Pump unit

Abstract

To provide a pump unit capable of being driven with high efficiency.SOLUTION: The pump unit includes a housing, a first shaft extending in the housing along a first axis, and an external gear having a hole portion along the first axis and provided coaxially with the first shaft such that an inner periphery of the hole portion covers an outer periphery of the first shaft. The pump unit includes an internal gear meshing with the external gear so as to be rotatable around a second axis different from the first axis, a space between the internal gear and the external gear serving as a flow path of a fluid, and a second shaft provided coaxially with the external gear and having an outer periphery supported by the casing with a bearing. The pump unit includes a stator connected to an inner wall of the housing coaxially with the internal gear and outside the second shaft and having an electromagnet, and a rotor that is separated from the stator, has an inner periphery connected to an outer periphery of the second shaft, and rotates around the second axis according to an energization state of the electromagnet.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a pump unit. [Background technology]

[0002] 2. Description of the Related Art Conventionally, pump units in which a pump and a motor are formed in a single housing have been known.

[0003] In this regard, Patent Document 1 discloses an electric pump unit that includes an internal gear pump having an outer gear and an inner gear that mesh with each other, and a stator that is provided on the outer periphery of the gear pump. In the electric pump unit described in Patent Document 1, the outer gear rotates as a rotor when electricity is applied to the stator. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4484030 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the technology described in Patent Document 1, when the pump unit is driven, the outer gear, which functions as a rotor, is pushed toward the fluid discharge port by the pressure of the fluid flowing into the gear pump. Therefore, with the technology described in Patent Document 1, there are problems such as a decrease in efficiency due to changes in rotational torque and increased noise when the pump unit is driven.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a pump unit that can be driven with high efficiency. [Means for solving the problem]

[0007] In order to solve the above problem, the pump unit of the present invention comprises: a housing having an intake port and an outlet port for a fluid; a first shaft provided within the housing and extending along an imaginary first axis; an external gear having a hole extending along the first axis, the inner periphery of the hole covering the outer periphery of the first shaft and provided coaxially with the first shaft; an internal gear meshing with the external gear rotatably around an imaginary second axis different from the first axis, the space between the external gear being connected to the intake port and the outlet and forming a flow path for the fluid; a second shaft provided coaxially with the internal gear so as to cover the outer surface of the internal gear, the outer periphery being supported by the housing via a bearing; a cylindrical stator connected to the inner wall of the housing so as to be coaxial with the internal gear and outward from the second shaft, the stator having an electromagnet; and a cylindrical rotor provided between the second shaft and the stator, spaced apart from the stator, the inner periphery being connected to the outer periphery of the second shaft, the rotor rotating around the second axis depending on the energization state of the electromagnet.

[0008] The housing also has a space therein, at least a portion of which is cylindrical, and the second shaft has an outer periphery connected to the inner periphery of the cylindrical portion of the space in the housing via a rolling bearing.

[0009] Moreover, the inner periphery of the hole of the external gear is connected to the outer periphery of the first shaft via a rolling bearing.

[0010] Furthermore, the inner periphery of the hole of the external gear is fixedly connected to the outer periphery of the first shaft, and the first shaft is connected to the housing so as to be rotatable around the first axis. [Effects of the Invention]

[0011] According to the present invention, the pump unit can be driven with high efficiency. [Brief explanation of the drawings]

[0012] [Figure 1A]2 is a diagram showing a first example of the configuration of a pump unit according to the present embodiment. FIG. [Figure 1B] 1B is a cross-sectional view of the pump unit shown in FIG. 1A taken along line II. [Figure 1C] FIG. 1B is a side view of the pump unit shown in FIG. 1A. [Figure 2] FIG. 4 is a diagram showing a second example of the configuration of the pump unit according to the present embodiment. [Figure 3] 10 is a diagram showing a third example of the configuration of the pump unit according to the present embodiment. FIG. [Figure 4] 10 is a diagram showing a fourth example of the configuration of the pump unit according to the present embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components and steps in each drawing will be designated by the same reference numerals as much as possible, and redundant description will be omitted.

[0014] <Configuration> FIG. 1A is a diagram showing a first example of the configuration of a pump unit 100A according to this embodiment. FIG. 1B is a cross-sectional view of the pump unit 100A shown in FIG. 1A taken along line II. FIG. 1C is a side view of the pump unit 100A shown in FIG. 1A. In FIG. 1A, the direction from the front side to the rear side is assumed to be the Y-axis direction. In FIG. 1A, the direction from the left side to the right side and perpendicular to the Y-axis direction is assumed to be the Z-axis direction. In FIG. 1A, the direction from the bottom side to the top side and perpendicular to the Y-axis and Z-axis directions is assumed to be the X-axis direction.

