Hydraulic drive device of a punching machine

Abstract

To provide a battery-powered hydraulic drive device excellent in energy efficiency while maintaining functional independence of a hydraulic pump.SOLUTION: A hydraulic drive device 20 mounted on a pile driver comprises a plurality of main electric motors M1, M2 connected in parallel to a battery 35, a plurality of sub electric motors M4, M5 connected in parallel to the battery and having a capacity smaller than that of the main electric motor, a control circuit consisting of an inverter 37 and a controller 38, a plurality of main hydraulic pumps P1, P2 respectively driven by a plurality of main electric motors, a plurality of sub hydraulic pumps P4, P5 each driven by a plurality of sub electric motors and having a capacity smaller than that of the main hydraulic pump, a variable capacity type auger rotary drive hydraulic motor 32 that receives pressurized oil from the main hydraulic pump, a hydraulic cylinder 36 for jack expansion / retraction operation that receives pressure oil supplied from a sub hydraulic pump.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a hydraulic driving device for a pile driver, and more particularly to a hydraulic driving device for a pile driver provided with a hydraulic pump driven by an electric motor as a power source.

Background Art

[0002] There is a hydraulic unit that uses a diesel engine as a driving source for a hydraulic pump (see, for example, Patent Document 1).

[0003] This type of hydraulic unit is mounted on various construction machines equipped with working devices, and includes a plurality of hydraulic pumps directly connected to the drive shaft of the engine or connected via a gear mechanism. The plurality of hydraulic pumps include, for example, in the case of a hydraulic unit mounted on a pile driver, a plurality of hydraulic pumps, that is, a main pump used for an auger, traveling and slewing, etc., and a sub-pump used for an oil cooler, a jack, a pilot, etc. Each pump is rotationally driven by the engine, and various operations can be performed by sending the generated fluid power to the hydraulic actuators of each part.

[0004] In such pile drivers, a series of functions suitable for various construction needs are combined (multi-functional development), and in some construction sites, the driving force is extremely large. Also, in terms of usage mode, after moving to the construction position, it stops at that place for a long time, so it adopts a characteristic static and dynamic process. Due to such circumstances, the plurality of hydraulic pumps constituting the hydraulic unit are optimized for each hydraulic actuator to be driven, and their independence is emphasized.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] From the perspective of environmental issues, there is an idea of equipping a pile driver with a battery instead of a diesel engine and obtaining the driving force of a hydraulic pump from the battery. The engine-type hydraulic unit described in Patent Document 1 certainly has the effect that efficient hydraulic drive can be performed by setting each pump according to the magnitude of the output. However, looking at the drawbacks, there is an energy loss caused by rotating the hydraulic pump to some extent. Therefore, in the electrification of a pile driver, in order to fully bring out its advantages, a hydraulic drive device that does not cause unnecessary energy loss is required.

[0007] Therefore, an object of the present invention is to provide a battery-type hydraulic drive device that is excellent in energy efficiency while maintaining the functional independence of a hydraulic pump.

Means for Solving the Problems

[0008] To achieve the above object, the hydraulic drive device of the present invention is mounted on a pile driver including a self-propelled base machine, a leader erected on the base machine, a jack for stabilizing the base machine, and an auger mounted on the leader and rotationally driven in a stable state of the base machine, and includes an electric motor, a hydraulic pump driven by the electric motor, a hydraulic actuator actuated by the pressure oil discharged from the hydraulic pump, and a control circuit including an inverter for controlling the rotational speed of the electric motor and a controller for controlling the inverter. In the hydraulic drive device, the electric motor includes a plurality of main electric motors connected in parallel to a battery and a plurality of sub-electric motors connected in parallel to the battery and having a smaller capacity than the main electric motors. The hydraulic pump includes a plurality of main hydraulic pumps respectively driven by the plurality of main electric motors and a plurality of sub-hydraulic pumps respectively driven by the plurality of sub-electric motors and having a smaller capacity than the main hydraulic pumps. The hydraulic actuator includes a variable-capacity type hydraulic motor for rotationally driving the auger receiving the supply of pressure oil from the main hydraulic pump and a hydraulic cylinder for telescopic operation of the jack receiving the supply of pressure oil from the sub-hydraulic pump.

