Submerged electric pump device for construction machine, and construction machine provided with same

Abstract

This submerged electric pump device for a construction machine is mounted on a construction machine, and comprises: an electric pump unit including a hydraulic pump that discharges a working fluid when a drive shaft rotates, and an electric motor that rotationally drives the drive shaft; and a tank that stores the working fluid discharged from the hydraulic pump and that is disposed upright in a first direction. The electric pump unit is provided in the tank such that the hydraulic pump and the electric motor are aligned in the first direction and the hydraulic pump is submerged in the working fluid in the tank.

Description

Electric submerged pump device for construction machinery, and construction machinery equipped with the same

[0001] The present disclosure relates to an electric submerged pump device for use in a construction machine that is mounted on the construction machine, and a construction machine that includes the same.

[0002] BACKGROUND ART Construction machines such as excavators are increasingly being electrified, and the drive source of hydraulic pumps is being replaced from an internal combustion engine with an electric motor. One example of such construction machines is an electric excavator disclosed in Patent Document 1.

[0003] Japanese Patent Application Laid-Open No. 2022-163964

[0004] Electric motors used as the drive source for hydraulic pumps in electric excavators are quieter than internal combustion engines. However, the noise emitted by hydraulic pumps has become more noticeable, necessitating measures to reduce the noise level of hydraulic pumps. Furthermore, the use of electric motors has led to the rotational speed of hydraulic pumps becoming higher. This has resulted in an increase in the amount of heat generated by hydraulic pumps, necessitating measures to cool the hydraulic pumps.

[0005] Therefore, an object of the present disclosure is to provide an electric submerged pump device for construction machinery that can cool a hydraulic pump while taking measures to reduce noise from the hydraulic pump, and a construction machine equipped with the same.

[0006] The immersed electric pump device for construction machinery disclosed herein is mounted on construction machinery and comprises an electric pump unit including a hydraulic pump that discharges hydraulic fluid when a drive shaft rotates and an electric motor that drives the drive shaft to rotate, and a tank that stores the hydraulic fluid discharged from the hydraulic pump and is erected in a first direction, wherein the electric pump unit is provided in the tank so that the hydraulic pump and the electric motor are aligned in the first direction and the hydraulic pump is immersed in the hydraulic fluid in the tank.

[0007] According to the present disclosure, the electric pump unit is mounted in the tank so that the hydraulic pump is submerged in the hydraulic fluid in the tank. Therefore, vibrations of the hydraulic pump are less likely to be transmitted to the outside of the tank by the hydraulic fluid in the tank, and noise caused by the hydraulic pump can be suppressed. In other words, noise reduction measures can be taken for the hydraulic pump 21. Furthermore, because the hydraulic pump is submerged in the hydraulic fluid in the tank, the hydraulic pump can be cooled. Furthermore, because the hydraulic pump and the electric motor are mounted in the tank aligned in the first direction, the installation area occupied by the submerged electric pump device for construction machinery in the construction machine can be reduced.

[0008] The construction machine of the present disclosure is equipped with a hydraulic actuator, and is provided with the above-mentioned liquid-immersed electric pump device for construction machines, and a control valve that supplies working fluid discharged from the hydraulic pump of the liquid-immersed electric pump device for construction machines to the hydraulic actuator.

[0009] According to the above configuration, the construction machine includes the above-described electric immersion pump device for construction machine, and therefore, it is possible to realize a construction machine that provides the above-described operational effects.

[0010] According to the present disclosure, it is possible to cool the hydraulic pump while taking measures to reduce noise from the hydraulic pump.

[0011] The above and other objects, features, and advantages of the present disclosure will become apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings.

[0012] 1 is a perspective view showing an excavator on which an immersed electric pump device according to a first embodiment of the present disclosure is mounted. FIG. 2 is a schematic plan view showing a hydraulic drive system mounted on the excavator of FIG. 1. FIG. 3 is an enlarged perspective view showing an enlarged version of the immersed electric pump device provided in the hydraulic drive system of FIG. 2. FIG. 4 is a cross-sectional view of the immersed electric pump device of FIG. 2 taken along section line IV-IV. FIG. 5 is a cross-sectional view of the immersed electric pump device of FIG. 2 taken along section line V-V. FIG. 6 is a schematic side view showing the hydraulic drive system of FIG. 2. FIG. 7 is an enlarged perspective view showing an enlarged version of the immersed electric pump device according to a second embodiment of the present disclosure. FIG. 8 is a cross-sectional view of the immersed electric pump device of FIG. 7 taken along section line VIII-VIII.

[0013] The following describes the submerged electric pump systems 1, 1A and construction machines 2, 2A equipped with the same according to first and second embodiments of the present disclosure, with reference to the drawings. Note that the concepts of directions used in the following description are used for convenience of explanation and do not limit the orientation of the configuration of the present disclosure to those directions. Furthermore, the submerged electric pump systems 1, 1A and construction machines 2, 2A described below are merely one embodiment of the present disclosure. Therefore, the present disclosure is not limited to the embodiments, and additions, deletions, and modifications are possible within the scope of the spirit of the present disclosure.

[0014] <First Embodiment> [Construction Machine] A construction machine 2 according to the first embodiment shown in FIG. 1 performs various tasks by moving a bucket 15 and an attachment such as a crane (not shown). In this embodiment, the construction machine 2 is an electric shovel (hereinafter simply referred to as "shovel") 2. However, the construction machine 2 is not limited to a shovel, and may be a crane, a wheel loader, or an industrial vehicle such as a forklift. In other words, the construction machine 2 may be any machine that performs various tasks by moving an attachment. The shovel 2 includes a traveling device 11, a revolving body 12, a boom 13, an arm 14, and a 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 revolving body 12 is mounted on the traveling device 11 so as to be rotatable about a rotation axis L1 extending in the vertical direction. The boom 13 is mounted on the revolving body 12 so as to be swingable in the vertical direction. The arm 14 is provided at the tip of the boom 13 so as to be swingable in the front-to-rear direction. Furthermore, the bucket 15 is provided at the tip of the arm 14 so as to be swingable in the front-to-rear direction or the up-to-down direction. The front-to-rear direction is, for example, the direction in which the boom 13 extends.

