JP2013053535A - Gear pump, fluid jetting device, and fluid transfer method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve cleanability of a gear pump by discharging a fluid, which leaks out to the outside of a gear housing from a rotating shaft part (shaft hole) protruding from the gear housing, together with a fluid which flows through an internal space of the rotating shaft and outside the gear housing.SOLUTION: The gear pump includes: a gear; a gear housing which includes a gear accommodation part for accommodating the gear, and an inlet port and an exhaust port for a fluid, communicating with the gear accommodation part; and the rotating shaft which is attached to the gear and rotated integrally with the gear. The rotating shaft is a hollow rotating shaft, and the fluid flows in from one end of the rotating shaft and flows out from the other end of the rotating shaft.

Description

  The present invention relates to a gear pump, a fluid ejection device, and a fluid transfer method.

  As an example of a gear pump, one that is housed in a housing in a state in which a drive gear and a driven gear mesh with each other is known. In the gear pump, one end side of the rotation shaft is inserted into the shaft hole of the drive gear, and the other end side of the rotation shaft protrudes from the housing and is connected to a rotation drive source. When the rotating shaft rotates by the drive source and the gear rotates, the fluid is sucked into the gear housing portion from the suction port, and then the fluid is confined in the space formed by the gear mesh and the inner wall of the gear housing portion. And are sequentially delivered to the discharge port. Therefore, the fluid is transferred by the gear pump (for example, refer to Patent Document 1).

JP 2005-163711 A

  In the gear pump of Patent Document 1, in order to prevent fluid leakage from the rotating shaft portion (shaft hole) protruding from the housing, the housing and the cover covering the housing are brought into close contact with each other via a seal member, or attached to the rotating shaft. A seal member is provided. However, it is difficult to completely prevent fluid leakage from the rotating shaft portion, and fluid leaks out of the housing. When the fluid passes only through the housing in which the gear is accommodated as in the gear pump of Patent Document 1, in order to clean the fluid that has leaked out of the housing, a large amount of cleaning liquid is passed through the gear pump, The gear pump has to be disassembled and the cleanability is poor.

  Therefore, an object of the present invention is to improve the washability of the gear pump.

A main invention for solving the above problems includes a gear, a gear housing portion that houses the gear, a fluid suction port that communicates with the gear housing portion, a gear housing provided with a discharge port, and the gear. A rotating shaft attached and rotating integrally with the gear;
The rotary shaft is a hollow rotary shaft, and the fluid flows in from one end of the rotary shaft, and the fluid flows out from the other end of the rotary shaft.
Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

It is the schematic of an inkjet printer. 2A is a cross-sectional view of a gear pump of a comparative example, and FIG. 2B is a top view of a pump housing of the gear pump of the comparative example. FIG. 3A is a sectional view of the gear pump of the present embodiment, and FIG. 3B is a view of the pump housing as seen from above. It is a figure explaining the flow path of the fluid which flows through the inside of a pump housing. It is a figure explaining the flow path of the fluid which flows through the inside of a gear pump.

=== Summary of disclosure ===
At least the following will become apparent from the description of the present specification and the accompanying drawings.

That is, a gear, a gear housing that houses the gear, a fluid housing that communicates with the gear housing, a gear housing provided with a discharge port, and a gear housing that is attached to the gear and rotates together with the gear. A rotary shaft, and the rotary shaft is a hollow rotary shaft, and the fluid flows from one end of the rotary shaft and the fluid flows from the other end of the rotary shaft. It is.
According to such a gear pump, the fluid leaking out of the gear housing from the rotating shaft portion (shaft hole) protruding from the gear housing can flow along with the fluid flowing outside the gear housing and the inner space of the rotating shaft, The washability of the gear pump can be improved.

Such a gear pump, comprising: a rotor that is attached to the rotating shaft and rotates the rotating shaft; and a rotor housing that is provided with a rotor housing portion that houses the rotor. Fluid flowing into the end portion of the rotating shaft located inside or fluid flowing out from the end portion of the rotating shaft flows in the rotor housing portion.
According to such a gear pump, the fluid leaking into the rotor accommodating portion from the rotating shaft portion (shaft hole) protruding from the gear housing to the rotor housing is caused to flow together with the fluid flowing through the rotating shaft and the rotor accommodating portion. And the washability of the gear pump can be improved.

Such a gear pump is provided on the outer periphery of the rotor housing and includes an external rotor that is rotated by a drive motor, and is provided to each of the rotor and the external rotor as the external rotor rotates. The rotor is rotated by the magnetic force generated between the magnets, and the rotating shaft and the gear are rotated with the rotation of the rotor.
According to such a gear pump, since fluid leakage to the outside of the rotor housing can be suppressed, the inside of the gear pump can be sufficiently cleaned by flowing a fluid into the rotor housing portion. Further, since the rotor rotates without contact with the drive motor and the heat of the drive motor is difficult to be transmitted to the fluid, changes in the viscosity and composition of the fluid can be prevented.

