Fluid machinery

Abstract

To improve the durability of fluid machinery. [Solution] A fluid machine according to at least one embodiment of the present disclosure is a fluid machine comprising a pair of male and female screw rotors having a screw portion and shaft portions protruding from both ends of the screw portion, wherein the male rotor of the pair of male and female screw rotors is configured such that a driving force from an external drive source is input to a first shaft portion on one side of the two shaft portions of the male rotor in the extending direction, and comprises a first mechanical shaft seal including a first rotating ring attached to the first shaft portion and rotating together with the first shaft portion, and a first stationary ring in contact with the first rotating ring, and a second mechanical shaft seal including a second rotating ring attached to the second shaft portion on the other side of the two shaft portions of the male rotor in the extending direction and rotating together with the second shaft portion, and a second stationary ring in contact with the second rotating ring.

Description

Technical Field

[0001] The present disclosure relates to fluid machinery.

Background Art

[0002] Fluid machinery for transferring or compressing fluids, such as screw pumps, screw compressors, gear pumps, etc., is known. In such fluid machinery, a shaft for transmitting an external driving force or the like may protrude from the casing of the fluid machinery. Therefore, a mechanical shaft seal may be used as a sealing device for sealing this shaft (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a mechanical shaft seal is provided only on one side of the drive shaft with a gear interposed therebetween as in the gear pump described in Patent Document 1, due to the pressure difference across the sliding surface between the rotating ring and the stationary ring in the mechanical shaft seal, a thrust force acts on the drive shaft in either one direction or the other in the extending direction thereof. Therefore, when the pressure difference increases, the thrust force also increases, which may affect the durability of the fluid machinery.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to improve the durability of fluid machinery.

Means for Solving the Problems

[0006] The fluid machinery according to at least one embodiment of the present disclosure is A fluid machine comprising a pair of male and female screw rotors having a screw portion and shaft portions protruding from both ends of the screw portion, The male rotor of the pair of male and female screw rotors is configured such that a driving force from an external drive source is input to the first shaft portion of the two shaft portions of the male rotor, which is on one side in the direction of extension of the male rotor. A first mechanical shaft seal includes a first rotating ring attached to the first shaft and rotating together with the first shaft, and a first stationary ring in contact with the first rotating ring, A second mechanical shaft seal includes a second rotating ring attached to the second shaft portion on the other side in the extending direction of the two shaft portions of the male rotor and rotating together with the second shaft portion, and a second stationary ring in contact with the second rotating ring, It is equipped with. [Effects of the Invention]

[0007] According to at least one embodiment of the present disclosure, the durability of fluid machinery can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view of a screw pump according to one embodiment, as an example of a fluid machine. [Figure 2] This is a partial enlargement of Figure 1. [Modes for carrying out the invention]

[0009] Hereinafter, several embodiments of this disclosure will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described or shown in the drawings as embodiments are not intended to limit the scope of this disclosure, but are merely illustrative examples. For example, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" should not only strictly describe such arrangements, but also describe states of relative displacement with tolerances or angles or distances that allow for the same function to be achieved. For example, expressions such as "identical," "equal," and "homogeneous" that describe things being in an equal state not only describe a state of being strictly equal, but also describe a state in which there is a tolerance or a difference that is sufficient to achieve the same function. For example, expressions describing shapes such as squares or cylinders shall not only represent geometrically precise shapes such as squares or cylinders, but also shapes that include protrusions, chamfers, etc., to the extent that the same effect can be achieved. On the other hand, expressions such as "to possess," "to be equipped with," "to have," "to include," or "to have" a single component are not exclusive expressions that exclude the existence of other components.

[0010] (Screw pump configuration) Figure 1 is a schematic cross-sectional view of a screw pump according to one embodiment, which is an example of a fluid machine. Figure 2 is a partially enlarged view of Figure 1. Note that, for the sake of clarity, Figure 2 shows the second male screw portion 22 (described later) in cross-section rather than its external shape. A screw pump 1 according to one embodiment is a fluid machine that is a pump for transferring fluid and comprises a pair of male and female screw rotors 10 having a screw portion 11 and shaft portions 12 protruding from both ends of the screw portion 11. The screw pump 1 comprises a pair of male and female screw rotors 10 and a casing 13 that houses the pair of male and female screw rotors 10. One embodiment of the screw pump 1 is, for example, an oil pump. The casing 13 has a screw chamber 13a inside which a pair of male and female screw rotors 10, the screw portions 11 of which will be described later, are housed.

[0011] (Screw rotor 10) The pair of male and female screw rotors 10 are rotatably supported by sliding bearings 18 located within the casing 13, with shaft portions 12 protruding from both ends of the respective screw portions 11. The sliding bearings 18 support the radial load of the pair of male and female screw rotors 10 and restrict the axial movement of the pair of male and female screw rotors 10 by having their sides abut against the sides of the screw portions 11.

