Shaft seal structure for fluid machinery

Abstract

To improve the sealing performance of a mechanical seal. [Solution] The shaft seal section 30 comprises a housing 31 having a partition wall 35 with an opening 35A through which the rotating shaft 10 is inserted, and a mechanical seal 33 including a rotating ring 33A fixed to the rotating shaft 10, and a fixed ring 33B fixed to the partition wall 35 and through which the rotating shaft 10 is inserted, the rotating shaft 10 having a fixed ring arrangement portion 11 arranged inside the fixed ring 33B, and an opening arrangement portion 12 arranged inside the opening 35A and having a smaller diameter than the fixed ring arrangement portion 11, the inner diameter D12 of the opening 35A being smaller than the outer diameter D1 of the fixed ring arrangement portion 11, and the peripheral portion of the opening 35A facing a step portion 13 between the fixed ring arrangement portion 11 and the opening arrangement portion 12 in the axial direction.

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a shaft seal structure for a fluid machine. [Background technology]

[0002] Fluid machinery such as pumps may be provided with a shaft sealing structure using a mechanical seal to prevent fluid from leaking through a rotating shaft. Patent Document 1 discloses an example of a mechanical seal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-87251 Summary of the Invention [Problem to be solved by the invention]

[0004] Mechanical seals limit fluid leakage to an acceptable level through mechanical contact between the stationary ring and rotating ring that make up the seal portion. In mechanical seals, fluid leaks through the path between the stationary ring and rotating shaft and through the seal portion. To limit fluid leakage, it is desirable to improve the sealing performance of mechanical seals.

[0005] The technology disclosed in this specification aims to improve the sealing performance of a mechanical seal. [Means for solving the problem]

[0006] This specification discloses a shaft seal structure for a fluid machine. The shaft seal structure for a fluid machine has a rotating shaft, and includes a housing having a partition wall with an opening through which the rotating shaft is inserted, a mechanical seal including a rotating ring fixed to the rotating shaft, and a stationary ring fixed to the partition wall and through which the rotating shaft is inserted, the rotating shaft having a stationary ring arrangement portion disposed inside the stationary ring and an opening arrangement portion disposed inside the opening and having a smaller diameter than the stationary ring arrangement portion, the inner diameter of the opening being smaller than the outer diameter of the stationary ring arrangement portion, and a peripheral edge of the opening facing a step portion between the stationary ring arrangement portion and the opening arrangement portion in the axial direction. [Effects of the Invention]

[0007] According to the technology disclosed in this specification, the sealing performance of the mechanical seal is improved. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a vane pump according to an embodiment. [Figure 2] FIG. 2 is an exploded perspective view showing the main structure of the vane pump according to the embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing a vane pump according to the embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view showing the inside of the pump chamber. [Figure 5] FIG. 5 is an enlarged cross-sectional view of the shaft seal portion according to the embodiment. [Figure 6] FIG. 6 is an enlarged cross-sectional view of the vicinity of the opening of the partition wall of the shaft seal unit according to the embodiment. [Figure 7] FIG. 7 is an enlarged cross-sectional view showing the partition wall and the guide ring according to the embodiment. [Figure 8] FIG. 8 is an enlarged cross-sectional view showing the vicinity of the rotary ring according to the embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing a first stage of the assembly procedure for the vane pump according to the embodiment. [Figure 10]FIG. 10 is a cross-sectional view showing a second stage of the assembly procedure for the vane pump according to the embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing a third stage of the assembly procedure for the vane pump according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the drawings. In the embodiments, a three-dimensional Cartesian coordinate system is set, and the positional relationship of each part will be described with reference to the three-dimensional Cartesian coordinate system. The direction parallel to the X axis in a horizontal plane is defined as the X-axis direction. The direction parallel to the Y axis, which is orthogonal to the X axis in a horizontal plane, is defined as the Y-axis direction. The direction parallel to the Z axis, which is orthogonal to both the X axis and the Y axis, is defined as the Z-axis direction. The +Z side (+Z direction) is the upper side (upper), and the -Z side (-Z direction) is the lower side (lower).

[0010] The fluid machine to which the shaft seal structure according to the embodiment is applied is not particularly limited as long as it has a rotating shaft and a structure in which a fluid may leak through the rotating shaft. The fluid handled by the fluid machine is a liquid. The fluid is not particularly limited as long as it is a liquid. The fluid machine may be, for example, a pump, an agitator, a water turbine, or the like. In the embodiment, a pump is shown as an example of the fluid machine. The type of pump is not particularly limited, and it may be a positive displacement pump or a non-positive displacement pump. The pump may be, for example, a rotary pump. In the embodiment, a vane pump 1 is shown as an example of a pump. The vane pump 1 according to the embodiment has a structure suitable for applications requiring particularly high hygiene, such as liquid food or chemicals. Below, an example in which the shaft seal structure according to the embodiment is applied to a shaft seal portion 30 of the vane pump 1 will be described. The shaft seal portion 30 is an example of the shaft seal structure according to the embodiment.

[0011] FIG. 1 is a perspective view showing a vane pump according to an embodiment. FIG. 2 is an exploded perspective view showing the main structure of the vane pump according to an embodiment. FIG. 3 is a cross-sectional view showing the vane pump according to an embodiment. FIG. 4 is a schematic cross-sectional view showing the inside of a pump chamber. FIGS. 1 and 2 are a perspective view and an exploded perspective view, respectively, of the vane pump 1 as viewed from the +Y direction. FIG. 3 is a cross-sectional view of a cross section along the rotary shaft 10 of the vane pump 1 as viewed from the -X side. FIG. 4 is a view of an XZ cross section of a pump chamber 41A of the vane pump 1 as viewed from the +Y side.