In such a gear pump, the gear housing is provided with a flow path that communicates the suction port or the discharge port with the end of the rotating shaft located in the gear housing.
According to such a gear pump, fluid can be flowed into the internal space of the rotating shaft.

In such a gear pump, the end of the rotating shaft located in the rotor housing is located above the outflow port for allowing fluid to flow out of the gear pump in the vertical direction.
According to such a gear pump, a component that easily settles (for example, an ink coloring material) contained in the fluid can be easily directed to the outlet by gravity, and the component that easily settles stays in the gear pump. Can be suppressed.

In this gear pump, the end portion of the rotating shaft located in the rotor housing is positioned below the vertical direction from the outlet that allows the fluid to flow out of the gear pump.
According to such a gear pump, the bubbles contained in the fluid can be easily directed to the outlet by buoyancy, and the retention of bubbles in the gear pump can be suppressed.

A fluid ejecting apparatus that transports fluid using such a gear pump.
According to such a fluid ejecting apparatus, it is possible to transfer the fluid with the gear pump having improved cleaning properties, and it is possible to improve the replaceability of the fluid flowing in the fluid ejecting apparatus.

A fluid transfer method for transferring a fluid using such a gear pump.
According to such a fluid transfer method, the fluid can be transferred by the gear pump having improved cleaning properties, and the replaceability of the fluid can be improved.

=== About Printer 1 ===
FIG. 1 is a schematic diagram of an ink jet printer (hereinafter, printer 1). The embodiment will be described using the printer 1 as an example of the “fluid ejecting apparatus”. The printer 1 includes an ink tank 10, an outward tube 11 a, a return tube 11 b, a head 12, a cap 13, and a platen 14.

  The head 12 includes a plurality of nozzles Nz, an ink chamber 121 provided for each nozzle Nz and communicating with each nozzle Nz, and a common ink chamber 122 communicating with the plurality of ink chambers 121. The ink ejection method from the nozzle Nz is a method in which ink is ejected from the nozzle Nz by applying a voltage to the drive element (piezo element) to expand and contract the ink chamber 121, or a nozzle by a drive element (heat generating element). There is a system in which bubbles are generated in Nz and ink is ejected from the nozzles Nz with the bubbles.

  The ink tank 10 that stores ink communicates with the common ink chamber 122 of the head 12 via the forward tube 11a and the return tube 11b. A gear pump P is provided in the middle of the forward tube 11a.

  In the printing mode, an image forming operation in which ink is ejected while the head 12 moves in the moving direction toward the recording medium S (paper, film, etc.) supported by the platen 14 and recording is performed in a direction crossing the moving direction. The transport operation for transporting the medium S is repeated. As a result, dots are formed in the subsequent image forming operation at positions on the recording medium S different from the positions of the dots formed by the previous image forming operation, and a two-dimensional image is formed on the recording medium S. Printed. When ink is consumed in the printing mode, the controller (not shown) of the printer 1 operates the gear pump P, transfers the ink in the ink tank 10 to the head 12, and supplies the ink to the head 12.

  In addition, bubbles may be mixed in the ink in the head 12 or the ink flow path (the forward path tube 11a and the return path tube 11b). As a result, the nozzle Nz is clogged or the ink in the ink chamber 121 cannot be properly pressurized, and an appropriate amount of ink is not ejected from the nozzle Nz. Further, the air bubbles obstruct the flow of ink, and a sufficient amount of ink cannot be supplied to the head 12.

  Therefore, the printer 1 periodically executes a “maintenance mode” for removing bubbles in the ink. In the maintenance mode, the controller moves the head 12 to the home position (a region not facing the recording medium S) and seals the nozzle surface of the head 12 with the cap 13. In this state, the controller operates the gear pump P and circulates ink in the order of the ink tank 10, the forward path tube 11a, the head 12, and the return path tube 11b. By doing so, air bubbles mixed in the ink in the head 12 and the ink flow path can be sent to the ink tank 10. The bubbles sent to the ink tank 10 are bounced off at the ink level and disappear. In this way, the bubbles mixed in the ink in the head 12 and the ink flow path can be removed.

  Note that at the end of the maintenance mode, the head 12 and the cap 13 may be separated while the air layer of the ink tank 10 is pressurized with an air pump (not shown) and the ink in the head 12 is pressurized. Then, bubbles are ejected vigorously from the nozzle Nz together with the ink, and the bubbles mixed in the ink in the head 12 can be more reliably removed.

=== About Gear Pump P ===
<< Gear Pump P 'of Comparative Example >>
FIG. 2A is a cross-sectional view of a gear pump P ′ of a comparative example, and FIG. 2B is a view of the pump housing 25 in which gears 26, 27 and the like are accommodated in the gear pump P ′ of the comparative example as viewed from above. 2A is a cross-sectional view of the gear pump P ′ of the comparative example cut along the axial direction (vertical direction) at the center in the Y direction (position AA ′ in FIG. 2B).

