Electric pump system for construction machine, and construction machine

Abstract

An electric pump system for a construction machine mounted on a construction machine, said electric pump system for a construction machine comprising: an electric pump unit including a hydraulic pump for discharging a hydraulic fluid when a drive shaft rotates, and a drive device for performing rotary driving of the drive shaft in accordance with supplied electric power; and a cooling system device including a radiator for cooling a coolant, a cooling system flow passage through which coolant circulating between the radiator and the drive device flows, and a cooling liquid pump that is provided in the cooling system flow passage and that circulates the coolant flowing in the cooling system flow passage. In the electric pump unit, the hydraulic pump and the drive device are arranged side by side in the stated order from below. The cooling system device further includes an air vent port connected to the cooling system flow passage and positioned higher than the cooling system flow passage, and an air vent valve for opening and closing the air vent port.

Description

Electric pump system for construction machinery, and construction machinery

[0001] The present disclosure relates to an electric pump system for a construction machine that is driven by supplied electric power, 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] In electric construction machines such as the electric shovel of Patent Document 1, a drive unit composed of an electric motor and an inverter generates heat, and therefore a cooling system is provided to cool the drive unit. The cooling system cools the drive unit, for example, by flowing a coolant through the drive unit. The coolant may contain air. Air reduces the cooling effect of the coolant. Therefore, it is preferable to remove air from the coolant flowing through the cooling system. On the other hand, air may form an air pocket without being carried away by the coolant. Depending on the location of the air pocket, it may be difficult to remove the air from the coolant.

[0005] Therefore, an object of the present disclosure is to provide an electric pump system for a construction machine that can easily perform air bleeding work in cooling system equipment, and a construction machine equipped with the same.

[0006] The electric pump system for construction machinery disclosed herein is an electric pump system 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 a drive device that rotationally drives the drive shaft in response to supplied power; a radiator that cools the coolant; a cooling system flow path through which the coolant circulates between the radiator and the drive device; and a cooling system device that is provided in the cooling system flow path and circulates the coolant that flows through the cooling system flow path; in the electric pump unit, the hydraulic pump and the drive device are arranged side by side from bottom to top, and the cooling system device further includes an air bleed port section that is connected to the cooling system flow path and is positioned higher than the cooling system flow path, and an air bleed valve that opens and closes the air bleed port section.

[0007] According to the present disclosure, a cooling system device includes an air vent port connected to a cooling system flow path and positioned higher than the cooling system flow path, and an air vent valve that opens and closes the air vent port. This allows air contained in the coolant to be collected toward the air vent port, and by opening the air vent port, the air collected in the air vent port can be released into the atmosphere. This makes it easy to bleed air from the cooling system device.

[0008] The construction machine of the present disclosure is equipped with the electric pump system for construction machine described above.

[0009] According to the present disclosure, a construction machine having the above-described functions can be realized.

[0010] According to the present disclosure, air bleeding can be easily performed in cooling system equipment.

[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] FIG. 1 is a perspective view showing a shovel of a first embodiment according to the present disclosure. FIG. 2 is a schematic plan view showing the shovel of FIG. 1. FIG. 3 is a schematic side view showing an electric pump system mounted on the shovel shown in FIG. 1. FIG. 4 is an enlarged perspective view showing an electric pump device of the electric pump system of FIG. 2. FIG. 5 is a cross-sectional view of the electric pump device of FIG. 4 taken along the cutting line V-V. FIG. 6 is a cross-sectional view of the electric pump device of FIG. 4 taken along the cutting line VI-VI. FIG. 7 is a schematic side view showing a shovel of a second embodiment according to the present disclosure.

[0013] Hereinafter, electric pump systems 1, 1A for construction machinery and construction machines 2, 2A equipped therewith according to first and second embodiments of the present disclosure will be described 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 electric pump systems 1, 1A for construction machinery (hereinafter simply referred to as "electric pump systems") 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 present disclosure.

[0014] [Construction Machine] The construction machine 2 shown in FIG. 1 performs various tasks by moving an attachment. The construction machine 2 is, for example, an electric shovel (hereinafter simply referred to as "shovel"). 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 up-down direction, which is an example of a first direction. The boom 13 is mounted on the revolving body 12 so as to be swingable in the up-down 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, thereby swinging the boom 13, the arm 14, and the bucket 15, respectively. The excavator 2 also includes a hydraulic drive system 3.