[0015] The traveling unit 11, the revolving unit 12, the boom 13, the arm 14, and the bucket 15 are each provided with a hydraulic actuator, such as a hydraulic motor and a cylinder. That is, each of the crawlers 11L, 11R of the traveling unit 11 is provided with a traveling hydraulic motor (not shown). The traveling motor drives the crawlers 11L, 11R by supplying hydraulic fluid. This allows the traveling unit 11 to move in various directions. The hydraulic fluid is, for example, a liquid such as oil. The revolving unit 12 is provided with a swing hydraulic motor (not shown). The swing hydraulic motor swings the revolving unit 12 by supplying hydraulic fluid. The boom 13 is provided with a boom cylinder 13a. The arm 14 and the bucket 15 are each provided with an arm cylinder and a bucket cylinder (not shown). The boom cylinder 13a, the arm cylinder, and the bucket cylinder are supplied with hydraulic fluid, which causes the boom 13, the arm 14, and the bucket 15 to swing, respectively.

[0016] [Hydraulic Drive System] The excavator 2 is also equipped with a hydraulic drive system 3 as shown in FIG. 2. More specifically, the hydraulic drive system 3 is disposed inside the revolving body 12. The hydraulic drive system 3 supplies hydraulic fluid to each of the hydraulic actuators described above. Furthermore, the hydraulic drive system 3 controls the flow (flow rate and flow direction) of the hydraulic fluid supplied to each hydraulic actuator. The hydraulic drive system 3 configured in this manner further includes the immersed electric pump device 1, a multi-control valve 4, and a battery 5 as shown in FIG. 2.

[0017] [Immersed Electric Pump Device] The immersed electric pump device 1, which is an example of an immersed electric pump device for construction machinery, is an electric hydraulic pump device mounted on an excavator 2. That is, the immersed electric pump device 1 is driven electrically and discharges hydraulic fluid when driven. The immersed electric pump device 1 includes a tank 18 and an electric pump unit 19. In the immersed electric pump device 1, hydraulic 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 hydraulic fluid in the tank 18. The immersed electric pump device 1 configured in this manner is arranged within the revolving body 12, for example, as follows.

[0018] The revolving structure 12 has a cabin 12b in which a driver (or operator) can ride. A boom 13 is provided on the front side of the revolving structure 12 in a left-right central portion, and the cabin 12b is disposed on one left-right side (e.g., the left side) of the front side of the revolving structure 12 adjacent to the boom 13. The immersed electric pump unit 1 is disposed on the opposite side of the cabin 12b within the revolving structure 12, with the boom 13 in between. That is, the immersed electric pump unit 1 is disposed on the other left-right side (e.g., the right side) of the front side of the revolving structure 12 adjacent to the boom 13. The immersed electric pump unit 1 further includes a vibration-isolating member 20, as shown in FIG. 3 . The tank 18, the electric pump unit 19, and the vibration-isolating member 20 will be described in more detail below.

[0019] [Tank] As shown in Figures 4 and 5, the tank 18 stores hydraulic fluid therein. The hydraulic fluid in the tank 18 is supplied to each of the hydraulic actuators from an electric pump unit 19, which will be described in detail later, via the multi-control valve 4. The hydraulic fluid is also returned to the tank 18 from each of the hydraulic actuators via the multi-control valve 4 (not shown). The electric pump unit 19 is also attached to the tank 18. More specifically, the tank 18 includes a mounting surface 18b to which the electric pump unit 19 is attached.

[0020] The mounting surface 18b is located below the liquid level H of the hydraulic fluid in the tank 18, which is on one side in the first direction. More specifically, the mounting surface 18b is located below the ceiling surface 18a. Here, the ceiling surface 18a is located at the uppermost part of the tank 18, which is on the other side in the first direction. An inlet (not shown) for injecting hydraulic fluid is formed in the ceiling surface 18a. Therefore, when hydraulic fluid is stored in the tank 18, the mounting surface 18b is located below the liquid level H of the hydraulic fluid. In this embodiment, the tank 18 has the following shape. That is, the tank 18 is formed, for example, in a hollow stepped shape. The ceiling surface 18a forms the upper surface of the highest step, and the mounting surface 18b forms the upper surface of the second step. The mounting surface 18b is formed flat so as to be perpendicular to, for example, the up-down direction, which is the first direction. Furthermore, an insertion hole 18c is formed in the mounting surface 18b. The insertion hole 18c penetrates in the vertical direction, and a hydraulic pump 21, which will be described in detail later, can be inserted in the vertical direction.

[0021] The tank 18 configured in this manner is arranged, for example, as follows within the revolving unit 12. That is, the tank 18 is arranged within the revolving unit 12 on the opposite side of the cabin 12b across the boom 13. In other words, the tank 18 is arranged on the front right side of the revolving unit 12 so as to be adjacent to the boom 13.

[0022] [Vibration-isolating members] The vibration-isolating members 20 suppress the transmission of vibrations. More specifically, the vibration-isolating members 20 are, for example, vibration-isolating rubber, and are provided on the bottom surface of the tank 18. In this embodiment, a plurality of vibration-isolating members 20 are provided on the bottom surface of the tank 18, and the tank 18 is attached to the construction machine 2 (more specifically, the revolving unit 12) via the plurality of vibration-isolating members 20. Therefore, the vibration-isolating members 20 can suppress the transmission of vibrations to the revolving unit 12 via the tank 18. Note that the vibration-isolating members 20 are not limited to vibration-isolating rubber, and may be vibration-isolating mechanisms such as dampers and hydraulic mounts.