First, the configuration of the gear pump P ′ of the comparative example will be described.
The gear pump P ′ of the comparative example includes a drive motor 20, a substantially cylindrical outer rotor 21 whose upper surface is closed, a substantially columnar inner rotor 22, a substantially cylindrical rotor housing 23 whose upper surface is closed, and a partition. The plate 24, a substantially rectangular parallelepiped pump housing 25, a drive gear 26, a drive shaft 26a, a driven gear 27, a driven shaft 27a, and a seal member 30 are provided. The external rotor 21 has an external magnet support member 211 and an external magnet 212, and the internal rotor 22 has an internal magnet support member 221 and an internal magnet 222.

  On the upper surface of the pump housing 25, there are provided a gear housing portion C1 (recessed portion) for housing the drive gear 26 and the driven gear 27, and a suction port 31 and a discharge port 32 (recessed portion) communicating with the gear housing portion C1. . The gear housing portion C1 has a shape in which a part of a cylindrical recess that houses the gears 26 and 27 is overlapped, and the drive gear 26 and the driven gear 27 are engaged with each other in the gear housing portion C1. Contained. The gear housing portion C1 is partitioned by a region where the teeth of the two gears 26 and 27 mesh with each other. As shown in FIG. 2B, the region on the near side in the Y direction with respect to the region where the teeth of the two gears 26 and 27 mesh with each other communicates with the suction port 31, and the region on the far side in the Y direction communicates with the discharge port 32. .

  The pump housing 25 communicates with the first inflow port 28a and the first outflow port 29a (hollow cylindrical portion) projecting from the lower surface, the first inflow port 28a and the suction port 31, and extends in the axial direction. A second inflow port 28b (space portion) and a second outflow port 29b (space portion) that communicates with the discharge port 32 and the first outflow port 29a and extends in the axial direction are provided. The pump housing 25 and the partition plate 24 are tightly coupled via a seal member 30 (for example, an O-ring) so that the partition plate 24 closes the upper surface of the pump housing 25.

  A drive shaft 26a is inserted into a shaft hole provided in the center of the drive gear 26, and the drive gear 26 and the drive shaft 26a are coupled so as to be integrally rotatable. Similarly, a driven shaft 27a is inserted into a shaft hole provided in the center of the driven gear 27, and the driven gear 27 and the driven shaft 27a are coupled so as to be integrally rotatable. When the gears 26 and 27 are viewed from above (FIG. 2B), the drive gear 26 rotates counterclockwise and the driven gear 27 rotates clockwise. The drive shaft 26a and the driven shaft 27a are cylindrical shafts having no space inside.

  The lower end of the drive shaft 26a and the lower end of the driven shaft 27a are rotatably supported by a bearing portion provided in the pump housing 25 (a recess provided in the lower surface of the gear housing portion C1). On the other hand, the upper end of the drive shaft 26 a protrudes from the pump housing 25 and the partition plate 24 and is rotatably supported by a bearing portion (concave portion) provided on the inner upper surface of the rotor housing 23. The upper end of the driven shaft 27 a is rotatably supported by a bearing portion (concave portion) provided on the partition plate 24.

  And the internal rotor 22 is attached to the part of the drive shaft 26a which protruded from the partition plate 24 so that integral rotation with the drive shaft 26a is possible. In other words, the internal magnet 222 is attached to the drive shaft 26 a via the internal magnet support member 221.

  Then, the rotor housing 23 covers the partition plate 24 so that the rotor housing 23 covers the inner rotor 22, that is, the inner rotor 22 is accommodated in the inner rotor accommodating portion C 2 provided in the rotor housing 23. It is attached. Note that the rotor housing 23 and the partition plate 24 are tightly coupled via a seal member 30.

  Further, the external rotor 21 is attached to the rotor housing 23 so as to cover the rotor housing 23. Then, the external magnet 212 located on the inner peripheral side of the external rotor 21 is in a state of facing the internal magnet 222 of the internal rotor 22 via the rotor housing 23. A drive motor 20 is attached to the upper portion of the external rotor 21.

Next, the operation of the gear pump P ′ of the comparative example will be described.
First, the external rotor 21 is rotated by driving the drive motor 20. Then, the internal rotor 22 rotates due to the magnetic force generated between the external magnet 212 and the internal magnet 222 via the rotor housing 23. The drive shaft 26 a and the drive gear 26 rotate with the rotation of the internal rotor 22, and the driven gear 27 and the driven shaft 27 a rotate with the rotation of the drive gear 26.

  When the drive gear 26 and the driven gear 27 rotate, the fluid (for example, ink) located in the suction port 31 is confined in the tooth space C3 formed by the gears of the gears 26 and 27 and the inner wall of the gear housing portion C1. And are sequentially sent to the discharge port 32. When the mesh space C3 containing the fluid reaches the discharge port 32, the teeth of the other gear enter the mesh space C3. Therefore, the fluid sent to the discharge port 32 cannot return to the suction port 31 and flows from the discharge port 32 to the second outlet 29b.