[0012] 1 to 4, the vane pump 1 is broadly composed of a rotating shaft 10, a bearing unit 20, a shaft seal unit 30, and a pump unit 40. The bearing unit 20, the shaft seal unit 30, and the pump unit 40 are arranged in this order from the -Y side to the +Y side. The rotating shaft 10 extends along the Y-axis direction and is inserted so as to straddle the interiors of the bearing unit 20, the shaft seal unit 30, and the pump unit 40.

[0013] The rotating shaft 10 is connected at its +Y side end to the rotor 42 of the pump unit 40. The -Y side end of the rotating shaft 10 protrudes outside from the bearing unit 20 and is connected to a drive unit (not shown) such as a motor. The rotating shaft 10 rotates around a central axis extending in the Y-axis direction. In the embodiment, the direction parallel to the central axis of the rotating shaft 10 (i.e., the Y direction) will be referred to as the axial direction as appropriate, the direction circumferential around the central axis of the rotating shaft 10 will be referred to as the circumferential direction or rotational direction as appropriate, and the radial direction of the central axis of the rotating shaft 10 will be referred to as the radial direction as appropriate.

[0014] The bearing unit 20 rotatably supports the rotating shaft 10. The bearing unit 20 has a plurality of bearings 22 that support the rotating shaft 10 inside a cylindrical bearing case 21. In the embodiment, three bearings 22 are provided, but the number of bearings 22 is not particularly limited. An oil seal 23A that seals between the rotating shaft 10 and the inner periphery of the opening is provided at the opening on the +Y side of the bearing case 21. A pressing plate 24 having an insertion hole for the rotating shaft 10 is attached to the -Y side of the bearing case 21 with bolts 25. An oil seal 23B is arranged between the insertion hole of the pressing plate 24 and the rotating shaft 10.

[0015] The shaft seal portion 30 (shaft seal structure) is disposed between the bearing portion 20 and the pump portion 40, and is connected to both the bearing portion 20 and the pump portion 40. The shaft seal portion 30 prevents fluid from leaking from the pump portion 40 through the rotating shaft 10 toward the bearing portion 20.

[0016] Shaft seal unit 30 includes housing 31, water-shedding member 32, and mechanical seal 33. Housing 31 has a cylindrical shape, and its +Y side end is connected to pump unit 40 by connecting bolt 51, and its -Y side is connected to bearing unit 20 by bolt 34A and nut 34B. Housing 31 functions as a housing member for mechanical seal 33 and also as a connector for connecting bearing unit 20 and pump unit 40. Housing 31 houses water-shedding member 32 and mechanical seal 33 inside. The -Y side end of housing 31 is open and is closed by bearing case 21. A partition wall 35 is provided at the +Y side end of housing 31, with opening 35A formed therein, through which rotating shaft 10 is inserted. Partition wall 35 separates shaft seal unit 30 from pump unit 40. In the embodiment, the partition wall 35 is integrally formed with the housing 31 and constitutes a part of the housing 31. The partition wall 35 may be provided separately (as a separate body) from the housing 31 and attached to the +Y side end face of the housing 31.

[0017] The water-splashing member 32 is disposed near the opening on the -Y side of the housing 31, and is fixedly attached to the rotating shaft 10. The water-splashing member 32 is provided on the -Y side (the bearing 20 side) of the mechanical seal 33. The water-splashing member 32 is provided on the +Y side of the oil seal 23A. The water-splashing member 32 rotates integrally with the rotating shaft 10. When the water-splashing member 32 comes into contact with a fluid (liquid), it blows the fluid away by centrifugal force, preventing the fluid from reaching the bearing 20. The blown-away fluid collides with the inner peripheral surface of the housing 31. Through holes 31A for discharging the fluid are formed in multiple locations on the peripheral wall of the housing 31.

[0018] The mechanical seal 33 is disposed near the opening (opening 35A) on the +Y side of the housing 31. The mechanical seal 33 is provided between the drain member 32 and the pump section 40. The mechanical seal 33 is cylindrical (annular), and the rotating shaft 10 is inserted inside.

[0019] Figure 5 is an enlarged cross-sectional view of the shaft seal according to the embodiment. As shown in Figure 5, the mechanical seal 33 includes a rotary ring 33A fixed to the rotary shaft 10 and a stationary ring 33B fixed to the partition wall 35 (i.e., the housing 31) and through which the rotary shaft 10 is inserted. The rotary ring 33A rotates integrally with the rotary shaft 10. The rotary ring 33A and the stationary ring 33B have sliding surfaces made of cemented carbide or the like, and one is pressed toward the other by a biasing member 64, causing the sliding surfaces to rotate relative to each other. In this way, the mechanical seal 33 suppresses leakage of fluid that attempts to pass between the rotary ring 33A and the stationary ring 33B.

[0020] Specifically, the rotary ring 33A includes a retaining portion 61, a seal ring 62, a guide pin 63, a biasing member 64, and a packing 65. The retaining portion 61 is cylindrical and fixed to the rotary shaft 10 by a set screw 61A. The seal ring 62 is annular and is provided with a small gap between it and the rotary shaft 10, which passes through the inside of the retaining portion 61. The seal ring 62 is retained by the retaining portion 61 and biased toward the fixed ring 33B via the biasing member 64. That is, the seal ring 62 is connected to the retaining portion 61 via the guide pin 63 and is linearly movable in the Y-axis direction. The seal ring 62 is biased toward the +Y side (i.e., toward the fixed ring 33B) by the biasing member 64. The biasing member 64 is a compression coil spring, and multiple biasing members 64 are provided around the circumferential direction of the retaining portion 61 so as to uniformly press the seal ring 62. The +Y-side end face of the seal ring 62 forms a sliding surface that contacts the fixed ring 33B. The packing 65 is provided between the seal ring 62 and the holding portion 61 and on the inner peripheral surface of the seal ring 62. The packing 65 seals the gap between the seal ring 62 and the holding portion 61.

