Rotating fluid machine

Abstract

A rotary valve of a rotating fluid machine is constructed by bringing into contact, on sliding faces which are orthogonal to an axis, a moving valve plate provided on a rotor and a stationary valve plate provided on a valve body. An annular member pivotably supports the valve body by a fulcrum shaft. The annular member has a pair of projections at its two ends. The pair of projections are engaged slidably in the direction of the axis with a pair of guide grooves formed in a rear cover. When the valve body is pressed in the direction of the axis to bring the sliding faces into close contact with each other, the pair of projections receive a uniform frictional resistance from the guide grooves, so that the annular member is prevented from inclining off a plane orthogonal to the axis. Therefore, the compliance of the sliding faces can be secured to prevent a working medium from leaking and to suppress uneven wear of the sliding faces.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a rotating fluid machine provided with a casing, a rotor rotatably supported by the casing, a working section provided on the rotor, and a rotary valve, provided between the casing and the rotor, for controlling the supply and discharge of the working medium to and from the working section.

[0003] 2. Description of the Related Art

[0004] In a rotary valve for rotating fluid machines of this kind, a moving valve plate provided on the rotor and a stationary valve plate provided on a valve body engaged with the casing to be unable to rotate and movable in the direction of the axis of the rotor are brought into contact with each other on sliding faces orthogonal to the axis, and the rotation of the moving valve plate relative to the stationary valve plate causes steam of high temperature and high pressure to be successively supplied to or discharged from a group of axial piston cylinders provided on the rotor. In that process, it is necessary to permit the valve body to move in the direction of the axis and secure the compliance of the sliding faces, while preventing the frictional force acting on the sliding faces between the moving valve plate rotating together with the rotor and the stationary valve plate from causing the valve body integrated with the stationary valve plate to be dragged by and accompany the rotor in the rotation.

[0005] In view of this problem, a rotating fluid machine described in Japanese Patent Laid-Open No. 2002-256805 has a pin planted in one position on the outer circumference of the valve body in the radial direction and engaged with a notch formed in the inner circumferential face of the casing in the direction of the axis.

[0006] The valve body accommodated in a concave in the casing via a sealing member secures the compliance of the sliding faces between the moving valve plate and the stationary valve plate while oscillating around the axis within the compression margin of the sealing member. However, in the conventional device, as the valve body is engaged with the casing in only one position on the outer circumferential face where the pin is planted, the valve body cannot smoothly oscillate around the axis, and the oscillation of the valve body around the pin in a position off the axis may not only deteriorate the compliance of the sliding faces but also cause uneven wear of the sliding faces.

[0007] In view of the problems noted above, the present invention has an object to increase the compliance of the sliding faces of the rotary valve of the rotating fluid machine, thereby preventing the working medium from leaking.

SUMMARY OF THE INVENTION

[0008] In order to achieve the object stated above, according to a first feature of the present invention, there is proposed a rotating fluid machine comprising: a casing; a rotor rotatably supported by the casing; a working section disposed on the rotor; and a rotary valve, provided between the casing and the rotor, for controlling the supply and discharge of a working medium to and from the working section, the rotary valve being constructed by bringing into contact, on sliding faces which are orthogonal to an axis of the rotor, a moving valve plate provided on the rotor and a stationary valve plate provided on a valve body engaged with the casing to be unable to rotate and movable in the direction of the axis, wherein two projections are provided in a first radial direction at two ends of an annular member loosely fitted onto the outer circumference of the valve body, and engaged slidably in the direction of the axis with guide grooves formed in the casing, and wherein the valve body is pivotably supported on the annular member via a fulcrum shaft arranged in a second radial direction orthogonal to the first radial direction.

[0009] With the configuration described above, two projections are provided in a first radial direction at two ends of an annular member loosely fitted onto the outer circumference of the valve body, and engaged slidably in the direction of the axis with guide grooves formed in the casing. Thus, when the valve body is biased in the axial direction so that the sliding faces of the stationary valve plate and the moving valve pate are brought into close contact with each other, the two projections receive a uniform frictional resistance, and the annular member is thereby prevented from inclining off the plane orthogonal to the axis. Even if the annular member is inclined due to the difference in frictional resistance which the two projections receives from the guide grooves, as the valve body is pivotably supported on the annular member via the fulcrum shaft arranged in the second radial direction, the valve body can be reliably prevented from inclining off the axis L, and the compliance of the sliding faces can be secured, thereby preventing the working medium from leaking and suppressing uneven wear of the sliding faces.

[0010] Further, according to a second feature of the present invention, in addition to the first feature, the two projections of the annular member can slide with respect to the guide grooves of the casing in the first radial direction, and the valve body can slide along the fulcrum shaft in the second radial direction.

[0011] With the configuration described above, the operation of the Oldham's coupling constructed of the annular member and the fulcrum shaft enables the valve body to freely move relative to the casing within the plane orthogonal to the axis. Therefore, even if the valve body becomes inclined off the axis, the free movement of the valve body within the plane orthogonal to the axis prevents wrenching from occurring between the valve body and the casing, thereby securing the compliance of the sliding faces.

[0012] A group of axial piston cylinders 56 in preferred embodiments correspond to the working section according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a vertical sectional view of an expander according to a first preferred embodiment.

[0014] FIG. 2 is a sectional view taken on line 2-2 in FIG. 1.

[0015] FIG. 3 is a view taken on line 3-3 in FIG. 1.

[0016] FIG. 4 is an enlarged view of Part 4 in FIG. 1.

