Technical Field
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The present disclosure relates to a submerged electric pump device for construction machines installed in a construction machine, and to the construction machine provided with the same.
Background Art
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The electrification of construction machines, such as excavators, has been advancing, with electric motors replacing internal combustion engines as the drive sources for hydraulic pumps. Known examples of such construction machines include the electric excavator disclosed in Patent Literature (PTL) 1.
Citation List
Patent Literature
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PTL 1:
Japanese Laid-Open Patent Application Publication No. 2022-163964
Summary of Invention
Technical Problem
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Electric motors utilized as the drive sources for hydraulic pumps in electric excavators generate less noise than internal combustion engines. Therefore, the noise emitted from the hydraulic pumps becomes noticeable, creating a need for noise reduction measures for the hydraulic pumps. Furthermore, the utilization of electric motors entails higher rotational speeds for the hydraulic pumps. This increases the amount of heat generated by the hydraulic pumps and necessitates the implementation of cooling measures for the hydraulic pumps.
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Thus, an object of the present disclosure is to provide a submerged electric pump device for construction machines that is capable of cooling a hydraulic pump while implementing noise reduction measures for the hydraulic pump, and provide a construction machine including the submerged electric pump device for construction machines.
Solution to Problem
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A submerged electric pump device for construction machines according to the present disclosure is installed in a construction machine and includes: an electric pump unit including a hydraulic pump that discharges working fluid upon rotation of a drive shaft, and an electric motor that rotatably drives the drive shaft; and a tank that extends in a first direction and stores the working fluid discharged from the hydraulic pump. The electric pump unit is mounted to the tank such that the hydraulic pump and the electric motor are arranged in the first direction and the hydraulic pump is immersed in the working fluid within the tank.
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According to the present disclosure, the electric pump unit is mounted to the tank such that the hydraulic pump is immersed in the working fluid within the tank. Therefore, the working fluid within the tank inhibits the transmission of vibration of the hydraulic pump to the outside of the tank, and noise emission attributable to the hydraulic pump can be reduced. In other words, noise reduction measures for the hydraulic pump 21 can be implemented. Furthermore, since the hydraulic pump is immersed in the working fluid within the tank, the hydraulic pump can be cooled. Moreover, since the hydraulic pump and the electric motor are arranged in the first direction when mounted to the tank, the installation footprint of the submerged electric pump device for construction machines in a construction machine can be reduced.
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A construction machine according to the present disclosure is a construction machine including a hydraulic actuator and includes: the submerged electric pump device for construction machines described above; and a control valve that supplies, to the hydraulic actuator, the working fluid discharged from the hydraulic pump of the submerged electric pump device for construction machines.
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According to this configuration, the construction machine includes the submerged electric pump device for construction machines described above. Therefore, a construction machine that produces the aforementioned advantageous effects can be realized.
Advantageous Effects of Invention
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According to the present disclosure, a hydraulic pump can be cooled while noise reduction measures for the hydraulic pump are implemented.
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The above object, other objects, features, and advantages of the present disclosure will be made clear by the following detailed explanation of preferred embodiments with reference to the attached drawings.
Brief Description of Drawings
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- [Fig. 1] Fig. 1 is a perspective view of an excavator in which a submerged electric pump device according to Embodiment 1 of the present disclosure is installed.
- [Fig. 2] Fig. 2 is a schematic plan view of a hydraulic drive system installed in the excavator of Fig. 1.
- [Fig. 3] Fig. 3 is an enlarged perspective view of a submerged electric pump device included in the hydraulic drive system of Fig. 2.
- [Fig. 4] Fig. 4 is a cross-sectional view of the submerged electric pump device of Fig. 2 taken along line IV-IV.
- [Fig. 5] Fig. 5 is a cross-sectional view of the submerged electric pump device of Fig. 2 taken along line V-V.
- [Fig. 6] Fig. 6 is a schematic side view of the hydraulic drive system of Fig. 2.
- [Fig. 7] Fig. 7 is an enlarged perspective view of a submerged electric pump device according to Embodiment 2 of the present disclosure.
- [Fig. 8] Fig. 8 is a cross-sectional view of the submerged electric pump device of Fig. 7 taken along line VIII-VIII.
Description of Embodiments
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Hereinafter, submerged electric pump devices 1, 1A according to Embodiments 1, 2 of the present disclosure and construction machines 2, 2A including the submerged electric pump devices 1, 1A will be described with reference to the aforementioned drawings. Note that the concept of directions mentioned in the following description is used for the sake of explanation; the orientations, etc., of elements according to the present disclosure are not limited to these directions. The submerged electric pump devices 1, 1A and the construction machines 2, 2A described below are merely embodiments of the present disclosure. Thus, the present disclosure is not limited to the embodiments and may be subject to addition, deletion, and alteration within the scope of the essence of the present disclosure.
<Embodiment 1>
[Construction Machine]
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A construction machine 2 according to Embodiment 1 illustrated in Fig. 1 performs various tasks by moving a bucket 15 and attachments of a crane or the like not illustrated in the drawings. In the present embodiment, the construction machine 2 is an electric excavator (hereinafter referred to simply as "the excavator") 2. Note that the construction machine 2 is not limited to the excavator 2 and may alternatively be a crane, a wheel loader, or the like or may alternatively be an industrial vehicle such as a forklift. In other words, it is sufficient that the construction machine 2 be a machine that performs various tasks by moving the attachments. The excavator 2 includes a traveling device 11, a slewing body 12, a boom 13, an arm 14, and the bucket 15. The traveling device 11 includes, for example, a pair of crawlers 11L, 11R. Each of the crawlers 11L, 11R can be driven to move in various directions. The slewing body 12 is disposed on the traveling device 11 so as to be rotatable about a pivot axis L1 extending in the vertical direction. The boom 13 is disposed on the slewing body 12 so as to be vertically pivotable. The arm 14 is disposed on a leading end portion of the boom 13 so as to be pivotable in the longitudinal direction. Furthermore, the bucket 15 is disposed on a leading end portion of the arm 14 so as to be pivotable in the longitudinal direction or the vertical direction. Note that the longitudinal direction is, for example, the direction in which the boom 13 extends.
