Power unit and method for controlling power unit

Abstract

A power unit (1) that supplies motive power to construction equipment comprises a hydraulic fluid tank (26), a hydraulic pump (28) that supplies hydraulic fluid from the hydraulic fluid tank (26) to the construction equipment, an electric motor (27) that drives the hydraulic pump (28), and a battery system (40) that connects a plurality of battery packs that have battery management controllers (42a–42c) in parallel and has a master battery management system (43) that controls charging / discharging of the battery packs via the battery management controllers (42a–42c). The master battery management system (43) performs control so as to connect the battery pack that has the most remaining capacity to the electric motor first when performing discharging and to connect the battery pack that has the least remaining capacity to a power supply first when performing charging.

Description

[Technical field]

[0001] The present invention relates to a power unit that supplies power to a construction machine at a construction site. [Background technology]

[0002] Power units used at construction sites have been known for some time. For example, JP 2002-285856 A is a patent publication of a power generating unit applied for by the present applicant. In the power unit (power generating unit) described in this patent document, a hydraulic pump generates hydraulic pressure by driving an engine. As shown here as an example, conventional power units use fuel as the power source for the engine. Summary of the Invention [Problem to be solved by the invention]

[0003] Currently, there is a worldwide demand to reduce the use of fossil fuels in order to realize a carbon-free society. In light of this societal demand, our goal is to provide a power unit that reduces greenhouse gas emissions. [Means for solving the problem]

[0004] The power unit of the present invention is a power unit that supplies power to a construction machine, and includes a hydraulic oil tank, a hydraulic pump that supplies hydraulic oil in the hydraulic oil tank to the construction machine, an electric motor that drives the hydraulic pump, and a battery system that connects multiple battery packs each having a battery management controller in parallel and is equipped with a master battery management system that controls the charging and discharging of the battery packs and manages the remaining charge through the battery management controller, and the master battery management system controls the battery pack with the highest remaining charge to be connected to the electric motor first when discharging, and the battery pack with the lowest remaining charge to be connected to a power source first when charging.

[0005] By connecting multiple battery packs in parallel in this way, battery capacity is secured, and by having a master battery management system oversee and control each battery pack, the charging and discharging amounts can be optimized according to the situation, making it possible to operate with batteries with smaller capacities, and achieving smaller battery size and lighter weight.

[0006] In the power unit of the present invention, the battery pack may have a plurality of battery modules connected in series and in parallel. This configuration can increase the peak power of the battery system and provide sustained power.

[0007] In the power unit of the present invention, the plurality of battery packs may be connected in series in addition to being connected in parallel. This configuration makes it possible to increase the peak power of the battery system and obtain sustained power.

[0008] In the power unit of the present invention, the master battery management system may be capable of discharging from the remaining battery packs while some of the battery packs are isolated on the circuit. With this configuration, the remaining charge can be adjusted by discharging from the remaining battery packs excluding the battery packs that are isolated on the circuit. Furthermore, when some of the battery packs fail, it becomes possible to discharge from the other battery packs that are not failed, thereby ensuring the operation of the construction machine.

[0009] In the power unit of the present invention, the master battery management system may be capable of discharging the remaining battery packs while some of the battery packs are removed. With this configuration, the battery packs can be replaced in sequence while the construction machine is in operation, enabling continuous operation of the construction machine.

[0010] In the power unit of the present invention, the battery pack may have a plurality of battery modules, and the power unit may further include a cooler for liquid-cooling the battery modules and a fan cooler for air-cooling the hydraulic oil tank. With this configuration, the temperature of the battery pack can be maintained by liquid cooling to maintain charge / discharge efficiency, and the hydraulic oil tank can be cooled at low cost by air cooling.

[0011] In the power unit of the present invention, an exhaust port is formed on the side opposite to the intake port for taking in air, and the cooler and the fan cooler may be arranged side by side adjacent to the exhaust port. With this configuration, the air for cooling the coolant of the cooler can also be used to cool the hydraulic oil tank.

[0012] In the power unit of the present invention, the battery pack may be disposed opposite to an upper surface of the housing of the power unit. With this configuration, the battery pack can be easily replaced.