[0016] [Hydraulic Drive System] The hydraulic drive system 3 is disposed within the revolving unit 12 as shown in Figure 2. The hydraulic drive system 3 operates each of the hydraulic actuators described above by supplying hydraulic fluid to each of the hydraulic actuators. The hydraulic drive system 3 also controls the movement of each of the hydraulic actuators by controlling the flow (flow rate and flow direction) of hydraulic fluid supplied to each of the hydraulic actuators. The hydraulic drive system 3 configured in this manner includes a tank 21, an electric pump system 1, a multi-control valve 23, and a battery 24.

[0017] [Tank] The tank 21 stores hydraulic fluid discharged from the electric pump system 1, which will be described in detail later. That is, the hydraulic fluid in the tank 21 is sucked into the electric pump system 1, discharged, and then supplied to each hydraulic actuator via the multi-control valve 23. The hydraulic fluid is also returned from each hydraulic actuator to the tank 21 via the multi-control valve 23. The tank 21 is located on the right side of the revolving unit 12. More specifically, the revolving unit 12 has a cabin 12a in which a driver (or operator) can ride. As described above, the revolving unit 12 is provided with a boom 13, which, in this embodiment, is provided in the front of the revolving unit 12, in a central portion in the left-right direction. The cabin 12a is located on the left side of the revolving unit 12 adjacent to the boom 13. The tank 21 is located on the opposite side of the cabin 12a across the boom 13. That is, the tank 21 is located on the right side of the revolving unit 12 adjacent to the boom 13.

[0018] [Electric Pump System] The electric pump system 1 is an electric hydraulic pump system mounted on the excavator 2. The electric pump system 1 is disposed adjacent to the tank 21 within the revolving body 12 (see also FIG. 3 ). More specifically, the electric pump system 1 is provided behind the tank 21. That is, the electric pump system 1 is disposed on the right side within the revolving body 12. The electric pump system 1 also includes an electric pump unit 25 and a cooling system 26. The electric pump system 1 discharges hydraulic fluid from the electric pump unit 25, and the cooling system 26 cools the electric pump unit 25 (more specifically, the inverter 36 and the electric motor 35, which will be described later). More specifically, the electric pump system 1 also includes a support frame 27, and the electric pump unit 25, together with the support frame 27, constitutes the electric pump device 4. Each component of the electric pump system 1 will be described in more detail below.

[0019] [Electric Pump Unit] The electric pump unit 25 is an electrically driven hydraulic pump unit. More specifically, the electric pump unit 25 is driven by a supply of electric power to discharge hydraulic fluid. In this embodiment, the electric pump unit 25 is electrically connected to the battery 24 and is driven by electric power supplied from the battery 24. The electric pump unit 25 is also connected to the tank 21 via an intake pipe 25a and to the multi-control valve 23 via an outlet pipe 25b. When driven, the electric pump unit 25 draws hydraulic fluid from the tank 21 via the intake pipe 25a and discharges hydraulic fluid to the multi-control valve 23 via the outlet pipe 25b.

[0020] As shown in FIG. 4 , the electric pump unit 25 includes a hydraulic pump 31 and a drive device 32. The hydraulic pump 31 and the drive device 32 are arranged side by side in that order from the bottom up in the electric pump unit 25. The electric pump unit 25 is supported by a support frame 27, as will be described in detail later. As shown in FIG. 3 , the electric pump unit 25 is supported by the support frame 27 and arranged in the revolving structure 12 so as to be adjacent to the rear of the tank 21. That is, the electric pump unit 25 is located on the opposite side of the cabin 12a within the revolving structure 12, with the boom 13 in between. The electric pump unit 25 configured in this manner further includes a connecting member 33 in addition to the hydraulic pump 31 and the drive device 32 described above. Each component of the electric pump unit 25 will be described in more detail below.