[0023] [Electric Pump Unit] As described above, the electric pump unit 19 is an electrically driven hydraulic pump unit that is driven by a supply of electric current to discharge hydraulic fluid. More specifically, the electric pump unit 19 is electrically connected to the battery 5. Furthermore, the electric pump unit 19 is provided in the tank 18, and the hydraulic pump 21 is immersed in the hydraulic fluid in the tank 18, as will be described in detail later.

[0024] More specifically, the electric pump unit 19 includes a hydraulic pump 21 and an electric motor 22. The electric pump unit 19 is provided in the tank 18 so that the hydraulic pump 21 and the electric motor 22 are aligned vertically and the hydraulic pump 21 is immersed in the hydraulic fluid in the tank 18. In this embodiment, the electric pump unit 19 is attached to the mounting surface 18b so that the hydraulic pump 21 and the electric motor 22 are aligned vertically and the hydraulic pump 21 is positioned below the mounting surface 18b. This allows almost the entire hydraulic pump 21 to be immersed in the hydraulic fluid. Note that "the hydraulic pump 21 is positioned below the mounting surface 18b" does not necessarily mean that the entire hydraulic pump 21 is positioned below the mounting surface 18b. For example, the drive shaft 21a may protrude upward from the mounting surface 18b. On the other hand, in this embodiment, the electric motor 22 is positioned outside the tank 18. The electric pump unit 19 configured in this manner further includes, in addition to the hydraulic pump 21 and the electric motor 22, an inverter 23, a connecting member 24, a mounting plate 25, a discharge pipe 26, and a plurality of hanging fixtures 27. Each component of the electric pump unit 19 will be described in more detail below.

[0025] [Hydraulic Pump] The hydraulic pump 21 has a drive shaft 21a. The hydraulic pump 21 discharges hydraulic fluid when the drive shaft 21a is rotated. The hydraulic pump 21 is, for example, a tandem pump having two variable displacement pump sections (variable displacement swash plate pumps in this embodiment) 21c, 21d (see also FIG. 4). The variable displacement pump sections (hereinafter simply referred to as "pump sections") 21c, 21d share the aforementioned drive shaft 21a. The pump sections 21c, 21d are arranged side by side in the vertical direction along which the drive shaft 21a extends. A housing 21e is interposed between the pump sections 21c, 21d. Therefore, in this embodiment, the hydraulic pump 21 is formed elongated in the first direction. Meanwhile, the hydraulic pump 21 is configured to be insertable into the insertion hole 18c of the mounting surface 18b with the drive shaft 21a extending in the vertical direction. That is, the outer shape of the insertion hole 18 c is formed to be larger than the outer shape of the hydraulic pump 21 .

[0026] Additionally, a suction port 21f and discharge ports 21g, 21h are formed on the side surface of the hydraulic pump 21. More specifically, one suction port 21f and two discharge ports 21g, 21h are formed on the side surface of the housing 21e. The suction port 21f and the discharge ports 21g, 21h each open in a direction perpendicular to the first direction (e.g., a second direction and a third direction, which will be described in detail later) on the side surface of the housing 21e. In this embodiment, the discharge ports 21g, 21h open in the same direction. Furthermore, the discharge ports 21g, 21h and the suction port 21f open in directions perpendicular to each other. Note that the discharge ports 21g, 21h and the suction port 21f may open on opposite sides. The pump sections 21c, 21d share the single suction port 21f and each have their own discharge ports 21g, 21h. Therefore, the hydraulic pump 21 draws hydraulic fluid through the suction port 21f and discharges it from the two ports 21g and 21h. The pump sections 21c and 21d are provided with regulators 21i and 21j, respectively. The regulators 21i and 21j change the discharge capacity of the pump sections 21c and 21d.

[0027] [Electric Motor] The electric motor 22 is coupled to the drive shaft 21a. The electric motor 22 drives the drive shaft 21a to rotate. More specifically, when an electric current is supplied to the electric motor 22, the electric motor 22 drives the drive shaft 21a. This causes the hydraulic pump 21 to discharge hydraulic fluid. The electric motor 22 is, for example, a three-phase AC motor. More specifically, the electric motor 22 is formed in a cylindrical shape and is arranged coaxially with the drive shaft 21a. That is, the electric motor 22 is aligned 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. However, the electric motor 22 does not necessarily have to be aligned in a straight line with the hydraulic pump 21. The electric motor 22 and the hydraulic pump 21 may be arranged parallel to each other but with their axes offset, or the axis of the electric motor 22 may be arranged so as to intersect the drive shaft 21a diagonally or at a right angle.

[0028] [Inverter] The inverter 23 converts the frequency of the current supplied to the electric motor 22. In this embodiment, the inverter 23 converts direct current into alternating current. The inverter 23 is electrically connected to the electric motor 22 and the battery 5, which will be described later. The inverter 23 converts direct current supplied from the battery 5 into alternating current and supplies the alternating current to the electric motor 22. This causes the electric motor 22 to rotate the drive shaft 21a. The inverter 23 is provided, for example, in the electric motor 22. In this embodiment, the inverter 23 is integrally configured with the electric motor 22 so as to be located on the opposite side of the hydraulic pump 21 in the up-down direction. In other words, the inverter 23 is located above the mounting surface 18b.

[0029] [Coupling Member] The coupling member 24 couples the hydraulic pump 21 and the electric motor 22. The coupling member 24 is, for example, a bell housing. The coupling member 24 has a tubular portion 24a and a flange 24b. The tubular portion 24a couples the hydraulic pump 21 and the electric motor 22. More specifically, the tubular portion 24a is formed, for example, in a cylindrical shape. In this embodiment, the tubular portion 24a has an axis extending in the vertical direction and is tapered so that its diameter increases from bottom to top. The hydraulic pump 21 is attached to the lower end of the tubular portion 24a, and the electric motor 22 is attached to the upper end. Thus, the hydraulic pump 21 and the electric motor 22 are coupled to each other by the coupling member 24. The drive shaft 21a extends within the tubular portion 24a along the axis of the tubular portion 24a and is coupled to the electric motor 22. The flange 24b is formed around the entire circumferential circumference of the other end of the cylindrical portion 24a and protrudes radially outward from the other end of the cylindrical portion 24a.