[0009] Further, the control circuit includes one inverter and a switch circuit for individually switching a number of on-off switches corresponding to the number of the electric motors. Furthermore, the control circuit has a number of inverters corresponding to the number of the electric motors and is configured to be able to individually control the rotational speed of each electric motor.

[0010] In addition, it is provided with a merging oil passage for merging the pressure oil from the plurality of main hydraulic pumps and sending it to the hydraulic motor for rotationally driving the auger, and the controller is configured to be able to selectively execute an auger low rotation control for individually driving the plurality of main electric motors and an auger high rotation control for driving them simultaneously.

Advantages of the Invention

[0011] According to the hydraulic drive device of the present invention, it is provided with a plurality of hydraulic pumps with different large and small capacities according to the load of the hydraulic actuator, and a plurality of electric motors set according to these capacities. The auger rotation drive hydraulic motor with a large load is supplied with pressure oil from the main hydraulic pump driven by the main electric motor, and the jack telescopic operation hydraulic cylinder with a relatively small load is supplied with pressure oil from the sub-hydraulic pump driven by the sub-electric motor respectively. Therefore, while maintaining the functional independence of the hydraulic pump as the power source of the pile driver, it is possible to use only the necessary amount of hydraulic energy at the optimum time of the process of exerting the pile driving function, and a highly efficient battery-type hydraulic drive device with an appropriately distributed power supply capacity can be achieved.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0013] Figs. 1 to 3 are diagrams in which the hydraulic drive device of the present invention is applied to a pile driver. As shown in Fig. 1, the pile driver 11 is a dual-purpose machine capable of switching between steel pipe pile construction and ground improvement construction, and includes a lower traveling body 12 having left and right crawlers, and a base machine (airframe) 14 composed of an upper slewing body 13 rotatably provided on the lower traveling body 12, a leader 15 erected at the front of the upper slewing body 13, and a hoisting cylinder 16 that supports the leader 15 from behind.

[0014] At the front of the upper revolving body 13, a leader support 17 for supporting the leader 15 so as to be able to rise and fall is provided, and above the front of the upper revolving body 13, a pipe support member 18 for supporting pipes is provided. Further, a driver's cab 19 is mounted on the right side of the upper revolving body 13, and a hydraulic drive device 20 serving as a power source for the pile driver 11 is mounted on the left side. Furthermore, jacks 21 for grounding and stabilizing the base machine 14 are provided at four locations on the front, rear, left, and right of the upper revolving body 13.

[0015] The leader 15 is formed by connecting a plurality of leader members having a rectangular tube-shaped cross section to each other, and is rotatably attached to a support shaft in the vehicle width direction provided on the leader support 17. At the upper end of the leader 15, a top sheave 22 around which a lifting rope is wound is arranged, and at the lower front, an openable and closable vibration preventing member 24 for preventing the swing of the steel pipe pile 23 is arranged. In the center of the front surface of the leader 15, a rack gear 25 is provided as a component of a rack and pinion type lifting device, and a pair of left and right guide pipes 26, 26 are continuously provided at the front end portions of both side surfaces over the entire length of the leader 15, and serve as a mounting portion for a hydraulic auger 27 which is an example of a rotational drive device.

[0016] In adjacent portions of each leader member, connecting flanges corresponding to the cross-sectional shape of the leader 15 are brought into contact with each other and formed, and are stably coupled using a plurality of bolts and nuts. Each flange coupling portion has the same structure with the same shape of the connecting flange, size of the bolt holes, arrangement pitch, etc., and by removing the bolts and nuts to release the flange coupling, although not shown in the figure, it is possible to recombine into a long specification with a large number of leader members and a short specification with a small number of leader members. In this case, the lengths of a plurality of hydraulic hoses 28 connecting between the upper revolving body 13 and the auger 27 are changed according to the leader length.

[0017] The hydraulic hose 28 is routed along the leader 15 via a pipe support member 18 rising from the upper swing body 13, and the portion beyond the pipe support member 18 is unrestrainedly connected to the concentrator connector 29 of the auger 27. This unrestrained portion has a substantially U-shaped slack 28a and is movable vertically following the raising and lowering of the auger 27, and its length is set according to when the height position of the auger 27 is at its maximum (Fig. 1). Thereby, when the auger 27 reaches the upper end (lifting limit position) or the lower end (lowering limit position) of the leader 15, the shape of the slack 28a does not deform excessively.