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Furthermore, hydraulic actuators such as a hydraulic motor and a cylinder are disposed in each of the traveling device 11, the slewing body 12, the boom 13, the arm 14, and the bucket 15. Specifically, a traveling hydraulic motor (not illustrated in the drawings) is disposed in each of the crawlers 11L, 11R of the traveling device 11. The traveling motor is supplied with working fluid to drive the crawlers 11L, 11R. This allows the traveling device 11 to move in various directions. Note that the working fluid is, for example, a liquid such as oil. A slewing hydraulic motor not illustrated in the drawings is disposed in the slewing body 12. When supplied with the working fluid, the slewing hydraulic motor causes the slewing body 12 to slew. A boom cylinder 13a is disposed on the boom 13. An arm cylinder and a bucket cylinder not illustrated in the drawings are disposed on the arm 14 and the bucket 15, respectively. When supplied with the working fluid, the boom cylinder 13a, the arm cylinder, and the bucket cylinder pivot the boom 13, the arm 14, and the bucket 15, respectively.
[Hydraulic Drive System]
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Furthermore, a hydraulic drive system 3 is installed in the excavator 2, as illustrated in Fig. 2. More specifically, the hydraulic drive system 3 is disposed within the slewing body 12. The hydraulic drive system 3 supplies the working fluid to each of the aforementioned hydraulic actuators. Moreover, the hydraulic drive system 3 controls the flow (the flow rate and the flow direction) of the working fluid supplied to each of the hydraulic actuators. The hydraulic drive system 3 configured as just described further includes a submerged electric pump device 1, a multi-control valve 4, and a battery 5, as illustrated in Fig. 2.
[Submerged Electric Pump Device]
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The submerged electric pump device 1, which is an example of the submerged electric pump device for construction machines, is an electric hydraulic pump device installed in the excavator 2. Specifically, the submerged electric pump device 1 is electrically driven and, when driven, discharges working fluid. The submerged electric pump device 1 includes a tank 18 and an electric pump unit 19. In the submerged electric pump device 1, the working fluid is stored in the tank 18 as will be described in detail later, and at least a portion of the electric pump unit 19 is immersed in the working fluid within the tank 18. The submerged electric pump device 1 configured as just described is positioned within the slewing body 12 as follows, for example.
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The slewing body 12 includes a cabin 12b in which a driver (or an operator) can be seated. The boom 13 is disposed on the front portion of the slewing body 12 that is located in the middle in the lateral direction, and the cabin 12b is disposed in the front area of the slewing body 12 that is on one side in the lateral direction (for example, on the left side) so as to adjoin the boom 13. The submerged electric pump device 1 is disposed within the slewing body 12 on the side opposite the cabin 12b, with the boom 13 interposed therebetween. In other words, the submerged electric pump device 1 is disposed in the front area of the slewing body 12 that is located on the other side in the lateral direction (for example, on the right side) so as to adjoin the boom 13. The submerged electric pump device 1 further includes a vibration-isolation member 20, as illustrated in Fig. 3. Hereinafter, the tank 18, the electric pump unit 19, and the vibration-isolation member 20 will be described in more detail.
[Tank]
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The tank 18 stores the working fluid therein, as illustrated in Figs. 4 and 5. The working fluid within the tank 18 is supplied from the electric pump unit 19, which will be described in detail later, to each of the hydraulic actuators via the multi-control valve 4. Furthermore, the working fluid is brought back from each of the hydraulic actuators to the tank 18 via the multi-control valve 4 (not illustrated). Moreover, the electric pump unit 19 is attached to the tank 18. More specifically, the tank 18 includes an attachment surface 18b to which the electric pump unit 19 is attached.
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The attachment surface 18b is located on the lower side of a fluid level H of the working fluid within the tank 18, which is one side in the first direction. More specifically, the attachment surface 18b is located on the lower side of a ceiling surface 18a. The ceiling surface 18a is located on the uppermost side in the tank 18, which is the other side in the first direction. Furthermore, a fluid inlet (not illustrated in the drawings) for introducing the working fluid is formed in the ceiling surface 18a. Therefore, when the working fluid is stored in the tank 18, the attachment surface 18b is located on the lower side of the fluid level H of the working fluid. In the present embodiment, the tank 18 has the following shape. Specifically, the tank 18 is formed, for example, in a hollow stepped shape. The ceiling surface 18a forms the top surface of the uppermost step, and the attachment surface 18b forms the top surface of the second uppermost step. The attachment surface 18b is formed, for example, as a flat surface perpendicular to the vertical direction which is the first direction. Furthermore, an insertion hole 18c is formed in the attachment surface 18b. The insertion hole 18c extends vertically through the attachment surface 18b and allows vertical insertion of a hydraulic pump 21, which will be described in detail later.
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The tank 18 configured as just described is positioned within the slewing body 12 as follows, for example. Specifically, the tank 18 is disposed within the slewing body 12 on the side opposite the cabin 12b, with the boom 13 interposed therebetween. In other words, the tank 18 is disposed in a right front area of the slewing body 12 adjacent to the boom 13.