[0030] [Mounting Plate] The mounting plate 25, which is an example of a mounting member, is configured to mount the hydraulic pump 21 and the electric motor 22. In this embodiment, the hydraulic pump 21 and the electric motor 22 are mounted to the mounting plate 25 via a connecting member 24. More specifically, the mounting plate 25 has a through hole 25a that penetrates in the vertical direction. The connecting member 24 is attached to the mounting plate 25 so as to be inserted into the through hole 25a and close the through hole 25a. More specifically, the through hole 25a has a diameter larger than that of the cylindrical portion 24a of the connecting member 24 but smaller than that of the flange 24b. The connecting member 24 is positioned so that the cylindrical portion 24a is inserted into the through hole 25a and the flange 24b rests on the peripheral portion of the through hole 25a. The connecting member 24 is fixed to the mounting plate 25 by, for example, fastening the flange 24b to the mounting plate 25 in a sealed state. As a result, the connecting member 24 is inserted into the through hole 25 a and attached to the mounting plate 25 so as to close the through hole 25 a, and the hydraulic pump 21 and the electric motor 22 are attached to the mounting plate 25 via the connecting member 24 .

[0031] Furthermore, the outer shape of the mounting plate 25 is larger than the outer shape of the insertion hole 18c in the mounting surface 18b in a plan view from above. In this embodiment, the mounting plate 25 is formed, for example, in a square shape in a plan view, with one side larger than the diameter of the circular insertion hole 18c. The mounting plate 25 is attached to the mounting surface 18b so that the hydraulic pump 21 is inserted through the insertion hole 18c and so that the mounting plate 25 blocks the insertion hole 18c from above. In this embodiment, the mounting plate 25 is fixed to the mounting surface 18b by fastening or the like in a sealed state. The shape of the mounting plate 25 is not limited to a square, and may be a rectangle, a polygon, or a circle, as long as it can block the insertion hole 18c.

[0032] [Hanging Tools] A plurality of hanging tools 27 are provided on the mounting plate 25. In this embodiment, four hanging tools 27 are provided on the mounting plate 25 for lifting the electric pump unit 19. The hanging tools 27 can be attached to a lifting device (not shown), such as a crane. Specifically, a hanging tool, such as a hook of the hanging device, can be attached to the hanging tools 27. The electric pump unit 19 is then lifted by lifting the hanging tools. In this embodiment, the hanging tools 27 are arranged, for example, two on each of the left and right edges of the mounting plate 25 in the third direction, and spaced apart from each other in the front-rear direction, which is also the third direction. Note that the hanging tools 27 may be arranged so that the drive shaft 21 a extends substantially vertically when the electric pump unit 19 is lifted by the hanging tool, i.e., so that the center of gravity of the plurality of hanging tools 27 is located on the drive shaft 21 a in a plan view. As a result, by lowering the lifted electric pump unit 19, the hydraulic pump 21 can be placed in the tank 18 through the insertion hole 18c. Also, by pulling up the electric pump unit 19, the hydraulic pump 21 can be pulled out of the tank 18 through the insertion hole 18c.

[0033] [Discharge Piping] The discharge pipe 26 is connected to the discharge ports 21g and 21h of the hydraulic pump 21. The discharge pipe 26 penetrates the mounting plate 25 and protrudes outside the tank 18. More specifically, the discharge ports 21g and 21h of the hydraulic pump 21 face in one direction (leftward in this embodiment) perpendicular to the vertical direction. The discharge pipe 26 extends in a crank shape from the discharge ports 21g and 21h, and the upwardly extending portion penetrates the mounting plate 25. More specifically, the discharge pipe 26 is connected to the discharge ports 21g and 21h, bends from there, and rises upward. The upwardly extending portion of the discharge pipe 26 penetrates the mounting plate 25 and protrudes outside the tank 18. After protruding from the mounting plate 25, the discharge pipe 26 bends again and faces leftward. The discharge pipe 26 configured in this manner is attached to the mounting plate 25 together with the hydraulic pump 21 and the electric motor 22. Therefore, the discharge pipe 26 can be removed from the tank 18 by removing the mounting plate 25 from the tank 18. Therefore, the electric pump unit 19 can be easily removed from the tank 18.

[0034] 2 supplies the hydraulic fluid discharged from the immersed electric pump system 1 to each of the hydraulic actuators. The multi-control valve 4 also controls the flow of the supplied hydraulic fluid. Explaining in more detail, as described above, the multi-control valve 4 is connected to the hydraulic pump 21 (more specifically, the discharge ports 21g and 21h) of the immersed electric pump system 1 via the discharge piping 26. The multi-control valve 4 configured in this manner is located behind the boom 13 within the revolving structure 12. In this embodiment, the multi-control valve 4 is located adjacent to the immersed electric pump system 1 within the revolving structure 12.

[0035] [Battery] The battery 5 is electrically connected to the immersed electric pump device 1 (more specifically, to the inverter 23). The battery 5 supplies direct current to the inverter 23. This drives the immersed electric pump device 1 to discharge the working fluid. The battery 5 is disposed inside the revolving structure 12. More specifically, the battery 5 is disposed rearward of the immersed electric pump device 1 inside the revolving structure 12. In this embodiment, a counterweight 16 is disposed at the rearmost position inside the revolving structure 12, as shown in FIG. 6 . The battery 5 is disposed between the counterweight 16 and the immersed electric pump device 1.

