Electric work vehicle

Abstract

To provide an electric work vehicle capable of keeping travel performance even when a work device is operated while traveling under a temperature environment where power output from a battery is not enough.SOLUTION: An electric wheel loader 1 comprises: a battery 30; a driving device 3A for traveling; a clutch driving device 3B; a driving device 4 for work; main controllers 5, 5A, 5B, 5C controlling each of the driving device 3A for traveling and the driving device 4 for work, wherein the main controllers 5, 5A, 5B, 5C calculate output possible power Pout of the battery 30, first consumption power P1 being power consumed by a hydraulic motor 36, and second consumption power P2 being power consumed by a motor 31 for traveling, to limit a drive command to the driving device 4 for work when total consumption power P1+P2 of the first consumption power P1 and the second consumption power P2 overpasses the output possible power Pout of the battery 30.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an electric work vehicle that uses a battery as a power source. [Background technology]

[0002] In recent years, electric vehicles that use batteries instead of engines as a power source have become popular in order to reduce the burden on the environment, and electric work vehicles equipped with batteries, such as wheel loaders and hydraulic excavators, have been developed. Generally, batteries can normally supply power at temperatures between 15 and 35°C, but cannot supply sufficient power in harsh environments, such as low temperatures below 0°C or high temperatures above 60°C.

[0003] In electrically powered vehicles, excess energy is recovered while driving and used to charge the battery, but if the amount of energy regenerated is reduced to protect the battery when the battery temperature drops during this energy regeneration, free running occurs. Therefore, for example, in the electric vehicle described in Patent Document 1, the supply power, which is adjusted by a resistor connected between the generator and the battery, is controlled according to the battery temperature, allowing the generator to smoothly regenerate energy when the battery is at a low temperature. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-291106 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the case of an electric work vehicle, even if the technology described in Patent Document 1 is adopted, if the working equipment is operated while driving when the battery temperature is low, the power supply will be significantly insufficient compared to an electric vehicle. As a result, the rotation speed of the main hydraulic pump, which is the power source for the working equipment, will drop significantly. As a result, the discharge flow rate of the charge pump that supplies hydraulic oil to the transmission clutch will also decrease, and the clutch will not be able to maintain its engaged state, making it more likely to run idle.

[0006] Therefore, an object of the present invention is to provide an electric work vehicle that can maintain driving performance even when a work implement is operated while traveling in a temperature environment where the battery output is insufficient. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a vehicle body provided with wheels, a battery mounted on the vehicle body, a traveling electric motor and a hydraulic electric motor driven by electric power output from the battery, a traveling drive device which causes the vehicle body to travel by transmitting the output torque of the traveling electric motor to the wheels via a transmission, a clutch drive device having a charge pump driven by the hydraulic electric motor to supply pressure oil to a plurality of clutches of the transmission and which drives the plurality of clutches, a working device attached to the vehicle body, and a work drive device having a main pump driven by the hydraulic electric motor and which drives the working device by controlling the flow of pressure oil discharged from the main pump, and and a main controller, wherein the main controller calculates an available output power, which is the power that the battery can output, based on the available output current of the battery and the voltage of the battery, calculates a first power consumption, which is the power consumed by the hydraulic motor, based on the discharge pressure of the main pump, the discharge flow rate of the main pump, the discharge pressure of the charge pump, and the discharge flow rate of the charge pump, calculates a second power consumption, which is the power consumed by the traveling motor, based on data indicating a driving state of the traveling motor, and limits a command to the work drive device related to driving the working device when a total power consumption obtained by adding together the first power consumption and the second power consumption exceeds the available output power of the battery. Effect of the Invention

[0008] According to the present invention, even if the working implement is operated while traveling in a temperature environment where the battery output is insufficient, the traveling performance can be maintained. Problems, configurations, and effects other than those described above will become apparent from the description of the embodiments below. [Brief description of the drawings]

[0009] [Figure 1]1 is an external side view showing one configuration example of a wheel loader according to each embodiment of the present invention. FIG. [Diagram 2] FIG. 1 is a system configuration diagram showing an example of a drive system for a wheel loader according to a first embodiment. [Diagram 3] 1 is a hydraulic circuit diagram showing one configuration example of a working drive device. [Figure 4] FIG. 2 is a functional block diagram showing functions of a main controller according to the first embodiment. [Diagram 5] 5 is a flowchart showing a flow of processing executed by a main controller according to the first embodiment. [Figure 6] 10 is a flowchart showing a flow of processing executed by a main controller according to a modified example. [Figure 7] FIG. 11 is a functional block diagram showing functions of a main controller according to a second embodiment. [Figure 8] 10 is a flowchart showing a flow of processing executed by a main controller according to the second embodiment. [Figure 9] FIG. 11 is a functional block diagram showing functions of a main controller according to a third embodiment. [Figure 10] 13 is a flowchart showing a flow of processing executed by a main controller according to the third embodiment. [Figure 11] FIG. 13 is a functional block diagram showing functions of a main controller according to a fourth embodiment. [Figure 12] 13 is a flowchart showing a flow of processing executed by a main controller according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In the following, an electrically driven wheel loader that performs loading and unloading operations such as excavating work objects such as soil and minerals and loading them into dump trucks, hoppers, etc. will be described as an example of one form of an electric work vehicle according to each embodiment of the present invention.

[0011] <Overall configuration of wheel loader 1> First, the overall configuration of a wheel loader 1 according to each embodiment of the present invention will be described with reference to FIG.

[0012] FIG. 1 is an external side view showing an example of the configuration of a wheel loader 1 according to each embodiment of the present invention.