[0021] [Hydraulic Pump] As shown in FIGS. 5 and 6 , the hydraulic pump 31 has a drive shaft 31a. The hydraulic pump 31 discharges hydraulic fluid when the drive shaft 31a is rotated. The hydraulic pump 31 is, for example, a tandem pump having two variable displacement pump sections (variable displacement swash plate pumps in this embodiment) 31c, 31d. Note that the hydraulic pump 31 does not necessarily have to be a tandem pump and may be a single pump. Furthermore, the hydraulic pump 31 does not necessarily have to be a swash plate pump and may be another type of pump, such as a bent axis pump or a gear pump. The variable displacement pump sections (hereinafter simply referred to as "pump sections") 31c, 31d share the aforementioned drive shaft 31a. The pump sections 31c, 31d are arranged side by side in the vertical direction along the drive shaft 31a. A housing 31e is interposed between the pump sections 31c, 31d. The side surface of the housing 31e is formed with one suction port 31f and two discharge ports 31g, 31h. The suction port 31f opens, for example, to the right on the side surface of the housing 31e. The discharge ports 31g, 31h open, for example, to the rear on the side surface of the housing 31e. However, the opening direction of each port 31f-h is not limited to the above-described direction. The pump sections 31c, 31d share the single suction port 31f and each have a discharge port 31g, 31h. The suction piping 25a is connected to the suction port 31f, and the discharge piping 25b is connected to the two ports 31g, 31h, respectively. Each of the pump sections 31c, 31d draws in hydraulic fluid through the suction port 31f and discharges hydraulic fluid from the two discharge ports 31g, 31h. Each of the pump sections 31c, 31d is provided with a regulator 31i, 31j. The regulators 31i and 31j change the discharge capacity of the pump sections 31c and 31d, respectively.

[0022] [Driver] The drive device 32 drives the drive shaft 31a to rotate in response to the supplied power. More specifically, the drive device 32 is coupled to the drive shaft 31a. The drive device 32 is also electrically connected to the battery 24, which will be described in detail later. The drive device 32 drives the drive shaft 31a to rotate in response to the power supplied from the battery 24. The drive device 32 configured in this manner includes an electric motor 35 and an inverter 36.

[0023] [Electric Motor] The electric motor 35 is coupled to the drive shaft 31a. The electric motor 35 rotates the drive shaft 31a. More specifically, when power is supplied to the electric motor 35, the electric motor 35 rotates the drive shaft 31a. This causes the hydraulic pump 31 to discharge hydraulic fluid. The electric motor 35 is, for example, a three-phase AC motor. However, the electric motor 35 is not limited to a three-phase AC motor and may be a DC motor. More specifically, the electric motor 35 is, for example, cylindrical and arranged coaxially with the drive shaft 31a. That is, the electric motor 35 is aligned vertically in a straight line with the hydraulic pump 31. However, the electric motor 35 does not necessarily have to be aligned in a straight line with the hydraulic pump 31. The electric motor 35 and the hydraulic pump 31 may be arranged parallel to each other but offset from each other, or the axis of the electric motor 35 may be arranged so as to intersect the drive shaft 31a at an angle or at a right angle.

[0024] [Inverter] The inverter 36 converts the frequency of the power supplied to the electric motor 35. In this embodiment, the inverter 36 converts direct current into alternating current. The inverter 36 is electrically connected to the electric motor 35 and the battery 24, which will be described later. The inverter 36 converts the direct current supplied from the battery 24 into alternating current and supplies the alternating current to the electric motor 35. This causes the electric motor 35 to rotate the drive shaft 31a. The inverter 36 is provided, for example, in the electric motor 35. In this embodiment, the inverter 36 is configured integrally with the electric motor 35 so as to be located opposite (i.e., above) the hydraulic pump 31 in the vertical direction.

[0025] [Coupling Member] The coupling member 33 couples the hydraulic pump 31 and the electric motor 35. The coupling member 33 is, for example, a bell housing. The coupling member 33 has a tubular portion 33a and a flange 33b. The tubular portion 33a couples the hydraulic pump 31 and the electric motor 35. More specifically, the tubular portion 33a is formed, for example, in a cylindrical shape. In this embodiment, the tubular portion 33a has an axis extending in the vertical direction and is tapered so that its diameter increases upward. The hydraulic pump 31 is attached to one vertical end of the tubular portion 33a, and the electric motor 35 is attached to the other vertical end. Thus, the hydraulic pump 31 and the electric motor 35 are coupled by the coupling member 33. Within the tubular portion 33a, the drive shaft 31a extends along the axis of the tubular portion 33a (i.e., upward) and is coupled to the electric motor 35. The flange 33b is formed around the entire circumferential circumference of the other end of the cylindrical portion 33a and protrudes radially outward from the other end of the cylindrical portion 33a.