[Vibration-isolation Member]
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The vibration-isolation member 20 reduces the transmission of vibration. More specifically, the vibration-isolation member 20 is, for example, vibration-isolation rubber and provided on the bottom surface of the tank 18. In the present embodiment, a plurality of vibration-isolation members 20 are provided on the bottom surface of the tank 18, and the tank 18 is disposed on the construction machine 2 (more specifically, the slewing body 12) via the plurality of vibration-isolation members 20. Therefore, the vibration-isolation members 20 can suppress the transmission of vibration to the slewing body 12 via the tank 18. Note that the vibration-isolation member 20 is not limited to vibration-isolation rubber and may alternatively be a vibration-isolation mechanism such as a damper or a liquid-filled mount.
[Electric Pump Unit]
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The electric pump unit 19, which is an electrically driven hydraulic pump unit as mentioned above, is driven to discharge the working fluid when supplied with an electric current. More specifically, the electric pump unit 19 is electrically connected to the battery 5. Furthermore, the electric pump unit 19 is mounted to the tank 18, and the hydraulic pump 21 is immersed in the working fluid within the tank 18 as will be described in detail later.
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More specifically, the electric pump unit 19 includes the hydraulic pump 21 and an electric motor 22. The electric pump unit 19 is mounted to the tank 18 such that the hydraulic pump 21 and the electric motor 22 are arranged in the vertical direction and the hydraulic pump 21 is immersed in the working fluid within the tank 18. In the present embodiment, the electric pump unit 19 is attached to the attachment surface 18b such that the hydraulic pump 21 and the electric motor 22 are arranged in the vertical direction and the hydraulic pump 21 is positioned below the attachment surface 18b. Accordingly, substantially the entire hydraulic pump 21 is immersed in the working fluid. Note that the description of the hydraulic pump 21 being positioned below the attachment surface 18b does not necessarily require the entire hydraulic pump 21 to be located below the attachment surface 18b; for example, a drive shaft 21a may project upward from the attachment surface 18b. Meanwhile, the electric motor 22 is disposed outside the tank 18 in the present embodiment. The electric pump unit 19 configured as just described further includes, in addition to the hydraulic pump 21 and the electric motor 22, an inverter 23, a coupling member 24, an attachment plate 25, a discharge pipe 26, and a plurality of lifting links 27. Hereinafter, the elements of the electric pump unit 19 will be described in more detail.
[Hydraulic Pump]
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The hydraulic pump 21 includes the drive shaft 21a. When the drive shaft 21a is driven to rotate, the hydraulic pump 21 discharges the working fluid. The hydraulic pump 21 is, for example, a tandem pump including two pump parts 21c, 21d of the variable capacity type (which are swash plate pumps of the variable capacity type in the present embodiment) (refer also to Fig. 4). The pump parts 21c, 21d of the variable capacity type (hereinafter referred to simply as "the pump parts") share the aforementioned drive shaft 21a. The pump parts 21c, 21d are arranged in the vertical direction in which the drive shaft 21a extends. Furthermore, a housing 21e is disposed between the pump parts 21c, 21d. Therefore, the hydraulic pump 21 is elongated in the first direction in the present embodiment. Meanwhile, the hydraulic pump 21 is configured to be insertable into the insertion hole 18c of the attachment surface 18b when the drive shaft 21a extends in the vertical direction. This means that the profile of the insertion hole 18c is made larger than the profile of the hydraulic pump 21.
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Furthermore, a suction port 21f and discharge ports 21g, 21h are formed in the side surfaces of the hydraulic pump 21. More specifically, one suction port 21f and two discharge ports 21g, 21h are formed in the side surfaces of the housing 21e. The suction port 21f and the discharge ports 21g, 21h are open on the side surfaces of the housing 21e in the directions perpendicular to the first direction (for example, the second direction and the third direction to be described in detail later). In the present embodiment, the discharge ports 21g, 21h are open in the same direction. The discharge ports 21g, 21h and the suction port 21f are open in the directions perpendicular to each other. Note that the discharge ports 21g, 21h and the suction port 21f may be open in the opposite directions. The pump parts 21c, 21d share the one suction port 21f and include the discharge ports 21g, 21h, respectively. Therefore, the hydraulic pump 21 draws the working fluid through the suction port 21f and discharges the working fluid through the two ports 21g, 21h. Furthermore, regulators 21i, 21j are disposed on the pump parts 21c, 21d, respectively. The regulators 21i, 21j change the respective discharge capacities of the pump parts 21c, 21d.
[Electric Motor]
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The electric motor 22 is coupled to the drive shaft 21a. Furthermore, the electric motor 22 rotatably drives the drive shaft 21a. More specifically, when an electric current is supplied to the electric motor 22, the electric motor 22 drives the drive shaft 21a. As a result, the electric motor 22 causes the hydraulic pump 21 to discharge the working fluid. The electric motor 22 is, for example, a three-phase alternating current motor. More specifically, the electric motor 22 is formed in the shape of a circular column and disposed coaxially with the drive shaft 21a. This means that the electric motor 22 is aligned in a straight line coaxially with the hydraulic pump 21. In other words, the electric motor 22 is aligned in a straight line with the hydraulic pump 21 in the first direction. Note that the electric motor 22 does not necessarily need to be aligned in a straight line with the hydraulic pump 21; for example, the electric motor 22 and the hydraulic pump 21 may be positioned parallel to each other with offset axes or may be positioned so that the axis of the electric motor 22 intersects the drive shaft 21a diagonally or at a right angle.
[Inverter]
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The inverter 23 converts the frequency of the electric current supplied to the electric motor 22. In the present embodiment, the inverter 23 converts a direct current into an alternating current. The inverter 23 is electrically connected to the electric motor 22 and the battery 5 to be described later. The inverter 23 converts the direct current supplied from the battery 5 into an alternating current and provides the alternating current to the electric motor 22. With this, the electric motor 22 rotatably drives the drive shaft 21a. The inverter 23 is disposed, for example, on the electric motor 22. In the present embodiment, the inverter 23 is formed integrally with the electric motor 22 so as to be positioned on the side opposite the hydraulic pump 21 in the vertical direction. In other words, the inverter 23 is disposed above the attachment surface 18b.