[0017] FIG. 5 is an enlarged view of Part 5 in FIG. 1.

[0018] FIG. 6 is an exploded perspective view of a rotor.

[0019] FIG. 7 is a sectional view taken on line 7-7 in FIG. 4.

[0020] FIG. 8 is a sectional view taken on line 8-8 in FIG. 4.

[0021] FIG. 9 is an enlarged view of Part 9 in FIG. 4.

[0022] FIG. 10 is a sectional view taken on line 10-10 in FIG. 5.

[0023] FIG. 11 is a sectional view taken on line 11-11 in FIG. 5.

[0024] FIG. 12 is a sectional view taken on line 12-12 in FIG. 5.

[0025] FIG. 13 is a sectional view taken on line 13-13 in FIG. 5.

[0026] FIG. 14 is a view in arrowed direction 14 in FIG. 13.

[0027] FIG. 15 is a view in arrowed direction 15 in FIG. 13.

[0028] FIG. 16 is an exploded perspective view of an Oldham's coupling.

[0029] FIG. 17 is an exploded perspective view of an Oldham's coupling in a second preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

[0031] As shown in FIG. 1 through FIG. 9, an expander E according to a first embodiment is used in, for example, a Rankine cycle system. It converts thermal energy and pressure energy of high-temperature high-pressure steam as a working medium into mechanical energy and supplies the converted energy. The casing 11 of the expander E is provided with a casing body 12, a front cover 15 connected to the front opening of the casing body 12 with a plurality of bolts 14 . . . with a sealing member 13 therebetween, a rear cover 18 fitted to the rear opening of the casing body 12 with a plurality of bolts 17 . . . with a sealing member 16 therebetween, and an oil pan 21 fitted to the bottom opening of the casing body 12 with a plurality of bolts 20 . . . with a sealing member 19 therebetween.

[0032] A rotor 22 is arranged to be rotatable around an axis L extending in the middle of the casing 11 in the back and forth directions, and supported in front by combined angular bearings 23f and 23r disposed on the front cover 15 and on the back by a radial bearing 24 disposed on the casing body 12. A swash plate holder 28 is integrally formed on the rear face of the front cover 15. A swash plate 31 is rotatably supported by this swash plate holder 28 via an angular bearing 30. The axis of the swash plate 31 is inclined relative to the axis L of the rotor 22 at a fixed angle.

[0033] The rotor 22 is provided with an output shaft 32 supported on the front cover 15 with the combined angular bearings 23f and 23r, three sleeve supporting flanges 33, 34 and 35 formed integrally with one another on the rear part of the output shaft 32 via notches 57 and 58 of a predetermined width (see FIG. 4 and FIG. 9), a rotor head 38 connected to the rear sleeve supporting flange 35 with a plurality of bolts 37 . . . via a metal gasket 36 integrally and supported on the casing body 12 by the radial bearing 24, and a thermally insulating cover 40 fitted onto the three sleeve supporting flanges 33, 34 and 35 from front and connected with a plurality of bolts 39 . . . to the front sleeve supporting flange 33.

[0034] Five sleeve supporting holes 33a . . . , 34a . . . and 35a . . . are respectively bored in the three sleeve supporting flanges 33, 34 and 35 around the axis L at 72° intervals. Five cylinder sleeves 41 . . . are fitted into the respective sleeve supporting holes 33a . . . , 34a . . . and 35a . . . from behind. Formed at the rear end of each of the cylinder sleeves 41 is a flange 41a, which is positioned in the axial direction in contact with the metal gasket 36 in a state in which it is fitted onto a stepped portion 35b formed in the sleeve supporting hole 35a of the rear sleeve supporting flange 35 (see FIG. 9). A piston 42 is slidably fitted within each of the cylinder sleeves 41, the front end of the piston 42 is in contact with a dimple 31a formed in the swash plate 31, and a steam expansion chamber 43 is partitioned between the rear end of the piston 42 and the rotor head 38.

[0035] A plate-shaped bearing holder 92 is laid over the front face of the front cover 15 with a sealing member 91 therebetween and fixed with bolts 93 . . . . A pump body 95 is laid over the front face of the bearing holder 92 with a sealing member 94 therebetween and fixed with bolts 96 . . . . The combined angular bearings 23f and 23r are positioned between the stepped portion of the front cover 15 and the bearing holder 92, and fixed in the direction of the axis L.

[0036] A shim 97 of a predetermined thickness is placed between a flange 32d formed in the output shaft 32 supporting the combined angular bearings 23f and 23r and the inner races of the combined angular bearings 23f and 23r. The inner races of the combined angular bearings 23f and 23r are fastened with nuts 98 screwed onto the outer circumference of the output shaft 32. As a result, the output shaft 32 is positioned in the direction of the axis L relative to the combined angular bearings 23f and 23r, namely with respect to the casing 11.

[0037] The combined angular bearings 23f and 23r are attached in mutually reverse orientations, and support the output shaft 32 not only in the radial direction but also immovably in the direction of the axis L. Thus, one combined angular bearing 23f is arranged to restrict the forward movement of the output shaft 32, while the other combined angular bearing 23r is arranged to restrict the backward movement of the output shaft 32.