When the drive gear 26 and the driven gear 27 rotate in this way, the fluid in the suction port 31 is sequentially sent to the discharge port 32, and the suction port 31 is in a lower pressure state than the discharge port 32, and from the outside of the gear pump P ′. The fluid flows into the suction port 31 through the first inlet 28a and the second inlet 28b. Further, the discharge port 32 is in a higher pressure state than the suction port 31, and fluid is pumped from the discharge port 32 to the outside of the gear pump P ′ through the second outlet port 29b and the first outlet port 29a.
As described above, in the gear pump P ′ of the comparative example, the first inlet 28a, the second inlet 28b, the suction port 31, the gear housing portion C1, the discharge port 32, the second outlet 29b, and the first outlet 29a. In this order, fluid flows.

Next, the problem of the gear pump P ′ of the comparative example will be described.
In the gear pump P ′ of the comparative example, the rotational force of the drive motor 20 is driven by the external magnet 212 of the external rotor 21 and the internal magnet 222 of the internal rotor 22 while the drive motor 20 and the drive shaft 26a are not in contact with each other. It is transmitted to the shaft 26a. Therefore, the drive shaft 26a protruding from the partition plate 24 can be sealed by the rotor housing 23 and the partition plate 24, and has a structure that hardly leaks from the fluid to the outside of the gear pump P ′.

  However, the fluid flowing in the gear housing portion C1 from the shaft hole of the drive shaft 26a provided in the partition plate 24, that is, the gap between the partition plate 24 and the drive shaft 26a (hereinafter referred to as the through portion of the drive shaft 26a) There is a risk of leakage into the rotor accommodating portion C2. On the contrary, there is a possibility that the fluid leaking into the inner rotor accommodating portion C2 flows backward from the penetrating portion of the drive shaft 26a to the gear accommodating portion C1. Even if a seal member (not shown) is provided in the penetrating portion of the drive shaft 26a, it is difficult to completely prevent fluid leakage between the gear housing portion C1 and the internal rotor housing portion C2.

  Even if the fluid leaks into the internal rotor accommodating portion C2, it is difficult to remove the fluid leaking into the internal rotor accommodating portion C2 when the fluid flows only in the pump housing 25 as in the gear pump P ′ of the comparative example. . For example, a large amount of cleaning liquid must be allowed to flow through the gear pump P 'or the gear pump P' must be disassembled. That is, the gear pump P ′ of the comparative example has poor cleaning properties.

  If the cleaning performance is poor as in the gear pump P ′ of the comparative example and the fluid remains leaking into the internal rotor accommodating portion C2, the color of the ink used in the printer 1, that is, the ink flowing through the gear pump P ′ is replaced. In this case, there is a possibility that the ink of the previous color that has leaked into the internal rotor accommodating portion C2 flows back to the gear accommodating portion C1, and the ink colors are mixed. Further, if the cleaning liquid that has flowed during the cleaning of the gear pump P ′ remains leaking into the internal rotor accommodating portion C2, the cleaning liquid may flow backward into the gear accommodating portion C1, and the cleaning liquid and ink may be mixed. If it does so, the image quality of a printed image will fall.

That is, when the fluid used for the rotary pump P ′ of the comparative example is replaced with the fluid used for the rotary pump P ′ of the comparative example, if the cleaning performance of the fluid leaking into the internal rotor accommodating portion C2 is poor like the rotary pump P ′ of the comparative example, This causes a problem that the fluids are mixed.
Therefore, the gear pump P of the present embodiment aims to improve the cleaning performance of the gear pump P and improve the replacement performance of the fluid used for the gear pump P.

<< Gear Pump P of this Embodiment >>
FIG. 3A is a cross-sectional view of the gear pump P of the present embodiment, and FIG. 3B is a view of the pump housing 25 in a state where the gears 26, 27, etc. are accommodated, as viewed from above. 3A is a cross-sectional view of the gear pump P cut along the axial direction at the center in the Y direction (position AA ′ in FIG. 3B), and the right view of FIG. 3A shows the gear pump P. Is a cross-sectional view taken along the axial direction at the center in the X direction (position BB ′ in FIG. 3B) (viewed from the right side in the X direction). FIG. 4 is a diagram illustrating the flow path of the fluid flowing in the pump housing 25, and FIG. 5 is a diagram illustrating the entire flow path of the fluid flowing in the gear pump P. 4 and 5, the outer shape of the pump housing 25 is not shown, and only the flow path of the fluid flowing in the pump housing 25 is shown.