[0021] Fixed ring 33B is annular and is provided with a gap between it and rotating shaft 10, which passes through the inside. The +Y side end face of fixed ring 33B contacts partition wall 35, and the outer circumferential surface of fixed ring 33B contacts housing 31. The outer circumferential portion of the -Y side end face of fixed ring 33B is pressed by retaining ring 36B via washer 36A, thereby fixing fixed ring 33B to housing 31. Retaining ring 36B is attached to a fixing groove on the inner circumferential surface of housing 31. The inner circumferential portion of the -Y side end face of fixed ring 33B is a sliding surface that contacts rotating ring 33A (seal ring 62).

[0022] 1 and 3, the pump unit 40 is connected to the +Y side of the shaft seal unit 30. The pump unit 40 has an intake port FI and an outlet port FO, and takes in fluid through the intake port FI and delivers the fluid through the outlet port FO as the rotating shaft 10 rotates. The pump unit 40 includes a casing 41, a rotor 42, a plurality of vanes 43, and a guide ring 44.

[0023] The casing 41 has a hollow structure and defines an accommodation space for containing a fluid. The casing 41 accommodates a rotor 42, a plurality of vanes 43, and a guide ring 44, and has a pump chamber 41A for containing a fluid. The pump chamber 41A is open to the +Y side of the casing 41 and is closed by a cover 45. The cover 45 is fixed together with the casing 41 and the housing 31 by connecting bolts 51 (see FIG. 2) that pass through the casing 41 and nuts 52. O-rings 45A seal between the casing 41 and the cover 45, and between the casing 41 and the housing 31. The pump chamber 41A opens to the -Y side end face of the casing 41 and communicates with an opening 35A in the partition wall 35. The +Y side end of the rotating shaft 10, which passes through the opening 35A, is disposed inside the pump chamber 41A.

[0024] 4, pump chamber 41A is connected to intake port FI via intake passage 41B, and to discharge port FO via discharge passage 41C. Intake passage 41B and discharge passage 41C open to the outer peripheral surface of casing 41, and each is connected to a nozzle 46. The nozzle 46 constituting intake port FI is connected to a fluid supply source, and the nozzle 46 constituting discharge port FO is connected to a fluid destination.

[0025] The nozzle 46 has a cylindrical portion 46A and a flange portion 46B that protrudes outward from the end of the cylindrical portion 46A on the casing 41 side. The nozzle 46 is attached to the casing 41 by fastening the flange portion 46B to the casing 41 with bolts 53. Four bolts 53 (see FIG. 1 ) that surround the periphery of the cylindrical portion 46A are attached to the flange portion 46B. As a result, in this embodiment, the shape of the connection surface is simplified compared to when the nozzle 46 and the casing 41 are connected with a male-female threaded structure, for example, and the connection surface is easier to clean. Furthermore, because the nozzle 46 is fastened with the bolts 53, there is no need to use a tool on the nozzle 46, and the nozzle 46 is less likely to be scratched or stained. This achieves high hygiene.

[0026] The nozzle 46 also has an annular protrusion 46C that protrudes from the surface of the flange portion 46B facing the casing 41 toward the casing 41. The annular protrusion 46C is disposed on the outer peripheral surface of the casing 41, forming a connection recess 41D. The connection recess 41D is recessed relative to the mounting surface 41E that contacts the flange portion 46B. When the nozzle 46 is attached to the casing 41, the flange portion 46B and the mounting surface 41E are in surface contact, and the end face of the annular protrusion 46C abuts against the bottom surface of the connection recess 41D. The connection recess 41D is formed slightly larger than the annular protrusion 46C, and an O-ring 47 is provided between the inner peripheral surface of the connection recess 41D and the outer peripheral surface of the annular protrusion 46C. The O-ring 47 seals the gap between the casing 41 and the flange portion 46B around the annular protrusion 46C. A primary seal is formed between the annular protrusion 46C and the connection recess 41D, and a secondary seal is formed by the O-ring 47, which is located on the outer periphery of the annular protrusion 46C. Thus, by being provided on the outer periphery of the cylindrical annular protrusion 46C, the O-ring 47 is isolated from the fluid flow path. This prevents fluid from leaking to the location where the O-ring 47 is installed, and prevents fluid from accumulating at the location where the O-ring 47 is installed. Furthermore, because the O-ring 47 is located away from the fluid flow path, even if the O-ring 47 becomes wedged between the nozzle 46 and the casing 41, the risk of tiny fragments of the O-ring 47 being mixed into the discharged fluid is reduced. This achieves high hygiene and reduces the risk of foreign matter being mixed in.

[0027] As shown in FIGS. 2 and 3, the rotor 42 has a cylindrical shape extending along the Y-axis. The rotor 42 is fixed to the +Y-side end of the rotary shaft 10 by a bolt 48C via a rotor washer 48A and a spring washer 48B. The rotor 42 engages with the rotary shaft 10 by a parallel key 48D (see FIG. 2) that fits into keyways formed in the outer circumferential surface of the rotary shaft 10 and the inner circumferential surface of the rotor 42, and rotates integrally with the rotary shaft 10. As shown in FIG. 4, the rotor 42 has retaining grooves 42A that extend radially outward and open to the outer circumferential surface of the rotor 42. A plurality of retaining grooves 42A (six in FIG. 4) are formed at intervals around the circumferential direction of the rotor 42. Vanes 43 are disposed in these retaining grooves 42A. The vanes 43 have a flat plate shape. Six vanes 43 are provided, one in each retaining groove 42A of the rotor 42, and each is retained in the retaining groove 42A. The vanes 43 rotate (move in the circumferential direction) together with the rotor 42 as the rotor 42 rotates. For convenience, only one of the six vanes 43 is shown in FIG.