[0026] [Support Frame] As shown in Fig. 3 , the support frame 27 is provided upright within the revolving body 12 of the excavator 2. The support frame 27 supports the electric pump unit 25 so that the hydraulic pump 31, the electric motor 35, and the inverter 36 are lined up in that order from below (i.e., vertically oriented). More specifically, as shown in Figs. 4 to 6 , the support frame 27 is, for example, a substantially rectangular parallelepiped frame, and supports the electric pump unit 25 so that the hydraulic pump 31 is housed therein. In this embodiment, the support frame 27 supports the electric pump unit 25 so that it is vertically oriented, with the electric pump unit 25 inserted through a ceiling portion 27a and the flange 33b of the connecting member 33 placed and fixed on the ceiling portion 27a.

[0027] [Cooling System Equipment] The cooling system equipment 26 cools the drive unit 32 with coolant. More specifically, the cooling system equipment 26 cools the electric motor 35 and the inverter 36 with coolant. The cooling system equipment 26 having such a function includes a radiator 41, a cooling system flow path 42, a coolant pump 43, an air bleed port 44, and an air bleed valve 45.

[0028] [Radiator] The radiator 41 cools the coolant. More specifically, the radiator 41 cools the coolant that has absorbed heat from the electric motor 35 and the inverter 36, as will be described in detail later. In this embodiment, the radiator 41 is disposed at a lower position than the air bleed port 44, which will be described in detail later. As shown in FIG. 3 , the radiator 41 includes a radiator core 41a and a cooling fan 41b. The radiator core 41a is a so-called heat exchanger. That is, the radiator core 41a allows the coolant to flow therethrough and exchanges heat between the coolant flowing therethrough and the outside air. The cooling fan 41b further cools the coolant by blowing air onto the radiator core 41a.

[0029] [Cooling System Flow Path] The cooling system flow path 42 is a flow path through which the coolant circulates between the radiator 41 and the drive unit 32. In the present embodiment, the cooling system flow path 42 is configured so that the coolant flows from the electric motor 35 toward the inverter 36. That is, the coolant circulates through the cooling system flow path 42, passing from the radiator 41 through the electric motor 35 and the inverter 36 in that order, and returning to the radiator 41. The cooling system flow path 42 is formed at a position lower than the ceiling surface 36b of the inverter 36. In the present embodiment, the entire cooling system flow path 42 is formed at a position lower than the ceiling surface 36b of the inverter 36. It is preferable that the cooling system flow path 42 does not have a shape that bends upward and downward (e.g., an S-shape). The cooling system flow path 42 configured in this manner includes an inverter-side flow path portion 42a, an electric motor-side flow path portion 42b, a supply flow path portion 42c, and a discharge flow path portion 42d.

[0030] The inverter-side flow path 42a is formed inside the inverter 36 (in the present embodiment, the casing 36a of the inverter 36). That is, the inverter 36 is a water-cooled inverter, and is cooled by flowing a coolant through the inverter-side flow path 42a. Note that the inverter-side flow path 42a does not necessarily have to be formed inside the inverter 36 (in the present embodiment, the casing 36a of the inverter 36), and may be a pipe, a jacket, or the like provided on the outer surface of the casing 36a.

[0031] The motor-side flow passage 42b is formed inside the electric motor 35 (in the present embodiment, the casing 35a of the electric motor 35). That is, the electric motor 35 is a water-cooled electric motor, and is cooled by flowing coolant through the motor-side flow passage 42b. Note that the motor-side flow passage 42b does not necessarily have to be formed inside the electric motor 35 (in the present embodiment, the casing 35a of the electric motor 35), and may be a pipe or a jacket provided on the outer surface of the casing 35a. The electric motor-side flow passage 42b is also connected to the inverter-side flow passage 42a. Therefore, the coolant flows from the electric motor 35 to the inverter 36.

[0032] The supply flow path portion 42c is connected to the radiator 41 and the electric motor 35. The supply flow path portion 42c guides the coolant cooled by the radiator 41 to the electric motor 35. More specifically, the supply flow path portion 42c is connected to the electric motor side flow path portion 42b and guides the coolant cooled by the radiator 41 to the electric motor side flow path portion 42b. In this embodiment, the supply flow path portion 42c is formed of a pipe.