[Coupling Member]
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The coupling member 24 couples the hydraulic pump 21 and the electric motor 22. The coupling member 24 is, for example, a bellhousing. The coupling member 24 includes a cylindrical part 24a and a flange 24b. The cylindrical part 24a couples the hydraulic pump 21 and the electric motor 22. More specifically, the cylindrical part 24a is formed, for example, in the shape of a circular cylinder. In the present embodiment, the cylindrical part 24a is formed into a tapered shape such that the axis thereof extends in the vertical direction and the cylindrical part 24a expands in diameter from a lower area to an upper area. The hydraulic pump 21 is attached to a lower end portion of the cylindrical part 24a, and the electric motor 22 is attached to an upper end portion of the cylindrical part 24a. Thus, the hydraulic pump 21 and the electric motor 22 are coupled using the coupling member 24. The drive shaft 21a extends within the cylindrical part 24a along the axis of the cylindrical part 24a and is coupled to the electric motor 22. The flange 24b is formed along the entire circumference of the other end portion of the cylindrical part 24a. The flange 24b projects radially outward from the other end portion of the cylindrical part 24a.
[Attachment Plate]
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The attachment plate 25, which is an example of the attachment member, is configured such that the hydraulic pump 21 and the electric motor 22 are attached to the attachment plate 25. In the present embodiment, the hydraulic pump 21 and the electric motor 22 are attached to the attachment plate 25 via the coupling member 24. More specifically, the attachment plate 25 has a through-hole 25a extending vertically therethrough. The coupling member 24 is inserted into the through-hole 25a and attached to the attachment plate 25 to seal the through-hole 25a. More specifically, the through-hole 25a is formed to be larger in diameter than the cylindrical part 24a of the coupling member 24 and smaller in diameter than the flange 24b of the coupling member 24. The coupling member 24 is disposed such that the cylindrical part 24a is inserted into the through-hole 25a and the flange 24b is positioned along a peripheral edge portion of the through-hole 25a. Furthermore, the coupling member 24 is secured to the attachment plate 25, for example, with the flange 24b fastened in a sealed manner to the attachment plate 25. Thus, the coupling member 24 is inserted into the through-hole 25a and attached to the attachment plate 25 to seal the through-hole 25a, and the hydraulic pump 21 and the electric motor 22 are attached to the attachment plate 25 via the coupling member 24.
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Furthermore, in a plan view from above, the profile of the attachment plate 25 is made larger than the profile of the insertion hole 18c of the attachment surface 18b. In the present embodiment, the attachment plate 25 is formed, for example, as a square in a plan view, with one side larger than the diameter of the circular insertion hole 18c. The attachment plate 25 is attached to the attachment surface 18b such that the hydraulic pump 21 is inserted through the insertion hole 18c and the attachment plate 25 seals the insertion hole 18c from above. In the present embodiment, the attachment plate 25 is secured to the attachment surface 18b, for example, by being fastened thereto in a sealed manner. Note that the shape of the attachment plate 25 is not limited to a square and may alternatively be a rectangle, a polygon, or a circle that can seal the insertion hole 18c.
[Lifting Link]
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The plurality of lifting links 27 are provided on the attachment plate 25. In the present embodiment, four lifting links 27 on the attachment plate 25 are for hoisting the electric pump unit 19. The lifting link 27 can be attached, for example, to a lifting device (not illustrated in the drawings) such as a crane. Specifically, the lifting link 27 can engage with a suspension element, such as a hook, of a lifting device. When the suspension element is lifted, the electric pump unit 19 is lifted. In the present embodiment, for example, two lifting links 27 are disposed with spacing therebetween at edge portions of the attachment plate 25 that are opposite in the lateral direction, which is the third direction, and two lifting links 27 are disposed with spacing therebetween at edge portions of the attachment plate 25 that are opposite in the longitudinal direction, which is the third direction. It is sufficient that the lifting links 27 be arranged such that when the electric pump unit 19 is lifted by the suspension element, the drive shaft 21a extends substantially perpendicularly, in other words, the center of gravity of the plurality of lifting links 27 is positioned on the drive shaft 21a in a plan view. Accordingly, by lowering the lifted electric pump unit 19, the hydraulic pump 21 can be positioned in the tank 18 through the insertion hole 18c. Furthermore, by lifting the electric pump unit 19, the hydraulic pump 21 can be pulled out of the tank 18 through the insertion hole 18c.
[Discharge Pipe]
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The discharge pipe 26 is connected to the discharge ports 21g, 21h of the hydraulic pump 21. The discharge pipe 26 extends through the attachment plate 25 and projects outward from the tank 18. More specifically, the discharge ports 21g, 21h of the hydraulic pump 21 are oriented on one side in the third direction (to the left in the present embodiment), which is perpendicular to the vertical direction. The discharge pipe 26 extends in a crank-shaped form from each of the discharge ports 21g, 21h, and an upwardly extending portion of the discharge pipe 26 extends through the attachment plate 25. More specifically, the discharge pipe 26 is connected to each of the discharge ports 21g, 21h and bends upward from the discharge port. Furthermore, the upwardly extending portion of the discharge pipe 26 extends through the attachment plate 25 and projects outward from the tank 18. Moreover, after projecting through the attachment plate 25, the discharge pipe 26 bends again to the left. The discharge pipe 26 configured as just described is attached to the attachment plate 25 together with the hydraulic pump 21 and the electric motor 22. Therefore, the discharge pipe 26 can be detached from the tank 18 by detaching the attachment plate 25 from the tank 18. Thus, the electric pump unit 19 can be easily removed from the tank 18.