[0015] 1A to 1C, pump unit 100A is an integrated pump formed by mounting an internal gear type positive displacement pump inside rotor 31 of a prime mover. Pump unit 100A draws in fluid such as oil or water from suction port 13 of casing 10, and discharges the fluid from discharge port 14 at a discharge pressure and flow rate that correspond to the rotational speed of the internal gear type positive displacement pump. The main parts of pump unit 100A include, for example, casing 10, shafts 11 and 12, external gear 21, internal gear 22, rotor 31, stator 32, and bearings 41 and 42.

[0016] Housing 10 is a member for housing or arranging each component of pump unit 100A, and functions as a wall for separating the inside and outside of pump unit 100A. Housing 10 has a space therein in which shafts 11 and 12, external gear 21, internal gear 22, rotor 31, stator 32, and bearings 41 and 42 are provided. Housing 10 has an intake port 13 and an exhaust port 14 on its side surface in the Z-axis direction.

[0017] Space a1 is a space formed by the inner periphery of internal gear 22, the outer periphery of external gear 21, the inner side surface of housing 10 on the Z-axis side, and the inner side surface of housing 10 on the opposite side to the Z-axis. Space a1 has multiple gaps that change with the rotational motion of internal gear 22 and external gear 21. One of the multiple gaps in space a1 is connected to intake port 13. In addition, another gap different from the one of the multiple gaps in space a1 is connected to discharge port 14.

[0018] Space a2 is a space formed by the outer periphery of shaft 12, the outer periphery of rotor 31, the inner periphery of stator 32, the gap of rolling bearing 42, and the inner wall of housing 10. At least a part of space a2, specifically the part where rolling bearing 42 is provided, is formed cylindrical. Space a2 is shielded from space a1 by shaft 12 and internal gear 22.

[0019] Inlet port 13 is a portion of the internal gear type positive displacement pump that draws in fluid from the outside. Inlet port 13 is provided on the side surface of housing 10 on the Z-axis direction side, and is connected to space a1 inside housing 10 that is formed by the outer periphery of external gear 21, the inner periphery of internal gear 22, and part of the inner wall of housing 10.

[0020] The discharge port 14 is a portion of the internal gear type displacement pump that discharges fluid to the outside. The discharge port 14 is provided on the side surface of the housing 10 on the Z-axis direction side, and is connected to the space a1 inside the housing 10.

[0021] The shaft 11 is a cylindrical member that is provided inside the housing 10 so as to extend along an imaginary axis L1 that extends parallel to the Z-axis direction. The shaft 11 supports the external gear 21 rotatably around the axis L1 via a rolling bearing 41 provided on the outer periphery.

[0022] The external gear 21 is a component that functions as an inner gear of an internal gear type positive displacement pump, and the internal gear 22 and the housing 10 form an internal gear type positive displacement pump. The external gear 21 has a hole extending along the axis L1, and is provided coaxially with the shaft 11 so that the inner periphery of the hole covers the outer periphery of the shaft 11. In this example, the external gear 21 is connected to the shaft 11 so as to be rotatable around the axis L1. Specifically, the inner periphery of the hole of the external gear 21 is connected to the outer periphery of the shaft 11 via a rolling bearing 41. Furthermore, the external gear 21 has fewer teeth than the internal gear 22, and in this example, it has six teeth.

[0023] The internal gear 22 is a component that functions as the outer gear of an internal gear type displacement pump, and the external gear 21 and the housing 10 form an internal gear type displacement pump. Specifically, the internal gear 22 is provided within the housing 10 so as to mesh with the external gear 21 and be rotatable around an axis L2 that is eccentric with respect to the external gear 21. The axis L2 is an imaginary axis that extends parallel to the axis L1. The internal gear 22 is also provided so that a space a1 between the internal gear 22 and the external gear 21 is connected to the suction port 13 and the discharge port 14 and serves as a fluid flow path.

[0024] The shaft 12 is a cylindrical member that supports the internal gear 22 and the rotor 31, and is provided within the housing 10. The outer periphery of the shaft 12 is supported by the housing 10 via a rolling bearing 42. Specifically, the shaft 12 is connected to the inner periphery of a cylindrical portion in the space a2 within the housing 10 via the rolling bearing 42, both ends of which are ball bearings. Note that the shaft 12 may be supported within the housing 10 via the rolling bearing 42 at only one end, rather than at both ends. The inner periphery of the shaft 12 is connected to the outer periphery of the internal gear 22, and the outer periphery is connected to the inner periphery of the rotor 31. Specifically, the inner periphery of the shaft 12 is connected to the outer periphery of the internal gear 22 so as to cover the outer periphery of the internal gear 22, and the inner periphery of the rotor 31 is connected to a portion of the outer periphery that does not interfere with the rolling bearing 42, and the shaft 12 is provided within the housing 10 so as to be coaxial with the internal gear 22. The shaft 12 may be supported by the housing 10 via a rolling bearing 42 at its inner periphery rather than its outer periphery.