[0018] The auger 27 is configured around a device body 27a rotatably provided with a drive shaft 30, and a pair of left and right guide gibs 27b, 27b that are in sliding contact with the guide pipes 26, 26 of the leader 15 protrude rearward. By rotationally driving a pair of left and right pinions (not shown) that mesh with the rack gear 25 by a hydraulic motor 31 for driving the auger up and down, it moves up and down along the front surface of the leader 15.

[0019] Further, the auger 27 includes a hydraulic motor 32 for driving the auger to rotate, which is connected to a speed reduction mechanism in the device body 27a, an electromagnetic proportional pressure reducing valve 33 attached thereto, and a hydraulic cylinder for chucking the drive shaft 30 (not shown). The hydraulic motor 32 for driving the auger to rotate is a swash plate type variable displacement hydraulic motor capable of changing its capacity by changing the tilt angle of the swash plate. The tilt angle of the swash plate, that is, the displacement volume (discharge flow rate per motor rotation) is adjusted by a regulator. This regulator is controlled by the control pressure output from the electromagnetic proportional pressure reducing valve 33.

[0020] As shown in Fig. 2, the electromagnetic proportional pressure reducing valve 33 changes the control pressure based on the control command of the construction management device 34 mounted on the pile driver 11. Specifically, it is configured to change the pressure reduction degree as the control command current input to the solenoid increases or decreases. When a control command is input, the generated command pilot pressure (secondary pressure) increases, and the operating of the regulator gradually reduces the displacement volume to operate the auger rotation drive hydraulic motor 32. On the other hand, when the control command is fixed at the minimum, the displacement volume is adjusted to the maximum to operate the auger rotation drive hydraulic motor 32.

[0021] That is, the control command current of the electromagnetic proportional pressure reducing valve 33 and the control pressure are in a proportional relationship, but the control pressure and the displacement volume are in an inverse proportional relationship. As a result, if the flow rate is constant, the smaller the displacement volume of the auger rotation drive hydraulic motor 32, the higher the motor rotates, and the larger the displacement volume, the lower the rotation speed. However, since it rotates using a large amount of hydraulic oil, it generates a large torque. In the stepless control of the torque and rotation speed of such a hydraulic motor 32, although the details will be described later, by arbitrarily adjusting the supply flow rate to the hydraulic motor 32, the rotation state of the auger 27 can be widely changed from low speed to high speed.

[0022] By the way, against the background of environmental problems such as global warming, energy saving has become even more important in the field of pile drivers in order to reduce carbon dioxide emissions during construction. Therefore, a method of obtaining the driving force of the hydraulic pump serving as the hydraulic source from a battery by mounting a battery instead of a diesel engine is conceivable. However, when an electric motor is adopted as the drive source of the hydraulic pump, the electric motor needs to be a large-capacity one to cope with the starting load such as the auger rotation drive hydraulic motor 32. However, if this large-capacity electric motor is rotated at a specified speed even in a no-load state (unloaded state) or a low-load state where only the hydraulic jack 21 is operated, current will always flow and the power consumption will increase. As a result, the problem that the battery has to be frequently charged occurs.

[0023] Therefore, the pile driver 11 is equipped with a battery-powered hydraulic drive device 20 that fully exploits the advantages of electrification with a battery as the power source and does not cause unnecessary energy losses.

[0024] As shown in Fig. 2, the hydraulic drive device 20 mainly includes a battery (DC power supply) 35, electric motors M1, M2, M4, M5, hydraulic pumps P1, P2, P4, P5 driven by these electric motors, various hydraulic actuators such as a hydraulic motor 32 and a hydraulic cylinder 36 actuated by the pressure oil discharged from the hydraulic pumps, a control circuit mainly composed of an inverter 37 for controlling the rotational speed of the electric motors and a controller 38 for controlling the inverter 37 based on a drive command, and various hydraulic devices such as a valve 39 and a sensor 40 incorporated in the hydraulic circuit between the hydraulic pump and the hydraulic actuator.