[0038] As the combined angular bearings 23f and 23r are used as a bearing for the front part of the rotor 22, one of the loads arising toward the opposite ends of the axis L in the expansion chambers 43 . . . in a predetermined operating state of the expander E is transmitted via the rotor 22 to the inner races of the combined angular bearings 23f and 23r, and the other load is transmitted via the swash plate 31 and the swash plate holder 28 of the front cover 15 to the outer races of the combined angular bearings 23f and 23r. These two loads compress the swash plate holder 28 of the front cover 15 held between the angular bearing 30 supporting the swash plate 31 and the combined angular bearings 23f and 23r supporting the rotor 22, resulting in an enhanced rigidity of the mechanism. Moreover, the integral configuration of the swash plate holder 28 with the front cover 15 as in this embodiment of the invention makes the structure more rigid and simpler.

[0039] Further, by incorporating the angular bearing 30 supporting the swash plate 31 and the combined angular bearings 23f and 23r supporting the rotor 22 into the front cover 15, it is possible to accomplish the assembling process in the units of “the rotor 22 and the piston 42 . . . ”, “assembly of the front cover 15” and “the pump body 95” thereby improving the efficiency of procedures such as rearrangement of the piston 42 . . . and the replacement of an oil pump 49.

[0040] The radial bearing 24 supporting the rotor head 38 which constitutes the rear end of the rotor 22 is an ordinary ball bearing supporting only the load in the radial direction. To enable the rotor head 38 to slide in the direction of the axis L relative to the radial bearing 24, a gap a is formed between the rotor head 38 and the inner race of the radial bearing 24 (see FIG. 5).

[0041] An oil passage 32a extending on the axis L is formed within the output shaft 32 integral with the rotor 22. The front end of the oil passage 32a branches in radial directions to communicate with an annular groove 32b on the outer circumference of the output shaft 32. In a radially inner position of the sleeve supporting flange 34 at the center of the rotor 22, an oil passage blocking member 45 is screwed into the inner circumference of the oil passage 32a with a sealing member 44 therebetween. A plurality of oil holes 32c . . . extend from the nearby oil passage 32a outward in the radial direction, and open in the outer circumferential face of the output shaft 32.

[0042] A trochoidal oil pump 49 is arranged between a concave 95a formed in the front face of the pump body 95 and a pump cover 48 fixed with a plurality of bolts 47 . . . to the front face of the pump body 95 with a sealing member 46 therebetween, and includes an outer rotor 50 rotatably fitted into the concave 95a, and an inner rotor 51 fixed to the outer circumference of the output shaft 32 to engage with the outer rotor 50. The inner space of the oil pan 21 communicates with the intake port 53 of the oil pump 49 via an oil pipe 52 and the oil passage 95b of the pump body 95. The discharge port 54 of the oil pump 49 communicates with the annular groove 32b of the output shaft 32 via the oil passage 95c of the pump body 95.

[0043] The piston 42 slidably fitted into the cylinder sleeve 41 consists of an end portion 61, a middle portion 62 and a top portion 63. The end portion 61 is a member having a spherical portion 61a in contact with the dimple 31a of the swash plate 31, and is welded onto the tip of the middle portion 62. The middle portion 62 is a cylindrical member having a large-capacity hollow space 62a, and has in the outer circumferential part near the top portion 63 a smaller diameter part 62b slightly reduced in diameter. A plurality of oil holes 62c . . . are formed to penetrate the smaller diameter part 62b in the radial direction. A plurality of spiral oil grooves 62d . . . are formed in the outer circumferential part ahead of the smaller diameter part 62b. The top portion 63 facing the expansion chambers 43 is formed integrally with the middle portion 62. A thermally insulating space 65 (see FIG. 9) is formed between a partition wall 63a formed inside the space and a lid member 64 fitted and welded onto its rear end face. Fitted to the outer circumference of the top portion 63 are two compression rings 66 and one oil ring 67. An oil ring groove 63b into which the oil ring 67 is fitted, communicates via a plurality of oil holes 63c . . . with the hollow space 62a of the middle portion 62.

[0044] The end portion 61 and the middle portion 62 of the piston 42 are built of high carbon steel, and the top portion 63, of stainless steel. The end portion 61 undergoes induction quenching, and the middle portion 62, plain quenching. As a result, the piston 42 obtains a high surface stress resistance in the end portion 61 which is in contact with the swash plate 31 under a high surface stress, a wear resistance in the middle portion 62 which is in sliding contact with the cylinder sleeves 41 under poor lubricating conditions, and a heat and corrosion resistance in the top portion 63 which faces the expansion chambers 43 to be exposed to high temperature and high pressure.

[0045] An annual groove 41b (see FIG. 6 and FIG. 9) is formed in the outer circumference of the middle portion of each cylinder sleeve 41, and a plurality of oil holes 41c . . . are formed in this annual groove 41b. Irrespective of the mounting position of the cylinder sleeve 41 in the rotating direction, the oil holes 32c . . . formed in the output shaft 32 and oil holes 34b . . . (see FIG. 4 and FIG. 6) formed in the middle sleeve supporting flange 34 of the rotor 22 communicate with the annual groove 41b. A space 68 formed between the thermally insulating cover 40 and the sleeve supporting flanges 33 and 35 respectively before and behind the rotor 22 communicates with the inner space of the casing 11 via oil holes 40a . . . (see FIG. 4 and FIG. 7) formed in the thermally insulating cover 40.

[0046] An annular lid member 69 is welded onto the front side of the rotor head 38 connected with the bolts 37 . . . to the rear face of the sleeve supporting flange 33 in the front side of the rotor 22, or onto the expansion chambers 43 . . . . An annular thermally insulating space 70 (see FIG. 9) is defined on the back or rear face of the lid member 69. The rotor head 38 is positioned in the rotating direction by a knock pin 55 relative to the rear sleeve supporting flange 35.