[0012] (Screw section 11) The screw portion 11 of the male rotor 10A of the pair of male and female screw rotors 10 includes a first male screw portion 21 and a second male screw portion 22, which have symmetrical shapes on one side and the other side of the extending direction DR of the male rotor 10A, with respect to the center c of the extending direction DR of the screw portion 11. The first male screw portion 21 and the second male screw portion 22 are arranged adjacent to each other in the extending direction DR, with the first male screw portion 21 located on the left side as shown in Figure 1 and the second male screw portion 22 located on the right side as shown in Figure 1.

[0013] The first male screw portion 21 and the second male screw portion 22 have helical teeth, as will be described later. As mentioned above, the first male screw portion 21 and the second male screw portion 22 have symmetrical shapes, so the direction of tooth extension is different between the first male screw portion 21 and the second male screw portion 22. Therefore, in order to obtain the first male screw portion 21 and the second male screw portion 22 by machining, for example, the first male screw portion 21 and the second male screw portion 22 must be separate components. Therefore, the first male screw portion 21 and the second male screw portion 22 are separate components. Furthermore, the first male screw portion 21 and the second male screw portion 22 are separate components from the shaft portion 12 of the male rotor 10A, i.e., the rotor shaft 30 which will be described later.

[0014] The first male screw portion 21 and the second male screw portion 22 have through holes 11a through which the rotor shaft 30, which will be described later, is inserted. The inner diameter of the through hole 11a is equal to the diameter of the third shaft portion 33 of the rotor shaft 30, which will be described later, within the tolerance range. In the screw pump 1 according to one embodiment, the first male screw portion 21 and the second male screw portion 22, whose tooth extending directions are different from each other, are attached to a rotor shaft 30 described later, thereby integrating the first male screw portion 21 and the second male screw portion 22, which are separate members.

[0015] The screw portion 11 of the female rotor 10B among the pair of male and female screw rotors 10 includes a first female screw portion 23 and a second female screw portion 24 having symmetrical shapes on one side and the other side of the extending direction DR with the center c of the extending direction DR of the female rotor 10B in the screw portion 11, that is, the extending direction of the male rotor 10A as a boundary. The first female screw portion 23 and the second female screw portion 24 are arranged adjacent to each other in the extending direction DR. The first female screw portion 23 is located on the left side in the illustration of FIG. 1, and the second female screw portion 24 is located on the right side in the illustration of FIG. 1. For the same reason as in the case of the first male screw portion 21 and the second male screw portion 22, the first female screw portion 23 and the second female screw portion 24 are separate members. Also, the first female screw portion 23 and the second female screw portion 24 are separate members from the shaft portion 12 of the female rotor 10B.

[0016] The first male screw portion 21 and the first female screw portion 23 have spiral teeth that mesh with each other. A plurality of tooth groove spaces (chambers) are formed by the meshing of the teeth of the first male screw portion 21 and the first female screw portion 23 and the casing 13. Similarly, the second male screw portion 22 and the second female screw portion 24 have spiral teeth that mesh with each other. A plurality of tooth groove spaces (chambers) are formed by the meshing of the teeth of the second male screw portion 22 and the second female screw portion 24 and the casing 13.

[0017] Thus, in the screw pump 1 according to one embodiment, the screw portions 11 of each of the pair of male and female screw rotors 10 have symmetrical shapes on one side and the other side of the extending direction DR with respect to the center c of the extending direction DR of the male rotor 10A. Therefore, the thrust force acting on the screw portion 11 due to the pressure of the oil contacting the screw portion 11 is canceled on one side and the other side of the extending direction DR with respect to the center c, so that the durability of the screw pump 1 can be further improved.

[0018] (Shaft portion 12) Of the two shaft portions 12 of the male rotor 10A, the driving force from an external driving source is configured to be input to the first shaft portion 31 on one side of the extending direction DR of the male rotor 10A (the left side in the drawing in FIG. 1). The first shaft portion 31 is connected to the output shaft of a motor (not shown), for example, and is configured to be rotationally driven by the motor as indicated by the arrow a in FIG. 1. The screw portion 11 of the female rotor 10B that meshes with the screw portion 11 of the male rotor 10A is rotationally driven by the rotation of the male rotor 10A. The female rotor 10B rotates in the direction opposite to the rotation direction of the male rotor 10A as indicated by the arrow b in FIG. 1. When the male rotor 10A and the female rotor 10B rotate, the tooth groove space moves toward the back side of the paper surface in FIG. 1 along the inner peripheral surface of the casing 13. As a result, the oil from an oil inlet portion (not shown) provided on the front side of the paper surface in FIG. 1 moves toward the back side of the paper surface along with the movement of the tooth groove space and is sent to an oil outlet portion (not shown) provided on the back side of the paper surface in FIG. 1.