[0013] The wheel loader 1 is an articulated work vehicle that is steered by bending the vehicle body near the center. Specifically, a front frame 1A forming the front part of the vehicle body and a rear frame 1B forming the rear part of the vehicle body are connected by a center joint 10 so as to be rotatable in the left-right direction, and the front frame 1A bends in the left-right direction relative to the rear frame 1B. In the following description, of the left-right direction of the vehicle body, the left direction relative to the forward direction is referred to as the "left direction", and the right direction relative to the forward direction is referred to as the "right direction".

[0014] The vehicle body is provided with four wheels 11, two of which are front wheels 11A provided on both the left and right sides of the front frame 1A, and the remaining two wheels 11 are rear wheels 11B provided on both the left and right sides of the rear frame 1B. Of the four wheels 11, only the front wheel 11A and rear wheel 11B provided on the right side are shown in FIG.

[0015] A hydraulically driven working device 2 is attached to the front of the front frame 1A. The working device 2 has a lift arm 21 attached to the front frame 1A so as to be rotatable in the vertical direction, two lift arm cylinders 22L, 22R as hydraulic cylinders that drive the lift arm 21, a bucket 23 attached to the tip of the lift arm 21 so as to be rotatable in the vertical direction, a bucket cylinder 24 as a hydraulic cylinder that drives the bucket 23, and a bell crank 25 rotatably connected to the lift arm 21 to form a link mechanism between the bucket 23 and the bucket cylinder 24.

[0016] The two lift arm cylinders 22L, 22R are arranged side by side at a predetermined interval in the left-right direction of the vehicle body, but in FIG. 1, only the right lift arm cylinder 22R is shown by a dashed line.

[0017] The lift arm 21 rotates upward (raises) relative to the front frame 1A when the rods 220 of the two lift arm cylinders 22L, 22R extend, and rotates downward (lowers) relative to the front frame 1A when the rods 220 of the two lift arm cylinders 22L, 22R contract.

[0018] The bucket 23 rotates upward relative to the lift arm 21 as the rod 240 of the bucket cylinder 24 extends (tilt operation), and rotates downward relative to the lift arm 21 as the rod 240 of the bucket cylinder 24 contracts (dump operation). This allows the bucket 23 to scoop up and discharge (dig and dump) work objects such as soil and minerals.

[0019] The bucket 23 can be replaced with various attachments, such as a blade, and the wheel loader 1 can perform various tasks such as snow removal and earth-pulling in addition to loading and unloading operations using the bucket 23.

[0020] The rear frame 1B is provided with a cab 12 in which an operator sits, a machine room 13 that houses various devices required for driving the wheel loader 1, and a counterweight 14 for maintaining balance with the work implement 2 so that the vehicle body does not tilt. On the rear frame 1B, the cab 12 is located at the front, the counterweight 14 at the rear, and the machine room 13 between the cab 12 and the counterweight 14.

[0021] Next, a drive system for driving the wheel loader 1 will be described for each embodiment.

[0022] First Embodiment A drive system 100 of a wheel loader 1 in a first embodiment of the present invention will be described with reference to FIGS.

[0023] (Overall configuration of drive system 100) First, the overall configuration of the drive system 100 will be described with reference to FIGS.

[0024] Fig. 2 is a system configuration diagram showing an example of the drive system 100 of the wheel loader 1 according to the first embodiment. Fig. 3 is a hydraulic circuit diagram showing an example of the configuration of the work drive device 4.

[0025] The drive system 100 of the wheel loader 1 employs an electrically driven system that is driven using power output from a battery 30 mounted on the vehicle body. The battery 30 is controlled by a battery controller 30A. The battery controller 30A controls the current that the battery 30 can output and the voltage of the battery 30, and outputs this data to the main controller 5. The current that the battery 30 can output can be determined from the degree of deterioration of a number of cells inside the battery 30, the temperature and SOC of the battery 30, etc.

[0026] The drive system 100 of the wheel loader 1 is composed of a traveling drive device 3A that drives the vehicle body, a clutch drive device 3B that drives multiple clutches 331-333 of a transmission 33 that is one element that makes up the traveling drive device 3A, and a work drive device 4 that drives the work implement 2.

[0027] The running drive device 3A has a running motor 31 driven by power output from a battery 30, a running inverter 32 that controls the running motor 31, and a transmission 33 that changes the output torque of the running motor 31 and transmits it to each wheel 11.

[0028] The traveling inverter 32 controls the rotation speed and output torque of the traveling electric motor 31 based on a command signal output from the main controller 5, and also outputs actual data thereof to the main controller 5.

[0029] The transmission 33 is an automatic transmission that switches the traveling direction (forward / reverse) of the vehicle body and changes the rotation speed of the output shaft of the traveling motor 31. The rotation speed changed by the transmission 33 is transmitted to each of the wheels 11 (a pair of front wheels 11A and rear wheels 11B) via the drive shaft 15 and the front axle 16A and rear axle 16B, thereby causing the wheel loader 1 to travel.

[0030] The transmission 33 is composed of a clutch mechanism having a forward clutch 331 that switches the traveling direction of the vehicle body to forward, a reverse clutch 332 that switches the traveling direction of the vehicle body to reverse, and a plurality of speed stage clutches 333 (only two are shown in FIG. 2) that switch the speed stages of the vehicle body.