[0025] The electric motors M1, M2, M4, M5 are selected in terms of output, that is, motor capacity, according to the required force. It consists of a total of four alternating current electric motors, namely, two main electric motors M1, M2 connected in parallel to the battery 35, and two sub-electric motors M4, M5 connected in parallel to the battery 35 and having a smaller capacity than the main electric motors M1, M2. In the conventional engine-type hydraulic unit, a hydraulic circuit for cooling the hydraulic oil (equivalent to an oil cooler and a pump M3) was provided. However, in the battery-type of the present invention, it is not necessary to provide such a cooling circuit in the power system wiring path (power line), and instead, a fan (not shown) is provided separately.

[0026] Each of the hydraulic pumps P1, P2, P4, P5 consists of a total of four hydraulic pumps, namely, two main hydraulic pumps P1, P2 driven by the two main electric motors M1, M2 respectively, and two sub-hydraulic pumps P4, P5 driven by the two sub-electric motors M4, M5 respectively and having a smaller capacity than the main hydraulic pumps P1, P2. Here, the pump capacity is the discharge flow rate per pump rotation. Therefore, the discharge flow rate of the hydraulic pump is obtained by multiplying the pump capacity by the rotational speed of the electric motor.

[0027] Each of the main hydraulic pumps P1 and P2 is a variable displacement hydraulic pump (e.g., swash plate pump) with a variable tilt angle, having the same capacity, and is connected by a hydraulic circuit to various hydraulic actuators respectively associated via a control valve 39. Specifically, they are connected to the lower traveling body 12 mainly driven under high load, the auger 27, and various hydraulic motors for the winch (e.g., hydraulic motor for travel drive and hydraulic motor 32 for auger rotation drive). These hydraulic circuits are provided with a merging oil passage 41 that merges the pressure oil from each of the main hydraulic pumps P1 and P2 and sends it to the hydraulic motor 32 for auger rotation drive, and a drive pressure sensor 40 that measures the drive pressure of the hydraulic motor 32 for auger rotation drive downstream of the merging point 41a.

[0028] Each of the sub-hydraulic pumps P4 and P5 is a fixed displacement hydraulic pump (e.g., gear pump). The sub-hydraulic pump P4 is connected by a hydraulic circuit to a hydraulic actuator respectively associated via a control valve 39. Specifically, it is connected to a hydraulic cylinder 36 for jack telescopic operation for the jack 21 that operates under a relatively low load. On the other hand, the sub-hydraulic pump P5 has a smaller capacity than the sub-hydraulic pump P4 and is a pilot pump that discharges pressure oil for applying a pilot pressure to, for example, an operation valve and an electro-hydraulic proportional pressure reducing valve 33.

[0029] The controller 38 is mainly composed of a CPU that performs various arithmetic processes based on the operation commands of the operator and the state of the pile driver 11, forms the core of the system in cooperation with the construction management device 34, and mainly controls the power system comprehensively.

[0030] Each of the electric motors M1, M2, M4, and M5 is supplied with AC power controlled by one inverter 37 from the battery 35. The inverter 37 converts the DC power obtained from the battery 35 into AC power and drives each of the electric motors M1, M2, M4, and M5 with this AC power. Also, a switch circuit 43 capable of individually switching (on / off) four on-off switches 43a, 43b, 43c, and 43d corresponding to each of the electric motors is provided in a power line (branch line) 42 connected in parallel between the inverter 37 and each of the electric motors M1, M2, M4, and M5.

[0031] When an operation detection signal (e.g., a travel operation command) corresponding to various operation operations is input to the controller 38, both of the on-off switches 43a and 43b corresponding to the main electric motors M1 and M2 among the four on-off switches 43a, 43b, 43c, and 43d are turned on. Then, for the left and right travel drive hydraulic motors, a control signal is generated so that the supply flow rate from each of the main hydraulic pumps P1 and P2 is in an optimal state, and this control signal is transmitted to the inverter 37.

[0032] On the other hand, in the inverter 37, both of the main electric motors M1 and M2 are driven and controlled to a target rotational speed, and an optimal amount of hydraulic oil is discharged from each of the main hydraulic pumps P1 and P2. As a result, straight travel of the lower traveling body 12 (traveling in which the left and right crawlers are driven at the same speed) becomes possible. Also, by turning on only one of the on-off switches 43a and 43b, an optimal amount of hydraulic oil is discharged from only one of the corresponding main hydraulic pumps P1 and P2. As a result, pivot turning travel (travel in which one crawler is stopped and the other crawler is driven to turn) becomes possible.