[0019] (Rotor shaft 30) In the screw pump 1 according to one embodiment, the male rotor 10A has a rotor shaft 30 to which the first male screw portion 21 and the second male screw portion 22 are attached. The rotor shaft 30 includes the above-described first shaft portion 31, the second shaft portion 32 on the other side of the extending direction DR of the two shaft portions 12 of the male rotor 10A (the right side in the drawing in FIG. 1), and a third shaft portion 33 that connects the first shaft portion 31 and the second shaft portion 32. The rotor shaft 30 is a rotor shaft in which the first shaft portion 31, the second shaft portion 32, and the third shaft portion 33 are integrally formed.

[0020] In a screw pump 1 according to one embodiment, the first shaft portion 31 includes a first region 41 supported by a sliding bearing 18, and a second region 42 extending from the first region 41 toward one side in the extending direction DR, where a first mechanical shaft seal 50A, described later, is located.

[0021] In a screw pump 1 according to one embodiment, the second shaft portion 32 includes a third region 43 which is inserted through a second sleeve 62 (described later) and supported by a sliding bearing 18 via the second sleeve 62, a fourth region 44 which is inserted through a first sleeve 61 (described later), and a fifth region 45 on which a regulating member 63 (described later) is attached. In the second shaft portion 32, the third region 43, the fourth region 44, and the fifth region 45 are arranged in order from one side to the other in the extending direction DR.

[0022] The diameter of the third region 43 is smaller than the diameter of the first region 41 of the first shaft portion 31, and the diameter of the fourth region 44 is smaller than the diameter of the third region 43.

[0023] In one embodiment of the screw pump 1, the third shaft portion 33 is inserted through the first male screw portion 21 and the second male screw portion 22. Relative movement between the third shaft portion 33 and the first male screw portion 21 and the second male screw portion 22 in the circumferential direction about the central axis AX of the rotor shaft 30 is prohibited.

[0024] The diameter of the third shaft portion 33 is smaller than the diameter of the first region 41 of the first shaft portion 31, and equal to the diameter of the third region 43 of the second shaft portion 32.

[0025] The outer circumference of the fifth region 45 has a male threaded portion 45a which is screwed into the female threaded portion 63a of the regulating member 63, which will be described later.

[0026] (Regarding the structure that covers the end of the casing 13 in the extending direction DR) One embodiment of the screw pump 1 includes a first seal cover 14A that covers one end of the casing 13 in the extending direction DR, and a first seal retaining lid 16A that covers the first seal cover 14A from one side in the extending direction DR. Another embodiment of the screw pump 1 includes a second seal cover 14B that covers the other end of the casing 13 in the extending direction DR, and a second seal retaining lid 16B that covers the second seal cover 14B from the other side in the extending direction DR.

[0027] The first seal cover 14A has a through hole 15A through which the first shaft portion 31 of the male rotor 10A is inserted. The first seal retaining cover 16A has a retaining portion 71 for holding the first fixing ring 52A of the first mechanical shaft seal 50A, which will be described later, and a through hole 72 through which the first shaft portion 31 of the male rotor 10A is inserted.

[0028] The second seal cover 14B has a through hole 15B through which the second shaft portion 32 of the male rotor 10A is inserted. The second seal retaining cover 16B has a retaining portion 75 for holding the second fixing ring 52B of the second mechanical shaft seal 50B, which will be described later, a recess 76 that is recessed from the retaining portion 75 toward the other side in the extending direction DR, and a through hole 77 that connects the space surrounded by the recess 76 with the space outside the second seal retaining cover 16B when the second seal retaining cover 16B is attached to the second seal cover 14B.

[0029] In one embodiment of the screw pump 1, the other end of the second shaft portion 32 of the male rotor 10A in the extending direction DR is covered by the second seal retaining cover 16B, and does not protrude beyond the second seal retaining cover 16B in the extending direction DR.

[0030] (Regarding the seal on screw pump 1) In one embodiment of the screw pump 1, the male rotor 10A is configured to prevent oil from leaking from the screw portion 11 to the outside of the screw pump 1 by a first mechanical shaft seal 50A mounted on the first shaft portion 31 and a second mechanical shaft seal 50B mounted on the second shaft portion 32.