[0031] Each of the clutches 331 to 333 includes, for example, a pair of disk-shaped disc clutches. In the forward clutch 331, the pair of disc clutches are engaged to switch the traveling direction of the vehicle body to forward. Similarly, in the reverse clutch 332, the pair of disc clutches are engaged to switch the traveling direction of the vehicle body to reverse. In addition, in the multiple speed-stage clutches 333, for example, when the pair of disc clutches of the first-speed-stage clutch 333, which is a low speed, are engaged, the speed stage of the vehicle body is switched to the first-speed stage.

[0032] The clutch drive device 3B has a charge pump 34 that supplies pressure oil to the multiple clutches 331-333, and a clutch electromagnetic control valve 35 that controls each of the multiple clutches 331-333. Although only one clutch electromagnetic control valve 35 is shown in Fig. 2 for convenience, in reality, a plurality of clutch electromagnetic control valves 35 are provided corresponding to each of the multiple clutches 331-333.

[0033] The charge pump 34 is driven by a hydraulic motor 36, and in this embodiment, is a fixed displacement hydraulic pump. The charge pump 34 is provided with a first pressure sensor 341 that detects the discharge pressure of the charge pump 34, and a first rotation speed sensor 342 that detects the rotation speed of the charge pump 34. The discharge pressure of the charge pump 34 detected by the first pressure sensor 341 and the rotation speed of the charge pump 34 detected by the first rotation speed sensor 342 are each output to the main controller 5. In this embodiment, since the charge pump 34 is a fixed displacement hydraulic pump, the displacement volume is constant.

[0034] The hydraulic motor 36 is driven by the power output from the battery 30, and is controlled by a hydraulic inverter 37. Like the traveling inverter 32, the hydraulic inverter 37 controls the rotation speed and output torque of the hydraulic motor 36 based on a command signal output from the main controller 5, and also outputs actual data of these to the main controller 5.

[0035] The clutch electromagnetic control valves 35 engage the pair of disk clutches of each of the clutches 331 to 333 based on a command signal output from the main controller 5. For example, when a command signal related to forward movement is output from the main controller 5, the clutch electromagnetic control valve 35 corresponding to the forward clutch 331 engages the pair of disk clutches of the forward clutch 331.

[0036] The work drive device 4 includes the lift arm cylinders 22L, 22R, a bucket cylinder 24, a main pump 41 that supplies pressurized oil to the lift arm cylinders 22L, 22R and the bucket cylinder 24, a lift arm directional control valve 42 that controls the flow (direction and flow rate) of the pressurized oil discharged from the main pump 41 and supplied to the lift arm cylinders 22L, 22R, and a bucket directional control valve 44 that controls the flow (direction and flow rate) of the pressurized oil discharged from the main pump 41 and supplied to the bucket cylinder 24.

[0037] The main pump 41 is driven by the hydraulic motor 36, and in this embodiment, is a variable displacement hydraulic pump. That is, the hydraulic motor 36 drives the charge pump 34 and the main pump 41 in parallel. Note that the main pump 41 is a pump that discharges pressure oil for driving the working device 2, and therefore has a larger capacity than the charge pump 34.

[0038] 3, a regulator 410 is attached to the main pump 41. The regulator 410 controls the displacement (tilt angle) of the main pump 41 based on a command signal output from the main controller 5.

[0039] For example, when the regulator 410 limits the displacement of the main pump 41 (controls the tilt angle to be smaller), the flow rate of the pressure oil discharged from the main pump 41 decreases, and therefore the flow rate of the pressure oil supplied to the lift arm cylinders 22L, 22R and the bucket cylinder 24 decreases. This limits the operation of the working device 2.

[0040] A second pressure sensor 411 for detecting the discharge pressure of the main pump 41 and a main relief valve 41A for discharging pressure oil into the tank 40 when the discharge pressure of the main pump 41 reaches a predetermined relief pressure are provided on the main pipe 400 connected to the discharge side of the main pump 41. The second pressure sensor 411 outputs the detected discharge pressure of the main pump 41 to the main controller 5.

[0041] 2, the main pump 41 is provided with a second rotation speed sensor 412 that detects the rotation speed of the main pump 41. The second rotation speed sensor 412 outputs the detected rotation speed of the main pump 41 to the main controller 5.

[0042] In this embodiment, the lift arm directional control valve 42 has four switching positions: a neutral position 42N, a first switching position 42L, a second switching position 42R, and a third switching position 42F.

[0043] The neutral position 42N connects the main pipeline 400 and the tank 40, and guides the pressure oil discharged from the main pump 41 to the tank 40.

[0044] The first switching position 42L connects the main pipeline 400 to each rod chamber 221 of the lift arm cylinders 22L, 22R, and guides the pressurized oil discharged from the main pump 41 to each rod chamber 221, and also connects each bottom chamber 222 of the lift arm cylinders 22L, 22R to the tank 40, and guides the pressurized oil in each bottom chamber 222 to the tank 40.

[0045] The second switching position 42R connects the main pipeline 400 to each bottom chamber 222 of the lift arm cylinders 22L, 22R, and guides the pressurized oil discharged from the main pump 41 to each bottom chamber 222, and also connects each rod chamber 221 of the lift arm cylinders 22L, 22R to the tank 40, and guides the pressurized oil in each rod chamber 221 to the tank 40.

[0046] The third switching position 42F connects the main pipeline 400, each rod chamber 221 of the lift arm cylinders 22L, 22R, and each bottom chamber 222 of the lift arm cylinders 22L, 22R to the tank 40, and guides all of the pressurized oil discharged from the main pump 41 and the pressurized oil in the lift arm cylinders 22L, 22R to the tank 40.

