Liquid pump

Abstract

To smoothly discharge air in order to fill a liquid pump with liquid in a short time.SOLUTION: A liquid pump (10) according to an embodiment includes a housing (12), an impeller (24), a shaft (40), a shaft chamber (44) for storing the shaft, a bearing (42) rotatably holding the shaft in the shaft chamber, a bearing holder (46) formed in the housing, and a rotor (68) connected with the shaft. The shaft chamber is divided into a rotor side space (48) and an impeller side space (50) by the bearing holder. A first through hole (82) is formed in the bearing holder so as to communicate the rotor side space with the impeller side space, a second through hole (25) is formed in the impeller, and a third through hole (80) is formed in the housing so as to communicate the impeller side space with the outside. Gas in the shaft chamber sequentially passes through the first, second, and third through holes and escapes to the outside of the housing.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this application relates to a liquid pump. [Background technology]

[0002] In some liquid pumps, a through-hole for discharging gas to the outside is provided in the housing in addition to the passage for the liquid to be transported. For example, the vortex pump disclosed in Japanese Patent Laid-Open Publication No. 2006-170159 is provided with an air vent hole that connects a specific part of the housing to the discharge port to prevent air from accumulating between that part and the impeller. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-170159 Summary of the Invention [Problem to be solved by the invention]

[0004] The pump's internal space must be filled with liquid during operation. Furthermore, to prevent wear on the bearings that rotatably support the shaft, the space where the shaft is located may also be actively filled with liquid. To quickly fill the pump with liquid, smooth air discharge is an issue. This is particularly important when a dead-end space exists inside the pump, such as when the shaft is rotated from the outside of the housing via a magnetic coupling. The publications mentioned above do not address these issues. Furthermore, they do not consider air discharge when the pump is installed with the shaft facing sideways. Therefore, a liquid pump that can smoothly discharge air is desired in order to quickly fill the pump with liquid. [Means for solving the problem]

[0005] One aspect of the present technology is a liquid pump including: a housing; a rotatable impeller accommodated in the housing; a shaft coupled to the impeller; a shaft chamber formed in the housing and accommodating the shaft; a bearing that rotatably holds the shaft in the shaft chamber; a bearing holder formed in the housing and holding the bearing; and a rotor coupled to the shaft and rotated from outside the housing via a magnetic coupling, wherein the bearing holder divides the shaft chamber into a rotor-side space and an impeller-side space, and the rotor The impeller is positioned in the rotor-side space, and the center of the impeller is positioned in the impeller-side space. The impeller-side space is further defined by a first through-hole formed in the bearing holder that connects the rotor-side space of the shaft chamber to the impeller-side space, at least one second through-hole formed in the impeller, and a third through-hole formed in the housing that connects the impeller-side space of the shaft chamber to the outside of the housing. When filling the shaft chamber with liquid, gas in the rotor-side space of the shaft chamber passes through the first through-hole, the second through-hole, and the third through-hole in that order to escape to the outside of the housing. This creates a gas discharge line consisting of three through-holes in the shaft chamber, improving gas discharge from the shaft chamber regardless of whether the liquid pump is installed horizontally or vertically, thereby shortening the time required to fill the shaft chamber with liquid, for example. This also improves the discharge of gas that has flowed into the shaft chamber or that is generated in the shaft chamber during pump operation.

[0006] In some embodiments, when the liquid pump is installed with the shaft oriented horizontally, the first through-hole and the third through-hole are located at the top of the shaft chamber, thereby improving the gas discharge performance from the shaft chamber when the liquid pump is installed horizontally.

[0007] In some embodiments, when the liquid pump is installed with its shaft oriented horizontally, at least a portion of each of the first through hole and the third through hole is located at the top of the shaft chamber, which further improves gas discharge from the shaft chamber when the liquid pump is installed horizontally.

[0008] In some embodiments, the second through-hole is located on the peripheral wall surface of the shaft chamber, which improves the ability to discharge gas from the shaft chamber when the liquid pump is placed horizontally.

[0009] In some embodiments, the radial distances of the first through hole, the second through hole, and the third through hole when viewed from the rotation axis of the impeller are the same, which makes the gas discharge line linear depending on the position of the through hole of the impeller, improving the gas discharge efficiency from the shaft chamber.