[0031] The first mechanical shaft seal 50A includes a first rotating ring 51A that is attached to the first shaft portion 31 and rotates together with the first shaft portion 31, and a first fixed ring 52A that contacts the first rotating ring 51A. The first rotating ring 51A is directly attached to the second region 42 of the first shaft portion 31. The first fixed ring 52A is held by the retaining portion 71 of the first seal retaining cover 16A and is positioned on one side in the extending direction DR compared to the first rotating ring 51A.

[0032] The second mechanical shaft seal 50B includes a second rotating ring 51B that is attached to the second shaft portion 32 and rotates together with the second shaft portion 32, and a second fixed ring 52B that contacts the second rotating ring 51B. The second rotating ring 51B is attached to the fourth region 44 of the second shaft portion 32 via the first sleeve 61, which will be described later. The second fixed ring 52B is held by the retaining portion 75 of the second seal retaining cover 16B and is located on the other side of the extending direction DR compared to the second rotating ring 51B.

[0033] If a mechanical shaft seal is provided on only one of the shaft portions 12 at both ends of the male rotor 10A, a thrust force acts on the male rotor 10A in either one direction or the other in its extending direction DR due to the pressure difference across the sliding surface between the rotating ring and the stationary ring in the mechanical shaft seal. Therefore, as the pressure difference increases, the thrust force also increases, which may affect the durability of the screw pump 1. According to one embodiment of the screw pump 1, mechanical shaft seals (first mechanical shaft seal 50A, second mechanical shaft seal 50B) are provided on the shaft portions 12 at both ends of the male rotor 10A. As a result, the thrust force generated due to the pressure difference across the first sliding surface 53A, which is the sliding surface between the first rotating ring 51A and the first stationary ring 52A, can be reduced by the thrust force generated due to the pressure difference across the second sliding surface 53B, which is the sliding surface between the second rotating ring 51B and the second stationary ring 52B. This improves the durability of the screw pump 1.

[0034] In a screw pump 1 according to one embodiment, the first mechanical shaft seal 50A and the second mechanical shaft seal 50B are mechanical shaft seals of the same specifications. That is, the dimensions of each part of the first mechanical shaft seal 50A are the same as the dimensions of each part of the second mechanical shaft seal 50B. For example, the inner diameter of the first rotating ring 51A of the first mechanical shaft seal 50A is the same as the inner diameter of the second rotating ring 51B of the second mechanical shaft seal 50B.

[0035] As a result, the dimensions of each part of the second rotating ring 51B and the second fixed ring 52B become the same as the dimensions of each part of the first rotating ring 51A and the first fixed ring 52A. This reduces the difference in magnitude between the thrust force generated due to the pressure difference across the sliding surfaces of the first rotating ring 51A and the first fixed ring 52A, and the thrust force generated due to the pressure difference across the sliding surfaces of the second rotating ring 51B and the second fixed ring 52B. Therefore, the thrust force generated due to the pressure difference across the sliding surfaces of the first rotating ring 51A and the first fixed ring 52A can be effectively reduced by the thrust force generated due to the pressure difference across the sliding surfaces of the second rotating ring 51B and the second fixed ring 52B, thereby further improving the durability of the fluid machine.

[0036] Furthermore, according to the screw pump 1 of one embodiment, since the first mechanical shaft seal 50A and the second mechanical shaft seal 50B can use mechanical shaft seals of the same specifications, the cost increase can be reduced compared to the case where mechanical shaft seals of different specifications are used for the first mechanical shaft seal 50A and the second mechanical shaft seal 50B. In addition, since there is no need to distinguish between the first mechanical shaft seal 50A and the second mechanical shaft seal 50B during assembly, the ease of assembly is improved.

[0037] The first mechanical shaft seal 50A divides the screw chamber 13a into an internal space 80 and an external first external space 81, with the first sliding surface 53A between the first rotating ring 51A and the first fixed ring 52A as the boundary. The second mechanical shaft seal 50B divides the screw chamber 13a into an internal space 80 and an external second external space 82, with the second sliding surface 53B between the second rotating ring 51B and the second fixed ring 52B as the boundary. The first external space 81 is defined by the inner circumferential surface of the through hole 72 of the first seal retaining cover 16A, the inner circumferential surface of the first fixing ring 52A, and the outer circumferential surface of the second region 42 of the first shaft portion 31. The first external space 81 is in communication with the space outside the screw pump 1 through the through hole 72 of the first seal retaining cover 16A. The second external space 82 is a space covered on the other side in the extending direction DR and radially outside the central axis AX of the rotor shaft 30 by the recess 76 of the second seal retaining cover 16B and the inner circumferential surface of the second fixing ring 52B. The second external space 82 is in communication with the space outside the screw pump 1 through the through hole 77 of the second seal retaining cover 16B.