[0047] When the lift arm directional control valve 42 is switched to the neutral position 42N, the pressure oil discharged from the main pump 41 and guided to the main pipeline 400 flows out to the tank 40. As a result, pressure oil does not flow in or out of the lift arm cylinders 22L, 22R, so the operation of each rod 220 stops, and the operation of the lift arm 21 stops.

[0048] When the lift arm directional control valve 42 is switched to the first switching position 42L, the pressure oil discharged from the main pump 41 and guided to the main pipeline 400 flows into each rod chamber 221 of the lift arm cylinders 22L, 22R, and the pressure oil in each bottom chamber 222 of the lift arm cylinders 22L, 22R flows out to the tank 40. This causes each rod 220 to contract, and the lift arm 21 rotates downward (descends) relative to the front frame 1A.

[0049] When the lift arm directional control valve 42 is switched to the second switching position 42R, the pressure oil discharged from the main pump 41 and guided to the main pipeline 400 flows into each bottom chamber 222 of the lift arm cylinders 22L, 22R, and the pressure oil in each rod chamber 221 of the lift arm cylinders 22L, 22R flows out to the tank 40. This causes each rod 220 to extend, and the lift arm 21 rotates (rises) upward relative to the front frame 1A.

[0050] When the lift arm directional control valve 42 is switched to the third switch position 42F, both the pressure oil discharged from the main pump 41 and guided to the main pipeline 400 and the pressure oil in the lift arm cylinders 22L, 22R flow out to the tank 40. This causes the lift arm 21 to rotate (descend) downward relative to the front frame 1A under its own weight. Thus, in this embodiment, the work drive device 4 has a gravity descent function that causes the work device 2 to descend under its own weight.

[0051] When pilot pressure is applied to the lift arm directional control valve 42, an internal spool moves and the switching position is switched among a neutral position 42N, a first switching position 42L, a second switching position 42R, and a third switching position 42F.

[0052] The pilot pressure acting on the lift arm directional control valve 42 is controlled by a first solenoid control valve 420L and a second solenoid control valve 420R. The first solenoid control valve 420L and the second solenoid control valve 420R control the flow of pilot pressure oil discharged from the pilot pump 43 and supplied to the lift arm directional control valve 42, based on a command signal output from the main controller 5.

[0053] The bucket directional control valve 44 has three switching positions: a neutral position 44N, a first switching position 44L, and a second switching position 44R.

[0054] The neutral position 44N, like the neutral position 42N of the lift arm directional control valve 42, connects the main pipeline 400 and the tank 40 and guides the pressure oil discharged from the main pump 41 to the tank 40.

[0055] The first switching position 44L connects the main pipeline 400 and the rod chamber 241 of the bucket cylinder 24 to guide the pressurized oil discharged from the main pump 41 to the rod chamber 241, and also connects the bottom chamber 242 of the bucket cylinder 24 to the tank 40 to guide the pressurized oil in the bottom chamber 242 to the tank 40.

[0056] The second switching position 44R connects the main pipeline 400 and the bottom chamber 242 of the bucket cylinder 24 to guide the pressurized oil discharged from the main pump 41 to the bottom chamber 242, and also connects the rod chamber 241 of the bucket cylinder 24 to the tank 40 to guide the pressurized oil in the rod chamber 241 to the tank 40.

[0057] When the bucket directional control valve 44 switches to the neutral position 44N, the pressure oil discharged from the main pump 41 and guided to the main pipeline 400 flows out into the tank 40. As a result, pressure oil does not flow in or out of the bucket cylinder 24, so the movement of the rod 240 stops, and the movement of the bucket 23 stops.

[0058] When the bucket directional control valve 44 is switched to the first switching position 44L, the pressure oil discharged from the main pump 41 and guided to the main pipeline 400 flows into the rod chamber 241 of the bucket cylinder 24, and the pressure oil in the bottom chamber 242 of the bucket cylinder 24 flows out to the tank 40. This causes the rod 240 to contract, and the bucket 23 to rotate upward relative to the lift arm 21 (tilt operation).

[0059] When the bucket directional control valve 44 is switched to the second switching position 44R, the pressure oil discharged from the main pump 41 and guided to the main pipeline 400 flows into the bottom chamber 242 of the bucket cylinder 24, and the pressure oil in the rod chamber 241 of the bucket cylinder 24 flows out to the tank 40. This causes the rod 240 to extend, and the bucket 23 to rotate downward relative to the lift arm 21 (dump operation).

[0060] As with the lift arm directional control valve 42, when pilot pressure oil is supplied to the bucket directional control valve 44 (when pilot pressure is applied), an internal spool moves and the switching position is switched between a neutral position 44N, a first switching position 44L, and a second switching position 44R.

[0061] Like the pilot pressure acting on the lift arm directional control valve 42, the pilot pressure acting on the bucket directional control valve 44 is controlled by a third solenoid control valve 440L and a fourth solenoid control valve 440R. The third solenoid control valve 440L and the fourth solenoid control valve 440R control the flow of pilot pressure oil discharged from the pilot pump 43 and supplied to the bucket directional control valve 44, based on a command signal output from the main controller 5.

[0062] The pilot pump 43 is a fixed displacement hydraulic pump. A pilot relief valve 43A that discharges pilot pressure oil into the tank 40 when the discharge pressure of the pilot pump 43 reaches a predetermined relief pressure, and an electromagnetic switching valve 45 that switches between a communication position 45A and a cutoff position 45B based on a command signal output from the main controller 5 are provided on a pilot main line 430 connected to the discharge side of the pilot pump 43.