[0036] [Installation of Electric Pump Device] The immersed electric pump device 1 is installed in the revolving body 12 of the excavator 2 as follows. First, the tank 18 is provided in the revolving body 12 via the vibration-isolating member 20. More specifically, the tank 18 is disposed on the right side of the boom 13 within the revolving body 12, i.e., on the opposite side of the cabin 12b across the boom 13. Next, the electric pump unit 19 is attached to the tank 18. More specifically, a hoisting fixture of a hoisting device (not shown) is first attached to the hoisting fixture 27 of the electric pump unit 19. After attachment, the electric pump unit 19 is lifted by the hoisting device and transported onto the mounting surface 18b of the tank 18 (more specifically, the insertion hole 18c). The electric pump unit 19 is then lowered by the hoisting device, and the hydraulic pump 21 is inserted into the insertion hole 18c. As a result, the hydraulic pump 21 is eventually seated within the tank 18, and the cylindrical portion 24a of the connecting member 24 is also inserted into the insertion hole 18c. The mounting plate 25 is then placed on the periphery of the insertion hole 18c on the mounting surface 18b, and the mounting plate 25 is fixed to the mounting surface 18b by fastening or the like. After being fixed, the discharge pipe 26 is connected to the multi-control valve 4. Furthermore, in the immersed electric pump system 1, hydraulic fluid is injected into the tank 18 from an inlet (not shown) on the ceiling surface 18a. At this time, the hydraulic fluid is injected into the tank 18 so that the liquid level H is higher than the mounting surface 18b, as shown in FIGS. 4 and 5 . In this way, the immersed electric pump system 1 is installed within the main body (the revolving bed 12 in this embodiment) of the construction machine 2, as shown in FIG. 6 . Therefore, the immersed electric pump system 1 can be easily installed within the revolving bed 12.

[0037] [Operation of Hydraulic Drive System] As shown in Figure 2, a direct current flows from the battery 5 to the immersed electric pump device 1. This causes the immersed electric pump device 1 to operate as follows. The inverter 23 converts the direct current to an alternating current and passes the alternating current to the electric motor 22. This causes the electric motor 22 to rotate and drive the drive shaft 21a. As a result, the hydraulic pump 21 directly draws hydraulic fluid from the tank 18 through the suction port 21f and discharges it from the discharge ports 21g and 21h. The hydraulic fluid is guided from the discharge ports 21g and 21h through the discharge piping 26 to the multi-control valve 4, and is further supplied to each of the hydraulic actuators via the multi-control valve 4. This allows each of the hydraulic actuators to be operated.

[0038] In the immersed electric pump device 1 of this embodiment, the electric pump unit 19 is provided in the tank 18 so that the hydraulic pump 21 is immersed in the working fluid in the tank 18. Therefore, the working fluid in the tank 18 makes it difficult for vibrations of the hydraulic pump 21 to be transmitted to the outside of the tank 18, and noise caused by the hydraulic pump 21 can be suppressed. In other words, measures can be taken to reduce noise from the hydraulic pump 21. Furthermore, because the hydraulic pump 21 is immersed in the working fluid in the tank 18, the hydraulic pump 21 can be cooled. Furthermore, because the hydraulic pump 21 and the electric motor 22 are provided vertically side by side in the tank 18, the installation area occupied by the immersed electric pump device 1 in the excavator 2 can be reduced.

[0039] Furthermore, in the immersed electric pump device 1 of this embodiment, the mounting surface 18b is located below the liquid level H of the hydraulic fluid stored in the tank 18. Therefore, the hydraulic fluid fills the tank 18 at least up to the height of the mounting surface 18b. For example, even if the immersed electric pump device 1 is tilted, the hydraulic fluid can remain filled up to the height of the mounting surface 18b. This allows almost the entire hydraulic pump 21 to be immersed in the hydraulic fluid. Therefore, noise caused by the hydraulic pump 21 can be further suppressed, and the hydraulic pump 21 can be further cooled.

[0040] Furthermore, in the electric immersed pump device 1 of this embodiment, the mounting surface 18b has an insertion hole 18c through which the hydraulic pump 21 can be inserted. The electric pump unit 19 also includes a mounting plate 25 that is attached to the mounting surface 18b so as to block the insertion hole 18c from above. Therefore, the electric pump unit 19 can be easily attached to the tank 18 by lowering the electric pump unit 19 into the insertion hole 18c from above and attaching the mounting plate 25 to the mounting surface 18b. On the other hand, when 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 it up.

[0041] Furthermore, in the electric immersed pump device 1 of this embodiment, the discharge pipe 26 connected to the discharge ports 21g, 21h of the hydraulic pump 21 penetrates the mounting plate 25 and protrudes outside the tank 18. Therefore, the hydraulic pump 21, the electric motor 22, and the discharge pipe 26 are unitized on the mounting plate 25, making it easy to attach and detach the electric pump unit 19 to and from the tank 18.

[0042] Furthermore, in the electric immersed pump device 1 of this embodiment, the tank 18 is provided on the revolving body 12 via the vibration-isolating member 20. This makes it possible to suppress vibrations transmitted to the revolving body 12 via the tank 18. This makes it possible to suppress noise caused by vibrations of the hydraulic pump 21 inside the tank 18.

[0043] The shovel 2 of this embodiment includes the above-described electric immersed pump device 1. Therefore, it is possible to realize the shovel 2 that provides the above-described operational effects.

[0044] Second Embodiment The immersed electric pump system 1A and the shovel 2A of the second embodiment are similar in configuration to the immersed electric pump system 1 and the shovel 2 of the first embodiment, respectively. Therefore, the configurations of the immersed electric pump system 1A and the shovel 2A of the second embodiment will be mainly described in terms of differences from the immersed electric pump system 1 and the shovel 2 of the first embodiment, and the same configurations will be assigned the same reference numerals and descriptions thereof will be omitted.