[0038] According to one embodiment of the screw pump 1, the difference between the thrust force generated due to the pressure difference across the first sliding surface 53A and the thrust force generated due to the pressure difference across the second sliding surface 53B can be made smaller. As a result, the thrust force generated due to the pressure difference across the first sliding surface 53A can be effectively reduced by the thrust force generated due to the pressure difference across the second sliding surface 53B, thereby further improving the durability of the screw pump 1.

[0039] (Regarding fixed structure 60) As described above, in the screw pump 1 according to one embodiment, the first male screw portion 21, the second male screw portion 22, and the rotor shaft 30 are separate components in the male rotor 10A. Therefore, the screw pump 1 according to one embodiment is equipped with a fixing structure 60 that prevents the movement of the first male screw portion 21 and the second male screw portion 22 in the extending direction DR relative to the rotor shaft 30. As mentioned above, relative movement between the third shaft portion 33 and the first male screw portion 21 and the second male screw portion 22 in the circumferential direction around the central axis AX of the rotor shaft 30 is prohibited.

[0040] In a screw pump 1 according to one embodiment, the fixing structure 60 includes a first region 41 of the first shaft portion 31, a first sleeve 61, a second sleeve 62, and a regulating member 63. The first sleeve 61 is a cylindrical member positioned between at least a portion of the extending direction DR of the second rotating ring 51B and the fourth region 44 of the second shaft portion 32.

[0041] The first sleeve 61 has a large-diameter region 61a and a small-diameter region 61b with different outer diameters (Figure 2). The large-diameter region 61a on one side of the extending direction DR in the first sleeve 61 has a larger outer diameter than the small-diameter region 61b on the other side of the extending direction DR in the first sleeve 61. The outer diameter of the large-diameter region 61a is larger than the outer diameter of the third region 43 of the second shaft portion 32. The outer diameter of the small-diameter region 61b is equal to the diameter of the second region 42 of the first shaft portion 31. The small-diameter region 61b is inserted through the inner circumference of the second rotating ring 51B of the second mechanical shaft seal 50B. The inner diameter of the first sleeve 61 is equal to the outer diameter of the fourth region 44 of the second shaft portion 32, within the tolerance range.

[0042] The second sleeve 62 is a cylindrical member positioned between the second male screw portion 22 and the first sleeve 61 in the extending direction DR, with the third region 43 of the second shaft portion 32 inserted through its interior. The inner diameter of the second sleeve 62 is equal to the outer diameter of the third region 43 of the second shaft portion 32, within the tolerance range. The outer diameter of the second sleeve 62 is equal to the diameter of the first region 41 of the first shaft portion 31.

[0043] The restricting member 63 is a cylindrical member fixed to the fifth region 45 of the second shaft portion 32, and restricts the movement of the first sleeve 61 to the other side in the extending direction. The inner circumferential surface of the restricting member 63 has a female threaded portion 63a that is screwed into the male threaded portion 45a of the fifth region 45. The outer diameter of the regulating member 63 is larger than the inner diameter of the first sleeve 61.

[0044] Here, we will explain the relationships between the various components in the fixed structure 60. As described above, the inner diameter of the through hole 11a is equal to the diameter of the third shaft portion 33 of the rotor shaft 30 within the tolerance range. Also, the diameter of the third shaft portion 33 is smaller than the diameter of the first region 41 of the first shaft portion 31. Therefore, the outer diameter of the other end of the first region 41 in the extending direction DR is larger than the inner diameter of the through hole 11a of the first male screw portion 21. As a result, the other end of the first region 41 in the extending direction DR and the end face of the first male screw portion 21 in the extending direction DR come into contact, restricting the movement of the first male screw portion 21 to one side in the extending direction DR.

[0045] The end face of the first male screw portion 21 on the other side in the extending direction DR and the end face of the second male screw portion 22 on the one side in the extending direction DR come into contact, thereby restricting the movement of the second male screw portion 22 to one side in the extending direction DR by the first male screw portion 21.

[0046] As described above, the inner diameter of the through hole 11a of the second male screw portion 22 is equal to the diameter of the third shaft portion 33 of the rotor shaft 30 within the tolerance range, and therefore equal to the diameter of the third region 43 of the second shaft portion 32 within the tolerance range. Consequently, the outer diameter of the second sleeve 62 is larger than the inner diameter of the through hole 11a of the second male screw portion 22. Therefore, the other end face of the second male screw portion 22 in the extending direction DR and the one end of the second sleeve 62 in the extending direction DR come into contact, thereby restricting the movement of the second male screw portion 22 to the other side in the extending direction DR, and restricting the movement of the second sleeve 62 to one side in the extending direction DR. Furthermore, as will be explained below, the movement of the second sleeve 62 toward the other side in the extending direction DR is restricted by the first sleeve 61 and the regulating member 63.