[0013] In the power unit of the present invention, the exterior of the battery system may constitute a part of the exterior of the power unit. With this configuration, the battery system can be easily separated from the power unit, and the entire exterior can be replaced without exposing precision devices such as the battery module in the battery system, making it possible to safely replace the battery even in bad weather.

[0014] In the power unit of the present invention, the battery pack may have a plurality of battery modules, the battery modules being arranged in a hierarchical stack, and a configuration in which the battery modules are stacked by placing a lower battery module on a table for mounting, and then placing the battery module on the table for mounting. With this configuration, the gap between the upper and lower battery modules can be narrowed, and the volume occupied by the battery pack can be reduced.

[0015] The power unit of the present invention may further include a cooler that liquid-cools the battery pack. By liquid-cooling the battery pack in this manner, a temperature rise in the battery pack can be efficiently suppressed even in a configuration in which the gap between the battery modules is narrow.

[0016] The power unit of the present invention may be configured to include a power unit self-propelled drive device under the housing of the power unit, and to supply electric power from the battery pack to the power unit self-propelled drive device. With this configuration, the power unit itself can be self-propelled by utilizing the battery system included in the power unit.

[0017] In the power unit of the present invention, the power unit self-propelled drive device may be detachable from the housing of the power unit. With this configuration, the power unit itself can be self-propelled by utilizing the battery system provided in the power unit.

[0018] The power unit control method of the present invention determines whether or not power is being supplied to the construction machine, and charges the battery pack during the time when it is determined that power is not being supplied to the construction machine. With this configuration, the battery module can be charged by utilizing small chunks of time during the work process, thereby extending the continuous operating time of the power unit. [Brief description of the drawings]

[0019] [Figure 1] 1 is a diagram showing an overall configuration of a power unit according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a diagram showing the internal structure of the power unit. [Diagram 3] FIG. 2 is a diagram showing the internal structure of the power unit. [Figure 4] FIG. 2 is a diagram showing the internal structure of the power unit. [Diagram 5] 4 is a diagram showing a connection relationship between a battery module and a BMC. FIG. [Figure 6]FIG. 1 is a diagram showing a configuration of a battery system. [Figure 7] FIG. 2 is a partial cross-sectional view of the battery system. [Figure 8] FIG. 2 is a diagram for explaining the operation of the battery system. [Figure 9] 11A and 11B are diagrams showing a method for removing the battery system. [Figure 10] 11A and 11B are diagrams showing a method for removing the battery system. [Figure 11] 11A and 11B are diagrams showing a method for removing the battery system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, a power unit according to the present embodiment will be described with reference to the drawings. Note that the following description is merely an example of a preferred embodiment, and is not intended to limit the invention described in the claims.

[0021] 1 is a diagram showing the overall configuration of a power unit 1 according to the present embodiment. The power unit 1 according to the present embodiment generates power using a battery system and supplies it to a construction machine. In the present embodiment, a press-in machine that presses steel sheet piles into the ground will be described as an example of the construction machine.

[0022] As shown in FIG. 1, the power unit 1 includes a base member 10, a U-shaped support pillar 11 erected on the base member 10, and a bonnet 13 arranged to sandwich the support pillar 11, and has an overall box-like configuration. In the following description, the left side in FIG. 1 is referred to as the "front" and the right side as the "rear". The power unit 1 has a crawler 14 attached below the base member 10. The crawler 14 is a self-propelled drive device for self-propelling the power unit 1. The crawler 14 is attached by positioning using a positioning guide plate as a guide, and fixing it by passing a bolt through the frame of the base member 10 and the crawler 14 and fastening it with a nut. This configuration allows the crawler 14 to be easily attached and detached.

[0023] The base member 10 and the support pillars 11 are members that support the load of the power unit 1, and are more rigid than the bonnet 13. The support pillars 11 have two locking portions 12 at their upper portions for locking shackle bolts. The shackle bolts are fixed to the left and right locking portions 12 with nuts, and a wire is stretched across the shackle bolts. The power unit 1 can be lifted and transported by hanging the hook of a crane on the stretched wire and hoisting it up.