[0028] Accommodating recesses 42B recessed toward the center in the Y-axis direction are formed on the -Y side end face and the +Y side end face of rotor 42. One guide ring 44 is disposed in each of the -Y side accommodating recess 42B and the +Y side accommodating recess 42B.

[0029] The guide ring 44 has an annular shape with an inner diameter larger than the outer diameter of the rotary shaft 10 and smaller than the inner diameter of the installation recess 42B. The guide ring 44 is fixed to neither the rotor 42 nor the rotary shaft 10 inside the installation recess 42B. The guide ring 44 supports the radially inner end of each vane 43 on its outer circumferential surface. The guide ring 44 is arranged so that the radial distance between the outer circumferential surface of the guide ring 44 and the inner circumferential surface of the pump chamber 41A is the same size (outer diameter dimension) as the radial dimension of the vane 43. As a result, each vane 43 rotates in the circumferential direction with its inner circumferential end in contact with the guide ring 44 and its outer circumferential end in contact with the inner circumferential surface of the pump chamber 41A. The guide ring 44 is a guide that determines the radial position of each vane 43.

[0030] The inner circumferential surface 41F of the pump chamber 41A is circular in the XZ cross section. In the XZ cross section, the center position of the rotary shaft 10 is eccentric from the center position of the pump chamber 41A. Therefore, the distance between the outer circumferential surface of the rotor 42 and the inner circumferential surface 41F of the pump chamber 41A varies depending on the circumferential position. As a result, the volume of a space SP defined by two circumferentially adjacent vanes 43, the inner circumferential surface 41F of the pump chamber 41A, and the outer circumferential surface of the rotor 42 changes with the rotation of the rotor 42 and the vanes 43. The vane pump 1 accommodates and confines the fluid in the space SP between the vanes 43 by expanding the volume of the space SP near the connection position with the suction flow path 41B as the rotor 42 and the vanes 43 rotate. The vane pump 1 compresses the volume of the space SP near the connection position with the discharge flow path 41C, thereby expelling the fluid accommodated in the space SP into the discharge flow path 41C. As a result, the vane pump 1 utilizes the rotational driving force input to the rotary shaft 10 to take in fluid from the suction port FI and deliver it from the discharge port FO.

[0031] Next, the shaft seal structure according to the embodiment, i.e., the structure of the shaft seal portion 30, will be described in detail. Fig. 6 is an enlarged cross-sectional view of the vicinity of the opening of the partition wall of the shaft seal portion according to the embodiment. Fig. 7 is an enlarged cross-sectional view showing the partition wall and guide ring according to the embodiment.

[0032] (Restriction of fluid inflow) As shown in FIGS. 5 and 6, the shaft seal 30 according to this embodiment has a structure that prevents fluid from flowing into a leakage path LP (see FIG. 6) formed by a gap between the housing 31, the mechanical seal 33, and the rotating shaft 10. Specifically, during operation of the vane pump 1, some of the fluid flows from the pump chamber 41A into the shaft seal 30 through the opening 35A in the partition wall 35. Specifically, the leakage path LP travels along the rotating shaft 10, passes inside the opening 35A and the inside of the stationary ring 33B, passes between the sliding surfaces of the stationary ring 33B and the seal ring 62, and leaks into the internal space of the housing 31 (the outer circumferential side of the rotating ring 33A). The shaft seal 30 according to this embodiment prevents leakage by forming a bent labyrinth-shaped leakage path LP and reducing the gap that defines the leakage path LP.

[0033] Specifically, the rotating shaft 10 has a fixed ring arrangement portion 11 that is arranged inside the fixed ring 33B, and an opening arrangement portion 12 that is arranged inside the opening 35A and has a smaller diameter than the fixed ring arrangement portion 11. The fixed ring arrangement portion 11 and the opening arrangement portion 12 have outer diameters D1 and D2, respectively. The outer diameter relationship between the outer diameters is outer diameter D1 > outer diameter D2. As a result, the rotating shaft 10 has a step portion 13 between the fixed ring arrangement portion 11 and the opening arrangement portion 12. The step portion 13 has an annular axial end face 13A (see FIG. 6) that faces the +Y side. The radial width of the axial end face 13A corresponds to the difference between the outer diameters D1 and D2.

[0034] An inner diameter D12 of the opening 35A of the partition wall 35 is larger than an outer diameter D2 of the opening arrangement portion 12 and smaller than an outer diameter D1 of the fixed ring arrangement portion 11. Therefore, the peripheral edge of the opening 35A (i.e., the -Y side surface of the partition wall 35) faces a step 13 between the fixed ring arrangement portion 11 and the opening arrangement portion 12 in the axial direction (Y axis direction) of the rotating shaft 10.

[0035] 6, the leakage path LP is a curved path that passes in order through a gap CL2 between the opening 35A and the opening arrangement portion 12, a gap CL3 in the axial direction between the peripheral edge of the opening 35A and the step portion 13, and a gap CL1 between the fixed ring 33B and the fixed ring arrangement portion 11. The curved leakage path LP has a higher flow path resistance than a simple path that extends in a straight line, and therefore, fluid leakage is suppressed.