[0033] When the hydraulic drive device 20 configured as described above is operated and the pile driver 11 is used for the purpose of driving steel pipe piles, a steel pipe pile 23 is used as a construction member (FIG. 1). The steel pipe pile 23 is connected via an adapter 45 provided at the lower end of the drive shaft 30, and is press-fitted into the ground by lowering the auger 27 while rotating the drive shaft 30. Further, when the pile driver 11 is used for the purpose of ground improvement, a hollow rod (not shown) is used as a construction member. The upper end of the hollow rod is connected to a swivel above the auger 27, and the lower end is connected to an excavation head. While rotating this hollow rod, a ground improvement agent such as cement milk injected from the tip of the excavation head through the hollow rod is injected into the ground.

[0034] In order to perform various construction methods such as pile driving and ground improvement, in the cab 19, devices such as operation levers, operation pedals, operation switches, and a touch panel display for performing traveling, turning, raising and lowering and rotation driving of the auger 27 are intensively arranged in the vicinity of the driver's seat in consideration of operability. Furthermore, a construction management device 34 electrically connected to an operation detection unit 44 associated with these devices and an operation sensor of the pile driver 11 is installed.

[0035] The construction management device 34 is mainly composed of a CPU that executes a construction management program for various construction method controls and performs arithmetic processing such as data processing and determination. It includes a FLASH ROM that stores the construction management program, a RAM that temporarily stores various data during processing, a storage unit that stores construction plan data such as the planned pile driving position and target depth at the construction site and various data during actual construction created by the execution of the construction management program, and a display for the operator to confirm the execution result of the construction management program on the display screen or input data by touch panel operation.

[0036] The plurality of sensors constituting the operation sensor of the auger 27 include a torque sensor, a depth sensor, a rotation sensor, and the like. For example, the torque sensor is a sensor that measures the torque of the construction member held by the auger 27, and examples thereof include a drive pressure sensor 40. The drive pressure sensor 40 is provided on the auger 27 and measures the differential pressure (pressure difference between the primary pressure and the secondary pressure) at the inlet and outlet of the hydraulic motor 32 for driving the auger rotation in a set of two. In the construction management device 34, the drive pressure of the hydraulic motor 32 for driving the auger rotation is determined based on the measured differential pressure, and the construction torque is calculated as the construction load based on this drive pressure and the displacement volume corresponding to the control pressure. Also, the depth, the integrated rotation speed, and the rotation speed are calculated based on the signals measured by the encoders, proximity sensors, etc. provided in each part, respectively.

[0037] Hereinafter, the specific procedure of pile driving (steel pipe embedding) will be described. After the pile driver 11 carried into the construction site moves to the construction site by self-propulsion, all four jacks 21 at the front, rear, left, and right are grounded to stabilize the machine body. In this case, in the hydraulic drive device 20, when an operation detection signal corresponding to the jack operation is input to the controller 38, the controller 38 turns on the open / close switch 43c corresponding to the sub-electric motor M4. Then, a control signal is generated so that the supply flow rate from the sub-hydraulic pump P4 becomes an optimal state for the four hydraulic cylinders 36 for jack telescopic operation, and the control signal is transmitted to the inverter 37.

[0038] On the other hand, the inverter 37 drives the sub-electric motor M4 to control it to the target rotation speed and discharges an optimal amount of hydraulic oil from the sub-hydraulic pump P4. As a result, all four hydraulic cylinders 36 for jack telescopic operation extend, and the attached grounding plates are grounded respectively, so that the hydraulic circuit is increased to the set relief pressure, and the grounding state of the jack 21, that is, the stationary stable state of the base machine 14 is created.

[0039] In such a static stable state, the display of the construction management device 34 is switched to the construction screen, and the pile driving operation is carried out as planned until the target depth is reached while creating construction data. The operation of the operator is, for example, to tilt the lever to perform the right rotation operation and the lowering operation of the auger 27, and while maintaining the operation, operate the volume for torque adjustment according to the excavation resistance. Here, at the start of excavation, the torque is made small and the rotation speed is increased to promote construction with an emphasis on efficiency.