First, the structure of the gear pump P of this embodiment is demonstrated. The difference from the gear pump P ′ of the comparative example will be mainly described.
The gear pump P of the present embodiment includes a drive motor 20, an external rotor 21, an internal rotor 22, a rotor housing 23, a partition plate 24, a pump housing 25 (corresponding to a gear housing), and a drive gear 26 (gear). ), A drive shaft 40 (corresponding to a rotation shaft), a driven gear 27, a driven shaft 27a, and a seal member 30. The internal rotor 22 is accommodated in the internal rotor accommodating portion C <b> 2 without contacting the inner peripheral surface of the rotor housing 23 and the upper surface of the partition plate 24. That is, a space is provided between the rotor housing 23 and the partition plate 24 over the entire circumference of the inner rotor 22. Therefore, the fluid can pass through the inner rotor accommodating portion C2.

  In the gear pump P of the present embodiment, the driven shaft 27 is a cylindrical shaft having no space inside, whereas the drive shaft 40 (corresponding to a rotating shaft) is a cylindrical shaft having a space C4 inside. That is, it is a hollow shaft. Therefore, the fluid can pass through the internal space C4 of the drive shaft 40. Further, the upper end portion of the drive shaft 40 is provided in a recess (hereinafter referred to as a ceiling recess C <b> 5) provided on the inner upper surface of the rotor housing 23. The upper end of the drive shaft 40 is supported at the ceiling recess C5 at a plurality of points (for example, four points in a cross shape) on the upper end surface of the drive shaft 40 so that the entire inner space C4 is not blocked. A member 231 (rib member) is rotatably supported. Accordingly, the internal space C4 of the drive shaft 40 communicates with the internal rotor accommodating portion C2.

  The pump housing 25 communicates with the “first inflow port 28a (hollow cylindrical portion)” and the “first outflow port 29a (hollow cylindrical portion)” protruding from the lower surface, and in the axial direction. "Second inlet 28b (space part)" extending to the "second inlet 28b" and "suction port 31 (concave part)" extending in the Y direction to the gear accommodating part C1, and "gear accommodating" "First intermediate flow path 41" that communicates the "portion C1 (recessed portion)", the "discharge port 32 (recessed portion)" extending in the Y direction from the gear housing portion C1, and the inner space C4 of the drive shaft 40. (Space part) ".

  As shown in the right view of FIG. 3A and FIG. 4, the first intermediate flow path 41 is a space that extends downward from the discharge port 32 and then bends 90 degrees to the lower end of the drive shaft 40 in the Y direction. Thus, by providing the pump housing 25 with the first intermediate flow path 41 that communicates the discharge port 32 and the lower end of the drive shaft 40 (that is, the end of the drive shaft 40 located in the pump housing 25), A fluid can flow in the internal space C4 of the drive shaft 40.

  Furthermore, the partition plate 24 is provided with a “second intermediate flow path 42 (space part)” that penetrates in the axial direction from the upper surface to the lower surface, and the pump housing 25 has “second” that penetrates in the axial direction from the upper surface to the lower surface. 3 intermediate flow path 43 (space part) "is provided. The second intermediate flow path 42 communicates with the inner rotor accommodating portion C2 and the third intermediate flow path 43, and the third intermediate flow path 43 communicates with the second intermediate flow path 42 and the first outlet 29a.

Next, operation | movement of the gear pump P of this embodiment is demonstrated.
The external rotor 21 is rotated by driving the drive motor 20. Then, the internal rotor 22 rotates due to the magnetic force generated between the external magnet 212 and the internal magnet 222 via the rotor housing 23. The drive shaft 40 and the drive gear 26 rotate with the rotation of the internal rotor 22, and the driven gear 27 and the driven shaft 27 a rotate with the rotation of the drive gear 26.

  When the drive gear 26 and the driven gear 27 rotate, the fluid in the suction port 31 is sequentially sent to the discharge port 32 as shown in FIG. 4, and the suction port 31 is in a lower pressure state than the discharge port 32. Then, fluid flows into the suction port 31 from the outside of the gear pump P through the first inlet 28a and the second inlet 28b. On the other hand, the discharge port 32 is in a higher pressure state than the suction port 31, and fluid flows out from the discharge port 32.

  As shown in FIGS. 4 and 5, the fluid flowing out from the discharge port 32 flows through the first intermediate flow path 41, and flows through the internal space C <b> 4 of the drive shaft 40 from the lower end to the upper end of the hollow drive shaft 40. . The fluid that has flowed through the internal space C4 of the drive shaft 40 flows out from the portion of the upper end surface of the drive shaft 40 that is not supported by the support member 231 (that is, from between the support members 231) to the internal rotor accommodating portion C2. To do. That is, the lower end of the hollow drive shaft 40 serves as a fluid inflow port, and the upper end of the drive shaft 40 serves as a fluid outflow port.

  The fluid that has flowed out of the drive shaft 40 into the inner rotor accommodating portion C2 flows between the outer peripheral surface of the inner rotor 22 and the inner peripheral surface of the rotor housing 23, that is, flows through the upper surface and side surfaces of the inner rotor 22, and the partition plate 24 Reach the top of the. The fluid reaching the upper surface of the partition plate 24 flows to the second intermediate flow path 42 between the lower surface of the internal rotor 22 and the upper surface of the partition plate 24. Thereafter, the fluid sequentially flows through the second intermediate flow path 42 and the third intermediate flow path 43 and flows out of the gear pump P through the first outlet 29a.