[0036] In the embodiment, the dimensions of each component are set so that the gap CL1 between the fixed ring 33B and the fixed ring arrangement portion 11, the gap CL2 between the opening 35A and the opening arrangement portion 12, and the axial gap CL3 between the peripheral edge of the opening 35A and the step portion 13, which constitute the leakage path LP, are all very small.

[0037] 5, the inner diameter D11 of the stationary ring 33B is larger than and substantially equal to the outer diameter D1 of the stationary ring arrangement portion 11. The inner diameter D12 of the opening 35A is larger than and substantially equal to the outer diameter D2 of the opening portion 12. This effectively increases the flow path resistance of the leakage path LP. The inner diameter D11 is, for example, preferably greater than 102% and not greater than 120% of the outer diameter D1, more preferably not greater than 115%, and even more preferably not greater than 110%. The inner diameter D12 is, for example, preferably greater than 102% and not greater than 125%, more preferably not greater than 120%, and even more preferably not greater than 115% of the outer diameter D2. By setting the inner diameter D11 of the stationary ring 33B and the inner diameter D12 of the opening 35A within these ranges, the flow path resistance of the leakage path LP can be increased even more effectively.

[0038] As shown in FIG. 6 , in this embodiment, the gap CL1 between the fixed ring 33B and the fixed ring arrangement portion 11 and the gap CL2 between the opening 35A and the opening arrangement portion 12 are smaller than the height Hw of the step portion 13. The height of the step portion 13 is the radial width of the step portion 13, which is the difference between the radius (D1 / 2) of the fixed ring arrangement portion 11 and the radius (D2 / 2) of the opening arrangement portion 12. Furthermore, the axial gap CL3 between the peripheral edge of the opening 35A and the step portion 13 is smaller than the height Hw of the step portion 13. As described above, in this embodiment, the sizes of the gaps CL1, CL2, and CL3 are uniformed so that they are approximately equal (smaller than the height Hw). The sizes of the gaps CL1, CL2, and CL3 are, for example, 2 mm or less, preferably 1.5 mm or less, and more preferably 1.2 mm or less. In one example, the sizes of the gaps CL1, CL2, and CL3 are approximately 1 mm.

[0039] Furthermore, some of the fluid that enters the leakage path LP flows inside the seal ring 62 and reaches the position of the packing 65. There is a possibility that the fluid may accumulate between the opening 35A of the partition wall 35, the inner circumferential surfaces of the stationary ring 33B and the seal ring 62 and the outer circumferential surface of the rotating shaft 10, and in the area on the +Y side of the packing 65. By making the gaps CL1, CL2, and CL3 small, the amount of fluid that accumulates inside the mechanical seal 33 is reduced. This allows the vane pump 1 to achieve high hygiene.

[0040] As shown in FIG. 7 , the inner diameter D12 of the opening 35A is smaller than the inner diameter Dr of the guide ring 44. This effectively reduces the gap CL2. Furthermore, because the inner diameter D12 of the opening 35A is smaller than the inner diameter Dr, the peripheral edge of the opening 35A (partition wall 35) is located radially inward of the inner circumferential surface of the installation recess 42B of the rotor 42. Therefore, the peripheral edge of the opening 35A faces the axial end face (-Y side end face) of the guide ring 44 in the Y-axis direction along the entire circumference of the guide ring 44. This allows the partition wall 35 constituting the peripheral edge of the opening 35A to function as a restrictor that restricts tilt and axial movement of the guide ring 44 relative to the rotary shaft 10. As described above, the guide ring 44 is not fixed to either the rotor 42 or the rotary shaft 10 inside the installation recess 42B of the rotor 42. For this reason, even when guide ring 44 is in contact with each vane 43, there is a possibility that guide ring 44 may tilt or move toward shaft seal portion 30, but partition wall 35 comes into contact with the axial end face of guide ring 44, thereby preventing tilt or displacement of guide ring 44. Note that cover 45 can prevent tilt or displacement of the guide ring 44 on the +Y side of the two guide rings 44.

[0041] (Mechanical seal positioning) FIG. 8 is an enlarged cross-sectional view showing the vicinity of the rotating ring according to the embodiment. As described above, in the mechanical seal 33, the biasing force of the biasing member 64 causes the sliding surfaces of the stationary ring 33B and the rotating ring 33A to contact each other appropriately, thereby blocking the leakage path LP. In this embodiment, as shown in FIG. 8, the magnitude of the biasing force of the biasing member 64 is determined by the amount of precompression of the biasing member 64, i.e., the distance L in the Y-axis direction from the stationary ring 33B to the retaining portion 61. Because the stationary ring 33B is fixed to the housing 31, the magnitude of the distance L varies depending on the mounting position (Y-axis position) of the retaining portion 61 relative to the rotating shaft 10. Note that the Y-axis position of the retaining portion 61 may be based on any part of the retaining portion 61, but here, the position of the -Y-side end face of the retaining portion 61 is used as the reference. If the retaining portion 61 is too far from the stationary ring 33B and the distance L is greater than the allowable range, the biasing force is insufficient, resulting in a deterioration in the sealing performance of the leakage path LP. In other words, fluid leakage is more likely to occur. If the retaining portion 61 is too close to the fixed ring 33B and the distance L is smaller than the allowable range, the biasing force becomes excessive, accelerating wear of the sliding surfaces (deterioration of sealing performance over time). To prevent fluid leakage, it is important to properly determine the axial position of the rotating ring 33A (retaining portion 61).

[0042] Therefore, in the embodiment, the rotating ring 33A (holding portion 61) is positioned by a water draining member 32 provided separately from the rotating ring 33A. That is, the water draining member 32 comes into axial contact with the step portion 17 formed on the rotating shaft 10, and also comes into contact with the axial end face of the rotating ring 33A, thereby determining the axial position of the rotating ring 33A.