[0010] In some embodiments, the second through-hole formed in the impeller is elongated in the circumferential direction, which increases the likelihood that a portion of the through-hole of the impeller will be located at the top (or the uppermost part) of the shaft chamber when the pump is stopped, improving gas discharge performance from the shaft chamber.

[0011] In some embodiments, the at least one second through-hole formed in the impeller is a plurality of second through-holes arranged on the same circumference around the rotation axis, which increases the likelihood that one of the through-holes in the impeller will be located at the top (or the top) of the shaft chamber when the pump is stopped, improving the efficiency of gas discharge from the shaft chamber.

[0012] In some embodiments, the apparatus further includes a control device that rotates the impeller so that the second through-hole is positioned at the top of the shaft chamber when the shaft chamber is filled with liquid, thereby ensuring that the through-hole of the impeller is positioned at the top of the shaft chamber and improving gas discharge performance from the shaft chamber.

[0013] In some embodiments, the liquid is a pressurized liquid, such as liquefied ammonia, and is filled into the shaft chamber under its own pressure, thereby increasing the efficiency of filling the shaft chamber by not only forcing the liquid into the shaft chamber under its own pressure but also by promoting the evacuation of gas from the shaft chamber.

[0014] In some embodiments, the liquid is a corrosive liquid, such as liquefied ammonia, which allows for improved gas evacuation from the shaft chamber when filling the liquid, even if the shaft chamber is corrosive and therefore closed to the motor driving the liquid pump. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view showing a liquid pump according to one embodiment, taken along a plane passing through a shaft. [Figure 2] 2 is a view of a through hole formed in a bearing support portion of the liquid pump of FIG. 1, viewed from the rotor side in the direction of arrow II in FIG. 1. [Figure 3] 3 is a view of the impeller of the liquid pump of FIG. 1 and the through-hole formed therein, as viewed in the direction of arrow III in FIG. [Figure 4] 4 is a view of a gas discharge hole formed in a front cover of the liquid pump of FIG. 1, viewed in the direction of arrow IV in FIG. [Figure 5] FIG. 10 is a front view showing an elongated through-hole formed in an impeller according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Various embodiments of the present technology will be described below with reference to the drawings. A pump 10 shown in FIG. 1 as one embodiment can be used to transfer liquid, and is provided, for example, as a component of a fuel supply system. The pump 10 can be provided as an in-line liquid supply pump in a supply line that connects a liquid supply source, such as a tank, to a place where the liquid is used. A shutoff valve can be provided in the upstream portion of the supply line.

[0017] Liquid fuels also include liquefied gaseous fuels. Liquid fuels are corrosive or pressurized fuels, such as liquefied ammonia. Liquefied ammonia can be used as a fuel directly or can be used to produce hydrogen fuel by pyrolysis downstream of pump 10.

[0018] [housing] As shown in Figure 1, the pump 10 includes a housing 12. In one embodiment, the housing 12 can be divided into a body member 14, a front cover member 18, and a rear cover member 22. The front cover member 18 and the rear cover member 22 can be fixed to the body member 14 by an appropriate method, such as bolting. O-rings for sealing are disposed between the body member 14 and the front cover member 18 and between the body member 14 and the rear cover member 22, respectively. The body member 14 is provided with an intake port 16 that is connected to a liquid supply source, and the front cover member 18 is provided with an outlet port 20 that is connected to a place where the liquid is used.

[0019] [Impeller] The pump 10 may be, for example, a vortex pump (also known as a Westco pump or regenerative pump). An impeller 24 is provided within the housing 12 between the body member 14 and the front cover member 18. The impeller 24 is disc-shaped, with numerous blades 26 formed on its periphery by holes or recesses that communicate with both sides (see FIG. 3). The impeller 24 is coupled to a shaft 40, which is rotatably supported by the body member 14 via bearings 42.

[0020] [Boost passage] A boost passage 28 is formed between the body member 14 and the front cover member 18, extending over a range less than one circumference along the blades 26 at the peripheral edge of the impeller 24. Specifically, it is formed by a passage groove 30 formed in the body member 14 and a passage groove 32 formed in the front cover member 18. An inlet passage 34 connecting the suction port 16 and the boost passage 28 is formed in the body member 14, and an outlet passage 36 connecting the boost passage 28 and the discharge port is formed in the front cover member 18.