[0063] The communication position 45A connects the pilot main line 430 to each of the first to fourth electromagnetic control valves 420L, 420R, 440L, 440R, and guides the pilot pressure oil discharged from the pilot pump 43 to each of the lift arm directional control valve 42 and the bucket directional control valve 44.

[0064] On the other hand, the shut-off position 45B cuts off the connection between the pilot main line 430 and each of the first to fourth electromagnetic control valves 420L, 420R, 440L, and 440R, and cuts off the pilot pressure oil guided from the pilot pump 43 to the lift arm directional control valve 42 and the bucket directional control valve 44.

[0065] When the solenoid directional control valve 45 is switched to the shutoff position 45B, pilot pressure oil is not guided to the lift arm directional control valve 42 and the bucket directional control valve 44, and therefore, regardless of the states of the first to fourth solenoid control valves 420L, 420R, 440L, 440R, pilot pressure is not applied to the lift arm directional control valve 42 and the bucket directional control valve 44. In this case, the lift arm directional control valve 42 and the bucket directional control valve 44 are in the neutral positions 42N and 44N, respectively.

[0066] (Main controller 5 configuration) Next, the configuration of the main controller 5 will be described with reference to FIG.

[0067] FIG. 4 is a functional block diagram showing functions of the main controller 5 according to the first embodiment.

[0068] The main controller 5 has, as its hardware configuration, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), an input I / F (Interface), and an output I / F (Interface). These components are connected to each other via a common bus.

[0069] The CPU is a calculation means and controls the overall operation of the main controller 5. The RAM is a volatile storage medium that allows high speed reading and writing of information, and is used, for example, as a working area when the CPU processes management information. The ROM is a read-only non-volatile storage medium that stores programs such as firmware.

[0070] An HDD is a non-volatile storage medium that can read and write information and has a large storage capacity, and stores an OS (Operating System), control programs for executing various information processing operations described below, and application programs, etc. Note that an HDD can be substituted with any type of device, for example an SSD (Solid State Drive), as long as it realizes the functions of storing and managing information as a non-volatile storage medium.

[0071] The input I / F is a connection interface with the communication network on the input side of the main controller 5, and is connected to the battery controller 30A, the driving inverter 32, the first pressure sensor 341, the first rotation speed sensor 342, the second pressure sensor 411, and the second rotation speed sensor 412, etc.

[0072] The output I / F is a connection interface with a communication network on the output side of the main controller 5, and is connected to the first to fourth electromagnetic control valves 420L, 420R, 440L, 440R, etc.

[0073] The main controller 5 having such a hardware configuration is an information processing device that realizes processing functions by using the arithmetic functions of the CPU to process control programs stored in the ROM and control programs and application programs loaded from a storage medium such as an HDD to the RAM.

[0074] Execution of these information processes constitutes a software control unit including various functional modules in the main controller 5. A combination of the software control unit thus constituted and hardware resources including the above configuration constitutes a functional block that realizes the functions of the main controller 5.

[0075] In this embodiment, the configuration of the main controller 5 is described as a combination of software and hardware, but this is not limited to this, and it may also be configured using an integrated circuit that realizes the functions of a control program executed on the wheel loader 1 side.

[0076] As shown in FIG. 4, the main controller 5 includes a data acquisition unit 50, a battery power calculation unit 51, a pump power calculation unit 52, a driving motor power calculation unit 53, a power comparison and judgment unit 54, a memory unit 55, and a command signal output unit 56.

[0077] The data acquisition unit 50 acquires the outputtable current and voltage of the battery 30 output from the battery controller 30A, the discharge pressure of the charge pump 34 output from the first pressure sensor 341, the rotation speed of the charge pump 34 output from the first rotation speed sensor 342, the discharge pressure of the main pump 41 output from the second pressure sensor 411, the rotation speed of the main pump 41 output from the second rotation speed sensor 412, and the rotation speed and output torque of the running motor 31 output from the running inverter 32.

[0078] The battery power calculation unit 51 calculates the available output power Pout, which is the power that the battery 30 can output, based on the available output current of the battery 30 and the voltage of the battery 30 acquired by the data acquisition unit 50.

[0079] The pump power calculation unit 52 first calculates the discharge flow rate of the charge pump 34 based on the rotation speed of the charge pump 34 and the displacement volume of the charge pump 34 acquired by the data acquisition unit 50. Similarly, the pump power calculation unit 52 calculates the discharge flow rate of the main pump 41 based on the rotation speed of the main pump 41 and the displacement volume of the main pump 41 acquired by the data acquisition unit 50.

[0080] In this embodiment, since the charge pump 34 is a fixed displacement hydraulic pump, the displacement volume of the charge pump 34 is a predetermined volume value (constant value) and is stored in advance in the storage unit 55 of the main controller 5. In addition, the displacement volume of the main pump 41 is a value that is set based on a command signal that the main controller 5 outputs to the regulator 410, and is stored in the storage unit 55.

[0081] Next, the pump power calculation unit 52 calculates the power Pc consumed by the charge pump 34 based on the discharge pressure of the charge pump 34 acquired by the data acquisition unit 50 and the calculated discharge flow rate of the charge pump 34. Similarly, the pump power calculation unit 52 calculates the power Pm consumed by the main pump 41 based on the discharge pressure of the main pump 41 acquired by the data acquisition unit 50 and the calculated discharge flow rate of the main pump 41.

[0082] Then, the pump power calculation unit 52 adds the power Pc consumed by the charge pump and the power Pm consumed by the main pump 41 together to calculate the first consumed power P1, which is the power consumed by the hydraulic motor .