[0024] The power unit 1 has a solar panel 15 in front of the top surface of the bonnet 13. The power unit 1 is charged with electricity generated by the solar panel 15 and used as a driving power source to start outputting from a battery module described later. With this configuration, the driving power source is not affected by the battery running out.

[0025] The bonnet 13 has a plurality of maintenance doors 16. By opening the maintenance doors 16, the internal configuration of the bonnet 13 can be accessed and maintenance can be performed.

[0026] A control box 20 is disposed near the front of the power unit 1. The control box 20 controls the entire power unit 1, and also controls the operation of a construction machine connected to the power unit 1. The control box 20 has a control panel 21 for operating the power unit 1. Since the front of the control box 20 is open, the control panel 21 can be operated from outside the power unit 1. The control box 20 also has a charging terminal 22 used when charging the battery system 40. A notch is formed in part of the bottom surface on the front side of the power unit 1 (see FIG. 2), and this notch serves as an intake port 34 for drawing air into the inside of the power unit 1.

[0027] Fig. 2 is a diagram showing the internal structure of the power unit 1 with the bonnet 13 removed. Note that Fig. 2 omits a portion of the rear internal structure. Figs. 3 and 4 are similar diagrams showing the internal structure of the power unit 1, but are views from a different direction than Fig. 2. Below, the internal structure of the power unit 1 will be described in order.

[0028] The power unit 1 has a battery system 40 including a plurality of battery modules 41a to 41l. The twelve battery modules 41a to 41l have the same configuration. The battery modules 41a to 41l are collectively referred to as "battery modules 41". The battery system 40 is mounted on a battery mounting frame 23 and disposed in front of the power unit 1. Specifically, the battery system 40 is disposed so as to face the upper surface of the power unit 1. This arrangement allows the bonnet 13 to be removed and the battery system 40 to be pulled up, making it easy to remove the battery system 40.

[0029] The battery system 40 has 12 battery modules 41a to 41l, three battery management controllers (hereinafter referred to as "BMC") 42a to 42c that control charging and discharging of the battery modules 41, and a master battery management system (hereinafter referred to as "MBMS") 43 that controls the battery management controllers 42a to 42c. The three BMCs 42a to 42c have the same configuration. The BMCs 42a to 42c are collectively referred to as "BMC 42."

[0030] 5 is a diagram showing the connection relationship between the battery modules 41 and the BMC 42 that constitute the battery system 40. The battery modules 41a to 41d are connected in series, and the BMC 42a is connected to the four battery modules 41a to 41d that are connected in series. A set of the battery modules 41a to 41d and the BMC 42a is called a "battery pack." Similarly, the battery pack is configured by connecting the BMC 42b to the four battery modules 41e to 41h that are connected in series, and the battery pack is configured by connecting the BMC 42c to the four battery modules 41i to 41l that are connected in series.

[0031] Each battery module 41 is a module formed by combining battery cells. Since a large number of battery modules 41 are required to operate a construction machine such as a press-in machine for a day, the weight and occupied volume of the battery system 40 become quite large.

[0032] The battery system 40 is configured by connecting three battery packs in parallel. By connecting battery packs made up of battery modules 41 connected in series in this way in parallel, it is possible to increase the output current and to extend the operating time of the battery system 40.

[0033] The MBMS 43 has a function of controlling battery-related control and controlling the charging and discharging of the three battery packs. Specifically, when discharging, the MBMS 43 first connects the battery pack with the highest remaining charge to the electric motor 27, and when charging, the MBMS 43 first connects the battery pack with the lowest remaining charge to the power source. By controlling each battery pack in this manner, the MBMS 43 can optimize the charge and discharge amounts according to the situation. Note that, for the remaining battery packs, the MBMS 43 may connect them to the electric motor 27 in order starting from the battery pack with the highest charge when discharging. Also, when charging, the MBMS 43 may connect them to the power source in order starting from the battery pack with the lowest charge.