[0021] [Shaft chamber] The bearing 42 is held by a bearing holder 46 formed in the body member 14. The shaft 40 is accommodated in a shaft chamber 44 formed in the housing. The shaft chamber 44 may be cylindrical, for example, with a substantially constant radius. The bearing holder 46 is formed to protrude radially inward from the peripheral wall of the shaft chamber 44, dividing the shaft chamber 44 into a rotor-side space 48 and an impeller-side space 50. The rotor-side space 48 is formed between the rear cover member 22 and the body member 14, and the impeller-side space 50 is formed between the body member 14 and the front cover member 18. The rotor is located in the rotor-side space 48. The peripheral edge of the impeller 24 is located in the boost passage 28, while the center is located in the impeller-side space 50 of the shaft chamber 44.

[0022] [Impeller through-hole] As shown in Figure 3, a plurality of through holes 25 are formed in the impeller 24. The through holes 25 are arranged with as uniform an angular distribution as possible. These through holes 25 enable pressure balance on both sides of the impeller 24. The through holes 25 can be arranged on a plurality of circumferences C1, C2, and C3 having different radii. The plurality of through holes 25 located on the same circumference can be, for example, two or more, three or more, or four or more (four in the figure) arranged at equal angular intervals.

[0023] [Motor] 1, the pump 10 includes a motor 60 for rotating the impeller 24. The motor 60 is fixed to the rear cover member 22 via a bracket 63. The pump 10 is controlled by a control device (not shown) electrically connected to the motor 60. The control device includes a processor and a memory, and controls the pump 10 by having the processor execute a control program stored in the memory.

[0024] [Magnetic Coupling] The shaft 40 of the impeller 24 is connected to the housing 12 from the outside via a magnetic coupling. In one embodiment, the magnetic coupling can be configured to couple the opposing outer rotor 66 and inner rotor 68 with a radial magnetic flux. For example, the outer rotor 66 is disposed on the motor side and the inner rotor 68 is disposed on the pump 10 side, with the cup-shaped portion 64 of the rear cover member 22 sandwiched between them. The outer rotor 66 is a cylindrical body equipped with a plurality of magnets 70, and is coupled to the output shaft 62 of the motor 60. The inner rotor 68 is equipped with a plurality of magnets 72, and is coupled to the shaft 40 of the impeller 24.

[0025] In the above embodiment, the motor 60 is fixed to the outside of the housing 12 via the bracket 63, but in another embodiment (not shown), it is also possible to house both the motor 60 and the pump 10 in the same housing. Even in such an embodiment, when transferring a corrosive liquid such as liquefied ammonia or a high-pressure liquid, the interior of the motor may be separated from the interior of the pump 10 (the pressurization passage 28 or the shaft chamber 44) by a partition similar to the cup-shaped portion 64 of the rear cover member 22 so that the interior of the motor does not communicate with the interior of the pump 10 (the pressurization passage 28 or the shaft chamber 44). Torque from the motor is transmitted to the shaft across this partition by a magnetic coupling similar to that described above.

[0026] In yet another embodiment (not shown), the magnetic coupling may be configured to couple two facing disks with magnetic flux in the axial direction.

[0027] [Pump operation] When the pump 10 is filled with liquid and the motor 60 drives the impeller 24 to rotate, the liquid is drawn in from the supply source through the inlet passage 34, gains energy in the pressure boost passage, and is then discharged downstream through the outlet passage 36. Because the shaft chamber is also filled with liquid while the pump 10 is operating, the bearing 42 is immersed in the liquid, preventing wear due to dry sliding.

[0028] [Through holes for initial filling] As shown in FIG. 1, a gas discharge hole 80 is formed through the front cover member 18. At least one through hole 82 is formed in the bearing holder 46 of the body member 14. The through hole 82 in the bearing holder 46 may be a slit (long hole) having an arc-shaped cross section (see FIG. 2). The through holes 82 may be, for example, two or more, or three or more (three in the figure) arranged at equal angular intervals. The pump 10 may be installed not only with the shaft 40 oriented horizontally (horizontally), but also with the shaft 40 oriented vertically (vertically). In FIG. 1, the top of the pump 10 when horizontally oriented is at the top of the figure, but when the pump 10 is vertically oriented, the gas discharge hole 80 is oriented above the shaft chamber.