[0083] The running motor power calculation unit 53 calculates the second power consumption P2, which is the power consumed by the running motor 31, based on the rotation speed of the running motor 31 and the output torque of the running motor 31 acquired by the data acquisition unit 50.

[0084] In this embodiment, the calculation of the second power consumption P2 is based on the rotation speed and output torque of the traveling motor 31, but is not limited thereto, and may be based on, for example, the voltage and current consumed by the traveling motor 31. In this case, the data acquisition unit 50 acquires the voltage and current consumed by the traveling motor 31 from the traveling inverter 32. That is, the traveling motor power calculation unit 53 calculates the second power consumption P2 based on data indicating the driving state of the traveling motor 31.

[0085] The power comparison and determination unit 54 determines whether the total power consumption (P1+P2) obtained by adding up the first power consumption P1 calculated by the pump power calculation unit 52 and the second power consumption P2 calculated by the driving motor power calculation unit 53 exceeds the outputtable power Pout of the battery 30 calculated by the battery power calculation unit 51.

[0086] In this embodiment, the power comparison and determination unit 54 determines whether P1+P2>Pout, i.e., whether (P1+P2)-Pout>0, but this is not limited to this. For example, it may determine whether (P1+P2)-Pout is greater than a predetermined threshold value Pth stored in the memory unit 55.

[0087] When the power comparison and judgment unit 54 judges that the total power consumption (P1+P2) exceeds the output power Pout of the battery 30 (P1+P2>Pout), the command signal output unit 56 stops outputting command signals to the first to fourth electromagnetic control valves 420L, 420R, 440L, 440R.

[0088] When the power comparison and judgment unit 54 judges that the total power consumption (P1+P2) does not exceed the output power Pout of the battery 30 (P1+P2≦Pout), the command signal output unit 56 outputs a command signal generated based on the operation signal (including the operation direction and operation amount) output from the operation device (lift arm operation lever and bucket operation lever) for operating the work implement 2 to the first to fourth solenoid control valves 420L, 420R, 440L, 440R.

[0089] (Processing executed in the main controller 5) Next, the flow of processing executed within the main controller 5 will be described with reference to FIG.

[0090] FIG. 5 is a flowchart showing the flow of processing executed by the main controller 5 according to the first embodiment.

[0091] In the main controller 5, first, the data acquisition unit 50 acquires the available output current and voltage of the battery 30 output from the battery controller 30A (step S501).

[0092] Next, the battery power calculation unit 51 calculates the available output power Pout of the battery 30 based on the available output current and voltage of the battery 30 acquired in step S501 (step S502).

[0093] Next, the data acquisition unit 50 acquires the discharge pressure of the charge pump 34 output from the first pressure sensor 341, the rotation speed of the charge pump 34 output from the first rotation speed sensor 342, the discharge pressure of the main pump 41 output from the second pressure sensor 411, and the rotation speed of the main pump 41 output from the second rotation speed sensor 412 (step S503).

[0094] Next, the pump power calculation unit 52 calculates the discharge flow rate of the charge pump 34 based on the rotation speed of the charge pump 34 obtained in step S503 and the displacement volume of the charge pump 34 stored in the memory unit 55, and also calculates the discharge flow rate of the main pump 41 based on the rotation speed of the main pump 41 obtained in step S503 and the displacement volume of the main pump 41 stored in the memory unit 55.

[0095] Then, the pump power calculation unit 52 calculates the power consumption Pc of the charge pump 34 based on the discharge pressure of the charge pump 34 obtained in step S503 and the calculated discharge flow rate of the charge pump 34, and calculates the power consumption Pm of the main pump 41 based on the discharge pressure of the main pump 41 obtained in step S503 and the calculated discharge flow rate of the main pump 41.

[0096] Furthermore, the pump power calculation unit 52 calculates the power consumption P1 by adding up the calculated power consumption Pc of the charge pump 34 and the power consumption Pm of the main pump 41 (step S504). That is, in step S504, the pump power calculation unit 52 calculates the power P1 consumed by the hydraulic motor 36.

[0097] Next, the data acquiring unit 50 acquires the rotation speed and the output torque of the traveling electric motor 31 outputted from the traveling inverter 32 (step S505).

[0098] Next, the traveling motor power calculation unit 53 calculates the power consumption P2 of the traveling motor 31 based on the rotation speed and output torque of the traveling motor 31 acquired in step S505 (step S506).

[0099] Next, the power comparison and determination unit 54 determines whether the total power consumption (P1+P2) obtained by adding together the power consumption P1 of the hydraulic motor 36 calculated in step S504 and the power consumption P2 of the traveling motor 31 calculated in step S506 exceeds the output power Pout of the battery 30 calculated in step S502 (step S507).

[0100] If it is determined in step S507 that the total power consumption (P1+P2) exceeds the output power Pout of the battery 30 (P1+P2>Pout) (step S507 / YES), the command signal output unit 56 stops outputting command signals to the first to fourth solenoid control valves 420L, 420R, 440L, 440R (step S508), and the processing in the main controller 5 ends.

[0101] On the other hand, if it is determined in step S507 that the total power consumption (P1+P2) does not exceed the output power Pout of the battery 30, that is, that the total power consumption (P1+P2) is equal to or less than the output power Pout of the battery 30 (P1+P2≦Pout) (step S507 / NO), the processing in the main controller 5 ends as is.

[0102] In this way, when the total power consumption (P1+P2) exceeds the available output power Pout of the battery 30 (P1+P2>Pout), the power supplied from the battery 30 is insufficient, and the main controller 5 performs control to stop the operation of the working device 2. As a result, the power from the battery 30 is sufficiently supplied to the charge pump 34, so that the multiple clutches 331-333 can be maintained in an engaged state, and the occurrence of free running can be suppressed.