[0045] A construction machine 2A of the second embodiment shown in FIG. 1 is equipped with an immersed electric pump apparatus 1A of the second embodiment shown in FIG. 7 instead of the immersed electric pump apparatus 1 of the first embodiment. That is, the hydraulic drive system 3 further includes an immersed electric pump apparatus 1A, a multi-control valve 4, and a battery 5. The immersed electric pump apparatus 1A is an electric hydraulic pump apparatus like the immersed electric pump apparatus 1 of the first embodiment. The immersed electric pump apparatus 1A includes a tank 18A and an electric pump unit 19A. In the immersed electric pump apparatus 1A, the electric pump unit 19A is provided in the tank 18A so that both the hydraulic pump 21 and the electric motor 22 are immersed in the hydraulic fluid in the tank 18. More specifically, the electric pump unit 19A further includes an inverter 23, which is disposed outside the tank 18A, and which is provided in the tank 18A so that the hydraulic pump 21 and the electric motor 22 are immersed in the hydraulic fluid in the tank 18. Therefore, it is preferable that the working fluid be a liquid having insulating properties, although the working fluid is not limited to such a liquid.

[0046] The electric immersed pump system 1A configured as described above includes not only the tank 18A and the electric pump unit 19A, but also a vibration-isolating member 20. The following mainly describes the configurations of the tank 18A and the electric pump unit 19A, focusing on differences from the tank 18 and the electric pump unit 19 of the first embodiment.

[0047] As shown in FIG. 8 , the mounting surface 18Ab of the tank 18A is located below the liquid level H of the tank 18A, similar to the mounting surface 18b in the first embodiment. On the other hand, the mounting surface 18Ab is located above the mounting surface 18Ab in the first embodiment so that both the hydraulic pump 21 and the electric motor 22 can be accommodated within the tank 18A. The insertion hole 18Ac is configured to allow the electric motor 22 to be inserted in the vertical direction in addition to the hydraulic pump 21. That is, the outer shape of the insertion hole 18Ac is larger than the outer shapes of the hydraulic pump 21 and the electric motor 22. Explaining in more detail, the insertion hole 18Ac is configured to allow the electric motor 22 and the connecting member 24 to be inserted in the vertical direction in addition to the hydraulic pump 21.

[0048] The electric pump unit 19 includes a connecting member 24, a mounting plate 25A, and a discharge pipe 26 in addition to the hydraulic pump 21, the electric motor 22, and the inverter 23. The mounting plate 25A is configured to mount the hydraulic pump 21 and the electric motor 22. In this embodiment, the hydraulic pump 21 and the electric motor 22 are mounted to the mounting plate 25A via the inverter 23. More specifically, a through-hole 25a extending vertically through the mounting plate 25A is formed. The through-hole 25a is, for example, larger than the electric motor 22 but smaller than the inverter 23. Therefore, the electric motor 22 is inserted through the through-hole 25a of the mounting plate 25A, and the inverter 23 is placed on the peripheral portion of the through-hole 25a so as to block the through-hole 25a from above. The inverter 23 is then fixed to the mounting plate 25A by, for example, fastening the mounting plate 25A in a sealed state. In this manner, the hydraulic pump 21 and the electric motor 22 are attached to the mounting plate 25A via the inverter 23.

[0049] The outer shape of the mounting plate 25A is larger than the outer shape of the insertion hole 18Ac in a plan view, similar to the mounting plate 25A of the first embodiment. The mounting plate 25A is attached to the mounting surface 18Ab so that the hydraulic pump 21 is inserted into the insertion hole 18Ac and so that the mounting plate 25A closes the insertion hole 18Ac from above. In this embodiment, the mounting plate 25A is fixed to the mounting surface 18Ab by fastening or the like in a sealed state.

[0050] The immersed electric pump system 1A configured as described above is installed in the revolving body 12 of the excavator 2A in the same manner as the immersed electric pump system 1 of the first embodiment. The immersed electric pump system 1A also discharges hydraulic fluid in the same manner as the immersed electric pump system 1 of the first embodiment. The discharged hydraulic fluid is then supplied to each of the hydraulic actuators via the multi-control valve 4.

[0051] In the electric submerged pump system 1A of this embodiment, the electric pump unit 19A is provided in the tank 18A so 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 in the tank 18A.

[0052] Furthermore, in the immersed electric pump device 1A of this embodiment, the mounting surface 18Ab is located below the hydraulic fluid stored in the tank 18A. Therefore, the tank 18A is filled with hydraulic fluid up to at least the height of the mounting surface 18Ab. This allows the entire motor to be immersed in the hydraulic fluid, thereby further cooling the motor.

[0053] The shovel 2A of this embodiment includes the above-described electric immersion pump device 1A, and therefore, the shovel 2A can achieve the above-described effects.

[0054] In addition, the electric immersed pump device 1A of the second embodiment has the same functions and effects as the electric immersed pump device 1 of the first embodiment.

[0055] <Other Embodiments> In the immersed electric pump apparatus 1, 1A of this embodiment, the hydraulic pump 21 and the electric motor 22 are aligned coaxially in a row, but the electric motor 22 may be arranged so that the axis of the electric motor 22 intersects (for example, is perpendicular to) the axis of the hydraulic pump 21. That is, in the immersed electric pump apparatus 1, 1A, it is preferable that the hydraulic pump 21 is vertically disposed with the drive shaft 21a of the hydraulic pump 21 extending in the first direction. Note that in the immersed electric pump apparatus 1, 1A, the electric pump unit is vertically disposed in the tank 18, 18A, but the hydraulic pump 21 and the electric motor 22 may be horizontally disposed so that they are aligned in the left-right or front-rear direction.

[0056] Furthermore, in the electric immersed pump system 1, 1A of this embodiment, the hydraulic pump 21 is not limited to a tandem pump and may be a single pump. Furthermore, the hydraulic pump 21 is not limited to a swash plate pump and may be a bent-axis pump or a gear pump. Furthermore, the hydraulic pump 21 may be disposed on the other side in the first direction (i.e., above) of the electric motor 22. Furthermore, the electric motor 22 is not limited to a three-phase AC motor and may be another motor such as a servo motor.