[0029] When the pump 10 is installed not inside a tank (in-tank type) but in the middle of a supply line (in-line type), a process is required to first fill the interior space of the pump 10 with the liquid to be supplied before operating the pump 10. Specifically, while the impeller 24 is stopped, the liquid supplied from a supply source such as a tank is filled into the interior of the pump 10 using its own pressure. During this initial filling, the liquid flows not only through the pressurization passage 28 but also into the shaft chamber 44 through the gap between the impeller 24 and the housing 12. At this time, air that has entered the shaft chamber 44 is discharged to the outside through the gas discharge hole 80 formed in the front cover member 18. In particular, regardless of whether the pump 10 is installed vertically or horizontally, air that was in the rotor-side space 48 of the shaft chamber 44 can escape to the outside of the housing by sequentially passing through the through-hole 82 in the bearing holder 46, the through-hole in the impeller 24, and the gas discharge hole 80 in the front cover member 18. By forming a gas discharge line consisting of a through-hole in the shaft chamber in this way, air can be efficiently discharged from the shaft chamber 44, allowing the shaft chamber 44 to be filled with liquid smoothly in a short time. Not only during the initial filling, but also gas that has entered from upstream of the pump 10 while the pump 10 is operating (while the impeller is rotating) and steam generated by evaporation of liquid inside the pump 10 are similarly discharged.

[0030] [Through-hole placement taking horizontal placement into consideration] As shown in Figures 1, 2, and 4, the gas discharge hole 80 of the front cover member 18 is located at the top of the impeller-side space 50 of the shaft chamber 44 (the uppermost part of the peripheral wall surface) when the pump 10 is placed horizontally. Similarly, a portion of one of the through-holes 82U of the bearing holder 46 is located at the top of the rotor-side space 48 of the shaft chamber 44 when the pump 10 is placed horizontally. Meanwhile, a portion of another through-hole 82L of the bearing holder 46 is located at the bottom of the rotor-side space 48 when the pump 10 is placed horizontally. When the pump 10 is placed horizontally, in the initial stage of filling, the liquid in the impeller-side space 50 flows into the rotor-side space 48 of the shaft chamber 44 through the through-hole 82L located at the bottom of the bearing holder 46. Meanwhile, in the final stage of filling, the air in the rotor-side space 48 does not accumulate at the ceiling but escapes to the impeller-side space 50 through the through-hole 82U located at the top and is then discharged to the outside through the gas discharge hole 80. In this way, when the pump 10 is placed horizontally, air can be efficiently discharged from the shaft chamber 44, so that the shaft chamber 44 can be smoothly filled with liquid in a short period of time.

[0031] As shown in FIGS. 1 and 3 , the four through-holes 84 located on the middle circumference C2 of the impeller 24 are positioned on the peripheral wall surface of the shaft chamber 44. As a result, when the pump 10 is placed horizontally, the through-holes 84 located on the peripheral wall surface of the shaft chamber 44 will be located at the upper or top of the shaft chamber 44 depending on the orientation of the impeller 24. Therefore, during the final stage of filling, air coming out of the through-holes 82 in the bearing holder 46 can smoothly escape toward the gas discharge hole 80 through the through-holes 84U in the impeller 24 located at the top of the shaft chamber 44. Thus, when the pump 10 is placed horizontally, depending on the orientation of the impeller 24, a gas discharge line L can be formed at the top of the shaft chamber 44, allowing for even smoother gas discharge. Although not shown, during initial filling, the motor 60 may be driven by the control device to stop the impeller 24 in an orientation such that the through-holes 25 are located at the top of the shaft chamber 44.

[0032] Furthermore, the four through holes 84 arranged on the peripheral wall surface of the shaft chamber 44 are located at substantially the same radial distance as the gas discharge hole 80 in the front cover member 18 and the through hole 82 in the bearing holder 46 when viewed from the impeller rotation axis. This allows a linear gas discharge line L to be formed depending on the orientation of the impeller 24, enabling smooth discharge of gas. Although not shown, even if the gas discharge line L is not formed at the top of the shaft chamber 44, the linear gas discharge line L allows smooth discharge of gas, particularly when the pump 10 is installed vertically.

[0033] 5, the four through holes 86 arranged on the peripheral wall surface of the shaft chamber 44 can be formed as elongated arc-shaped through holes 86 along the circumferential direction. This increases the probability that the impeller 24 will stop in an orientation such that any part of the elongated through holes 86 is near the gas discharge hole 80, enabling even smoother gas discharge.

