

[0100] The inflator in Appendix (9) is the inflator described in Appendix (8), The partition wall is positioned at an inclination with respect to the central axis.

[0101] The inflator in Appendix (10) is the inflator described in Appendix (9), The second through-hole is provided by penetrating the lowest end of the inclined upper surface of the partition wall.

[0102] The inflator in Appendix (11) is the same as the inflator described in Appendix (10), The partition wall portion has a stepped portion that protrudes upward from the upper surface, The first through-hole is provided by penetrating the stepped portion.

[0103] The inflator in Appendix (12) is the same as the inflator described in Appendix (11), The upper surface of the partition wall is exposed on the radial side of the stepped portion.

[0104] The inflator in Appendix (13) is the inflator described in any of Appendix (8) to (12), The inner shaft is a hollow shaft, The discharge pump discharges the oil into the interior of the inner shaft.

[0105] The inflator in Appendix (14) is the inflator described in any of Appendix (8) to (13), The aforementioned expansion unit is Fixed scrolling and, The expander includes a rotating scroll that rotates relative to the fixed scroll by the expansion of the working medium, thereby rotating the shaft of the expander.

[0106] The power generation system described in Appendix (15) is An inflator as described in any of the appendices (1) to (14), A condenser for cooling the working medium discharged from the expander, The system includes an evaporator that evaporates the working medium by heat exchange with the waste heat of a heat source and supplies it to the expander.

[0107] Although embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and it can be expanded or modified without departing from the spirit of the invention. [Industrial applicability]

[0108] The expander of the present invention can be used, for example, in a power generation system. [Explanation of Symbols]

[0109] 1. Power generation system 2. Inflator 3. Condenser 4. Evaporator 10 cabinets 14 Housing Section 20 expansion units 21 Fixed Scroll 22 Swivel Scroll 30 Generators 31 shafts 32 rotors 34 First bearing 34a First outer ring 34b First inner ring 35 Second bearing 35a Second outer ring 35b Second inner ring 41 Recess 41a Spline groove 41b Keyway 51 Convex part 51a Spline projection 51b Key 131 Oil Storage Chamber 132 Discharge pump 141 Bulkhead section 141U top 141UL End 141a 1st through hole 141b 2nd through hole 141d Step section 311 Inner shaft 311a 1st outer surface 312 Outer shaft 312a 2nd outer surface 312b Inner surface CA center axis H0 heat source OL Oil

Claims

1. An expander equipped with a generator that generates electricity using power produced by the expansion of a working medium, The aforementioned generator is The aforementioned power causes a shaft to rotate around a central axis extending in the vertical direction, The shaft comprises a rotor positioned radially outward from the shaft, The aforementioned shaft is The inner shaft and The system includes an outer shaft positioned radially outward from the inner shaft, through which the power is transmitted, The inner shaft is rotatably supported by the housing via a first bearing and is axially slidable with respect to the outer shaft and the first bearing. The outer shaft is fixed to the rotor and rotatably supported in the housing via a second bearing, in the expander.

2. The first bearing is, A first outer ring fixed to the housing, The expander according to claim 1, further comprising a first outer ring facing a first outer surface which is the outer surface of the inner shaft, with a gap between them.

3. The second bearing is, A second outer ring fixed to the aforementioned housing, The expander according to claim 2, further comprising a second inner ring to which the second outer surface, which is the outer surface of the outer shaft, is fixed.

4. The first bearing is positioned above the second bearing. The expander according to claim 3, wherein the inner shaft extends upward more than the outer shaft.

5. A recess is provided on either the inner circumferential surface of the outer shaft or the first outer circumferential surface of the inner shaft. The expander according to claim 2, wherein a protrusion that fits into the recess is provided on the other of the inner circumferential surface of the outer shaft and the first outer circumferential surface of the inner shaft.

6. The recess is a spline groove extending along the central axis, The expansion machine according to claim 5, wherein the convex portion is a spline projection extending along the central axis.

7. The recess is a keyway, The expansion machine according to claim 5, wherein the protrusion is a key that fits into the keyway.

8. The aforementioned enclosure is The housing portion to which the first outer ring of the first bearing is fixed, It has an oil storage chamber located at the bottom, The housing portion has partition walls that extend in a direction intersecting the central axis of the shaft and divide the inside of the housing vertically. Inside the aforementioned enclosure, An expansion unit is positioned above the aforementioned partition wall and expands the working medium, A discharge pump is provided, which is driven by the rotation of the shaft of the generator and discharges the oil stored in the oil storage chamber. The aforementioned partition wall portion is A first through-hole through which the working medium discharged from the expansion unit passes, The expander according to claim 2, further comprising a second through-hole through which the oil, after being pumped up above the partition wall by the discharge pump, passes.

9. The expansion machine according to claim 8, wherein the partition wall portion is arranged at an inclination with respect to the central axis.

10. The expander according to claim 9, wherein the second through-hole is provided through the lowest end of the inclined upper surface of the partition wall.

11. The partition wall portion has a stepped portion that protrudes upward from the upper surface, The expander according to claim 10, wherein the first through-hole is provided through the stepped portion.

12. The expander according to claim 11, wherein the upper surface of the partition wall is exposed on the radial side of the stepped portion.

13. The inner shaft is a hollow shaft, The expander according to claim 8, wherein the discharge pump discharges the oil into the inner shaft.

14. The aforementioned expansion unit is Fixed scrolling and, The expander according to claim 8, further comprising a revolving scroll that rotates the shaft of the expander by revolving relative to the fixed scroll due to the expansion of the working medium.

15. An expander according to any one of claims 1 to 14, A condenser for cooling the working medium discharged from the expander, A power generation system comprising: an evaporator that evaporates the working medium by heat exchange with the waste heat of a heat source and supplies it to the expander.

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