[Multi-control Valve]
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The multi-control valve 4 illustrated in Fig. 2 supplies the working fluid discharged from the submerged electric pump device 1 to each of the hydraulic actuators. Furthermore, the multi-control valve 4 controls the flow of the working fluid supplied. More specifically, the multi-control valve 4 is connected to the hydraulic pump 21 (more specifically, the discharge ports 21g, 21h) of the submerged electric pump device 1 via the discharge pipe 26 as mentioned above. The multi-control valve 4 configured as just described is located rearward of the boom 13 in the slewing body 12. In the present embodiment, the multi-control valve 4 is located adjacent to the submerged electric pump device 1 in the slewing body 12.
[Battery]
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The battery 5 is electrically connected to the submerged electric pump device 1 (more specifically, the inverter 23). The battery 5 supplies a direct current to the inverter 23. With this, the submerged electric pump device 1 is driven to discharge the working fluid. The battery 5 is disposed within the slewing body 12. More specifically, the battery 5 is positioned rearward of the submerged electric pump device 1 in the slewing body 12. In the present embodiment, a counterweight 16 is disposed at the internal tail end of the slewing body 12, as illustrated in Fig. 6. The battery 5 is disposed between the counterweight 16 and the submerged electric pump device 1.
[Installation of Electric Pump Device]
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The submerged electric pump device 1 is installed within the slewing body 12 of the excavator 2 as follows. First, the tank 18 is disposed inside the slewing body 12 via the vibration-isolation member 20. More specifically, the tank 18 is disposed within the slewing body 12 on the right side of the boom 13, that is, on the side opposite the cabin 12b with the boom 13 interposed therebetween. Next, the electric pump unit 19 is attached to the tank 18. More specifically, first, a suspension element of a lifting device not illustrated in the drawings is attached to the lifting link 27 in the electric pump unit 19. After the attachment, the electric pump unit 19 is lifted by the lifting device and transferred to a position above the attachment surface 18b (more specifically, the insertion hole 18c) of the tank 18. Thereafter, the electric pump unit 19 is lowered by the lifting device, and the hydraulic pump 21 is inserted through the insertion hole 18c. Consequently, the hydraulic pump 21 is housed within the tank 18, and the cylindrical part 24a of the coupling member 24 is likewise inserted through the insertion hole 18c. The attachment plate 25 is then positioned around a peripheral edge portion of the insertion hole 18c of the attachment surface 18b and is secured to the attachment surface 18b, for example, by being fastened thereto. After the securement, the discharge pipe 26 is connected to the multi-control valve 4. Furthermore, in the submerged electric pump device 1, the working fluid is introduced into the tank 18 through the fluid inlet (not illustrated in the drawings) of the ceiling surface 18a. At this time, the working fluid is introduced into the tank such that the fluid level H of the working fluid becomes higher than the attachment surface 18b, as illustrated in Figs. 4 and 5. In this manner, the submerged electric pump device 1 is disposed within the main body (which is the slewing body 12 in the present embodiment) of the construction machine 2, as illustrated in Fig. 6. Thus, the submerged electric pump device 1 can be easily disposed within the slewing body 12.
[Operation of Hydraulic Drive System]
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As illustrated in Fig. 2, a direct current flows from the battery 5 to the submerged electric pump device 1. Accordingly, the submerged electric pump device 1 operates as follows. Specifically, the inverter 23 converts the direct current into an alternating current and provides the alternating current to the electric motor 22. Accordingly, the electric motor 22 rotatably drives the drive shaft 21a. As a result, the hydraulic pump 21 draws the working fluid stored in the tank 18 directly from the suction port 21f and discharges the working fluid to the discharge ports 21g, 21h. The working fluid flows from the discharge ports 21g, 21h to the multi-control valve 4 through the discharge pipe 26 and then is supplied to each of the hydraulic actuators via the multi-control valve 4. Thus, each of the hydraulic actuators can be operated.
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In the submerged electric pump device 1 according to the present embodiment, the electric pump unit 19 is mounted to the tank 18 such that the hydraulic pump 21 is immersed in the working fluid within the tank 18. Therefore, the working fluid within the tank 18 inhibits the transmission of vibration of the hydraulic pump 21 to the outside of the tank 18, and noise emission attributable to the hydraulic pump 21 can be reduced. In other words, noise reduction measures for the hydraulic pump 21 can be implemented. Furthermore, since the hydraulic pump 21 is immersed in the working fluid within the tank 18, the hydraulic pump 21 can be cooled. Moreover, since the hydraulic pump 21 and the electric motor 22 are vertically arranged when mounted to the tank 18, the installation footprint of the submerged electric pump device 1 in the excavator 2 can be reduced.
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Furthermore, in the submerged electric pump device 1 according to the present embodiment, the attachment surface 18b is located lower than the fluid level H of the working fluid stored in the tank 18. Accordingly, the working fluid fills the tank 18 up to at least the height of the attachment surface 18b. For example, even when the submerged electric pump device 1 is inclined, the working fluid still reaches the height of the attachment surface 18b. This allows substantially the entire hydraulic pump 21 to be immersed in the working fluid. Therefore, noise emission attributable to the hydraulic pump 21 can be further reduced, and the hydraulic pump 21 can be further cooled.
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Furthermore, in the submerged electric pump device 1 according to the present embodiment, the attachment surface 18b has the insertion hole 18c through which the hydraulic pump 21 can be inserted. The electric pump unit 19 includes the attachment plate 25 that is attached to the attachment surface 18b to seal the insertion hole 18c from above. Therefore, by lowering the electric pump unit 19 from above to the insertion hole 18c and attaching the attachment plate 25 to the attachment surface 18b, the electric pump unit 19 can be easily attached to the tank 18. In contrast, in removing the electric pump unit 19 from the tank 18, the electric pump unit 19 can be easily removed from the tank 18 by lifting the electric pump unit 19.