[0040] In this case, in the hydraulic drive device 20, when an operation detection signal corresponding to the auger operation is input to the controller 38, the controller 38 turns on both the opening and closing switches 43a and 43b corresponding to the main electric motors M1 and M2. Then, for the hydraulic motor 31 for driving the elevation of the auger and the hydraulic motor 32 for driving the rotation of the auger, a control signal is generated so as to be in an optimal state where the supply flow rate from each main hydraulic pump P1 and P2 increases, and the control signal is transmitted to the inverter 37.

[0041] On the other hand, in the inverter 37, both main electric motors M1 and M2 are driven to be controlled to the target rotation speed, and an optimal amount of hydraulic oil corresponding to the load condition (light load) is discharged from each main hydraulic pump P1 and P2. As a result, the supply flow rate to the hydraulic motor 32 for driving the rotation of the auger is adjusted to increase, and as high rotation control of the auger, the rotation state of the auger 27 is controlled at a high speed (equivalent to two speeds).

[0042] Then, as the target depth is approached and the ground becomes harder, the excavation resistance increases and the rotation speed of the auger 27 decreases, so the volume is increased and the torque is gradually increased.

[0043] In this case, in the hydraulic drive device 20, an operation detection signal corresponding to the auger operation is input to the controller 38. Then, the controller 38 generates a control signal so that the supply flow rate from the main hydraulic pump P2 to the hydraulic motor 32 for driving the auger rotation is in an optimal state where both the opening / closing switches 43a and 43b corresponding to the main electric motors M1 and M2 are turned on, and transmits the control signal to the inverter 37.

[0044] On the other hand, in the inverter 37, the main electric motors M1 and M2 are continuously driven and controlled to the target rotational speed, and an optimal amount of hydraulic oil corresponding to the load conditions (high load) is discharged from each of the main hydraulic pumps P1 and P2. As a result, the supply flow rate to the hydraulic motor 32 for driving the auger rotation is adjusted to decrease, and as the auger low rotation control, the rotation state of the auger 27 is controlled to a low speed (equivalent to the first speed).

[0045] At this time, when the lowering of the auger 27 is stopped according to the situation, such as when a sudden load acts on the rotation of the auger 27, the controller 38 turns off only the opening / closing switch 43b and stops the driving of the main electric motor M2, for example, based on the input of the operation detection signal or the state detection signal. As a result, the discharge of the hydraulic oil from the main hydraulic pump P2, that is, the hydraulic supply to the hydraulic motor 31 for driving the auger lifting is stopped, and the rotation state of the auger 27 is maintained by the hydraulic supply from the main hydraulic pump P1 in a state where only the main electric motor M1 is individually driven.

[0046] In this way, in the hydraulic drive device 20, by controlling the rotation of the main electric motors M1 and M2, the supply flow rate to the hydraulic motor 32 for driving the auger rotation and the like is adjusted, and thereby the rotation state of the auger 27 is maintained at a speed suitable for the state of the ground.

[0047] Here, when adding a steel pipe pile, the embedded steel pipe pile 23 and the driving shaft 30 are separated, the vibration damping member 24 is opened, and the upper slewing body 13 is slewed in place with the jack 21 in a retracted state. As a result, the prepared additional steel pipe pile has its upper end connected to the driving shaft 30 via the adapter 45 in the area on the side of the machine body and is carried into the construction site (pile center) by the slewing operation in the opposite direction. After such a predetermined setup operation, the auger 27 is driven again to push the steel pipe pile 23 forward while applying rotation to it, so that the steel pipe pile 23 is embedded deep into the ground.

[0048] The pile driving procedure proceeds while repeating such partial working steps. In this case, the pile driver 11 appropriately sends the fluid power generated by the hydraulic drive device 20 to the hydraulic actuators of each part such as the jack 21, the upper slewing body 13, and the auger 27 that are sequentially driven in a timely manner. On the other hand, the construction management device 34 cooperates with the hydraulic drive device 20, calculates the construction torque based on the drive pressure of the hydraulic motor 32 for driving the auger rotation and the pushing-out volume corresponding to the control pressure, and displays the "construction torque" together with the "pile number" and "target depth" on the screen. This display is represented by, for example, a line graph in two-dimensional coordinates with the depth on the vertical axis and the magnitude of the construction torque on the horizontal axis, and it is a display for knowing the ground conditions. Simultaneously with such real-time display, the construction torque for each depth and the target pile number are associated and sequentially stored in the storage unit of the construction management device.