[0034] [Gas exhaust hole connection] The gas discharge hole 80 is connected to an appropriate external location. In an embodiment not shown, the gas discharge hole can be connected to a supply line downstream of the pump 10 via a bypass line. In this case, the gas discharge hole can be provided with, for example, a check valve that prevents backflow from the bypass line when the pump 10 is operating.

[0035] [Initial filling inlet] In an embodiment not shown, the housing may be provided with a liquid inlet in addition to the suction port 16, and connected to a supply line upstream of the pump 10 via a bypass line. This allows for more efficient filling than filling only through the space between the impeller and the housing.

[0036] [Multi-stage pump] In an embodiment not shown, the pump 10 may be a multi-stage vortex pump in which multiple impellers are arranged on either side of a plate member and which includes a pressure boost passage that spirally connects the inlet passage 34 and the outlet passage 36. In this case, too, the through-holes described above can be provided in each of the multiple impellers.

[0037] Although various embodiments have been described above, the present technology is not limited to these embodiments, and those skilled in the art can make various modifications, substitutions, and improvements. [Explanation of symbols]

[0038] 10 Pump 12 Housing 14 Body parts 16 Intake port 18 Front cover member 20 outlet 22 Rear cover member 24 impeller 25 Impeller through-hole C1, C2, C3 circumference 26 Feather 28 Booster Passage 30 Passage groove of body member 32 Passage groove of front cover member 34 Entrance Passage 36 Exit passage 40 shaft 42 Bearings 44 Shaft chamber 46 Bearing holder 48 Rotor side space 50 Impeller side space 60 motor 62 Output shaft 63 Bracket 64 Cup-shaped portion of rear cover member 66 outer rotor 68 Inner rotor 70, 72 Magnets 80 Gas exhaust hole 82 Through hole in bearing holder L Gas exhaust line when placed horizontally Through hole located at the top of 82U 82L Lower hole 84 Impeller through-hole located on the peripheral wall surface Through hole located at the top of 84U 86 Arc-shaped through hole

Claims

1. A liquid pump comprising: Housing and a rotatable impeller housed in the housing; a shaft coupled to the impeller; a shaft chamber formed in the housing and accommodating the shaft; a bearing that rotatably holds the shaft in the shaft chamber; a bearing holding portion formed in the housing to hold the bearing; a rotor coupled to the shaft and rotated from outside the housing via a magnetic coupling, The shaft chamber is divided into a rotor-side space and an impeller-side space by the bearing holder, the rotor is located in the rotor-side space, and a center portion of the impeller is located in the impeller-side space; and a first through hole formed in the bearing holder and communicating the rotor-side space and the impeller-side space of the shaft chamber; At least one second through hole formed in the impeller; a third through-hole formed in the housing, the third through-hole communicating the impeller-side space of the shaft chamber with the outside of the housing; A liquid pump in which, when filling the shaft chamber with liquid, gas in the rotor-side space of the shaft chamber passes through the first through hole, the second through hole, and the third through hole in sequence to escape to the outside of the housing.

2. 2. The liquid pump of claim 1, wherein when the liquid pump is installed with the shaft oriented horizontally, the first through hole and the third through hole are each located at an upper portion of the shaft chamber.

3. 3. A liquid pump according to claim 2, wherein when the liquid pump is installed with the shaft oriented horizontally, at least a portion of each of the first through hole and the third through hole is located at the top of the shaft chamber.

4. 2. The liquid pump according to claim 1, wherein the second through-hole is located in a peripheral wall surface of the shaft chamber.

5. 2. The liquid pump according to claim 1, wherein the radial distances of the first through hole, the second through hole, and the third through hole when viewed from the rotation axis of the impeller are the same.

6. 2. The liquid pump according to claim 1, wherein the second through-hole formed in the impeller is elongated along the circumferential direction.

7. 2. The liquid pump according to claim 1, wherein the at least one second through-hole formed in the impeller is a plurality of second through-holes arranged on the same circumference around the rotation axis.

8. 2. The liquid pump of claim 1, further comprising a control device, wherein the control device rotates the impeller so as to stop the impeller at a position where the second through hole is at the top of the shaft chamber when the liquid is filled into the shaft chamber.

9. 2. The liquid pump of claim 1, wherein the liquid is a pressurized liquid, such as liquefied ammonia, and fills the shaft chamber under its own pressure.

10. 2. The liquid pump of claim 1, wherein the liquid is a corrosive liquid such as liquefied ammonia.

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