[0025] The rotor 31 is a component that functions as the rotor of the prime mover and is formed into a cylindrical shape using a permanent magnet. The rotor 31 is disposed between the shaft 12 and the stator 32, spaced apart from the stator 32, and is disposed within the housing 10 so that its inner periphery is connected to the outer periphery of the shaft 12. The inner periphery of the rotor 31 is connected to a portion of the outer periphery of the shaft 12 that does not interfere with the rolling bearing 42. The rotor 31 is also coaxial with the internal gear 22 and can rotate around the axis L2. The rotor 31 rotates around the axis L2 together with the shaft 12 and the internal gear 22 in accordance with a magnetic field that changes depending on the energization state of each electromagnet of the stator 32, which will be described later.

[0026] The stator 32 is a component that functions as a stator of the prime mover and is formed in a cylindrical shape. The stator 32 is coaxial with the internal gear 22 and is disposed within the housing 10 so as to be outward of the rotor 31 and spaced apart from the outer circumferential surface of the rotor 31. The outer periphery of the stator 32 is connected to the inner wall of the housing 10. The stator 32 has a plurality of electromagnets disposed inside and around the circumference of the cylinder, each electromagnet being formed by a winding wound around an iron core extending along the Z-axis direction. The stator 32 rotates the rotor 31 around the axis L2 as a rotation axis depending on the state of current flow through the electromagnets. Specifically, the stator 32 generates a magnetic field from the electromagnet in accordance with the current supplied from a control device (not shown) of the pump unit 100A or the like, and the generated magnetic field rotates the rotor 31 around the axis L2 as a rotation axis.

[0027] <Operation> The configuration of pump unit 100A has been described above. Next, the operation of pump unit 100A will be described. Pump unit 100A generates a magnetic field from an electromagnet in accordance with a current supplied to stator 32 from a control device (not shown) of pump unit 100A. Pump unit 100A rotates rotor 31 around axis L2 as the rotation axis by the magnetic field generated from the electromagnet of stator 32.

[0028] In the pump unit 100A, as the rotor 31 rotates, the shaft 12 and the internal gear 22 connected to the rotor 31 rotate around the axis L2 as a rotation axis. In the pump unit 100A, as the internal gear 22 rotates, the external gear 21 meshing with the internal gear 22 rotates around the axis L1, which is different from the axis L2, as a rotation axis.

[0029] The pump unit 100A draws in fluid through the suction port 13 of the housing 10 while the external gear 21 and the internal gear 22 are rotating. The fluid drawn in through the suction port 13 first moves from the suction port 13 to a gap connected to the suction port 13 within the space a1. Next, the rotational motion of the internal gear 22 and the external gear 21 causes the fluid to move to the gap in the space a1 where the discharge port 14 is located. The pump unit 100A then discharges the fluid from the discharge port 14 to the outside of the pump unit 100A at a predetermined discharge pressure and discharge flow rate.

[0030] <Effects> As described above, in this embodiment, the pump unit 100A includes a housing 10 having a fluid inlet 13 and a discharge port 14, and a shaft 11 (first shaft) disposed within the housing 10 and extending along an imaginary axis L1 (first axis). The pump unit 100A also includes an external gear 21 having a hole extending along the axis L1, the external gear 21 being disposed coaxially with the shaft 11 so that the inner periphery of the hole covers the outer periphery of the shaft 11. The pump unit 100A also includes an internal gear 22 disposed in mesh with the external gear 21 to be rotatable about an imaginary axis L2 (second axis) eccentric with respect to the external gear 21, and such that a space a1 between the external gear 21 and the internal gear 22 is connected to the inlet 13 and the discharge port 14 and serves as a fluid flow path. The pump unit 100A also includes a shaft 12 (second shaft) disposed coaxially with the internal gear 22 so as to cover the outer periphery of the internal gear 22, the shaft 12 having an outer periphery supported by the housing 10 via a bearing 42. Pump unit 100A also includes a stator 32 that is cylindrically formed, connected to the inner wall of housing 10 so as to be coaxial with internal gear 22 and outside shaft 12, and has an electromagnet. Pump unit 100A also includes a rotor 31 that is cylindrically formed, provided between shaft 12 and stator 32, spaced apart from stator 32, with its inner periphery connected to the outer periphery of shaft 12, and that rotates around axis L2 depending on the energized state of the electromagnet.