[0034] When charging the battery system 40, the battery system 40 may be controlled so that the temperature of the battery system 40 is optimal for charging. When the temperature of the battery system 40 is higher than the optimal temperature, the water cooler 29 is used to lower the temperature of the battery system 40 to the optimal temperature. When the temperature of the battery system 40 is lower than the optimal temperature, the electric heater is driven by the battery, and the battery system 40 is warmed by the heat of the heater and the heat generated by the heater being energized. During operation of the electric motor, the heat generated by the electric motor itself or the heat of the hydraulic oil may be used to warm the battery temperature to the optimal temperature for charging while reusing mechanical energy, thereby optimizing the charging efficiency. To utilize the heat of the hydraulic oil, a portion of the hydraulic oil is taken out from the hydraulic oil tank 26. The battery system 40 may also be warmed by using an electric motor and an electric heater in combination.

[0035] The power unit 1 includes a converter 24 that converts alternating current (AC) to direct current (DC), an inverter 25 that converts the direct current (DC) to alternating current (AC), and a control filter 35 that reduces noise when electricity is applied. The converter 24, the inverter 25, and the control filter 35 are disposed under the battery mounting frame 23.

[0036] The power unit 1 includes a hydraulic oil tank 26 next to the battery system 40 across the support 11. An electric motor 27 and a hydraulic pump 28 are also provided below the hydraulic oil tank 26. The hydraulic pump 28 has a function of applying pressure to the hydraulic oil in the hydraulic oil tank 26. The power unit 1 supplies the pressurized oil generated by the hydraulic pump 28 to the construction machine via a pipe (not shown) connected to a hydraulic manifold 31. The electric motor 27 receives electric power from the battery system 40 and drives the hydraulic pump 28. The hydraulic pump 28 also supplies hydraulic oil to the crawler 14, and the power unit 1 drives the crawler 14. In this embodiment, an example is given in which the construction machine and the crawler 14 are driven by hydraulic oil, but the construction machine and the crawler 14 may be directly driven by electric power, or may be driven by a hybrid of electric power and hydraulics.

[0037] The power unit 1 has a water cooler 29 and a fan cooler 30 at the rear. The fan cooler 30 has the function of exhausting the air inside the power unit 1 to the outside. When the fan cooler 30 is driven, air flows in through an intake port 34 formed on the bottom surface on the front side of the power unit 1, and the air is exhausted from the rear. The fan cooler 30 passes air inside the power unit 1 to cool the converter 24, inverter 25, hydraulic oil tank 26, etc.

[0038] The water cooler 29 cools the coolant liquid, which is a cooling liquid, and circulates the cooled coolant liquid through a water-cooling line to the battery system 40, thereby cooling the battery system 40. In this embodiment, the water-cooling line to the battery system 40 is branched off to supply the coolant liquid to the converter 24, the inverter 25, and the control filter 35 for cooling. This makes it possible to deal with heat generation from the boards of the converter 24, the inverter 25, and the control filter 35, and to prevent control failures.

[0039] The water cooler 29 cools water by exchanging heat with air, and the air flow used for heat exchange is from the front to the rear of the power unit 1, similar to the fan cooler 30. Therefore, the air flow by the water cooler 29 also creates an air flow from the front to the rear of the power unit 1, making it possible to air-cool the inside of the power unit 1.

[0040] In the power unit 1 of this embodiment, the air warmed by exhaust heat trapped inside the power unit 1 can be actively discharged to the outside by matching the air flow by the water cooler 29 with the air flow by the fan cooler 30. Also, as shown in Figures 2 to 4, the water cooler 29 and the fan cooler 30 are both disposed on the upper side of the rear surface of the power unit 1, so that the warm air warmed by exhaust heat and collected on the upper side inside the power unit 1 can be efficiently discharged.

[0041] Fig. 6 is a diagram showing the configuration of the battery system 40, and Fig. 7 is an AA cross-sectional view of the battery system 40 shown in Fig. 6. The battery system 40 is mounted on a battery mounting frame 23. Three battery modules 41a, 41e, 41i are arranged on the battery mounting frame 23, a table 44 is placed on the battery modules 41a, 41e, 41i, and further three battery modules 41b, 41f, 41j are arranged on the table 44, thus forming a layered structure in which the battery modules 41 and the tables 44 are repeatedly arranged.