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Furthermore, in the submerged electric pump device 1 according to the present embodiment, the discharge pipe 26 connected to the discharge ports 21g, 21h of the hydraulic pump 21 extends through the attachment plate 25 and projects outward from the tank 18. Therefore, since the hydraulic pump 21, the electric motor 22, and the discharge pipe 26 are integrated on the attachment plate 25, the electric pump unit 19 is easily attached to and detached from the tank 18.
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Furthermore, in the submerged electric pump device 1 according to the present embodiment, the tank 18 is disposed on the slewing body 12 via the vibration-isolation member 20. Therefore, vibration transmitted to the slewing body 12 via the tank 18 can be reduced. Thus, noise emission attributable to the vibration of the hydraulic pump 21 in the tank 18 can be reduced.
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The excavator 2 according to the present embodiment includes the submerged electric pump device 1 described above. Therefore, the excavator 2 that produces the aforementioned advantageous effects can be realized.
<Embodiment 2>
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A submerged electric pump device 1A and an excavator 2A according to Embodiment 2 have configurations similar to those of the submerged electric pump device 1 and the excavator 2 according to Embodiment 1. Therefore, the configurations of the submerged electric pump device 1A and the excavator 2A according to Embodiment 2 will be described focusing on differences from the submerged electric pump device 1 and the excavator 2 according to Embodiment 1, and elements thereof that are the same as those according to Embodiment 1 will be assigned the same reference signs and description thereof will be omitted.
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In the construction machine 2A according to Embodiment 2 illustrated in Fig. 1, the submerged electric pump device 1A according to Embodiment 2 illustrated in Fig. 7 is installed instead of the submerged electric pump device 1 according to Embodiment 1. Specifically, the hydraulic drive system 3 further includes the submerged electric pump device 1A, the multi-control valve 4, and the battery 5. Similar to the submerged electric pump device 1 according to Embodiment 1, the submerged electric pump device 1A is an electric hydraulic pump device. The submerged electric pump device 1A includes a tank 18A and an electric pump unit 19A. In the submerged electric pump device 1A, the electric pump unit 19A is mounted to the tank 18A such that the hydraulic pump 21 and the electric motor 22 are both immersed in the working fluid within the tank 18. More specifically, the electric pump unit 19A further includes the inverter 23 and is mounted to the tank 18A such that the inverter 23 is disposed outside the tank 18A, while the hydraulic pump 21 and the electric motor 22 are immersed in the working fluid within the tank 18. Therefore, it is preferable to use an insulating liquid as the working fluid. However, the working fluid is not limited to such a liquid.
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The submerged electric pump device 1A configured as just described further includes the vibration-isolation member 20 in addition to the tank 18A and the electric pump unit 19A. Hereinafter, the configurations of the tank 18A and the electric pump unit 19A will be described focusing on differences from those of the tank 18 and the electric pump unit 19 according to Embodiment 1.
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As illustrated in Fig. 8, an attachment surface 18Ab of the tank 18A is located lower than the fluid level H in the tank 18A, similar to the attachment surface 18b according to Embodiment 1. However, the attachment surface 18Ab is located higher than the attachment surface 18Ab according to Embodiment 1 so that both the hydraulic pump 21 and the electric motor 22 are housed within the tank 18A. An insertion hole 18Ac is configured to allow vertical insertion of not only the hydraulic pump 21, but also the electric motor 22. This means that the profile of the insertion hole 18Ac is made larger than the profiles of the hydraulic pump 21 and the electric motor 22. More specifically, the insertion hole 18Ac is configured to allow vertical insertion of not only the hydraulic pump 21, but also the electric motor 22 and the coupling member 24.
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The electric pump unit 19 includes the coupling member 24, an attachment plate 25A, and the discharge pipe 26 in addition to the hydraulic pump 21, the electric motor 22, and the inverter 23. The attachment plate 25A is configured such that the hydraulic pump 21 and the electric motor 22 are attached to the attachment plate 25A. In the present embodiment, the hydraulic pump 21 and the electric motor 22 are attached to the attachment plate 25A via the inverter 23. More specifically, the attachment plate 25A has the through-hole 25a extending vertically therethrough. The through-hole 25a is dimensioned, for example, larger than the electric motor 22 and smaller than the inverter 23. Therefore, on the attachment plate 25A, the electric motor 22 is inserted through the through-hole 25a, and the inverter 23 is positioned along the peripheral edge portion of the through-hole 25a to seal the through-hole 25a from above. Furthermore, the inverter 23 is secured to the attachment plate 25A, for example, by being fastened thereto in a sealed manner. In this manner, the hydraulic pump 21 and the electric motor 22 are attached to the attachment plate 25A via the inverter 23.
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Furthermore, similar to the attachment plate 25A according to Embodiment 1, the attachment plate 25A is formed such that the profile thereof is larger in a plan view than the profile of the insertion hole 18Ac. The attachment plate 25A is attached to the attachment surface 18Ab such that the hydraulic pump 21 is inserted through the insertion hole 18c and the attachment plate 25A seals the insertion hole 18Ac from above. In the present embodiment, the attachment plate 25A is secured to the attachment surface 18Ab, for example, by being fastened thereto in a sealed manner.
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The submerged electric pump device 1A configured as just described is installed within the slewing body 12 of the excavator 2A in substantially the same manner as the submerged electric pump device 1 according to Embodiment 1. Similar to the submerged electric pump device 1 according to Embodiment 1, the submerged electric pump device 1A discharges the working fluid. Subsequently, the discharged working fluid is supplied to each of the hydraulic actuators via the multi-control valve 4.