[0043] As shown in Figure 8, the rotating shaft 10 has a step 17 adjacent to the -Y side of the arrangement position of the water-draining member 32. The step 17 determines the attachment position of the water-draining member 32 by bringing the -Y side surface of the water-draining member 32 into contact with the axial end face of the step 17 facing the +Y side. The axial end face of the step 17 also serves as an axial support surface that prevents the water-draining member 32 from shifting out of position to the -Y side.

[0044] Specifically, the rotating shaft 10 has a drip-water arrangement portion 14 disposed inside the drip-water member 32, an adjacent portion 15 adjacent to the -Y side of the drip-water arrangement portion 14 and having a larger diameter than the drip-water arrangement portion 14, and a rotating ring arrangement portion 16 adjacent to the +Y side of the drip-water arrangement portion 14. The adjacent portion 15 is where the oil seal 23A is disposed, but it may also be where a component other than the oil seal 23A is disposed. As shown in FIG. 5 , the drip-water arrangement portion 14, the rotating ring arrangement portion 16, and the fixed ring arrangement portion 11 all have the same outer diameter, D1. The adjacent portion 15 has an outer diameter D3. The outer diameter relationship between the outer diameters is outer diameter D3 > outer diameter D1. As a result, the rotating shaft 10 has a step portion 17 between the drip-water arrangement portion 14 and the adjacent portion 15. The step portion 17 has an annular axial end face facing the +Y side and contacts the drip-water member 32.

[0045] As shown in Figure 8, the water-removing member 32 has a hole 32A through which the rotating shaft 10 is inserted, and has a flat plate shape (annular flat plate shape) with a constant thickness t. The hole 32A of the water-removing member 32 fits onto the outer periphery of the rotating ring arrangement portion 16. The -Y side surface of the water-removing member 32 contacts the axial end face of the stepped portion 17, and the +Y side surface contacts the fixed ring 33B, so that the water-removing member 32 is sandwiched between the stepped portion 17 and the fixed ring 33B. As a result, the water-removing member 32 is fixed to the rotating shaft 10 and rotates integrally with the rotating shaft 10.

[0046] The axial end face (i.e., the -Y side end face) of the retaining portion 61 comes into contact with the water-removing member 32. The water-removing member 32 positions the retaining portion 61 at a position offset from the step portion 17 toward the +Y side by the thickness t. Therefore, the distance L from the fixed ring 33B to the retaining portion 61 is determined depending on the thickness t of the water-removing member 32. The thickness t of the water-removing member 32 is set to achieve the distance L when the pre-compression amount of the biasing member 64 is an appropriate value. In other words, when the Y-axis distance from the sliding surface of the fixed ring 33B to the step portion 17 is L0, the thickness t is set to satisfy the relationship t = L0 - L (here, L is the distance when the pre-compression amount is an appropriate value).

[0047] The draining member 32 is formed, for example, from a resin material. In this embodiment, the draining member 32 is formed from a self-lubricating resin. Examples of self-lubricating resins include polyacetal (POM), polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polyether ether ketone (PEEK), polybutylene terephthalate (PBT), polyamide (PA), polypropylene (PP), and polyphenylene sulfide (PPS). The draining member 32 is formed from a self-lubricating resin, for example, polyacetal (POM). Self-lubricating resins are suitable for machining, and can be precisely finished to the desired dimensions by cutting a resin rod manufactured by extrusion molding, compression molding, or the like. Furthermore, self-lubricating resins have low water absorption and hygroscopicity, and dimensional change over time is small. Therefore, when the draining member 32 serves to position the holder 61, high positioning accuracy can be achieved. The −Y side surface and the +Y side surface of the water draining member 32 are machined surfaces, which improves the dimensional accuracy of the thickness t of the water draining member 32, thereby enabling the appropriate distance L to be achieved with high accuracy.

[0048] With this configuration, in this embodiment, simply by positioning the draining member 32 so that it contacts the stepped portion 17 of the rotating shaft 10 and then positioning the rotating ring 33A so that the retaining portion 61 contacts the draining member 32, it is possible to fix the retaining portion 61 in a position that achieves the appropriate distance L. Because the draining member 32 is separate from the retaining portion 61 and the retaining portion 61 is fixed to the rotating shaft 10 with the set screw 61A, even if a reaction force of the biasing force applied by the biasing member 64 to the seal ring 62 acts on the retaining portion 61, the reaction force is not transmitted to the draining member 32 via the retaining portion 61. Therefore, the reaction force does not cause the draining member 32 to be compressed or bent in the Y direction, which would cause the distance L to fluctuate.

[0049] Furthermore, in the embodiment, the gap CL11 between the outer periphery of the draining member 32 and the inner circumferential surface of the housing 31 is smaller than the thickness t of the draining member 32. Therefore, even if the fluid reaches the draining member 32, the fluid is blown off by the rotating draining member 32 and collides with the inner circumferential surface of the housing 31 just outside, so that the fluid is prevented from crossing the gap CL11 and reaching the -Y side (the bearing 20 side).

[0050] In the above configuration, the axial position of the rotating shaft 10 relative to the housing 31 of the shaft seal portion 30 is important for properly setting the axial gap CL3 between the peripheral edge of the opening 35A and the step portion 13, and the distance L from the fixed ring 33B to the retaining portion 61. In the embodiment, the axial position of the rotating shaft 10 is determined by the support surface 21A formed on the bearing case 21 of the bearing portion 20.