  That is, in the gear pump P of the present embodiment, the first inlet 28a, the second inlet 28b, the suction port 31, the gear housing portion C1, the discharge port 32, the first intermediate flow path 41, the drive shaft 40 (internal space C4). ), The inner rotor accommodating portion C2, the second intermediate flow path 42, the third intermediate flow path 43, and the first outlet 29a in this order.

  In the present embodiment, the gear pump P is used for transferring ink by the printer 1 (FIG. 1). Specifically, a gear pump P is provided in the middle of the forward tube 11 a that connects the ink tank 10 and the head 12. Therefore, when the drive motor 20 rotates and the drive gear 26 and the driven gear 27 rotate, the ink in the ink tank 10 flows into the gear pump P, and the ink that flows out of the gear pump P is pumped (transferred) to the head 12. The

As described above, in the gear pump P of the present embodiment, the drive shaft 40 (corresponding to the rotation shaft) attached to the drive gear 26 is a hollow shaft, and fluid flows from one end (here, the lower end) of the drive shaft 40. Then, the fluid flows out from the other end (here, the upper end) of the drive shaft 40.
By doing so, even if fluid leaks from the penetrating portion of the drive shaft 40 (the gap between the partition plate 24 and the drive shaft 40) to the outside of the gear housing portion C1, the upper end of the drive shaft 40 protruding from the partition plate 24 Thus, the fluid can flow outside the gear housing portion C1 (that is, to the portion where the fluid leaks). Accordingly, the fluid leaking from the penetrating portion of the drive shaft 40 to the outside of the gear housing portion C1 can be made to flow outside the gear pump P together with the fluid flowing out from the upper end of the drive shaft 40.

More specifically, the gear pump P of the present embodiment includes an internal rotor 22 (corresponding to a rotor) that is attached to the drive shaft 40 and rotates the drive shaft 40, and an internal rotor housing portion C <b> 2 that houses the internal rotor 22 ( And a rotor housing 23 (rotor housing) having a rotor accommodating portion). And the fluid which flows out from the upper end of the drive shaft 40 located in the rotor housing 23 is made to flow the inside of the internal rotor accommodating part C2.
By doing so, the fluid leaking from the penetrating portion of the drive shaft 40 to the internal rotor accommodating portion C2 flows out of the gear pump P together with the fluid flowing out from the upper end of the drive shaft 40 and flowing through the internal rotor accommodating portion C2. I can do it.

  That is, in the gear pump P of the present embodiment, the fluid actively flows to a portion where the fluid flowing through the gear housing portion C1 leaks from the penetrating portion of the drive shaft 40 (here, the internal rotor housing portion C2), and the fluid leaks. Make the location a fluid flow path. Therefore, in order to remove the leaked fluid, a large amount of cleaning liquid is flowed or the gear pump P ′ is disassembled like the gear pump P ′ of the comparative example in which the internal rotor accommodating portion C2 is not a fluid flow path. There is no need for the gear pump P of this embodiment. Therefore, the gear pump P of the present embodiment can improve the cleaning performance as compared with the gear pump P ′ of the comparative example.

  In the gear pump P of the present embodiment with improved detergency, after replacing the color of the ink flowing to the gear pump P, the ink of the previous color that leaked from the penetrating portion of the drive shaft 40 to the internal rotor accommodating portion C2 remains. Therefore, it is possible to prevent inks of different colors from being mixed. In addition, the cleaning liquid that flows when cleaning the gear pump P does not remain in the internal rotor accommodating portion C2, and it is possible to prevent the cleaning liquid and ink from being mixed. Thus, in the gear pump P of the present embodiment, in addition to the cleaning performance, the replacement performance of the fluid (ink or cleaning liquid) used for the gear pump P can be improved.

  Further, in the gear pump P ′ (FIG. 2) of the comparative example, since gas is present in the inner rotor accommodating portion C2, the gas in the inner rotor accommodating portion C2 is transferred from the penetrating portion of the drive shaft 40 into the gear accommodating portion C1. There is a risk of mixing. If bubbles are mixed in the fluid as described above, an appropriate amount of ink is not ejected from the nozzle Nz, or a sufficient amount of ink cannot be supplied to the head 12. On the other hand, in the gear pump P of the present embodiment, the internal rotor accommodating portion C2 serves as a fluid flow path, and the internal rotor accommodating portion C2 is filled with fluid. Therefore, in the gear pump P of this embodiment, it is difficult for gas (bubbles) to be mixed into the gear housing portion C1 from the penetrating portion of the drive shaft 40.