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In the submerged electric pump device 1A according to the present embodiment, the electric pump unit 19A is mounted to the tank 18A such that the electric motor 22 is immersed in the working fluid in the tank 18A. Therefore, the electric motor 22 can be cooled by the working fluid within the tank 18A.
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Furthermore, in the submerged electric pump device 1A according to the present embodiment, the attachment surface 18Ab is located lower than the working fluid stored in the tank 18A. Accordingly, the working fluid fills the tank 18A up to at least the height of the attachment surface 18Ab. This allows substantially the entire electric motor to be immersed in the working fluid. Therefore, the electric motor can be further cooled.
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The excavator 2A according to the present embodiment includes the submerged electric pump device 1A described above. Therefore, the excavator 2A that produces the aforementioned advantageous effects can be realized.
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The submerged electric pump device 1A according to Embodiment 2 produces substantially the same advantageous effects as those produced by the submerged electric pump device 1 according to Embodiment 1.
<Other Embodiments>
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In the submerged electric pump devices 1, 1A according to the present embodiments, the hydraulic pump 21 and the electric motor 22 are coaxially aligned; however, the hydraulic pump 21 and the electric motor 22 may alternatively be disposed such that the axis of the electric motor 22 intersects (for example, is perpendicular to) the axis of the hydraulic pump 21. In other words, it is sufficient that in the submerged electric pump devices 1, 1A, the hydraulic pump 21 and the electric motor 22 be placed upright such that the drive shaft 21a of the hydraulic pump 21 extends in the first direction. Note that while the electric pump unit is placed upright in the tanks 18, 18A of the submerged electric pump devices 1, 1A, the electric pump unit may alternatively be placed horizontally such that hydraulic pump 21 and the electric motor 22 are arranged in a lateral or longitudinal direction.
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Furthermore, in the submerged electric pump devices 1, 1A according to the present embodiments, the hydraulic pup 21 is not limited to a tandem pump and may alternatively be a single pump. Furthermore, the hydraulic pump 21 is not limited to a swash plate pump and may alternatively be an axial piston pump or a gear pump. Moreover, the hydraulic pump 21 may be disposed on the other side of the electric motor 22 in the first direction (that is, above the electric motor 22). Moreover, the electric motor 22 is not limited to a three-phase alternating current motor and may alternatively be another motor such as a servo motor.
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In the submerged electric pump devices 1, 1A according to the present embodiments, the hydraulic pump 21 and the electric motor 22 are coupled using the coupling member 24; however, the hydraulic pump 21 and the electric motor 22 may be directly attached to the attachment plate 25. The lifting link 27 does not necessarily need to be disposed on the attachment plate 25 and may be disposed on the coupling member 24 and the tanks 18, 18A. The flange 24b of the coupling member 24 does not necessarily need to be formed along the entire circumference of the cylindrical part 24a. For example, the flange 24b may be composed of a plurality of projections projecting radially outward from the cylindrical part 24a and spaced apart from each other in the circumferential direction; the shape of the flange 24b is not limited. Furthermore, the suction port 21f of the submerged electric pump devices 1, 1A does not necessarily need to be open on one side in the third direction and may be open on one side or the other side in the second direction or on the other side in the third direction. Similarly, the direction in which the discharge ports 21g, 21h are open is not limited to the other side in the second direction.
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The fluid level of the working fluid is located higher than the attachment surfaces 18b, 18Ab in the submerged electric pump devices 1, 1A according to the present embodiments, but may be located lower than the attachment surfaces 18b, 18Ab. Specifically, in the submerged electric pump devices 1, 1A, it is sufficient that the fluid level of the working fluid be located higher than the suction port 21f; it is sufficient that the hydraulic pump 21 be partially immersed in the working fluid or that the electric motor 22 be partially immersed in the working fluid. Furthermore, the shape of the tanks 18, 18A does not necessarily need to be a stepped shape; the attachment surfaces 18b, 18Ab are preferably located lower than the ceiling surface 18a. Specifically, the attachment surfaces 18b, 18Ab do not necessarily need to be located lower than the ceiling surface 18a and may alternatively be the ceiling surface 18a itself.
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In the submerged electric pump devices 1, 1A according to the present embodiments, the discharge pipe 26 extends through the attachment plate 25 and projects outward from the tanks 18, 18A. However, the discharge pipe 26 may be configured to project from the side surface, the bottom surface, or the like of the tanks 18, 18A to the outside of the tanks 18, 18A. Furthermore, the vibration-isolation member 20 is disposed on the bottom surface of the tanks 18, 18A, but may alternatively be disposed, for example, between the attachment place 25 and each of the attachment surfaces 18b, 18Ab and between the flange 24b and the attachment plate 25. In the present embodiments, the attachment member is exemplified by the attachment plate 25, but the attachment member is not limited to a plate-shaped member and may alternatively be a block-shaped member.
<Exemplary Embodiments>
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A submerged electric pump device for construction machines according to the first aspect is installed in a construction machine and includes: an electric pump unit including a hydraulic pump that discharges working fluid upon rotation of a drive shaft, and an electric motor that rotatably drives the drive shaft; and a tank that extends in a first direction and stores the working fluid discharged from the hydraulic pump. The electric pump unit is mounted to the tank such that the hydraulic pump and the electric motor are arranged in the first direction and the hydraulic pump is immersed in the working fluid within the tank.