[0057] In the immersed electric pump apparatus 1, 1A of this embodiment, the hydraulic pump 21 and the electric motor 22 are connected by the connecting member 24. However, the hydraulic pump 21 and the electric motor 22 may be directly attached to the mounting plate 25. Furthermore, the hoisting fixture 27 does not necessarily have to be provided on the mounting plate 25, but may be provided on the connecting member 24 and the tank 18, 18A. Furthermore, the flange 24b of the connecting member 24 does not necessarily have to be formed around the entire circumferential circumference of the cylindrical portion 24a. For example, the flange 24b may be formed by a plurality of protrusions that protrude radially outward from the cylindrical portion 24a and are spaced apart from one another in the circumferential direction, and the shape of the flange 24b is not important. Furthermore, the suction port 21f of the immersed electric pump apparatus 1, 1A does not necessarily have to open in one of the third directions, but may open in one and the other of the second directions and in the other of the third directions. Similarly, the direction in which the discharge ports 21g, 21h open is also not limited to the other of the second directions.

[0058] In the immersed electric pump device 1, 1A of this embodiment, the level of the hydraulic fluid is located above the mounting surfaces 18b, 18Ab, but it may be located below. That is, in the immersed electric pump device 1, 1A, it is sufficient that the level of the hydraulic fluid is located above the suction port 21f, and it is sufficient that the hydraulic pump 21 is partially immersed in the hydraulic fluid and the electric motor 22 is partially immersed in the hydraulic fluid. Furthermore, the shape of the tank 18, 18A does not necessarily have to be stepped, and it is preferable that the mounting surfaces 18b, 18Ab are located lower than the ceiling surface 18a. That is, the mounting surfaces 18b, 18Ab do not necessarily have to be located lower than the ceiling surface 18a, and may be the ceiling surface 18a itself.

[0059] In the immersed electric pump device 1, 1A of this embodiment, the discharge pipe 26 penetrates the mounting plate 25 and protrudes outside the tank 18, 18A. However, the discharge pipe 26 may be configured to protrude outside the tank 18, 18A from the side or bottom of the tank 18, 18A. Furthermore, while the vibration-damping member 20 is provided on the bottom of the tank 18, 18A, it may also be provided between the mounting plate 25 and the mounting surface 18b, 18Ab, or between the flange 24b and the mounting plate 25, for example. In this embodiment, the mounting plate 25 is given as an example of the mounting member, but the mounting member is not limited to being plate-shaped and may be block-shaped.

[0060] <Illustrative embodiment> A liquid-immersed electric pump device for construction machinery in a first aspect is a liquid-immersed electric pump device for construction machinery that is mounted on a construction machine, and comprises an electric pump unit including a hydraulic pump that discharges hydraulic fluid when a drive shaft rotates, and an electric motor that rotationally drives the drive shaft, and a tank that stores the hydraulic fluid discharged from the hydraulic pump and is erected in a first direction, wherein the electric pump unit is provided in the tank such that the hydraulic pump and the electric motor are aligned in the first direction and the hydraulic pump is immersed in the hydraulic fluid in the tank.

[0061] According to the above aspect, the electric pump unit is mounted in the tank so that the hydraulic pump is immersed in the hydraulic fluid in the tank. Therefore, vibrations of the hydraulic pump are less likely to be transmitted to the outside of the tank by the hydraulic fluid in the tank, and noise caused by the hydraulic pump can be suppressed. In other words, noise reduction measures can be taken for the hydraulic pump 21. Moreover, because the hydraulic pump is immersed in the hydraulic fluid in the tank, the hydraulic pump can be cooled. Furthermore, because the hydraulic pump and the electric motor are mounted in the tank side by side in the first direction, the installation area occupied by the submerged electric pump device for construction machinery in the construction machine can be reduced.

[0062] In a second aspect, the submerged electric pump device for construction machinery is the submerged electric pump device for construction machinery of the first aspect, wherein the tank includes a mounting surface to which the electric pump unit is attached, the hydraulic pump is disposed on one side of the mounting surface in a first direction and is immersed in the working fluid in the tank, and the mounting surface is located on one side of the liquid level of the working fluid stored in the tank in the first direction.

[0063] According to the above aspect, the mounting surface is located on one side in the first direction of the hydraulic fluid level stored in the tank. Therefore, the tank is filled with hydraulic fluid up to at least the height of the mounting surface. This allows the hydraulic pump to be substantially entirely submerged in hydraulic fluid. This further reduces noise caused by the hydraulic pump and further cools the hydraulic pump.

[0064] In a third aspect, the submerged electric pump device for construction machinery is the submerged electric pump device for construction machinery of the first or second aspect, wherein the tank includes a mounting surface to which the electric pump unit is attached, the hydraulic pump is arranged on one side in a first direction from the mounting surface and is immersed in the working fluid in the tank, the mounting surface has an insertion hole through which the hydraulic pump can be inserted in the first direction, the electric pump unit includes a mounting member to which the hydraulic pump and the electric motor are attached, and the mounting member is attached to the mounting surface so as to block the insertion hole from the other side in the first direction.

[0065] According to the above aspect, the mounting surface has an insertion hole through which the hydraulic pump can be inserted in the first direction. The electric pump unit also includes a mounting plate attached to the mounting surface so as to block the insertion hole from the other side in the first direction. Therefore, the electric pump unit can be easily mounted to the tank by lowering the electric pump unit into the insertion hole from the other side in the first direction and attaching the mounting plate to the mounting surface. On the other hand, when removing the electric pump unit from the tank, the electric pump unit can be easily removed from the tank by lifting it up.

[0066] In a fourth aspect, the submerged electric pump device for construction machinery is the submerged electric pump device for construction machinery of the third aspect, wherein the electric pump unit includes a discharge pipe connected to a discharge port of the hydraulic pump, and the discharge pipe penetrates the mounting member and protrudes outside the tank.