  Further, the pump P of the present embodiment is provided with an external rotor 21 (corresponding to an external rotor) that is rotated by the drive motor 20 on the outer periphery of the rotor housing 23 (corresponding to the rotor housing). As the external rotor 21 rotates, the internal rotor 22 rotates due to the magnetic force generated between the internal rotor 22 and the magnets (internal magnet 222 and external magnet 212) provided on the external rotor 21. The drive shaft 40, the drive gear 26, and the driven gear 27 are rotated along with the rotation.

  By doing so, the drive shaft 40 that protrudes from the partition plate 24 (the through portion of the drive shaft 40) can be sealed with the rotor housing 23 and the partition plate 24, and fluid leakage to the outside of the rotor housing 23 is suppressed. be able to. Therefore, if a fluid is allowed to flow from the drive shaft 40 into the rotor housing 23, the fluid leaking from the penetrating portion of the drive shaft 40 can be flowed, and the inside of the gear pump P can be sufficiently cleaned.

  Further, the internal rotor 22 accommodated in the internal rotor accommodating portion C <b> 2 rotates without contact with the drive motor 20. Therefore, it is difficult for heat generated by the drive motor 20 to be transmitted into the inner rotor accommodating portion C2, and the temperature in the inner rotor accommodating portion C2 is relatively low. Therefore, there is no problem even if a fluid that is easily affected by a temperature change (for example, an ink whose viscosity or composition is easily changed) is allowed to flow into the internal rotor accommodating portion C2. That is, in the gear pump P of the present embodiment, since the rotational force of the drive motor 20 is transmitted to the drive shaft 40 by the external magnet 212 and the internal magnet 222, the rotation source (in this case, the internal rotor 22) that rotates the drive shaft 40 is used. Even if a fluid is allowed to flow around, the influence of a temperature change on the fluid can be reduced.

  Further, in the gear pump P of the present embodiment, the end of the drive shaft 40 located in the rotor housing 23 is more than the first outlet 29a (corresponding to the outlet) that allows the fluid to flow out of the gear pump P. Located above the vertical direction. That is, the fluid flows in from the lower end of the drive shaft 40 and flows out from the upper end of the drive shaft 40.

  Therefore, for example, even when using ink in which the color material is likely to settle, the color material included in the ink flowing out from the upper end of the drive shaft 40 is likely to flow to the first outlet 29a by gravity. Accordingly, the retention of the coloring material in the gear pump P (particularly, in the internal rotor accommodating portion C2) can be suppressed, and an image can be printed with a desired concentration of ink.

=== Modification ===
In the above-described embodiment, the case in which the gear pump P is used in a posture in which the internal rotor 22 is positioned above the pump housing 25 in the vertical direction is described as an example.
For example, the gear pump P may be used in a posture in which the pump housing 25 is positioned above the inner rotor 22 in the vertical direction. That is, the end portion of the drive shaft 40 located in the rotor housing 23 may be positioned below the first outlet port 29a through which the fluid flows out of the gear pump P in the vertical direction. In this case, bubbles included in the fluid flowing out from the lower end of the drive shaft 40 are likely to rise toward the first outlet port 29a due to buoyancy. Therefore, the retention of bubbles in the gear pump P can be suppressed.

  In the above-described embodiment, the gear pump P is used in a posture in which the axial direction of the drive shaft 40 is along the vertical direction. However, the gear pump P is not limited thereto, and the gear shaft P is in a posture in which the axial direction of the drive shaft 40 is along the horizontal direction. A pump P may be used.

In the above-described embodiment, the fluid that has flowed into the gear pump P first passes through the gear housing portion C1, and then passes from the internal space C4 of the drive shaft 40 through the internal rotor housing portion C2 to the outside. To do. That is, the gear housing portion C1 is located on the upstream side of the flow path with respect to the internal rotor housing portion C2, but is not limited thereto.
For example, the fluid that has flowed into the gear pump P may first pass through the internal space C4 of the drive shaft 40, and then pass through the gear housing portion C1 from the internal rotor housing portion C2 and flow out to the outside. That is, the inner rotor accommodating portion C2 may be located on the upstream side of the flow path with respect to the gear accommodating portion C1. In this case, a flow path through which the fluid in the internal rotor accommodating part C2 flows is provided in the partition plate 24, and a flow path that communicates the flow path of the partition plate 24 and the suction port 31 of the gear accommodating part C1 is provided in the pump housing 25. .

In the above-described embodiment, the fluid flows in from the pump housing 25 and the fluid flows out from the pump housing 25. However, the present invention is not limited to this.
For example, the fluid flows into the inner rotor accommodating portion C2 from the side surfaces of the rotor housing 23 and the partition plate 24, and the fluid passes through the inner space C4 and the gear accommodating portion C1 of the drive shaft 40 in order, and then from the pump housing 25 to the outside. You may make it leak out. In this case, fluid flows into the end portion of the drive shaft 40 located in the rotor housing 23, and the end portion of the drive shaft 40 located in the pump housing 25 and the suction port 31 of the gear housing portion C1 communicate with each other. A flow path is provided in the pump housing 25.
Further, a fluid flows from the pump housing 25 into the gear housing portion C1, and after the fluid passes through the inner space C4 and the inner rotor housing portion C2 of the drive shaft 40 in order, the fluid flows from the side surfaces of the partition plate 24 and the rotor housing 23 to the outside. You may make it leak out.