[0031] According to this configuration, in the pump unit 100A, the external gear 21 is supported by the shaft 11, the internal gear 22 is connected to the shaft 12, and the shaft 12 is supported by the housing 10 via the bearing 42. Therefore, in the pump unit 100A, the internal gear 22 and the rotor 31 connected to the internal gear 22 are prevented from changing position within the housing 10 or from oscillating within the housing 10 due to the pressure of the fluid flowing within the space a1. Accordingly, in the pump unit 100A, fluctuations in the distance between the inner periphery of the stator 32 and the outer periphery of the rotor 31 are also suppressed. Because the force that the magnetic field generated by the stator 32 imparts to the rotor 31 is determined by the distance between the stator 32 and the rotor 31, unnecessary fluctuations in the force that rotates the rotor 31 from the stator 32 are also suppressed. Therefore, the pump unit 100A can be driven with high efficiency.

[0032] In this embodiment, the housing 10 has a space a2 therein, at least a portion of which is cylindrical. The outer periphery of the shaft 12 is connected to the inner periphery of the cylindrical portion of the space in the housing 10 via a rolling bearing 42. Therefore, the pump unit 100A only needs to have the cylindrical space a2 for accommodating the shaft 12 inside the housing 10, and can be driven with high efficiency using a simple configuration.

[0033] In this embodiment, the inner periphery of the hole of the external gear 21 is connected to the outer periphery of the shaft 11 via the rolling bearing 41. Therefore, in the pump unit 100A, the external gear 21 is connected to the shaft 11 by the rolling bearing 41, which has an extremely small friction torque, so that energy loss when the external gear 21 rotates along the axis L1 is suppressed, and the pump unit 100A can be driven with even higher efficiency.

[0034] <Modification> The present invention is not limited to the above-described embodiments. In other words, variations of the above-described embodiments, which are appropriately modified by a person skilled in the art, are also included within the scope of the present invention as long as they include the features of the present invention. Furthermore, the elements of the above-described embodiments and the modifications described below can be combined to the extent technically possible, and such combinations are also included within the scope of the present invention as long as they include the features of the present invention.

[0035] For example, in this embodiment, the shaft 12 is supported by the housing 10 by a rolling bearing 42, but this is not limited to this. Here, with reference to FIGS. 2 and 3, another example of the configuration of the pump unit 100A will be described. FIG. 2 is a diagram showing a second example of the configuration of the pump unit 100A according to this embodiment. FIG. 3 is a diagram showing a third example of the configuration of the pump unit 100A according to this embodiment. In FIGS. 2 and 3, the X-axis direction is the direction from the front side to the rear side. In addition, in FIGS. 2 and 3, the Z-axis direction is the direction from the left side to the right side and perpendicular to the X-axis direction. In addition, in FIGS. 2 and 3, the Y-axis direction is the direction from the bottom side to the top side and perpendicular to the X-axis direction and the Z-axis direction.

[0036] 2, pump unit 100B differs from pump unit 100A in that a plain bearing 43 is provided in housing 10 instead of rolling bearing 42. Referring to Fig. 3, pump unit 100C differs from pump unit 100A in that a needle bearing 44 is provided in housing 10 instead of rolling bearing 42, which is a ball bearing. With this configuration, pump units 100B and 100C can be driven with high efficiency even when rolling bearing 42 supporting shaft 12 is a bearing other than a ball bearing.

[0037] In addition, in this embodiment, the shaft 12 is formed in a cylindrical shape and both ends are supported by the housing 10 via rolling bearings 42, but this is not limited thereto. The shaft 12 may have any shape as long as the outer periphery of the internal gear 22 is connected to the inner periphery of the shaft 12 and the shaft 12 is supported within the housing 10 so as to be rotatable around the axis L2. Here, with reference to FIG. 4, another example of the configuration of the pump unit 100A will be described. FIG. 4 is a diagram showing a fourth example of the configuration of the pump unit 100A according to this embodiment. In FIG. 4, the Y-axis direction is the direction from the front side to the rear side. In addition, in FIG. 4, the Z-axis direction is the direction from the left side to the right side and perpendicular to the Y-axis direction. In addition, in FIG. 4, the X-axis direction is the direction from the bottom side to the top side and perpendicular to the Y-axis direction and the Z-axis direction.