[0047] The restricting member 63 is screwed into the male threaded portion 45a of the fifth region 45 and is fixed in contact with the other end of the first sleeve 61 in the extending direction DR. As a result, since the outer diameter of the restricting member 63 is larger than the inner diameter of the first sleeve 61, the movement of the first sleeve 61 in the extending direction DR to the other side is restricted by the restricting member 63.

[0048] The outer diameter of the large-diameter region 61a of the first sleeve 61 is larger than the outer diameter of the third region 43 of the second shaft portion 32, and therefore larger than the inner diameter of the second sleeve 62. As a result, the other end of the second sleeve 62 in the extending direction DR comes into contact with one end of the large-diameter region 61a of the first sleeve 61 in the extending direction DR, thereby restricting the movement of the second sleeve 62 to the other side in the extending direction DR.

[0049] In one embodiment of the screw pump 1, the second mechanical shaft seal 50B is not in contact with the regulating member 63, and therefore is not subjected to a thrust force by the fixing structure 60 that would prevent the first male screw portion 21 and the second male screw portion 22 from moving in the extending direction DR. The thrust force is borne by the first sleeve 61, whose movement in the extending direction DR is restricted to one side by the restricting member 63.

[0050] In this screw pump 1 according to one embodiment, the fixed structure 60 prevents the movement of the first male screw portion 21 and the second male screw portion 22 in the extending direction DR relative to the rotor shaft 30.

[0051] In one embodiment of the screw pump 1, the fixed structure 60 includes a first sleeve 61 positioned between at least a portion of the region of the second rotating ring 51B in the extending direction DR and the second shaft portion 32. As a result, the first sleeve 61 bears the thrust force that prevents the first male screw portion 21 and the second male screw portion 22 from moving in the extending direction DR due to the fixed structure 60, as described above, thereby preventing the first male screw portion 21 and the second male screw portion 22 from moving in the extending direction DR.

[0052] In a screw pump 1 according to one embodiment, the outer diameter of the small-diameter region 61b of the first sleeve 61 that overlaps with the second rotating ring 51B in the extending direction DR is equal to the outer diameter of the second region 42 of the first shaft portion 31 that overlaps with the first rotating ring 51A in the extending direction. This makes it possible to make the inner diameter of the portion of the first rotating ring 51A that contacts the outer circumferential surface of the second region 42 of the first shaft portion 31 equal to the inner diameter of the portion of the second rotating ring 51B that contacts the outer circumferential surface of the small diameter region 61b of the first sleeve 61. As a result, it becomes possible to use mechanical shaft seals of the same specifications for the first mechanical shaft seal 50A and the second mechanical shaft seal 50B. This reduces the cost increase of the screw pump 1 and improves ease of assembly because there is no need to distinguish between the first mechanical shaft seal 50A and the second mechanical shaft seal 50B during assembly.

[0053] In one embodiment of the screw pump 1, since the fixing structure 60 includes a second sleeve 62, the movement of the first male screw portion 21 and the second male screw portion 22 in the extending direction DR can be prohibited by the first sleeve 61 and the second sleeve 62.

[0054] This disclosure is not limited to the embodiments described above, but also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate. For example, in the above description, a screw pump 1 for transferring fluids such as oil was given as an example of fluid machinery, but the contents of this disclosure can be applied to fluid machinery other than screw pump 1, such as screw compressors and gear pumps, for transferring or compressing fluids.

[0055] The contents described in each of the above embodiments can be understood, for example, as follows: (1) A fluid machine according to at least one embodiment of the present disclosure is a fluid machine (screw pump 1) comprising a pair of male and female screw rotors 10 having a screw portion 11 and shaft portions 12 protruding from both ends of the screw portion 11. The male rotor (first male screw portion 21, second male screw portion 22) of the pair of male and female screw rotors 10 is configured such that a driving force from an external drive source is input to the first shaft portion 31 on one side of the male rotor (first male screw portion 21, second male screw portion 22) in the extending direction DR of the two shaft portions 12 of the male rotor (first male screw portion 21, second male screw portion 22). A fluid machine (screw pump 1) according to at least one embodiment of the present disclosure includes a first mechanical shaft seal 50A comprising a first rotating ring 51A attached to a first shaft portion 31 and rotating together with the first shaft portion 31, and a first stationary ring 52A in contact with the first rotating ring 51A; and a second mechanical shaft seal 50B comprising a second rotating ring 51B attached to a second shaft portion 32 on the other side of the extending direction DR of the two shaft portions 12 of a male rotor (first male screw portion 21, second male screw portion 22) and rotating together with the second shaft portion 32, and a second stationary ring 52B in contact with the second rotating ring 51B.