  In particular, when the gear pump P is used in a posture in which the axial direction of the drive shaft 40 is along the horizontal direction, bubbles are discharged by providing an outlet on the upper side of the rotor housing 23 or the partition plate 24 in the vertical direction. By providing the outflow port at the lower part in the vertical direction, it is possible to easily discharge the color material that tends to settle.

  In the above-described embodiment, the gear pump P that rotates while the drive gear 26 and the driven gear 27 are engaged with each other in the gear housing portion C1 is described as an example, but the present invention is not limited thereto. For example, a gear pump may be used in which teeth are provided on the inner wall of the accommodating portion that accommodates the gear, and the gear in the accommodating portion rotates while meshing with the teeth provided on the inner wall.

  In the above-described embodiment, as shown in FIG. 1, the gear pump P is provided in the middle of the tube connecting the ink tank 10 and the head 12. However, the present invention is not limited to this. For example, you may provide the gear pump P in the middle of the tube attached to the lower surface of the cap which forms a sealed space between the nozzle surfaces of the head 12. In this case, when the gear pump P is operated in a state where the head 12 and the cap are in contact with each other, the sealed space is in a negative pressure state, and the ink and foreign matters that are thickened from the nozzle Nz are forcibly sucked, and the nozzle Nz Clogging can be prevented.

  In the above-described embodiment, the gear pump P is used in the fluid ejection device. However, the present invention is not limited to this, and the gear pump P may be used in another device that needs to transfer fluid.

=== Other Embodiments ===
Although the above embodiments are mainly described with respect to a gear pump, disclosure of a fluid ejecting apparatus, a fluid transfer method, and the like is included. The above-described embodiments are for facilitating understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

<Fluid ejection device>
In the above-described embodiment, an ink jet printer is exemplified as the fluid ejecting apparatus, but is not limited thereto. For example, a fluid ejecting apparatus such as a color filter manufacturing apparatus, a display manufacturing apparatus, a semiconductor manufacturing apparatus, and a DNA chip manufacturing apparatus may be used.

1 Printer, 10 Ink tank, 11a Outward tube,
11b Return tube, 12 heads, 13 caps, 14 platens,
P gear pump, 20 drive motor, 21 external rotor,
211 External magnet support member, 212 External magnet,
22 internal rotor, 221 internal magnet support member,
222 inner magnet, 23 rotor housing, 24 partition plate,
25 pump housing, 26 drive gear, 40 drive shaft,
27 driven gear, 27a driven shaft, 28a first inlet,
28b 2nd inflow port, 29a 1st outflow port, 30 sealing member,
31 suction port, 32 discharge port, 41 first intermediate flow path, 42 second intermediate flow path,
43 Third intermediate flow path

Claims (8)

Gears,
A gear housing that houses the gear, a fluid suction port that communicates with the gear housing, and a gear housing provided with a discharge port;
A rotating shaft attached to the gear and rotating integrally with the gear;
With
The rotating shaft is a hollow rotating shaft,
The fluid flows in from one end of the rotating shaft, and the fluid flows out from the other end of the rotating shaft.
A gear pump characterized by that. The gear pump according to claim 1,
A rotor attached to the rotating shaft and rotating the rotating shaft;
A rotor housing provided with a rotor housing portion for housing the rotor;
With
A fluid flowing into an end of the rotating shaft located in the rotor housing or a fluid flowing out of the end of the rotating shaft flows in the rotor housing portion;
Gear pump. The gear pump according to claim 2,
Provided on the outer periphery of the rotor housing, provided with an external rotor that is rotated by a drive motor,
Along with the rotation of the external rotor, the rotor is rotated by a magnetic force generated between magnets provided on the rotor and the external rotor, respectively, and the rotation shaft and the rotor are rotated along with the rotation of the rotor. The gear rotates,
Gear pump. The gear pump according to claim 3,
A flow path is provided in the gear housing for communicating the suction port or the discharge port and the end of the rotating shaft located in the gear housing;
Gear pump. The gear pump according to any one of claims 2 to 4,
The end of the rotating shaft located in the rotor housing is located above the outlet in the vertical direction from which the fluid flows out of the gear pump.
Gear pump. The gear pump according to any one of claims 2 to 4,
The end of the rotating shaft located in the rotor housing is located below the vertical direction from the outlet that allows the fluid to flow out of the gear pump.
Gear pump.   A fluid ejecting apparatus that transports a fluid using the gear pump according to claim 1.   The fluid transfer method which transfers a fluid using the gear pump of any one of Claims 1-6.