[0038] 4, pump unit 100D differs from pump unit 100A in that shaft 121 is provided within housing 10 instead of shaft 12, and rolling bearing 45 is provided within housing 10 instead of rolling bearing 42. Pump unit 100D is similar to pump unit 100A except that the shape of shaft 121 and the position at which shaft 121 is supported by housing 10 and rolling bearing 45 are different.

[0039] The shaft 121 is a cylindrical member formed integrally with or connected to a cup-shaped member formed in a cylindrical cup shape at the center outside the bottom surface of the cup-shaped member. Both the cup-shaped member and the cylindrical member have axis L2 as their central axes. The shaft 121 is located within the housing 10 so that the cup-shaped member covers the outer periphery of the internal gear 22 and is coaxial with the internal gear 22. The inner periphery of the rotor 31 is connected to the outer periphery of the cup-shaped member, and the shaft 121 rotates in response to the rotation of the rotor 31 about axis L2 as its rotation axis. The outer periphery of the cylindrical member of the shaft 121 is supported by the inner wall of the housing 10 via a rolling bearing 45.

[0040] In pump unit 100D, space a1 is a space that includes the inner bottom surface of the cup-shaped member of shaft 121, the inner periphery of internal gear 22, the outer periphery of external gear 21, and the inner side surface on the Z-axis side of housing 10, and is connected to intake port 13 and discharge port 14. In pump unit 100D, space a2 is a space that includes the gap of rolling bearing 45 in housing 10, the gap between rotor 31 and stator 32, and the gap between the cup-shaped member of shaft 121 and the inner wall of housing 10.

[0041] According to this configuration, pump unit 100D supports the outer periphery of the cylindrical member of shaft 121 with rolling bearings 45, and can therefore operate with high efficiency even when there is insufficient space to provide rolling bearings 42 between both ends of shaft 121 and the space within housing 10. Furthermore, because shaft 121 includes a cup-shaped member, pump unit 100D can reduce leakage of fluid from space a1 to space a2, etc., and can operate with high efficiency while improving airtightness.

[0042] Furthermore, in the present embodiment, the pump unit 100A has the inner periphery of the external gear 21 supported by the shaft 11 via the rolling bearing 41, but this is not limited to this. The inner periphery of the hole of the external gear 21 may be fixedly connected to the outer periphery of the shaft 11. Furthermore, the shaft 11 may be connected to the housing 10 by a rolling bearing, a plain bearing, or the like so as to be rotatable around the axis L1. With this configuration, the pump unit 100A can save space by removing the rolling bearing 41 provided between the shaft 11 and the external gear 21, and therefore can be driven with high efficiency while suppressing an increase in size. [Explanation of symbols]

[0043] 100A... pump unit, 10... housing, 11... shaft (first shaft), 12... shaft (second shaft), 13... intake port, 14... discharge port, 21... external gear, 22... internal gear, 31... rotor, 32... stator, 42... bearing, L1... shaft (first shaft), L2... shaft (second shaft), a1... space

Claims

1. a housing having a fluid inlet and outlet; a first shaft provided within the housing and extending along an imaginary first axis; an external gear having a hole extending along the first axis, the internal circumference of the hole covering the external circumference of the first shaft and being coaxial with the first shaft; an internal gear that meshes with the external gear so as to be rotatable around a virtual second axis different from the first axis, and a space between the external gear and the internal gear is connected to the suction port and the discharge port, forming a flow path for the fluid; a second shaft provided coaxially with the internal gear so as to cover the outer peripheral surface of the internal gear, the outer periphery of which is supported by the housing via a bearing; a stator formed in a cylindrical shape, connected to an inner wall of the housing so as to be coaxial with the internal gear and outside the second shaft, and having an electromagnet; a rotor formed in a cylindrical shape, disposed between the second shaft and the stator and spaced apart from the stator, with its inner periphery connected to the outer periphery of the second shaft, and rotating around the second axis in response to a current-carrying state of the electromagnet; A pump unit comprising:

2. The housing has a space therein, at least a portion of which is formed in a cylindrical shape, The pump unit according to claim 1 , wherein the outer periphery of the second shaft is connected to the inner periphery of a cylindrical portion in the space of the housing via a rolling bearing.

3. The pump unit according to claim 1 or 2, wherein the inner periphery of the hole of the external gear is connected to the outer periphery of the first shaft via a rolling bearing.

4. The inner periphery of the hole of the external gear is fixedly connected to the outer periphery of the first shaft, The pump unit according to claim 1 or 2, wherein the first shaft is connected to the housing so as to be rotatable about the first axis.

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