[0103] Therefore, with the wheel loader 1, even when the working implement 2 is operated while traveling in a temperature environment where the output of the battery 30 is insufficient, such as a low temperature, the traveling performance can be maintained.

[0104] (Modification) Next, a main controller 5 according to a modification of the first embodiment will be described with reference to Fig. 6. In Fig. 6, components common to those described in the first embodiment are given the same reference numerals and description thereof will be omitted. The same applies to the second to fourth embodiments below.

[0105] In the main controller 5 of this modified example, when it is determined in step S507 that the total power consumption (P1+P2) exceeds the output power Pout of the battery 30 (P1+P2>Pout) (step S507 / YES), the command signal output unit 56 reduces the current value (output current value) of the command signal output to the first to fourth electromagnetic control valves 420L, 420R, 440L, 440R (step S509).

[0106] That is, unlike the main controller 5 according to the first embodiment, the main controller 5 according to this modification reduces the operation of the working device 2 rather than stopping it. This reduces the power consumption Pm of the main pump 41, and the power from the battery 30 is supplied to the charge pump 34 accordingly, thereby making it possible to suppress the occurrence of free running.

[0107] In this way, when the total power consumption (P1+P2) exceeds the output power Pout of the battery 30 and the power supply from the battery 30 becomes insufficient, the main controller 5 performs control to limit (including control to stop) the operation of the working device 2.

[0108] <Second embodiment> Next, a main controller 5A according to a second embodiment of the present invention will be described with reference to FIGS.

[0109] Fig. 7 is a functional block diagram showing functions of the main controller 5A according to the second embodiment. Fig. 8 is a flowchart showing the flow of processing executed by the main controller 5A according to the second embodiment.

[0110] In this embodiment, as shown in FIG. 8, when it is determined in step S507 that the total power consumption (P1+P2) exceeds the output power Pout of the battery 30 (P1+P2>Pout) (step S507 / YES), the main controller 5A determines whether or not the mode is gravity descent mode (step S510).

[0111] The main controller 5A determines that the mode is gravity descent mode when the data acquisition unit 50A acquires an operation signal related to gravity descent from the lift arm operation lever 121 in step S510. The lift arm operation lever 121 is an operation device provided in the cab 12 for operating the lift arm 21, and when the operator operates the lever to one end in the operation direction related to descent (detent function), for example, the gravity descent mode is enabled.

[0112] If it is determined in step S510 that the mode is gravity descent mode (step S510 / YES), the command signal output unit 56A outputs a gravity descent command signal to the first electromagnetic control valve 420L and the second electromagnetic control valve 420R (step S511), and the processing in the main controller 5A ends.

[0113] The first electromagnetic control valve 420L and the second electromagnetic control valve 420R control the lift arm directional control valve 42 to be switched to the third switching position 42F based on a gravity descent command signal output from the main controller 5A.

[0114] On the other hand, if it is not determined in step S510 that the mode is gravity descent mode, that is, if the data acquisition unit 50A has not acquired an operation signal related to gravity descent from the lift arm operation lever 121 (step S510 / NO), the command signal output unit 56A reduces the current value of the command signal output to the first to fourth solenoid control valves 420L, 420R, 440L, 440R (step S509), and the processing in the main controller 5A ends.

[0115] In addition, in this embodiment, if it is not determined that the mode is gravity descent mode in step S510 (step S510 / NO), the main controller 5A performs processing of step S509, but this is not limited to this, and the main controller 5A may perform processing of step S508 in the first embodiment.

[0116] In this way, when the wheel loader 1 is equipped with a gravity descent function, this gravity descent function can be used to reduce the load on the work drive device 4, allowing sufficient power to be supplied from the battery 30 to the clutch drive device 3B.

[0117] <Third embodiment> Next, a main controller 5B according to a third embodiment of the present invention will be described with reference to FIGS.

[0118] Fig. 9 is a functional block diagram showing functions of the main controller 5B according to the third embodiment. Fig. 10 is a flowchart showing the flow of processing executed by the main controller 5B according to the third embodiment.

[0119] In the main controller 5B according to this embodiment, as shown in FIG. 10, when it is determined in step S507 that the total power consumption (P1+P2) exceeds the output power Pout of the battery 30 (P1+P2>Pout) (step S507 / YES), the command signal output unit 56B outputs a shutoff command signal to command the solenoid switching valve 45 to switch to the shutoff position 45B (step S512), and the processing in the main controller 5B ends.

[0120] That is, in this embodiment, the destination of the command signal from the main controller 5B is the solenoid switching valve 45, not the first to fourth solenoid control valves 420L, 420R, 440L, 440R, as shown in FIG.

[0121] In this way, when the total power consumption (P1+P2) exceeds the output power Pout of the battery 30 and the power supply from the battery 30 becomes insufficient, the main controller 5B cuts off the pilot pressure oil guided from the pilot pump 43 to the lift arm directional control valve 42 and the bucket directional control valve 44. This stops the operation of the working device 2, so that power from the battery 30 can be sufficiently supplied to the clutch drive device 3B.

[0122] <Fourth embodiment> Next, a main controller 5C according to a fourth embodiment of the present invention will be described with reference to FIGS.

[0123] Fig. 11 is a functional block diagram showing functions of the main controller 5C according to the fourth embodiment. Fig. 12 is a flowchart showing the flow of processing executed by the main controller 5C according to the fourth embodiment.