[0033] The discharge flow path 42d is connected to the radiator 41 and the inverter 36. The discharge flow path 42d returns the coolant that has absorbed heat from the electric motor 35 and the inverter 36 to the radiator 41. More specifically, the discharge flow path 42d is connected to the inverter-side flow path 42a, and returns the coolant that has absorbed heat by passing through the electric motor-side flow path 42b and the inverter-side flow path 42a to the radiator 41. In this embodiment, the discharge flow path 42d is configured by piping.

[0034] [Coolant Pump] The coolant pump 43 is provided in the cooling system flow path 42. The coolant pump 43 circulates the coolant flowing through the cooling system flow path 42. In this embodiment, the coolant pump 43 is a metering pump, such as a gear pump. However, the coolant pump 43 is not limited to a gear pump or a metering pump. In this embodiment, the coolant pump 43 is interposed in the supply flow path portion 42c. The coolant pump 43 circulates the coolant in the cooling system flow path 42 by sending the coolant from the radiator 41 toward the electric motor 35.

[0035] [Air Vent Port] The air vent port 44 is connected to the cooling system flow path 42. The air vent port 44 is positioned higher than the cooling system flow path 42. Furthermore, in this embodiment, the air vent port 44 is positioned higher than the radiator 41. More specifically, as shown in FIG. 3 , the air vent port 44 is formed on the ceiling surface 36b of the casing 36a of the inverter 36. In this embodiment, the air vent port 44 extends downward from the ceiling surface 36b and connects to the cooling system flow path 42. That is, the air vent port 44 branches off from the cooling system flow path 42 and extends upward. Therefore, when air contained in the coolant flowing through the cooling system flow path 42 reaches the connection point between the cooling system flow path 42 and the air vent port 44, it flows toward the air vent port 44. Therefore, the air vent port 44 can collect and store air contained in the coolant.

[0036] [Air Bleed Valve] The air bleed valve 45 opens and closes the air bleed port 44. More specifically, the air bleed valve 45 is provided on the inverter 36 so as to close the air bleed port 44. In this embodiment, the air bleed valve 45 is screwed into the air bleed port 44. As a result, the air bleed valve 45 closes the air bleed port 44. The air bleed valve 45 is also formed with, for example, an air bleed flow path 45a. The air bleed flow path 45a is closed when the air bleed valve 45 is screwed to a predetermined position in the air bleed port 44. On the other hand, when the air bleed valve 45 is loosened, the air bleed flow path 45a connects the inside of the air bleed port 44 to the outside of the inverter 36. As a result, air accumulated in the air bleed port 44 can be bled to the outside.

[0037] 2 supplies hydraulic fluid discharged from the electric pump unit 25 to each of the hydraulic actuators and controls the flow of the supplied hydraulic fluid. As described above, the multi-control valve 23 is connected to the hydraulic pump 31 (more specifically, the discharge ports 31g and 31h) of the electric pump unit 25 via the discharge pipe 25b. The multi-control valve 23 configured in this manner is located behind the boom 13 within the revolving unit 12.

[0038] [Battery] The battery 24 is electrically connected to the electric pump unit 25 (more specifically, the inverter 36). The battery 24 supplies power to the inverter 36 (in this embodiment, direct current flows through it). The battery 24 is disposed inside the revolving structure 12. More specifically, the battery 24 is disposed rearward of the electric pump unit 25 inside the revolving structure 12. In this embodiment, the counterweight 16 is disposed at the rearmost position inside the revolving structure 12. The battery 24 is disposed between the counterweight 16 and the electric pump unit 25.

[0039] [Operation of Hydraulic Drive System] Electric power is supplied from the battery 24 to the electric pump unit 25 of the electric pump system 1 shown in FIG. 2 . The electric pump unit 25 operates as follows. Specifically, in the electric pump unit 25, the power (i.e., DC current) from the battery 24 is supplied to the inverter 36. The inverter 36 converts the DC current to AC current and supplies it to the electric motor 35. The electric motor 35 then drives the drive shaft 31a to rotate. As a result, the hydraulic pump 31 draws hydraulic fluid from the tank 21 through the suction port 31f via the suction pipe 25a and discharges it to the discharge ports 31g and 31h. The hydraulic fluid is guided from the discharge ports 31g and 31h through the discharge pipe 25b to the multi-control valve 23 and further supplied to each of the hydraulic actuators via the multi-control valve 23. This allows each of the hydraulic actuators to be operated.