[0056] According to the configuration of (1) above, since mechanical shaft seals are provided on the shaft portions 12 at both ends of the male rotor (first male screw portion 21, second male screw portion 22), the thrust force generated due to the pressure difference at the sliding surface (first sliding surface 53A) between the first rotating ring 51A and the first fixed ring 52A can be reduced by the thrust force generated due to the pressure difference at the sliding surface (second sliding surface 53B) between the second rotating ring 51B and the second fixed ring 52B. This improves the durability of the fluid machine (screw pump 1).

[0057] (2) In some embodiments, in the configuration of (1) above, the first mechanical shaft seal 50A and the second mechanical shaft seal 50B may be mechanical shaft seals of the same specifications.

[0058] According to the configuration described in (2) above, the dimensions of each part of the second rotating ring 51B and the second stationary ring 52B are the same as the dimensions of each part of the first rotating ring 51A and the first stationary ring 52A. This makes it possible to reduce the difference in magnitude between the thrust force generated due to the pressure difference across the sliding surfaces of the first rotating ring 51A and the first stationary ring 52A, and the thrust force generated due to the pressure difference across the sliding surfaces of the second rotating ring 51B and the second stationary ring 52B. As a result, the thrust force generated due to the pressure difference across the sliding surfaces of the first rotating ring 51A and the first stationary ring 52A can be effectively reduced by the thrust force generated due to the pressure difference across the sliding surfaces of the second rotating ring 51B and the second stationary ring 52B, thereby further improving the durability of the fluid machine. Furthermore, according to the configuration described in (2) above, since the same mechanical shaft seal can be used for both the first mechanical shaft seal 50A and the second mechanical shaft seal 50B, the cost increase can be reduced compared to the case where different mechanical shaft seals are used for the first mechanical shaft seal 50A and the second mechanical shaft seal 50B. In addition, assembly is easier because there is no need to distinguish between the first mechanical shaft seal 50A and the second mechanical shaft seal 50B during assembly.

[0059] (3) In some embodiments, the configuration of (1) or (2) above may include a casing 13 having a screw chamber 13a inside which a pair of male and female screw rotors 10 screw portions 11 are housed. The first mechanical shaft seal 50A may be divided into an internal space 80 and an external first external space 81 of the screw chamber 13a, with the first sliding surface 53A of the first rotating ring 51A and the first stationary ring 52A as the boundary. The second mechanical shaft seal 50B may be divided into an internal space 80 and an external second external space 82 of the screw chamber 13a, with the second sliding surface 53B of the second rotating ring 51B and the second stationary ring 52B as the boundary. The first external space 81 and the second external space 82 may be in communication with the space outside the fluid machine (screw pump 1).

[0060] According to the configuration of (3) above, the difference between the thrust force generated due to the pressure difference across the first sliding surface 53A and the thrust force generated due to the pressure difference across the second sliding surface 53B can be made smaller. As a result, the thrust force generated due to the pressure difference across the first sliding surface 53A can be effectively reduced by the thrust force generated due to the pressure difference across the second sliding surface 53B, thereby further improving the durability of the fluid machine (screw pump 1).

[0061] (4) In some embodiments, in any of the configurations (1) to (3) above, each of the screw portions 11 of the pair of male and female screw rotors 10 may have a symmetrical shape on one side and the other side of the extending direction DR with respect to the center c of the extending direction DR of the screw portion 11.

[0062] According to the configuration described in (4) above, the thrust force acting on the screw portion 11 due to the pressure of the fluid in contact with the screw portion 11 is canceled out on one side and the other side of the extension direction DR with respect to the center c, thereby further improving the durability of the fluid machine (screw pump 1).

[0063] (5) In some embodiments, in any of the configurations (1) to (4) above, the male rotor 10A may include a male screw portion (first male screw portion 21, second male screw portion 22) which is the screw portion 11 of the male rotor 10A, and a male rotor shaft (rotor shaft 30) which is a separate member from the male screw portion (first male screw portion 21, second male screw portion 22) and has a first shaft portion 31 and a second shaft portion 32 protruding from both ends of the male screw portion (first male screw portion 21, second male screw portion 22). In some embodiments, a fixing structure 60 may be provided that prevents the movement of the male screw portion (first male screw portion 21, second male screw portion 22) in the extending direction DR relative to the male rotor shaft (rotor shaft 30). The fixing structure 60 may include a first sleeve 61 disposed between at least a portion of the extending direction DR of the second rotating ring 51B and the second shaft portion 32.

[0064] According to the configuration of (5) above, movement of the male screw portion (first male screw portion 21, second male screw portion 22) in the extension direction DR can be prohibited.