[0124] As shown in FIG. 12, when the main controller 5C according to this embodiment determines in step S507 that the total power consumption (P1+P2) exceeds the output power Pout of the battery 30 (P1+P2>Pout) (step S507 / YES), the command signal output unit 56C outputs a limit command signal to the regulator 410 of the main pump 41 to limit the displacement volume (tilt angle) to a small value (step S513), and the processing in the main controller 5C ends.

[0125] That is, in this embodiment, the destination of the command signal from the main controller 5C is not the first to fourth electromagnetic control valves 420L, 420R, 440L, 440R or the electromagnetic switching valve 45, but the regulator 410, as shown in FIG.

[0126] In this way, when the total power consumption (P1+P2) exceeds the available output power Pout of the battery 30 and the power supply from the battery 30 is insufficient, the main controller 5C reduces the displacement volume of the main pump 41 to limit the flow rate of the pressure oil discharged from the main pump 41. This reduces the operation of the working device 2, so that more power can be supplied from the battery 30 to the clutch drive device 3B.

[0127] Each embodiment of the present invention has been described above. Note that the present invention is not limited to each of the above-mentioned embodiments, and various modified examples are included. For example, each of the above-mentioned embodiments has been described in detail to clearly explain the present invention, and is not necessarily limited to those having all of the configurations described. In addition, it is possible to replace a part of the configuration of each embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of each embodiment. Furthermore, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0128] For example, in the above embodiment, the wheel loader 1 has been given as an example of one aspect of an electrically powered work vehicle, but the present invention is not limited to this and may be applied to other work vehicles as long as they are electrically powered. [Explanation of symbols]

[0129] 1: Wheel loader (electric work vehicle) 1A: Front frame (body) 1B: Rear frame (body) 2: Working equipment 3A: Driving device 3B: Clutch drive device 4: Working drive unit 5, 5A, 5B, 5C: Main controller 11,11A: Front wheel (wheel) 11,11B: Rear wheel (wheel) 22L, 22R: Lift arm cylinder (hydraulic cylinder) 24: Bucket cylinder (hydraulic cylinder) 30: Battery 30A: Battery controller 31: Electric motor for driving 33: Transmission 34: Charge pump 36: Hydraulic motor 41: Main pump 42: Directional control valve for lift arm (directional control valve) 43: Pilot pump 44: Bucket directional control valve (directional control valve) 45: Solenoid valve 45A: Communication position 45B: Cutoff position 331~333: Clutch 410: Regulator 420L, 420R, 440L, 440R: 1st to 4th solenoid control valves (solenoid control valves) Pout: Outputable power P1: 1st power consumption P2: 2nd power consumption

Claims

1. A vehicle body having wheels; A battery mounted on the vehicle body; a traveling electric motor and a hydraulic electric motor driven by the electric power output from the battery; a driving device for driving the vehicle body by transmitting an output torque of the electric motor for driving to the wheels via a transmission; a clutch drive device having a charge pump driven by the hydraulic motor to supply pressure oil to a plurality of clutches of the transmission, the clutch drive device driving the plurality of clutches; A working device attached to the vehicle body; a work drive device that has a main pump driven by the hydraulic motor and drives the work device by controlling a flow of pressure oil discharged from the main pump; a main controller that controls the traveling drive device and the working drive device; In an electric work vehicle equipped with The main controller Calculating an available output power, which is the power that the battery can output, based on an available output current of the battery and a voltage of the battery; calculating a first power consumption which is power consumed by the hydraulic motor based on a discharge pressure of the main pump, a discharge flow rate of the main pump, a discharge pressure of the charge pump, and a discharge flow rate of the charge pump; Calculating second power consumption, which is power consumed by the traveling motor, based on data indicating a drive state of the traveling motor; When a total power consumption obtained by adding up the first power consumption and the second power consumption exceeds the available output power of the battery, a command for driving the working drive device is limited. An electric work vehicle characterized by:

2. The electric work vehicle according to claim 1, The working drive device is A self-weight lowering function for lowering the working device by its own weight, The main controller Even if the total power consumption exceeds the available output power of the battery, if the self-gravity descent function is active, a command signal related to the self-gravity descent is output to the work drive device. An electric work vehicle characterized by:

3. The electric work vehicle according to claim 1, The working drive device is A hydraulic cylinder that drives the working device; a directional control valve for controlling a flow of pressure oil supplied from the main pump to the hydraulic cylinder; an electromagnetic control valve that controls the directional control valve based on a command signal output from the main controller, The main controller When the total power consumption exceeds the available power output of the battery, an output current value of a command signal related to driving of the working device output to the electromagnetic control valve is limited. An electric work vehicle characterized by:

4. The electric work vehicle according to claim 1, The working drive device is A hydraulic cylinder that drives the working device; a directional control valve for controlling a flow of pressure oil supplied from the main pump to the hydraulic cylinder; a pilot pump for supplying pilot pressure oil to the directional control valve; a solenoid switching valve that switches between a communication position at which the pilot pressure oil is guided from the pilot pump to the directional control valve and a cut-off position at which the pilot pressure oil guided from the pilot pump to the directional control valve is cut off, The main controller When the total power consumption exceeds the available power output of the battery, a command signal for commanding the solenoid switching valve to switch to the cut-off position is output to the solenoid switching valve. An electric work vehicle characterized by:

5. The electric work vehicle according to claim 1, The main pump is A variable displacement hydraulic pump, the displacement of which is controlled by a regulator; The main controller When the total power consumption exceeds the available power output of the battery, a command signal for limiting the displacement of the main pump is output to the regulator. An electric work vehicle characterized by:

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