[0040] [Operation of Cooling System Devices] In the cooling system device 26 of the electric pump system 1, when the inverter 36 and the electric motor 35 are heated, the coolant pump 43 is driven to circulate the coolant. More specifically, the coolant pump 43 draws the coolant from the radiator 41 and supplies it to the motor-side flow path 42b. The coolant then passes through the motor-side flow path 42b and the inverter-side flow path 42a and is discharged to the discharge flow path 42d. At this time, the coolant absorbs heat from the electric motor 35 and the inverter 36 to cool them. The coolant discharged to the discharge flow path 42d is returned to the radiator 41. The returned coolant is cooled by heat exchange with outside air in the radiator 41. After being cooled, the coolant is again drawn by the coolant pump 43 and supplied to the motor-side flow path 42b. In this way, in the cooling system device 26, the coolant is circulated by the coolant pump 43, and the circulating coolant cools the inverter 36 and the electric motor 35.

[0041] In the cooling system device 26, air contained in the coolant is collected in the air vent port 44. More specifically, air contained in the coolant tends to rise to a higher position. Therefore, when the air contained in the coolant reaches the connection point between the cooling system flow path 42 and the air vent port 44, it flows from the cooling system flow path 42 toward the air vent port 44. This allows the air to be removed from the coolant flowing through the cooling system flow path 42 at the air vent port 44, and the air to be stored in the air vent port 44. Then, in the cooling system device 26, an air venting operation is performed to vent the air stored in the air vent port 44. That is, in the cooling system device 26, when the air vent port 44 is opened by the air vent valve 45, the inside and outside of the air vent port 44 are connected. This allows the air stored in the air vent port 44 to be released to the outside. In this manner, the air venting operation is performed in the cooling system device 26.

[0042] In the electric pump system 1 of this embodiment, the cooling system device 26 includes an air vent port 44 that is connected to the cooling system flow path 42 and is located higher than the cooling system flow path 42, and an air vent valve 45 that opens and closes the air vent port 44. Therefore, air contained in the coolant can be collected toward the air vent port 44, and by opening the air vent port 44, the air collected in the air vent port 44 can be released into the atmosphere. This makes it easy to perform an air venting operation in the cooling system device 26.

[0043] Furthermore, in the electric pump system 1 of this embodiment, the electric pump unit 25 includes the hydraulic pump 31, the electric motor 35, and the inverter 36, which are arranged in this order from bottom to top. The cooling system flow path 42 has an inverter-side flow path portion 42a that is provided in the inverter 36. Therefore, the air bleed port portion 44 can be arranged at a position higher than the inverter 36, which is located at the top of the electric pump unit 25, and height restrictions on the arrangement of the radiator 41 and the coolant pump 43 can be reduced.

[0044] Furthermore, in the electric pump system 1 of this embodiment, the cooling system flow path 42 is located at a position lower than the ceiling surface 36b of the inverter 36. Furthermore, the air vent port 44 is formed in the ceiling surface 36b of the inverter 36. Therefore, air contained in the coolant flowing through the cooling system flow path 42 can be collected in the air vent port 44, and air can be prevented from accumulating in the drive unit 32 other than at the air vent port 44. Therefore, a decrease in the cooling efficiency of the drive unit 32 due to air can be prevented.

[0045] Furthermore, in the electric pump system 1 of this embodiment, the cooling system flow path 42 is formed so that the coolant flows from the electric motor 35 toward the inverter 36 in the drive device 32. Therefore, the cooling system flow path 42 is formed so as to extend upward in the drive device 32, and therefore, air accumulation in the drive device 32 can be suppressed.

[0046] Furthermore, in the electric pump system 1 of this embodiment, the radiator 41 is disposed at a lower position than the air vent port 44. Therefore, the air vent port 44 can be disposed at the highest position in the cooling system equipment 26. This allows the air contained in the coolant circulating inside the cooling system equipment 26 to be collected by the air vent port 44.

[0047] The excavator 2 of this embodiment can realize a construction machine 2 having the above-described functions.

[0048] Second Embodiment An electric pump system 1A and a shovel 2A of a second embodiment are similar in configuration to the shovel 2 of the electric pump system 1 of the first embodiment. Therefore, with regard to the configurations of the electric pump system 1A and the shovel 2A of the second embodiment, differences from the electric pump system 1 and the shovel 2 of the first embodiment will mainly be described, and the same components will be denoted by the same reference numerals and description thereof will be omitted.