[0047] The five cylinder sleeves 41 . . . and the five pistons 42 . . . constitute a group of axial piston cylinders 56 according to the present invention.

[0048] Next will be described with reference to FIG. 5 and FIG. 10 through FIG. 15 the structure of a rotary valve 71 for supplying and discharging steam to and from the five expansion chambers 43 . . . of the rotor 22.

[0049] As shown in FIG. 5, the rotary valve 71 arranged along the axis L of the rotor 22 is provided with a valve body 72, a cap member 102 fitted onto the rear outer circumference of the valve body 72 with a sealing member 101 therebetween, an annular member 104 loosely fitted onto the middle outer circumference of the valve body 72 and oscillatably supported by a fulcrum shaft 103, a stationary valve plate 73, and a moving valve plate 74. The moving valve plate 74, in a state of being positioned by a knock pin 75 in the rotating direction on the rear side of the rotor 22, is fixed with bolts 76 screwed onto the oil passage blocking member 45 (see FIG. 4). The bolts 76 also have a function to fix the rotor head 38 to the output shaft 32.

[0050] As is clear from FIG. 5 when referenced together with FIG. 13 through FIG. 16, the annular member 104 includes, at the opposite ends of a first radial direction X-X, a pair of projections 104a and 104b. Those projections 104a and 104b have a rectangular section with its corners rounded, and are engaged with a pair of guide grooves 18c and 18c formed in the rear cover 18, in the direction of the axis L, to be slidable in the direction of the axis L and in the radial direction (first radial direction X-X). The fulcrum shaft 103 pressed into two through holes 104c and 104c formed in the annular member 104 is arranged in a second radial direction Y-Y orthogonal to the first radial direction X-X. The fulcrum shaft 103 loosely penetrates the valve body 72, and therefore the valve body 72 can slide relative to the annular member 104 in the second radial direction Y-Y and oscillate relative to the annular member 104 around the fulcrum shaft 103.

[0051] In other words, since the engagement of the projections 104a and 104b with the guide grooves 18c and 18c enables the annular member 104 to move relative to the rear cover 18 in the first radial direction X-X, and the valve body 72 is guided by the fulcrum shaft 103 to reliably move in relative terms in the second radial direction Y-Y, the valve body 72 can freely move relative to the rear cover 18 in the plane orthogonal to the axis L. Therefore, the annular member 104 and the fulcrum shaft 103, while restricting the rotation of the valve body 72 relative to the rear cover 18, constitute an Oldham's coupling which permits axial misalignment between the rear cover 18 and the valve body 72.

[0052] Referring again to FIG. 5, the stationary valve plate 73 in contact with the moving valve plate 74 via the flat sliding faces 77 is fixed to the center of the front face of the valve body 72 with a single bolt 78, and fixed to the outer circumference of the valve body 72 with an annular fixed ring 79 and a plurality of bolts 80. When it is fixed, a stepped portion 79a formed on the inner circumference of the fixed ring 79 is pressed onto the outer circumference of the stationary valve plate 73 in a spigot-fit manner, and a stepped portion 79b formed on the outer circumference of the fixed ring 79 is spigot-fitted onto the outer circumference of the valve body 72, thereby ensuring a coaxial relationship of the stationary valve plate 73 to the valve body 72. Further, a knock pin 81 for positioning the stationary valve plate 73 in the rotational direction is arranged between the valve body 72 and the stationary valve plate 73.

[0053] Therefore, as the rotor 22 turns, the moving valve plate 74 and the stationary valve plate 73 turn relative to each other in close contact with each other on the sliding faces 77. The stationary valve plate 73 and the moving valve plate 74 are made of a highly durable material, such as carbon or ceramic, and their durability can be further enhanced by affixing a member having excellent heat resistance, lubricating performance, corrosion resistance and wear resistance to the sliding faces 77, or by coating them with such a material.

[0054] The cap member 102 fitted onto the outer circumference of the valve body 72 has a larger diameter part 102a and a smaller diameter part 102b. The outer circumferential faces of those larger diameter part 102a and smaller diameter part 102b are fitted onto supporting faces 18a and 18b having a circular section in the rear cover 18 with sealing members 82 and 83 therebetween, respectively, to be slidable in the direction of the axis L.

[0055] A plurality of preload springs 85 . . . are supported by the rear cover 18 so as to surround the axis L, and the valve body 72 whose stepped part 102c between the larger diameter part 102a and the smaller diameter part 102b is pressed by these preload springs 85 . . . is urged forward to bring the sliding faces 77 of the stationary valve plate 73 and the moving valve plate 74 into close contact with each other.

[0056] A steam feed pipe 86 connected to the rear face of the valve body 72 communicates with the sliding faces 77 via a first steam passage P1 formed within the valve body 72 and a second steam passage P2 formed in the stationary valve plate 73. Among the casing body 12, the rear cover 18 and the rotor 22, there is formed a steam discharge chamber 88 sealed with a sealing member 87. The steam discharge chamber 88 communicates with the sliding faces 77 via sixth and seventh steam passages P6 and P7 formed within the valve body 72 and a fifth steam passage P5 formed in the stationary valve plate 73. Between the mating faces of the valve body 72 and the stationary valve plate 73 are provided with sealing members 89 surrounding the connecting part between the first and second steam passages P1 and P2 and sealing members 90 surrounding the connecting part between the fifth and sixth steam passages P5 and P6.