[0049] Thus, according to the hydraulic drive device 20 of the present invention, a plurality of hydraulic pumps P1, P2, P4, P5 with different large and small capacities according to the load of the hydraulic actuator, and a plurality of electric motors M1, M2, M4, M5 set according to these capacities are provided. The auger rotation drive hydraulic motor 32 with a large load is supplied with pressure oil from the main hydraulic pumps P1, P2 driven by the main electric motors M1, M2, and the jack telescopic operation hydraulic cylinder 36 with a relatively small load is supplied with pressure oil from the sub hydraulic pump P4 driven by the sub electric motor M4. Therefore, while maintaining the functional independence of the hydraulic pump as the power source of the pile driver 11, it is possible to use only the amount of hydraulic energy required at the optimum time of the process of exerting the pile driving function, and a highly efficient battery type hydraulic drive device 20 with an appropriately distributed power supply capacity can be achieved.

[0050] Also, in the control circuit, since it includes one inverter 37 and a switch circuit 43 that individually switches the number of on-off switches 43a, 43b, 43c, 43d corresponding to the number of electric motors M1, M2, M4, M5, it is possible to stop the electric motors that are not required for the work to prevent the battery 35 from being consumed, and at the same time reduce the energy consumption for cooling the hydraulic oil by suppressing the unnecessary rise in the oil temperature. Also, even when adding a hydraulic pump, the circuit configuration becomes simple, and the hydraulic drive device 20 suitable for various construction needs can be manufactured at low cost.

[0051] Furthermore, in the hydraulic circuit, it is provided with a confluence oil passage 41 that combines the pressure oil from the plurality of main hydraulic pumps P1, P2 and sends it to the auger rotation drive hydraulic motor 32, and the controller 38 is configured to be able to selectively execute the auger low rotation control for individually driving the plurality of main electric motors M1, M2 and the auger high rotation control for driving them simultaneously. Therefore, in the operation peculiar to pile driving where the rotational speed and torque of the electric motor change greatly as the work progresses, it is particularly beneficial for low fuel consumption (energy saving) countermeasures.

[0052] FIG. 3 shows a modified example of the pile driver equipped with the hydraulic drive device of the present invention. In the following description, the same components as those shown in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

[0053] The hydraulic drive device 51 has the hydraulic circuit of the above-described embodiment as it is, and instead of the switch circuit 43, four inverters 52, 53, 54, 55 corresponding to the respective electric motors M1, M2, M4, M5 are incorporated into the control circuit, whereby the rotational speeds of the respective electric motors M1, M2, M4, M5 can be individually controlled. Each of the inverters 52, 53, 54, 55 is provided on a power line (branch line) 56 that is connected in parallel between the battery 35 and the respective electric motors M1, M2, M4, M5, and it is possible to individually transmit a drive command from the controller 38 to each of the inverters 52, 53, 54, 55.

[0054] When an operation detection signal (for example, a travel operation command) corresponding to various operation operations is input to the controller 38, the controller 38 identifies the inverters 52, 53 corresponding to the main electric motors M1, M2 among the four inverters 52, 53, 54, 55. Then, a control signal is generated so that the supply flow rates from the respective main hydraulic pumps P1, P2 become optimal for the left and right travel drive hydraulic motors, and the control signal is transmitted to the inverters 52, 53.

[0055] On the other hand, in the inverters 52, 53, both of the main electric motors M1, M2 are driven and controlled to the target rotational speed, and an optimal amount of hydraulic oil is discharged from the respective main hydraulic pumps P1, P2. As a result, straight travel of the lower traveling body 12 (travel in which the left and right crawlers are driven at the same speed) can be performed. Further, by providing a rotational difference between the main electric motors M1, M2, different optimal amounts of hydraulic oil are discharged from the corresponding main hydraulic pumps P1, P2. As a result, slalom turning travel (travel in which the left and right crawlers are driven at different speeds in the same direction to change the travel direction) can be performed.