[0051] Specifically, as shown in FIG. 3 , a protrusion 24A that protrudes toward the +Y side and presses against the bearing 22 is provided on the +Y side surface of the retainer plate 24. The bearing 22 that contacts the protrusion 24A comes into contact with the rotating shaft 10 in the Y-axis direction at the stepped portion 18A of the rotating shaft 10, and the rotating shaft 10 comes into contact with the +Y-side bearing 22 in the Y-axis direction at the stepped portion 18B. The +Y-side bearing 22 then comes into contact with the support surface 21A of the bearing case 21 in the Y-axis direction. When the retainer plate 24 is fixed with the bolts 25, the -Y-side bearing 22, the rotating shaft 10, and the +Y-side bearing 22 are pressed in the +Y direction toward the support surface 21A by the protrusion 24A. The bearings 22 and the rotating shaft 10 are sandwiched in the Y-axis direction between the support surface 21A and the protrusion 24A. As a result, the position of the rotating shaft 10 in the Y-axis direction is determined based on the support surface 21A. The bearing case 21 and the housing 31 of the shaft seal portion 30 are fixed with bolts 34A and nuts 34B, thereby determining the relative positions in the Y-axis direction between the support surface 21A (rotating shaft 10) and the partition wall 35 (fixed ring 33B). As a result, the rotating shaft 10 is positioned so that the gap CL3 falls within an allowable range with respect to the design value, and the distance L falls within an allowable range with respect to the design value.

[0052] (Assembly Instructions) Next, the assembly procedure for the vane pump 1 according to the embodiment will be described, focusing particularly on the shaft seal portion 30. Fig. 9 is a cross-sectional view showing a first stage of the assembly procedure for the vane pump according to the embodiment. Fig. 10 is a cross-sectional view showing a second stage of the assembly procedure for the vane pump according to the embodiment. Fig. 11 is a cross-sectional view showing a third stage of the assembly procedure for the vane pump according to the embodiment.

[0053] First, as shown in Fig. 9, the bearing portion 20 is assembled to the rotating shaft 10. After the oil seal 23A and the bearings 22 are attached to the rotating shaft 10 and inserted into the bearing case 21, the pressing plate 24 and the oil seal 23B are attached to the bearing case 21 and the pressing plate 24 is fixed with bolts 25.

[0054] Next, the water drain member 32 is attached to the rotating shaft 10 protruding from the bearing case 21. The water drain member 32 is attached to the water drain arrangement portion 14 so as to contact the step portion 17 from the +Y side of the rotating shaft 10.

[0055] Next, as shown in Figure 10, the rotary ring 33A is attached to the rotary shaft 10. The rotary ring 33A is attached to the rotary ring placement portion 16 from the +Y side of the rotary shaft 10 so that the retaining portion 61 contacts the draining member 32. The retaining portion 61 is fixed to the rotary shaft 10 with a set screw 61A. In reality, the biasing member 64 will be in its natural length, but for convenience's sake, Figure 10 shows it in a pre-compressed state.

[0056] Next, as shown in Figure 11, the housing 31, to which the fixed ring 33B has been previously attached, is attached to the bearing case 21 with bolts 34A and nuts 34B. At this time, the rotating shaft 10 is inserted through the fixed ring 33B and the opening 35A of the partition wall 35. The fixed ring 33B comes into contact with the seal ring 62 of the rotatable ring 33A, compressing the biasing member 64, and is positioned so that the distance L between the retaining portion 61 and the rotatable ring 33A is an appropriate value. As a result, the biasing member 64 is compressed to a predetermined pre-compression amount.

[0057] In this way, in the embodiment, the rotating ring 33A can be positioned so that the distance L between the holding portion 61 and the rotating ring 33A is an appropriate value simply by butting the water draining member 32 against the step portion 17 and then butting and fixing the rotating ring 33A against the water draining member 32.

[0058] Thereafter, the rotating shaft 10 protruding from the opening 35A of the partition wall 35 to the +Y side is inserted into the pump chamber 41A of the casing 41, and various components such as the guide ring 44 and the rotor 42 are attached to the rotating shaft 10. The pump chamber 41A is then closed with the cover 45, and the nozzles 46 of the intake port FI and the discharge port FO are attached to the casing 41, thereby assembling the vane pump 1 as shown in FIG. 3.

[0059] As described above, the shaft seal portion 30 (shaft seal structure of a fluid machine) according to the embodiment is a shaft seal structure of a fluid machine having a rotating shaft 10, and includes a housing 31 having a partition wall 35 with an opening 35A through which the rotating shaft 10 is inserted, a mechanical seal 33 including a rotating ring 33A fixed to the rotating shaft 10, and a stationary ring 33B fixed to the partition wall 35 and through which the rotating shaft 10 is inserted. The rotating shaft 10 has a stationary ring arrangement portion 11 arranged inside the stationary ring 33B, and an opening arrangement portion 12 arranged inside the opening 35A and having a smaller diameter than the stationary ring arrangement portion 11. The inner diameter D12 of the opening 35A is smaller than the outer diameter D1 of the stationary ring arrangement portion 11. The peripheral edge of the opening 35A faces a step 13 between the stationary ring arrangement portion 11 and the opening arrangement portion 12 in the axial direction.

[0060] According to the embodiment, the peripheral edge of the opening 35A faces the step 13 between the fixed ring arrangement portion 11 and the opening arrangement portion 12 in the axial direction, so that the leakage path LP of the fluid passing through the gap CL2 between the opening 35A and the opening arrangement portion 12 and the gap CL1 between the fixed ring 33B and the fixed ring arrangement portion 11 has a bent shape (a so-called labyrinth shape) at the step 13. The bent leakage path LP has a higher flow path resistance than a simple path extending in a straight line, so that leakage of the fluid is suppressed. As a result, the sealing performance of the mechanical seal 33 is improved.

