Construction machine

Abstract

This construction machine comprises: a first electric circuit including an electric motor for driving a hydraulic pump, a first battery of a power supply, and an inverter for adjusting supply power to the electric motor; a low-voltage second electric circuit including a second battery, an electric fan for cooling hydraulic oil of the hydraulic pump, and a control device for controlling the electric fan and the electric motor; and a DC / DC converter for converting electric power of the first electric circuit to voltage and outputting the voltage to the second electric circuit. The construction machine furthermore comprises a converter controller for detecting an abnormality of the DC / DC converter and limiting driving of the DC / DC converter. The control device restricts driving of the electric fan when an abnormality of the DC / DC converter is detected.

Description

Construction machinery

[0001] The present invention relates to a construction machine, and more particularly to a construction machine that uses a battery as a drive source to drive a hydraulic actuator.

[0002] In recent years, construction machinery such as hydraulic excavators and wheel loaders have been developed with environmental considerations in mind, using battery-powered electric motors instead of engines as the drive source for hydraulic pumps that supply pressure oil to hydraulic actuators (see, for example, Patent Document 1). Such construction machinery is equipped with two electrical circuits: a low-voltage electrical circuit (control system electrical circuit) designed with a rated voltage of 12 V or 24 V, and a high-voltage electrical circuit (drive system electrical circuit) designed with a rated voltage of 350 V or 700 V.

[0003] A lead-acid battery is connected to the control system electrical circuit, while a drive system battery, such as a lithium-ion battery, is connected to the drive system electrical circuit. Control system devices such as a vehicle controller that controls the operation of the construction machine are connected to the control system electrical circuit, and the construction machine system, including the vehicle controller, is started up using power from the lead-acid battery. Meanwhile, the drive system electrical circuit is connected to an electric motor and inverter for driving a hydraulic pump, and the drive system battery serves as the power supply source. The control system electrical circuit and the drive system electrical circuit are connected via, for example, a DC / DC converter. During operation after the construction machine system is started up, a portion of the power from the drive system battery is stepped down via the DC / DC converter and supplied to the control system electrical circuit, thereby charging the lead-acid battery and operating the control system devices, including the vehicle controller.

[0004] In construction machinery equipped with an engine, the power of a lead-acid battery is generally used to start the system (control devices such as a vehicle controller) and then to drive a starter motor that starts the engine. Because a large current (e.g., over 300 A) flows through a starter motor due to its characteristics, a large-capacity lead-acid battery must be installed to cover this current. On the other hand, in battery-powered construction machinery using an electric motor as a drive source, the power of the lead-acid battery is used only to start the system. Therefore, a smaller current (e.g., approximately 10 A) is required compared to when an engine is installed, making it possible to install a small-capacity lead-acid battery.

[0005] In some battery-powered construction machines, electrically driven electric cooling equipment, such as a cooling fan for an oil cooler, is connected to the control system electrical circuit. While the construction machine is in operation, such electric cooling equipment is powered by power supplied from the drive system electrical circuit to the control system electrical circuit via a DC / DC converter. Because the electric cooling equipment consumes more power (e.g., approximately 70 A) than control system equipment such as the vehicle controller, a DC / DC converter with a capacity sufficient to cover this power consumption is installed.

[0006] In the rotating work machine described in Patent Document 1, the drive motors that drive the radiator fan and oil cooler fan are connected to a battery unit (drive system battery) via a DC / DC converter and are also connected to an on-board battery (lead-acid battery). However, from the standpoint of cost, there are also models in which the drive motor for the electric cooling device is connected directly to the circuit (control system electrical circuit) of the on-board battery (lead-acid battery) without going through a DC / DC converter.

[0007] Japanese Patent Application Laid-Open No. 2021-80709

[0008] In a battery-powered construction machine, when the vehicle controller and electric cooling equipment are operated by power supplied from the drive system electrical circuit to the control system electrical circuit via a DC / DC converter during operation, if an abnormality occurs in the DC / DC converter and the machine enters into retracted operation, the power supplied from the drive system electrical circuit to the control system electrical circuit via the DC / DC converter is limited. In this case, if the limited output power of the DC / DC converter cannot cover the power consumption of the vehicle controller and electric cooling equipment, power from the lead-acid battery connected to the control system electrical circuit will be consumed. However, as mentioned above, lead-acid batteries installed in battery-powered construction machines have a small capacity, so there is a concern that a large current drawn by the electric cooling equipment will cause a sudden voltage drop. If the lead-acid battery falls into this state, the vehicle controller, which receives power from the lead-acid battery, will no longer function properly, causing the construction machine to stop operating.