[0057] Five third steam passages P3 . . . arranged at equal intervals around the axis L penetrate the moving valve plate 74, and both ends of five fourth steam passages P4 . . . formed in the rotor 22 so as to surround the axis L communicate with the third steam passages P3 . . . and the expansion chambers 43 . . . , respectively. While the parts opening in the sliding faces 77 of the second steam passages P2 are circular, those opening in the sliding faces 77 of the fifth steam passage P5 are formed in an arcuate shape centering on the axis L.

[0058] Next will be described the operation of the expander E according to the first embodiment configured as described above.

[0059] High temperature high pressure steam generated by heating water in an evaporator flows from the steam feed pipe 86, and reaches the sliding face 77 of the moving valve plate 74 via the first steam passage P1 formed in the valve body 72 of the rotary valve 71 and the second steam passage P2 formed in the stationary valve plate 73 integral with this valve body 72. The second steam passage P2 opening in the sliding face 77 momentarily communicates for a predetermined air intake period with the corresponding third steam passage P3 formed in the moving valve plate 74 turning integrally with the rotor 22. The high temperature high pressure steam is supplied from the third steam passage P3 via the fourth steam passage P4 formed in the rotor 22, into the expansion chamber 43 within the cylinder sleeve 41.

[0060] Even after the communication between the second steam passage P2 and the third steam passage P3 is cut off along with the rotation of the rotor 22, expansion of the expansion chamber 43 causes the piston 42 fitted into the cylinder sleeve 41 to be thrust forward from the top dead center to the bottom dead center, so that the end portion 61 at the front end of the piston presses the dimple 31a in the swash plate 31. As a result, the reaction force which the piston 42 receives from the swash plate 31 gives a rotational torque to the rotor 22. Every time the rotor 22 turns a ⅕ round, high temperature high pressure steam is supplied to a newly adjacent expansion chamber 43 to drive the rotor 22 for continuous rotation.

[0061] While the piston 42 having reached the bottom dead center along with the rotation of the rotor 22 is pressed by the swash plate 31 to recede toward the top dead center, low temperature low pressure steam thrust out of the expansion chamber 43 is discharged, via the fourth steam passage P4 of the rotor 22, the third steam passage P3 of the moving valve plate 74, the sliding faces 77, the arcuate fifth steam passage P5 of the stationary valve plate 73 and the sixth and seventh steam passages P6 and P7 of the valve body 72, into the steam discharge chamber 88, and supplied therefrom to a condenser.

[0062] When the oil pump 49 provided on the output shaft 32 is actuated along with the rotation of the rotor 22, oil sucked from the oil pan 21 via the oil pipe 52, the oil passage 95b of the pump body 95 and the intake port 53 is discharged from the discharge port 54, and is supplied via the oil passage 95c of the pump body 95, the oil passage 32a of the output shaft 32, the annular groove 32b of the output shaft 32, the oil holes 32c . . . of the output shaft 32, the annual groove 41b of the cylinder sleeves 41 and the oil holes 41c . . . of the cylinder sleeves 41 to a space between the smaller diameter part 62b formed in the middle portion 62 of the piston 42 and the cylinder sleeves 41. Part of the oil held in the smaller diameter part 62b flows through the spiral oil grooves 62d . . . formed in the middle portion 62 of the piston 42 to lubricate the sliding face in contact with the cylinder sleeve 41, and another part of the oil lubricates the sliding faces of the compression rings 66 and the oil rings 67 provided on the top portions 63 of the piston 42 and of the cylinder sleeve 41.

[0063] It is inevitable for water generated by the condensation of part of the supplied high temperature high pressure steam to infiltrate from the expansion chambers 43 onto the sliding faces of the cylinder sleeves 41 and the pistons 42 to be mixed with oil. Therefore, the conditions of lubrication of the sliding faces are poor, but a sufficient oil film can be maintained to secure the required lubricating performance by supplying the required quantity of oil from the oil pump 49 through the inside of the output shaft 32 directly to the sliding faces of the cylinder sleeves 41 and the pistons 42. The size of the oil pump 49 can be therefore reduced.

[0064] The oil scraped off the sliding faces of the cylinder sleeves 41 and the pistons 42 by the oil ring 67 flows from the oil holes 63c . . . formed in the bottom of the oil ring groove 63b to the hollow spaces 62a within the pistons 42. The hollow spaces 62a communicate with the inside of the cylinder sleeves 41 via the plurality of oil holes 62c . . . penetrating the middle portion 62 of each piston 42, and the inside of the cylinder sleeves 41 communicates via the plurality of oil holes 41c . . . with the annual groove 41b in the outer circumferences of the cylinder sleeves 41. Although the circumference of the annual groove 41b is covered by the sleeve supporting flange 34 in the middle of the rotor 22, oil within the hollow spaces 62a in the pistons 42 is urged outward in the radial direction by a centrifugal force, and discharged into the space 68 within the thermally insulating cover 40 through the oil holes 34b in the sleeve supporting flange 34, because the oil holes 34b are formed in the sleeve supporting flange 34, and the oil is then returned therefrom to the oil pan 21 through the oil holes 40a . . . in the thermally insulating cover 40. Since the oil holes 34b are in positions deviating farther than the outer end of the sleeve supporting flange 34 in the radial direction toward the axis L, the oil positioned outward from the oil holes 34b in the radial direction is held by a centrifugal force in the hollow spaces 62a of the pistons 42.