[0049] The electric pump system 1A of the second embodiment shown in FIG. 7 is an electric hydraulic pump system mounted on a shovel 2A. The electric pump system 1A also includes an electric pump unit 25, a support frame 27, and a cooling system device 26A. The cooling system device 26A includes a radiator 41, a cooling system flow path 42, a coolant pump 43, an air vent port 44A, and an air vent valve 45. The air vent port 44A is formed so as to branch off from the discharge flow path 42d at the highest position of the discharge flow path 42d of the cooling system flow path 42. In this embodiment, the air vent port 44A extends upward from the discharge flow path 42d. The air vent valve 45 is provided in the air vent port 44A.

[0050] The air vent valve 45 opens and closes the air vent port 44A. More specifically, when the air vent valve 45 is screwed, it closes the air vent port 44A. On the other hand, when the air vent valve 45 is loosened, it connects the inside and outside of the air vent port 44A via the air vent flow path 45a. This allows air that has accumulated in the air vent port 44A to be released to the outside.

[0051] In the electric pump system 1 configured in this manner, the air vent port 44 is formed to branch off from the discharge flow path 42d at the highest position of the discharge flow path 42d, thereby preventing air contained in the coolant flowing through the air vent port 44 from accumulating inside the drive unit 32. This prevents the cooling efficiency of the drive unit 32 from being reduced by air.

[0052] In addition, the electric pump system 1A and the shovel 2A of the second embodiment have the same effects as the electric pump system 1 and the shovel 2 of the first embodiment.

[0053] In the electric pump systems 1 and 1A of the first and second embodiments, the cooling system flow path 42 is formed in both the electric motor 35 and the inverter 36 in the drive device 32, but it may be formed in at least one of them. Furthermore, in the cooling system flow path 42, the coolant does not necessarily have to flow from the electric motor 35 to the inverter 36, and may flow in the opposite direction.

[0054] In the electric pump systems 1, 1A of the first and second embodiments, the inverter 36 does not necessarily have to be disposed above the electric motor 35, but may be disposed on a side surface of the electric motor 35. In the electric pump system 1 of the first embodiment, the air bleed port 44 is formed on the ceiling surface 36b of the inverter 36, but may be disposed on the side surface of the inverter 36 as long as it is located higher than the cooling system flow path 42. In addition, the air bleed port 44 is disposed at a higher position than the radiator 41, but may be located lower than the radiator 41.

[0055] <Illustrative Embodiment> An electric pump system for a construction machine in a first aspect is an electric pump system for a construction machine that is mounted on a construction machine, and includes: an electric pump unit including a hydraulic pump that discharges hydraulic fluid when a drive shaft rotates; and a drive device that rotationally drives the drive shaft in response to supplied electric power; a radiator that cools a coolant; a cooling system flow path through which the coolant circulates between the radiator and the drive device; and a cooling system device that is provided in the cooling system flow path and circulates the coolant that flows through the cooling system flow path, and in the electric pump unit, the hydraulic pump and the drive device are arranged side by side in this order from bottom to top, and the cooling system device further includes an air bleed port portion that is connected to the cooling system flow path and is arranged at a position higher than the cooling system flow path, and an air bleed valve that opens and closes the air bleed port portion.

[0056] According to the above aspect, the cooling system device includes an air vent port connected to the cooling system flow path and positioned higher than the cooling system flow path, and an air vent valve that opens and closes the air vent port. Therefore, air contained in the coolant can be collected toward the air vent port, and by opening the air vent port, the air collected in the air vent port can be released to the atmosphere. This makes it easy to perform air bleeding operations in the cooling system device.

[0057] In a second aspect, the electric pump system for construction machinery is the electric pump system for construction machinery of the first aspect, wherein the drive device has an electric motor that rotates and drives the drive shaft in response to a supplied current, and an inverter that converts the frequency of the current supplied to the electric motor, and in the electric pump unit, the hydraulic pump, the electric motor, and the inverter are arranged in order from bottom to top, and the cooling system flow path has an inverter-side flow path portion provided in the inverter.

[0058] According to the above aspect, in the electric pump unit, the hydraulic pump, the electric motor, and the inverter are arranged in this order from bottom to top. The cooling system flow path has an inverter-side flow path portion provided in the inverter. Therefore, the air bleed port can be arranged higher than the inverter, which is the uppermost part of the electric pump unit, thereby minimizing height restrictions on the arrangement of the radiator and the coolant pump.