[0042] The stacked structure is not formed by inserting battery modules 41 into a rack formed by table 44, but is formed by placing the lowest battery modules 41a, 41e, 41i, and then covering them with table 44, and after covering table 44, placing battery modules 41b, 41f, 41j on top of that, and then covering it with table 44, as shown in FIG. 7.

[0043] 6 shows the gap G between the top surface of the bottommost battery modules 41a, 41e, 41i and the mounting surface of the second-lowest battery modules 41b, 41f, 41j, and the height H of the frame around the table 44. When placing the battery modules 41 in a rack prepared in advance, the gap G cannot be made narrower than the height H of the frame, but according to this embodiment, the gap G can be made narrower than the height H of the frame, and the battery system 40 can be made smaller in size.

[0044] 8(a) to 8(c) are diagrams for explaining the operation of the battery system 40. FIG. 8(a) is a diagram showing the operation of the battery system 40 during charging. During charging, the power unit 1 and a power source are connected, electricity from the power source 50 is received by the power receiving unit 32, and the converter 24 converts the electricity from AC to DC to charge the battery system 40. The power source is a generator, a commercial power source, or the like. FIG. 8(b) is a diagram showing the operation of the battery system 40 during discharging. During discharging, electricity stored in the battery module 41 is converted from DC to AC by the inverter 25 and supplied to the electric motor (AC motor) 27. The electric motor 27 drives the hydraulic pump 28 and supplies hydraulic oil to the press-in machine 60 via the hydraulic valve 33.

[0045] FIG. 8(c) is a diagram showing the operation of the battery system 40 during assisted discharging, in which discharging is performed while receiving assistance from the power source 50. During assisted discharging, the power unit 1 and the power source 50 are connected during charging. In addition to the discharging operation shown in FIG. 8(b), electricity from the power source 50 is supplied to the electric motor (AC motor) 27 via the power receiving unit 32, the converter 24, and the inverter 25. That is, in addition to discharging from the battery system 40, the electric motor 27 is driven using electricity from the power source 50. As a result, during assisted discharging, it becomes possible to drive the electric motor 27 with a driving voltage higher than that during discharging shown in FIG. 8(b).

[0046] 9 to 11 are diagrams showing a method of removing the battery system 40. When removing the battery system 40, first, the bonnet 13 on the front side of the support pillar 11 is removed as shown in FIG. 9. Next, the upper part of the support pillar 11 is removed as shown in FIG. 10. The support pillar 11 is configured to be separable into upper and lower parts at the height of the battery mounting frame 23, and the upper part is removed. Thereafter, the battery system 40 is disconnected from the converter 24 and the inverter 25, and the water cooling line from the water cooler 29 is disconnected, and the battery system 40 is taken out upward as shown in FIG. 11. The battery system 40 is disposed facing the upper surface of the power unit 1, and therefore can be easily removed as described in FIG. 9 to FIG. 11.

[0047] If the battery system 40 were placed on the base member 10 and the converter 24, inverter 25, etc. were located above the battery system 40, it would be necessary to move those components above the battery system 40 or pull out the battery system 40 to the side. As described above, the battery system 40 is quite heavy, but in this embodiment, in consideration of the convenience of removal, the battery system 40 is intentionally lifted up using the battery mounting frame 23 and disposed so as to face the upper surface of the power unit 1.

[0048] Next, the operation of a construction machine using the power unit 1 of this embodiment will be described. The power unit 1 is brought to a construction site, and a driving force is supplied to the construction site to perform construction work. In this embodiment, construction work is performed in which a steel sheet pile is pressed in by a press-in machine.

[0049] Basically, the battery system 40 is fully charged overnight, and the charged power is used to cover a day's work. However, during the operation process of the press-in machine, there are times when the press-in machine is stopped during the process of setting the steel sheet pile in the chuck with a crane and the process of checking the verticality of the set steel sheet pile (the operator visually checks by placing a spirit level against the steel sheet pile). The battery system 40 may be charged during these times. This allows a day's work to be performed with the battery system 40, which has a smaller capacity, compared to when charging is not performed during the operation.