[0065] As described above, the oil held in the hollow spaces 62a within the pistons 42 and the oil held in the smaller diameter part 62b on the outer circumference of the pistons 42 are supplied from the smaller diameter part 62b toward the top portion 63 in the expansion stroke in which the capacities of the expansion chambers 43 increase, and they are supplied from the smaller diameter part 62b toward the end portion 61 in the compression stroke in which the capacities of the expansion chambers 43 decrease, thereby reliably lubricating the whole area of the pistons 42 in the axial direction. Moreover, the flow of oil within the hollow space 62a of the pistons 42 enables the heat of the top portion 63 exposed to high temperature high pressure steam to be transmitted to the low temperature end portion 61, thereby avoiding a local temperature rise in the pistons 42.

[0066] When high temperature high pressure steam is supplied from the fourth steam passages P4 to the expansion chambers 43, the thermally insulating space 65 is formed between the top portion 63 and the middle portion 62 of each piston 42 facing the expansion chambers 43, and the thermally insulating space 70 is also formed in the rotor head 38 facing the expansion chambers 43. Therefore, the escape of heat from the expansion chambers 43 to the pistons 42 and the rotor head 38 can be minimized to contribute to improvement in the performance of the expander E. Furthermore, as the large capacity hollow space 62a is formed within each piston 42, not only can the weight of the piston 42 be reduced but also can the thermal mass of the piston 42 be curtailed for a more effective suppression of the escape of heat from the expansion chambers 43.

[0067] As the metal gasket 36 is disposed between the rear sleeve supporting flange 35 and the rotor head 38 to seal the expansion chambers 43, the dead volume around the seals can be reduced as compared with a case in which the expansion chambers 43 are sealed by thick annular sealing members, thereby securing a large volume ratio (expansion ratio) for the expander E and enhancing the thermal efficiency to increase the output. Further, as the cylinder sleeves 41 are configured as separate members from the rotor 22, the material of the cylinder sleeves 41 can be selected in consideration of thermal conductivity, thermal resistance, strength, wear resistance and the like, without being restricted by the material of the rotor 22. Furthermore, only the worn or damaged cylinder sleeve 41 needs to be replaced, resulting in an improved economy.

[0068] Moreover, because the outer circumferential faces of the cylinder sleeves 41 are exposed through the two notches 57 and 58 formed in the outer circumferential face of the rotor 22 in the circumferential direction, not only can the weight of the rotor 22 be reduced but also can the thermal mass of the rotor 22 be curtailed to enhance thermal efficiency. Moreover, by causing the notches 57 and 58 to function as thermally insulating spaces, the escape of heat from the cylinder sleeves 41 can be suppressed. Furthermore, as the outer circumference of the rotor 22 is covered with the thermally insulating cover 40, the escape of heat from the cylinder sleeves 41 can be suppressed even more effectively.

[0069] As the rotary valve 71 supplies and discharges steam to and from the group of axial piston cylinders 56 via the flat sliding faces 77 between the stationary valve plate 73 and the moving valve plate 74, the leakage of steam can be effectively prevented, because the flat sliding faces 77 can be readily machined with high accuracy and permit easier control of clearances than cylindrical sliding faces do. Moreover, as preset loads are given to the valve body 72 by the plurality of preload springs 85 . . . to generate surface stresses on the sliding faces 77 of the stationary valve plate 73 and the moving valve plate 74, steam leaks from the sliding faces 77 can be suppressed even more effectively.

[0070] When bringing the stationary valve plate 73 and the moving valve plate 74 into close contact with each other on their sliding faces 77 while urging the valve body 72 with the preload springs 85 . . . , as the annular member 104 supporting the valve body 72 on the rear cover 18 has the pair of projections 104a and 104b provided at the opposite ends in the first radial direction X-X guided by the guide grooves 18c and 18c of the rear cover 18 to be slidable in the direction of the axis L, the uniform frictional resistance which the pair of projections 104a and 104b receive from the guide grooves 18c and 18c of the rear cover 18 prevents the annular member 104 from inclining.

[0071] Even if the pair of projections 104a and 104b receive uneven friction from the guide grooves 18c and 18c and are inclined, as the valve body 72 is pivotably supported on the annular member 104 via the fulcrum shaft 103 arranged in the second radial direction Y-Y, the inclination of the valve body 72 is reliably prevented. The compliance of the sliding faces 77 of the stationary valve plate 73 and the moving valve plate 74 can be secured thereby to prevent high temperature high pressure steam from leaking and to restrain uneven wear of the sliding faces 77.

[0072] Furthermore, as the operation of the Oldham's coupling constructed of the annular member 104 and the fulcrum shaft 103 enables the annular member 104 to freely move relative to the rear cover 18 in the first radial direction X-X and enables the valve body 72 to move relative to the annular member 104 in the second radial direction Y-Y, the valve body 72 can freely move relative to the rear cover 18 within the plane orthogonal to the axis L. Therefore even if the valve body 72 becomes inclined off the axis L, the free movement of the valve body 72 within the plane orthogonal to the axis L prevents wrenching from occurring between the valve body 72 and the rear cover 18, thereby further enhancing the compliance of the sliding faces 77.