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According to this aspect, the electric pump unit is mounted to the tank such that the hydraulic pump is immersed in the working fluid within the tank. Therefore, the working fluid within the tank inhibits the transmission of vibration of the hydraulic pump to the outside of the tank, and noise emission attributable to the hydraulic pump can be reduced. In other words, noise reduction measures for the hydraulic pump 21 can be implemented. Furthermore, since the hydraulic pump is immersed in the working fluid within the tank, the hydraulic pump can be cooled. Moreover, since the hydraulic pump and the electric motor are arranged in the first direction when mounted to the tank, the installation footprint of the submerged electric pump device for construction machines in a construction machine can be reduced.
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A submerged electric pump device for construction machines according to the second aspect is the submerged electric pump device for construction machines according to the first aspect in which the tank includes an attachment surface to which the electric pump unit is attached, the hydraulic pump is disposed on one side in the first direction relative to the attachment surface and immersed in the working fluid within the tank, and the attachment surface is located on the one side in the first direction relative to a fluid level of the working fluid stored in the tank.
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According to this aspect, the attachment surface is located on the one side in the first direction relative to the fluid level of the working fluid stored in the tank. Accordingly, the working fluid fills the tank up to at least the height of the attachment surface. This allows substantially the entire hydraulic pump to be immersed in the working fluid. Therefore, noise emission attributable to the hydraulic pump can be further reduced, and the hydraulic pump can be further cooled.
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A submerged electric pump device for construction machines according to the third aspect is the submerged electric pump device for construction machines according to the first or second aspect in which the tank includes an attachment surface to which the electric pump unit is attached, the hydraulic pump is disposed on one side in the first direction relative to the attachment surface and immersed in the working fluid within the tank, the attachment surface includes an insertion hole that permits insertion of the hydraulic pump therethrough in the first direction, the electric pump unit includes an attachment member to which the hydraulic pump and the electric motor are attached, and the attachment member is attached to the attachment surface to seal the insertion hole on the other side in the first direction.
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According to this aspect, the attachment surface includes the insertion hole that permits insertion of the hydraulic pump therethrough in the first direction. Furthermore, the electric pump unit includes the attachment plate that is attached to the attachment surface to seal the insertion hole on the other side in the first direction. Therefore, by lowering the electric pump unit from an area on the other side in the first direction to the insertion hole and attaching the attachment plate to the attachment surface, the electric pump unit can be easily attached to the tank. In contrast, in removing the electric pump unit from the tank, the electric pump unit can be easily removed from the tank by lifting the electric pump unit.
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A submerged electric pump device for construction machines according to the fourth aspect is the submerged electric pump device for construction machines according to the third aspect in which the electric pump unit includes a discharge pipe connected to a discharge port of the hydraulic pump, and the discharge pipe extends through the attachment member and projects outward from the tank.
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According to this aspect, the discharge pipe connected to the discharge port of the hydraulic pump extends through the attachment plate and projects outward from the tank. Therefore, since the hydraulic pump, the electric motor, and the discharge pipe are integrated on the attachment plate, the electric pump unit is easily attached to and detached from the tank.
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A submerged electric pump device for construction machines according to the fifth aspect is the submerged electric pump device for construction machines according to any one of the first to fourth aspects that further includes: a vibration-isolation member that reduces transmission of vibration and in which the tank is disposed on the construction machine via the vibration-isolation member.
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According to this aspect, the tank is disposed on the construction machine via the vibration-isolation member. Therefore, vibration transmitted to the construction machine via the tank can be reduced. Thus, noise emission attributable to the vibration of the hydraulic pump in the tank can be reduced.
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A submerged electric pump device for construction machines according to the sixth aspect is the submerged electric pump device for construction machines according to any one of the first to fifth aspects in which the electric pump unit is mounted to the tank such that the electric motor is immersed in the working fluid within the tank.
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According to this aspect, the electric pump unit is mounted to the tank such that the electric motor is immersed in the working fluid within the tank. Therefore, the electric motor can be cooled by the working fluid within the tank.
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A submerged electric pump device for construction machines according to the seventh aspect is the submerged electric pump device for construction machines according to the sixth aspect in which the tank includes an attachment surface to which the electric pump unit is attached, the electric motor and the hydraulic pump are disposed on one side in the first direction relative to the attachment surface and immersed in the working fluid within the tank, and the attachment surface is located on the one side in the first direction relative to the working fluid stored in the tank.
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According to this aspect, the attachment surface is located on the one side in the first direction relative to the working fluid stored in the tank. Accordingly, the working fluid fills the tank up to at least the height of the attachment surface. This allows substantially the entire electric motor to be immersed in the working fluid. Therefore, the electric motor can be further cooled.
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A submerged electric pump device for construction machines according to the eighth aspect is the submerged electric pump device for construction machines according to the seventh aspect in which the electric pump unit further includes an inverter that converts a frequency of an electric current supplied to the electric motor, and the inverter is disposed on the other side in the first direction relative to the attachment surface.
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According to this aspect, the inverter is disposed on the other side in the first direction relative to the attachment surface. Therefore, the inverter can be disposed outside the tank. As a result, immersion of the inverter in the working fluid can be prevented.
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A construction machine according to the ninth aspect is a construction machine including a hydraulic actuator and includes: the submerged electric pump device for construction machines according to any one of the first to eighth aspects; and a control valve that supplies, to the hydraulic actuator, the working fluid discharged from the hydraulic pump of the submerged electric pump device for construction machines.
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According to this aspect, the construction machine includes the submerged electric pump device for construction machines described above. Therefore, a construction machine that produces the aforementioned advantageous effects can be realized.
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From the foregoing description, many modifications and other embodiments of the present disclosure would be obvious to a person having ordinary skill in the art. Therefore, the foregoing description should be interpreted only as an example and is provided for the purpose of teaching the best mode for carrying out the present disclosure to a person having ordinary skill in the art. Substantial changes in details of the structures and/or functions of the present disclosure are possible within the spirit of the present disclosure.