[0059] In a third aspect, the electric pump system for construction machinery is the electric pump system for construction machinery of the second aspect, wherein the cooling system flow path is located lower than a ceiling surface of the inverter, and the air bleed port portion is formed on the ceiling surface of the inverter.

[0060] According to the above aspect, the cooling system flow path is lower than the ceiling surface of the inverter, and the air vent port is formed in the ceiling surface of the inverter. Therefore, air contained in the coolant flowing through the cooling system flow path can be collected in the air vent port, which prevents air from accumulating in the drive device other than the air vent port. Therefore, it is possible to prevent a decrease in the cooling efficiency of the drive device due to air.

[0061] In a fourth aspect, the electric pump system for construction machinery is the electric pump system for construction machinery of any one of the first to third aspects, wherein the air bleed port portion is formed so as to branch off from the cooling system flow path at the highest position of the cooling system flow path.

[0062] According to the above aspect, the air bleed port is formed so as to branch off from the cooling system flow path at the highest position of the cooling system flow path. This makes it possible to prevent air contained in the coolant flowing through the cooling system flow path from accumulating inside the drive device. This makes it possible to prevent a decrease in the cooling efficiency of the drive device due to air.

[0063] In a fifth aspect, the electric pump system for construction machinery is the electric pump system for construction machinery of the second or third aspect, wherein the cooling system flow path is formed so that coolant flows from the electric motor to the inverter in the drive device.

[0064] According to the above aspect, the cooling system flow path is formed in the drive device so that the coolant flows from the electric motor to the inverter. Therefore, the cooling system flow path is formed to extend upward in the drive device, and therefore, it is possible to prevent air from accumulating in the drive device.

[0065] In a sixth aspect, the electric pump system for a construction machine is the electric pump system for a construction machine of any one of the first to fifth aspects, wherein the radiator is disposed at a position lower than the air bleeding port portion.

[0066] According to the above aspect, the radiator is disposed at a position lower than the air bleed port, and therefore the air bleed port can be disposed at the highest position in the cooling system equipment, allowing air contained in the coolant circulating in the cooling system equipment to be collected at the air bleed port.

[0067] A construction machine according to a seventh aspect includes the electric pump system for construction machine according to any one of the first to sixth aspects.

[0068] According to the above aspect, a construction machine having the above-mentioned functions can be realized.

[0069] 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. An electric pump system for construction machinery to be mounted on construction machinery, comprising: an electric pump unit including a hydraulic pump that discharges hydraulic fluid when a drive shaft rotates, and a drive unit that rotates and drives the drive shaft in response to supplied power; and cooling system equipment including a radiator that cools a coolant, a cooling system flow path through which the coolant circulates between the radiator and the drive unit, and a coolant pump that is provided in the cooling system flow path and circulates the coolant flowing through the cooling system flow path, wherein in the electric pump unit, the hydraulic pump and the drive unit are arranged side by side from bottom to top, and the cooling system equipment further includes an air bleed port section connected to the cooling system flow path and positioned higher than the cooling system flow path, and an air bleed valve that opens and closes the air bleed port section.

2. The electric pump system for construction machinery as described in claim 1, wherein the drive device has an electric motor that rotates and drives the drive shaft in response to a supplied current, and an inverter that converts the frequency of the current supplied to the electric motor, and in the electric pump unit, the hydraulic pump, the electric motor, and the inverter are arranged in sequence from the bottom up, and the cooling system flow path has an inverter-side flow path portion provided in the inverter.

3. An electric pump system for construction machinery according to claim 2, wherein the cooling system flow path is located lower than a ceiling surface of the inverter, and the air bleed port portion is formed in the ceiling surface of the inverter.

4. An electric pump system for construction machinery as set forth in claim 1, wherein the air bleed port portion is formed so as to branch off from the cooling system flow path at the highest position of the cooling system flow path.

5. An electric pump system for construction machinery as set forth in claim 2, wherein the cooling system flow path is formed so that coolant flows from the electric motor to the inverter in the drive device.

6. The electric pump system for a construction machine according to claim 1, wherein the radiator is disposed at a position lower than the air bleed port portion.

7. A construction machine comprising the electric pump system for construction machines according to claim 1.

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