[0065] (6) In some embodiments, in the configuration of (5) above, the outer diameter of at least the region of the first sleeve 61 that overlaps with the second rotating ring 51B in the extending direction DR (small diameter region 61b) is equal to the outer diameter of the region of the first shaft portion 31 that overlaps with the first rotating ring 51A in the extending direction DR (second region 42).

[0066] According to the configuration described in (6) above, the inner diameter of the portion of the first rotating ring 51A that contacts the outer surface of the first shaft portion 31 and the inner diameter of the portion of the second rotating ring 51B that contacts the outer surface of the first sleeve 61 can be made equal. This makes it possible to use mechanical shaft seals of the same specifications for the first mechanical shaft seal 50A and the second mechanical shaft seal 50B. This reduces the cost increase of the fluid machine (screw pump 1) and improves ease of assembly because there is no need to distinguish between the first mechanical shaft seal 50A and the second mechanical shaft seal 50B during assembly.

[0067] (7) In some embodiments, in the configuration of (5) or (6) above, the fixing structure 60 may include a second sleeve 62 which is positioned between the male screw portion (first male screw portion 21, second male screw portion 22) and the first sleeve 61 in the extending direction DR, and through which the second shaft portion 32 is inserted.

[0068] According to the configuration in (7) above, the first sleeve 61 and the second sleeve 62 can prevent the male screw portion (first male screw portion 21, second male screw portion 22) from moving in the extending direction DR. [Explanation of Symbols]

[0069] 1 Screw pump 10 Screw rotors 10A Male Rotor 10B Female Rotor 11 Screw section 12 Shaft section 13 Casing 13a Screw chamber 18 Plain bearings 21 First male screw section 22 Second male screw section 23 First female screw section 24 Second female screw section 30 Rotor Shaft 31 First shaft section 32 Second shaft section 33 Third shaft section 41 First area 42 Second area 43 Third area 44 4th area 45 5th area 50A First Mechanical Shaft Seal 51A First Rotating Ring 52A 1st fixed ring 53A First sliding surface 50B Second Mechanical Shaft Seal 51B Second Rotating Ring 52B 2nd fixed ring 53B 2nd sliding surface 61 First Sleeve 62 Sleeve 2 63 Regulatory Members 72 Through hole 76 recesses 77 Through hole 80 space 81 First external space 82 Second external space

Claims

1. A fluid machine comprising a pair of male and female screw rotors having a screw portion and shaft portions protruding from both ends of the screw portion, The male rotor of the pair of male and female screw rotors is configured such that a driving force from an external drive source is input to the first shaft portion of the two shaft portions of the male rotor, which is on one side in the direction of extension of the male rotor. A first mechanical shaft seal includes a first rotating ring attached to the first shaft and rotating together with the first shaft, and a first stationary ring in contact with the first rotating ring, A second mechanical shaft seal includes a second rotating ring attached to the second shaft portion on the other side in the extending direction of the two shaft portions of the male rotor and rotating together with the second shaft portion, and a second stationary ring that contacts the second rotating ring. A fluid machine equipped with the following features.

2. The first mechanical shaft seal and the second mechanical shaft seal are mechanical shaft seals of the same specifications. The fluid machine according to claim 1.

3. The casing comprises a screw chamber having a screw portion inside which the screw portion of the pair of male and female screw rotors is housed, The first mechanical shaft seal divides the screw chamber into an internal space and an external first space, with the first sliding surface between the first rotating ring and the first stationary ring as the boundary. The second mechanical shaft seal divides the screw chamber into an internal space and a second external space, with the second sliding surface between the second rotating ring and the second stationary ring as the boundary. The first external space and the second external space are in communication with the space outside the fluid machine. The fluid machine according to claim 1 or 2.

4. Each of the screw portions in the pair of male and female screw rotors has a symmetrical shape on one side and the other side in the extending direction, with respect to the center of the extending direction of the screw portion. The fluid machine according to claim 1 or 2.

5. The aforementioned male rotor is The male screw portion of the male rotor, A male rotor shaft having a first shaft portion and a second shaft portion protruding from both ends of the male screw portion, and being a separate component from the male screw portion, Includes, It includes a fixing structure that prevents the male screw portion from moving in the extending direction relative to the male rotor shaft, The fixing structure includes a first sleeve disposed between at least a portion of the extending direction region of the second rotating ring and the second shaft portion. The fluid machine according to claim 1 or 2.

6. The outer diameter of at least the region of the first sleeve that overlaps with the second rotating ring in the extending direction is equal to the outer diameter of the region of the first shaft that overlaps with the first rotating ring in the extending direction. The fluid machine according to claim 5.

7. The fixing structure includes a second sleeve, which is positioned between the male screw portion and the first sleeve in the extending direction, and through which the second shaft portion is inserted. The fluid machine according to claim 5.

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