[0061] In this embodiment, a rotor 42 that holds vanes 43 and a guide ring 44 that regulates the radial position of vanes 43 are inserted into the tip of the rotating shaft 10 that passes through the opening 35A. The inner diameter D12 of the opening 35A is smaller than the inner diameter D11 of the guide ring 44. This effectively reduces the gap CL2 between the opening 35A and the opening arrangement portion 12. Furthermore, because the opening 35A is small, the area of ​​the guide ring 44 that faces the partition wall 35 that forms the periphery of the opening 35A in the axial direction is large. Therefore, the partition wall 35 can suppress tilting and axial movement of the guide ring 44.

[0062] In the embodiment, the inner diameter D12 of the opening 35A is larger than and substantially equal to the outer diameter D2 of the opening arrangement portion 12. This minimizes the gap CL2 between the opening 35A and the opening arrangement portion 12. This increases the flow path resistance of the leakage path LP, thereby suppressing fluid leakage. Even if fluid enters the gap CL2, the volume of the gap CL2 is reduced, thereby suppressing the amount of fluid retained inside the mechanical seal 33. This suppression of the amount of fluid retained reduces the risk of contamination due to the retained fluid. This is suitable for situations where high hygiene is required of the vane pump 1, such as when handling food, medicine, or other fluids.

[0063] In the embodiment, the gap CL1 between the fixed ring 33B and the fixed ring arrangement portion 11 and the gap CL2 between the opening 35A and the opening arrangement portion 12 are smaller than the height of the step portion 13. This allows the gaps CL1 and CL2 that constitute the leakage path LP to be made smaller. The flow path resistance of the leakage path LP increases, thereby suppressing fluid leakage. Furthermore, the volume of the space that constitutes the leakage path LP is reduced, thereby effectively reducing the amount of fluid that remains inside the mechanical seal 33. This allows the vane pump 1 to be highly hygienic.

[0064] In the embodiment, the axial gap CL3 between the peripheral edge of the opening 35A and the step portion 13 is smaller than the height of the step portion 13. This allows the gap CL3 that constitutes the leakage path LP to be made smaller. The flow path resistance of the leakage path LP increases, thereby suppressing fluid leakage. Furthermore, the spatial volume of the gap CL3 that constitutes the leakage path LP is reduced, effectively reducing the amount of fluid that remains. This allows the vane pump 1 to achieve high hygiene. [Explanation of symbols]

[0065] 1... vane pump, 10... rotating shaft, 11... fixed ring arrangement portion, 12... opening arrangement portion, 13... step portion, 13A... axial end face, 14... water drain arrangement portion, 15... adjacent portion, 16... rotating ring arrangement portion, 17... step portion, 18A... step portion, 18B... step portion, 20... bearing portion, 21... bearing case, 21A... support surface, 22... bearing, 23A, 23B... oil seal, 24... push Plate, 24A...protrusion, 25...bolt, 30...shaft seal, 31...housing, 31A...through hole, 32...water drain member, 32A...hole, 33...mechanical seal, 33A...rotating ring, 33B...fixed ring, 34A...bolt, 34B...nut, 35...partition wall, 35A...opening, 36A...washer, 36B...retaining ring, 40...pump section, 41...casing, 41A...pump chamber, 41B...suction Flow path, 41C... discharge flow path, 41D... connection recess, 41E... mounting surface, 41F... inner peripheral surface, 42... rotor, 42A... holding groove, 42B... accommodation recess, 43... vane, 44... guide ring, 45... cover, 45A... O-ring, 46... nozzle, 46A... cylindrical portion, 46B... flange portion, 46C... annular protrusion, 47... O-ring, 48A... rotor washer, 48B... spring washer, 48C... bolt, 48 D...parallel key, 51...connecting bolt, 52...nut, 53...bolt, 61...retaining portion, 61A...set screw, 62...seal ring, 63...guide pin, 64...urging member, 65...packing, CL1...gap, CL2...gap, CL3...gap, CL11...gap, D1...outer diameter, D2...outer diameter, D3...outer diameter, D11...inner diameter, D12...inner diameter, Dr...inner diameter, Hw...height, L...distance, t...thickness.

Claims

1. A shaft seal structure for a fluid machine having a rotating shaft, a housing having a partition wall with an opening through which the rotating shaft is inserted; a mechanical seal including a rotary ring fixed to the rotary shaft and a stationary ring fixed to a partition wall and through which the rotary shaft is inserted, the rotating shaft has a fixed ring arrangement portion that is arranged inside the fixed ring, and an opening arrangement portion that is arranged inside the opening and has a smaller diameter than the fixed ring arrangement portion, an inner diameter of the opening is smaller than an outer diameter of the fixed ring arrangement portion, and a peripheral edge portion of the opening faces a step portion between the fixed ring arrangement portion and the opening arrangement portion in the axial direction; Shaft seal structure for fluid machinery.

2. the fluid machine is a vane pump, A rotor that holds a vane and a guide ring that regulates the radial position of the vane are inserted into the tip of the rotary shaft that passes through the opening, The inner diameter of the opening is smaller than the inner diameter of the guide ring. The shaft seal structure of a fluid machine according to claim 1.

3. The inner diameter of the opening is larger than and substantially equal to the outer diameter of the opening arrangement portion. The shaft seal structure of a fluid machine according to claim 1.

4. a gap between the fixed ring and the fixed ring arrangement portion, and a gap between the opening and the opening arrangement portion are smaller than the height of the step portion; The shaft seal structure of a fluid machine according to claim 1.

5. a gap in the axial direction between the peripheral edge of the opening and the step portion is smaller than a height of the step portion; The shaft seal structure of a fluid machine according to claim 1.

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