[0009] The present invention has been made based on the above-mentioned circumstances, and its object is to provide a construction machine that can prevent the construction machine from stopping operation even if an abnormality occurs in the DC / DC converter (power conversion device).

[0010] The present application includes a plurality of means for solving the above problems. One example thereof includes a first electric circuit having a hydraulic pump and an electric motor that drives the hydraulic pump, a second electric circuit having a rated voltage lower than that of the first electric circuit, and a voltage conversion device interposed between the first electric circuit and the second electric circuit for converting the voltage of electric power input from the first electric circuit and outputting the converted voltage to the second electric circuit, the first electric circuit including a first battery that is a power source for the electric motor, and an inverter connected to the first battery via a first power line for adjusting the electric power supplied from the first battery to the electric motor, and the second electric circuit having a rated voltage lower than that of the first battery. A construction machine including a second battery having a low voltage, an electric cooling device connected to the second battery via a second power line and configured to cool the hydraulic oil discharged by the hydraulic pump, and a control device connected to the second battery via the second power line and configured to control the electric cooling device and the electric motor, further comprising a conversion device abnormality detection device that detects an abnormality in the voltage conversion device and limits operation of the voltage conversion device when an abnormality in the voltage conversion device is detected, wherein the control device limits operation of the electric cooling device when an abnormality in the voltage conversion device is detected by the conversion device abnormality detection device.

[0011] According to one example of the present application, if an abnormality in the voltage conversion device is detected, the operation of the electric cooling device is limited, thereby preventing a sudden voltage drop in the second battery. Therefore, even if the power supply to the second electric circuit via the voltage conversion device is limited, normal operation of the control device can be maintained, allowing the operation of the construction machine to continue. In other words, even if an abnormality occurs in the power conversion device, it is possible to prevent the construction machine from stopping operation. Problems, configurations, and effects other than those described above will be made clear from the description of the following embodiments.

[0012] FIG. 1 is an external view showing a hydraulic excavator as a construction machine according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configurations of a hydraulic system, an electric system, and a cooling system equipped in the construction machine according to an embodiment. FIG. 3 is a block diagram showing the hardware configuration and functional configuration of the body controller of the construction machine according to the embodiment shown in FIG. 2, together with the functions of the converter controller and the inverter controller. FIG. 4 is a characteristics diagram showing an example of a table used for calculation by a DC / DC control unit in the converter controller of the construction machine according to the embodiment shown in FIG. 3. FIG. 4 is a flowchart showing an example of a processing procedure of a DC / DC command calculation unit in the body controller of the construction machine according to the embodiment shown in FIG. 3. FIG. 5 is a flowchart showing an example of a processing procedure of a motor command calculation unit in the body controller of the construction machine according to the embodiment shown in FIG. 3. FIG. 5 is a flowchart showing an example of a processing procedure of a fan command calculation unit in the body controller of the construction machine according to the embodiment shown in FIG. 3. FIG. 6 is a characteristics diagram showing an example of a table used for command calculation for a radiator fan by the fan command calculation unit in the body controller of the construction machine according to the embodiment shown in FIG. 3. 4 is a characteristic diagram showing an example of a table used in calculating a maximum command value by a fan command calculation unit in the vehicle body controller of the construction machine according to the embodiment shown in FIG. 3. FIG.

[0013] Hereinafter, an embodiment of a construction machine of the present invention will be described with reference to the drawings. In this embodiment, a hydraulic excavator will be described as an example of a construction machine. Note that the front, rear, left, and right directions described in this specification refer to directions as seen from the operator riding on the construction machine.

[0014] [One embodiment] First, the configuration of a hydraulic excavator as a construction machine according to one embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is an external view showing a hydraulic excavator as a construction machine according to one embodiment.

[0015] 1, a hydraulic excavator 1 serving as a construction machine is generally composed of a self-propelled running body 2, a rotating body 3 rotatably mounted on the running body 2, and a working device 4 provided at the front of the rotating body 3 so as to be capable of elevation and depression. The rotating body 3 is configured to rotate relative to the running body 2 by a swing hydraulic motor 5, which is a hydraulic actuator.