[0067] According to the above aspect, the discharge pipe connected to the discharge port of the hydraulic pump penetrates the mounting plate and protrudes outside the tank. Therefore, the hydraulic pump, the electric motor, and the discharge pipe are unitized on the mounting plate, making it easy to attach and detach the electric pump unit to and from the tank.

[0068] In a fifth aspect, the immersed electric pump device for construction machinery of any one of the first to fourth aspects further includes a vibration-damping member that suppresses transmission of vibrations, and the tank is mounted to the construction machinery via the vibration-damping member.

[0069] According to the above aspect, the tank is mounted to the construction machine via the vibration-isolating member. Therefore, it is possible to suppress vibrations transmitted to the construction machine via the tank. This makes it possible to suppress noise caused by vibrations of the hydraulic pump inside the tank.

[0070] In a sixth aspect, the electric pump device for construction machinery is the electric pump device for construction machinery of any one of the first to fifth aspects, wherein the electric pump unit is provided in the tank so that the electric motor is immersed in the working fluid in the tank.

[0071] According to the above aspect, the electric pump unit is provided in the tank so that the electric motor is immersed in the hydraulic fluid in the tank, and therefore the electric motor can be cooled by the hydraulic fluid in the tank.

[0072] In a seventh aspect, the immersed electric pump device for construction machinery is the immersed electric pump device for construction machinery of the sixth aspect, wherein the tank includes a mounting surface to which the electric pump unit is attached, the electric motor and the hydraulic pump are disposed on one side of the mounting surface in a first direction and are immersed in the working fluid in the tank, and the mounting surface is located on one side of the working fluid stored in the tank in the first direction.

[0073] According to the above aspect, the mounting surface is located on one side in the first direction of the hydraulic fluid stored in the tank. Therefore, the hydraulic fluid fills the tank up to at least the height of the mounting surface. This allows the entire motor to be immersed in the hydraulic fluid. Therefore, the motor can be further cooled.

[0074] In an eighth aspect, the submerged electric pump device for construction machinery is the submerged electric pump device for construction machinery of the seventh aspect, wherein the electric pump unit further includes an inverter that converts the frequency of the current supplied to the electric motor, and the inverter is arranged on the other side of the mounting surface in the first direction.

[0075] According to the above aspect, the inverter is disposed on the other side of the mounting surface in the first direction. Therefore, the inverter can be disposed outside the tank. This makes it possible to prevent the inverter from being immersed in the hydraulic fluid.

[0076] A construction machine in a ninth aspect is a construction machine equipped with a hydraulic actuator, and includes the electric pump device for construction machinery of any one of the first to eighth aspects, and a control valve that supplies working fluid discharged from the hydraulic pump of the electric pump device for construction machinery to the hydraulic actuator.

[0077] According to the above aspect, the construction machine includes the above-described electric immersion pump device for construction machine, and therefore, it is possible to realize a construction machine that provides the above-described operational effects.

[0078] From the above description, many modifications and other embodiments of the present disclosure will be apparent to those skilled in the art. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present disclosure. Details of the structure and / or function thereof can be substantially changed without departing from the spirit of the present disclosure.

Claims

1. A submerged electric pump device for construction machinery that is mounted on construction machinery, comprising: an electric pump unit including a hydraulic pump that discharges hydraulic fluid when a drive shaft rotates, and an electric motor that drives and rotates the drive shaft; and a tank that stores the hydraulic fluid to be discharged from the hydraulic pump and is uprightly disposed in a first direction, wherein the electric pump unit is provided in the tank such that the hydraulic pump and the electric motor are aligned in the first direction, and the hydraulic pump is immersed in the hydraulic fluid in the tank.

2. The submerged electric pump device for construction machinery as described in claim 1, wherein the tank includes a mounting surface to which the electric pump unit is attached, the hydraulic pump is disposed on one side in a first direction from the mounting surface and is immersed in the working fluid in the tank, and the mounting surface is located on one side in the first direction from the liquid level of the working fluid stored in the tank.

3. The submerged electric pump device for construction machinery as described in claim 1, wherein the tank includes a mounting surface to which the electric pump unit is attached, the hydraulic pump is arranged on one side in a first direction from the mounting surface and is immersed in the working fluid in the tank, the mounting surface has an insertion hole through which the hydraulic pump can be inserted in the first direction, the electric pump unit includes a mounting member to which the hydraulic pump and the electric motor are attached, and the mounting member is attached to the mounting surface so as to block the insertion hole from the other side in the first direction.

4. A submerged electric pump device for construction machinery as described in claim 3, wherein the electric pump unit includes a discharge piping connected to a discharge port of the hydraulic pump, the discharge piping penetrating the mounting member and protruding outside the tank.

5. The electric submerged pump device for construction machinery according to claim 1, further comprising a vibration-isolating member for suppressing transmission of vibrations, and the tank is mounted to the construction machinery via the vibration-isolating member.

6. The submerged electric pump device for construction machinery according to claim 1, wherein the electric pump unit is provided in the tank so that the electric motor is immersed in the hydraulic fluid in the tank.

7. The submerged electric pump device for construction machinery as described in claim 6, wherein the tank includes a mounting surface to which the electric pump unit is attached, the electric motor and the hydraulic pump are disposed on one side in a first direction from the mounting surface and are immersed in the working fluid in the tank, and the mounting surface is located on one side in the first direction from the working fluid stored in the tank.

8. The submerged electric pump device for construction machinery according to claim 7, wherein the electric pump unit further includes an inverter that converts the frequency of the current supplied to the electric motor, and the inverter is disposed on the other side in the first direction from the mounting surface.

9. A construction machine equipped with a hydraulic actuator, comprising: a submerged electric pump device for construction machines according to any one of claims 1 to 8; and a control valve that supplies hydraulic fluid discharged from the hydraulic pump of the submerged electric pump device for construction machines to the hydraulic actuator.

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