[0073] Further, as the valve body 72 of the rotary valve 71 is made of stainless steel providing a larger thermal expansion amount, and the stationary valve plate 73 fixed to the valve body 72 is made of carbon or ceramic providing a smaller thermal expansion amount, there is a possibility that the centering between them is displaced due to the difference in thermal expansion. However, as the fixed ring 79 is fixed to the valve body 72 with the plurality of bolts 80 . . . in a state in which the stepped portion 79a on the inner circumference of the fixed ring 79 is pressed in and spigot-fitted onto the outer circumference of the stationary valve plate 73 and the stepped portion 79b on the outer circumference of the fixed ring 79 is spigot-fitted onto the outer circumference of the valve body 72, it is possible to precisely center the stationary valve plate 73 relative to the valve body 72 by virtue of the aligning effect of spigot fitting, thereby preventing the expander E from deteriorating in performance by keeping the supply and discharge of steam in time. Moreover, the contact faces of the stationary valve plate 73 and the valve body 72 can be uniformly brought into close contact with each other with the fastening force of the bolts 80 . . . , thereby suppressing steam leakage from those contact faces.

[0074] Furthermore, since the rotary valve 71 can be attached to or detached from the casing body 12 by merely removing the rear cover 18 from the casing body 12, maintenance including repairs, cleaning and replacement can be significantly facilitated. Also, though the rotary valve 71 through which high temperature high pressure steam passes is increased in temperature, oil can be prevented from being heated by the high temperature of the rotary valve 71 to deteriorate the lubricating performance of the swash plate 31 and the output shaft 32 because the swash plate 31 and the output shaft 32 which require lubrication with oil are arranged on the other side of the rotor 22 than the rotary valve 71. The oil also performs the function to prevent overheating by cooling the rotary valve 71.

[0075] When assembling the expander E, it is necessary to adjust the magnitude of the dead volume between the bottom of the cylinder sleeves 41 (i.e., the lid member 69 supported by the rotor head 38) and the top of the pistons 42, namely the capacities of the expansion chambers 43 when the pistons 42 are at the top dead center. If the shim 97 intervening between the flange 32d of the output shaft 32 and the inner races of the combined angular bearings 23f and 23r is thinned, the output shaft 32 will move forward (rightward in FIG. 1), resulting in a rightward shift of the rotor head 38 as well, but the dead volume will decrease because the pistons 42 are restricted by the swash plate 31 to be unable to move forward. Conversely, if the shim 97 is thickened, the rotor head 38 will move backward (leftward in FIG. 1) together with the output shaft 32, and accordingly the dead volume will increase. As a result, it is possible to adjust the dead volume as desired by merely replacing the shim 97, and the step otherwise needed for dead volume adjustment can be eliminated to achieve a substantial time saving.

[0076] Further, as a single shim 97 having a predetermined thickness is sandwiched between the flange 32d of the output shaft 32 and the combined angular bearings 23f and 23r, to adjust the dead volume only by fastening with a single nut 98 the front cover 15 incorporating the angular bearing 30 supporting the swash plate 31 and the combined angular bearings 23f and 23r supporting the rotor 22 and the rotor 22 incorporating the pistons 42 . . . , the adjustment procedure is simplified as compared with the conventional adjustment procedure in which the thicknesses of two shims, front and rear, are individually adjusted. Moreover, since the rotor 22 incorporating the pistons 42 . . . can be kept assembled into the casing body 12 when adjusting the dead volume, the adjusted dead volume can be confirmed while directly watching the state of contact between the pistons 42 . . . and the swash plate 31.

[0077] When the position of the output shaft 32 relative to the combined angular bearings 23f and 23r is adjusted back and forth by varying the thickness of the shim 97, the position of the rotor head 38 at the rear end of the rotor 22 also shifts back and forth, but there is no problem in adjusting the position of the output shaft 32 because the rotor head 38 is slidable in the direction of the axis L relative to the inner race of the radial bearing 24 disposed between it and the casing body 12.

[0078] Then, when the pressure of high temperature high pressure steam supplied to the expansion chambers 43 urges the pistons 42 in the direction of being thrust out of the cylinder sleeves 41, the pressing force of the pistons 42 presses forward (rightward in FIG. 1) the outer race of the combined angular bearings 23f and 23r via the swash plate 31, the angular bearing 30, the swash plate holder 28 and the front cover 15, and the pressing force of the cylinder sleeves 41 reverse in direction to the suppressing force of the pistons 42 presses backward (leftward in FIG. 1) the inner race of the combined angular bearings 23f and 23r via the rotor head 38 and the output shaft 32. Thus, the load generated by the high temperature high pressure steam supplied to the expansion chambers 43 is cancelled within the combined angular bearings 23f and 23r, without being transmitted to the casing body 12.

[0079] While the rotor 22 constructed of the output shaft 32, the three sleeve supporting flanges 33, 34 and 35, the rotor head 38 and the thermally insulating cover 40 is made of a ferrous material whose thermal expansion is relatively small, the casing 11 which supports the rotor 22 via the combined angular bearings 23f and 23r and the radial bearing 24 is made of an aluminum-based material whose thermal expansion is relatively large. As a consequence, there arises a difference in the quantity of thermal expansion in the direction along the axis L between the high and low temperatures of the expander E.

[0080] The casing 11 which is greater in thermal expansion than the rotor 22 expands more than the rotor 22 and its size in relatively increases in the direction of the axis L when the temperature is high. Conversely, when the temperature is low, it contracts more and its size relatively decreases in the direction of the axis L. As the casing 11 and the rotor 22 are positioned in the direction of the axis L via the combined angular bearings 23f and 23r, the difference in thermal expansion between them is absorbed by the sliding contact of the rotor head 38 with the inner race of the radial bearing 24, so that an excessive load is prevented from acting in the direction of the axis L on the combined angular bearings 23f and 23r, the radial bearing 24 and the rotor 22. This not only contributes to an increase in the durability of the combined angular bearings 23f and 23r and of the radial bearing 24, but also to stabilization in support of the rotor 22, thereby facilitating its smooth rotation. Moreover, it is possible to prevent the fluctuation in dead volume between the top of the cylinder sleeves 41 and the top of the pistons 42 accompanying the change in temperature.