[0056] And also in this modified example configured as described above, the same effects as those in the case of using the above-described switch circuit 43 can be achieved. Furthermore, in the case of this modified example, it becomes possible to individually control the rotational speeds of the respective electric motors M1, M2, M4, and M5. As a result, the situation where a part of the hydraulic energy is converted into heat and wasted in the case of interlocking the hydraulic actuators is improved, and more efficient operation becomes possible.

[0057] Note that the present invention is not limited to the above-described respective exemplary embodiments, and the specifications of the hydraulic drive device can be appropriately changed according to the functions required for the pile driver. Also, the mounting position can be considered to be mounted in a unitized manner on one side (inside the house) of the upper swing body where the conventional engine was mounted, but it is not limited to this. The entire device can be configured in consideration of the positional relationship with other structures and devices, such as arranging the battery part in the space at the rear of the machine body with a counterweight. Further, in the embodiment, the steel pipe embedding was described as an example, but it is not limited to this, and it can also be applied to ground improvement.

Explanation of Reference Numerals

[0058] 11... Pile driver, 12... Lower traveling body, 13... Upper swing body, 14... Base machine, 15... Leader, 16... Hoisting cylinder, 17... Leader support, 18... Pipe support member, 19... Driver's cab, 20... Hydraulic drive device, 21... Jack, 22... Top sheave, 23... Steel pipe pile, 24... Anti-vibration member, 25... Rack gear, 26... Guide pipe, 27... Auger, 27a... Device main body, 27b... Guide gib, 28... Hydraulic hose, 28a... Slack, 29... Concentrator connector, 30... Drive shaft, 31... Hydraulic motor for auger lifting drive, 32... Hydraulic motor for auger rotation drive, 33... Electro-hydraulic proportional pressure reducing valve, 34... Construction management device, 35... Battery, 36... Hydraulic cylinder for jack telescopic operation, 37... Inverter, 38... Controller, 39... Control valve, 40... Drive pressure sensor, 41... Confluence oil passage, 41a... Confluence point, 42... Power line, 43... Switch circuit, 43a, 43b, 43c, 43d... Open / close switch, 44... Operation detection unit, 45... Adapter, 51... Hydraulic drive device, 52, 53, 54, 55... Inverter, 56... Power line

Claims

1. Mounted on a pile driver comprising a self-propelled base machine, a reader erected on the base machine, a jack for stabilizing the base machine, and an auger mounted on the reader and rotationally driven in a stable state of the base machine, an electric motor, a hydraulic pump driven by the electric motor, a hydraulic actuator actuated by the pressure oil discharged from the hydraulic pump, and a control circuit comprising an inverter for controlling the rotational speed of the electric motor and a controller for controlling the inverter. In the hydraulic drive device, the electric motor comprises a plurality of main electric motors connected in parallel to the battery and a plurality of sub-electric motors connected in parallel to the battery and having a smaller capacity than the main electric motors, the hydraulic pump comprises a plurality of main hydraulic pumps respectively driven by the plurality of main electric motors and a plurality of sub-hydraulic pumps respectively driven by the plurality of sub-electric motors and having a smaller capacity than the main hydraulic pumps, the hydraulic actuator includes a variable displacement type hydraulic motor for rotationally driving the auger receiving the supply of pressure oil from the main hydraulic pump and a hydraulic cylinder for telescopic operation of the jack receiving the supply of pressure oil from the sub-hydraulic pump. The hydraulic drive device is characterized by this.

2. The control circuit includes one of the inverters and a switch circuit for individually switching a number of on-off switches corresponding to the number of the electric motors. The hydraulic drive device according to Claim 1 is characterized by this.

3. The control circuit has a number of the inverters corresponding to the number of the electric motors and is configured to be able to individually control the rotational speed of each of the electric motors. The hydraulic drive device according to Claim 1 is characterized by this.

4. It is provided with a confluence oil passage for confluencing the pressure oil from the plurality of main hydraulic pumps and sending it to the hydraulic motor for rotationally driving the auger, and the controller is configured to be able to selectively execute an auger low rotation control for individually driving the plurality of main electric motors and an auger high rotation control for driving them simultaneously. The hydraulic drive device according to any one of Claims 1 to 3 is characterized by this.

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