[0050] Although the power unit 1 according to the embodiment of the present invention has been described above, the power unit of the present invention is not limited to the above-mentioned configuration. In the above embodiment, an example has been given in which the battery system is configured by connecting three battery packs in parallel, but the battery system 40 may be configured by connecting the battery packs in series in addition to the parallel connection. Also, the number of battery packs is not limited to three.

[0051] In the above embodiment, the battery pack has a configuration in which four battery modules 41 are connected in series, but the battery pack may have a configuration in which the battery modules 41 are connected in series and in parallel in combination. Furthermore, the number of battery modules 41 included in each battery pack is not limited to four.

[0052] In the above embodiment, an example in which the entire battery system is removed has been given, but only some of the battery packs may be removed and charged, and the electric motor may be driven by discharging from the remaining battery packs. For example, it is possible to remove one parallel battery pack out of the four series and three parallel battery packs and charge it, drive the electric motor with only the remaining two parallel battery packs, and replace the battery packs one by one. In addition, it is also possible to discharge from the remaining battery pack without physically removing one parallel battery pack out of the four series and three parallel battery packs, in a state where it is separated on the circuit, or conversely, it is also possible to separate one parallel battery pack from the remaining battery packs on the circuit, and connect the one parallel battery pack to a power source to charge it.

[0053] In addition, a battery pack connected in a circuit separate from the above-mentioned 4 series, 3 parallel battery system may be provided as a spare battery, and the 4 series, 3 parallel battery system may be removed while the vehicle is being driven by the spare battery.

[0054] In addition, the exterior of the battery system may form part of the exterior of the power unit. In the above embodiment, an example was given in which the battery system was removed after removing the bonnet and the upper part of the support, but if the exterior of the battery system forms the exterior of the power unit, the battery system can be removed without removing the bonnet.

Claims

1. A power unit for supplying power to a construction machine, A hydraulic oil tank; a hydraulic pump that supplies hydraulic oil in the hydraulic oil tank to the construction machine; an electric motor that drives the hydraulic pump; a battery system including a master battery management system in which a plurality of battery packs each having a battery management controller are connected in parallel and which controls charging and discharging of the battery packs and manages the remaining charge of the battery packs through the battery management controller; Equipped with The battery pack includes a plurality of battery modules; A cooler that liquid-cools the battery module; a fan cooler for air-cooling the hydraulic oil tank; Equipped with The power unit has an exhaust port formed on the opposite side to an intake port for taking in air, A power unit in which the liquid-cooling cooler and the fan cooler are arranged side by side adjacent to the exhaust port.

2. A power unit for supplying power to a construction machine, a housing having a base member, a support pillar erected on the base member, and a bonnet provided so as to sandwich the support pillar; A hydraulic oil tank; a hydraulic pump that supplies hydraulic oil in the hydraulic oil tank to the construction machine; an electric motor that drives the hydraulic pump; a battery system including a master battery management system in which a plurality of battery packs each having a battery management controller are connected in parallel and which controls charging and discharging of the battery packs and manages the remaining charge of the battery packs through the battery management controller; a battery mounting frame on which the battery system is mounted; and Equipped with the battery pack of the battery system mounted on the battery mounting frame faces an upper surface of the housing of the power unit; The support pillar can be separated into upper and lower parts at the height of the battery mounting frame, and the battery system can be removed upward by removing the bonnet and the upper part of the support pillar.

3. The power unit according to claim 1 , wherein the battery pack has a plurality of battery modules connected in series and in parallel.

4. The power unit according to claim 1 , wherein the plurality of battery packs are connected in series in addition to being connected in parallel.

5. 2. The power unit according to claim 1, wherein the master battery management system is capable of discharging from the remaining battery packs while isolating some of the battery packs on a circuit basis.

6. The power unit according to claim 1 , wherein the master battery management system is capable of discharging the remaining battery packs while some of the battery packs are removed.

7. 3. The power unit of claim 2, wherein the exterior of the battery system forms part of the exterior of the power unit.

8. The battery pack includes a plurality of battery modules; The battery modules are arranged in a hierarchical stack, 2. The power unit according to claim 1, wherein the battery modules are stacked by placing a lower battery module, covering it with a placement table, and placing a battery module on top of that.

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