[0081] The reason is that, supposing that both ends of the rotor 22 are restrained by the casing 11 to be immovable in the axial direction, as the casing 11 tends to contract in the direction of the axis L relative to the rotor 22 when the temperature is low, the pistons 42 whose top is in contact with the swash plate 31 supported by the swash plate holder 28 which is part of the casing 11, are pressed backward, and the rotor head 38 supported by the casing 11 via the radial bearing 24 is pressed forward, so that the pistons 42 are pressed into the cylinder sleeves 41 and the dead volume decreases accordingly. Conversely, when the temperature is high, as the casing 11 tends to extend in the direction of the axis L relative to the rotor 22, the pistons 42 are drawn out from the inside of the cylinder sleeves 41, resulting in an increase in dead volume, which in turn invites an increase in the initial volume of high temperature high pressure steam in the normal operating state after the warming-up, i.e. a drop in thermal efficiency due to a decrease in the volume ratio (expansion ratio) of the expander E.

[0082] By contrast, in this embodiment of the invention, as the rotor 22 is supported in a floating state in the direction of the axis L relative to the casing 11, the gaps between the combined angular bearings 23f and 23r and the radial bearing 24 are prevented from widening and so are the preloads from decreasing, and the dead volume is prevent from fluctuating due to temperature change. This enables the volume ratio (expansion ratio) of the expander E to be prevented from fluctuating, thereby achieving a stable performance.

[0083] Especially, for the expander E which uses high temperature high pressure steam as the working medium, the above-described advantage is highly effective because the difference is wide between high temperature and low temperature. Furthermore, although the difference between high temperature and low temperature is particularly wide in the vicinity of the rotary valve 71 to which high temperature high pressure steam is supplied, the difference in thermal expansion between the casing 11 and the rotor 22 can be absorbed without problem because the rotor head 38 can be in sliding contact in the direction of the axis L with the radial bearing 24 arranged closer to the rotary valve 71.

[0084] Further, out of the stationary valve plate 73 and the moving valve plate 74 of the rotary valve 71, as the stationary valve plate 73 supported by the casing 11 is urged by the springing force of the preload springs 85 . . . toward the moving valve plate 74 supported by the rotor 22, the sealing performance of the sliding faces 77 of the stationary valve plate 73 and the moving valve plate 74 will not be affected even if the positional relationship between the casing 11 and the rotor 22 in the direction of the axis L varies along with temperature variations. Not only that, an excessive load is prevented from acting on the combined angular bearings 23f and 23r and the radial bearing 24, resulting in stabilization of the rotational plane of the rotor 22 and accordingly in an improvement in the sealing performance of the sliding faces 77, to reduce the quantity of leaked steam.

[0085] Next will be described a second embodiment of the present invention with reference to FIG. 17.

[0086] In the above-described first embodiment, in order to cause the annular member 104 to be fitted onto the outer circumference of the valve body 72, part of the valve body 72 is separated as the cap member 102 and, after the annular member 104 is fitted onto the outer circumference of the valve body 72, the cap member 102 is coupled to the valve body 72.

[0087] The second embodiment is designed to configure the valve body 72 and the cap member 102 as a single member, by bisecting the annular member 104 at the center of the projections 104a and 104b for assembly. The bisected projections 104a are engaged integrally by a pin 105 penetrating the pin holes 104d and 104d, and the bisected projections 104b are engaged integrally by a pin 106 penetrating the pinholes 104e and 104e. As the projections 104a and 104b engage with the guide grooves 18c and 18c of the rear cover 18, the pins 105 and 106 cannot come off the pin holes 104d, 104d and 104e, 104e.

[0088] The second embodiment can also achieve operations and effects similar to that achieved by the first embodiment.

[0089] Although the preferred embodiments of the present invention has been described above, the invention may be modified in various ways without deviating from the subject matter.

[0090] For example, the rotating fluid machine according to the invention is not limited to the application to the expander E, and is also applicable to a compressor, a hydraulic pump, a hydraulic motor and the like.

[0091] Although the expander E in the embodiments is provided with the group of axial piston cylinders 56 as the working section, the structure of the working section is not limited thereto.

Claims

1. A rotating fluid machine comprising:

a casing;

a rotor rotatably supported by the casing;

a working section disposed on the rotor; and

a rotary valve, provided between the casing and the rotor, for controlling the supply and discharge of a working medium to and from the working section,

the rotary valve being constructed by bringing, into contact on sliding faces which are orthogonal to an axis of the rotor, a moving valve plate provided on the rotor and a stationary valve plate provided on a valve body engaged with the casing to be unable to rotate and movable in the direction of the axis,

wherein two projections are provided in a first radial direction at two ends of an annular member loosely fitted onto the outer circumference of the valve body, and engaged slidably in the direction of the axis with guide grooves formed in the casing, and

wherein the valve body is pivotably supported on the annular member via a fulcrum shaft arranged in a second radial direction orthogonal to the first radial direction.

2. The rotating fluid machine according to claim 1, wherein the two projections of the annular member can slide with respect to the guide grooves of the casing in the first radial direction, and the valve body can slide along the fulcrum shaft in the second radial direction.