[0016] The traveling body 2 is provided with left and right crawler-type traveling devices 6 (only one is shown). The left and right traveling devices 6 are configured to be driven by hydraulic traveling motors 7, which are hydraulic actuators.

[0017] The rotating body 3 is configured to include a rotating frame 9 as a support structure rotatably mounted on the traveling body 2, a cab 10 installed on the left front side of the rotating frame 9, a counterweight 11 provided at the rear end of the rotating frame 9, and a machine room 12 provided between the cab 10 and the counterweight 11. The cab 10 is equipped with a driver's seat (not shown) for an operator, a key switch and operating devices (neither of which are shown) for operating the hydraulic excavator 1, a rotation speed indicator dial 21 (see FIG. 3 described below), and the like. The counterweight 11 is used to achieve a weight balance with the working device 4. The machine room 12 accommodates various hydraulic devices such as a hydraulic pump 31 and a control valve unit 33 (both of which are shown in FIG. 2 described below) and various electrical devices such as batteries 52, 56 and an electric motor 51 (both of which are shown in FIG. 2 described below).

[0018] The work device 4 is an articulated device for performing excavation work and the like, and includes, for example, a boom 14, an arm 15, and a bucket 16 as a work implement. The base end of the boom 14 is rotatably connected to the front of the revolving unit 3. The base end of an arm 15 is rotatably connected to the tip of the boom 14. The base end of a bucket 16 is rotatably connected to the tip of the arm 15. The boom 14, arm 15, and bucket 16 are driven by hydraulic actuators: a boom cylinder 17, an arm cylinder 18, and a bucket cylinder 19, respectively.

[0019] Next, the configurations of the hydraulic system, electric system, and cooling system provided in the construction machine according to the embodiment will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the configurations of the hydraulic system, electric system, and cooling system provided in the construction machine according to the embodiment.

[0020] 2, the hydraulic excavator 1 is equipped with a hydraulic system 30 that hydraulically drives the traveling body 2, the revolving body 3, and the working device 4 (all of which are shown in FIG. 1). The hydraulic system 30 includes a hydraulic pump 31 that discharges pressurized oil, a plurality of hydraulic actuators that are driven by the pressurized oil supplied from the hydraulic pump 31, and a control valve unit 33 that controls the flow of pressurized oil supplied from the hydraulic pump 31 to the plurality of hydraulic actuators.

[0021] The hydraulic pump 31 is, for example, a variable displacement pump, and is configured so that the pump volume can be variably adjusted by changing the tilt angle of the swash plate or the inclined axis. The hydraulic pump 31 is configured so that the discharge flow rate (hydraulic output) per unit rotation is controlled by adjusting the pump volume in response to a command from a vehicle controller 70 (described later).

[0022] The multiple hydraulic actuators of the hydraulic system 30 include the swing hydraulic motor 5, traveling hydraulic motor 7, boom cylinder 17, arm cylinder 18, and bucket cylinder 19 (see FIG. 1 for all of these). The hydraulic excavator 1 performs a swing operation by driving the swing hydraulic motor 5. Also, it performs a traveling operation by driving the traveling hydraulic motor 7. Also, it performs an excavation operation and the like by driving the boom cylinder 17, arm cylinder 18, and bucket cylinder 19 in a combined manner.

[0023] The control valve unit 33 distributes the pressure oil discharged from the hydraulic pump 31 to the multiple hydraulic actuators 5, 7, 17, 18, and 19, and is an assembly of control valves corresponding to the respective hydraulic actuators 5, 7, 17, 18, and 19. Each control valve of the control valve unit 33 controls the flow of pressure oil supplied from the hydraulic pump 31 to the corresponding hydraulic actuator 5, 7, 17, 18, and 19, and also controls the flow of return oil discharged from the hydraulic actuators 5, 7, 17, 18, and 19 to the hydraulic oil tank 34.

[0024] The hydraulic excavator 1 according to this embodiment is a battery-powered type in which the hydraulic pump 31 of the hydraulic system 30 is driven by battery power, and includes an electric system 40. The electric system 40 includes a drive system electric circuit 41 (first electric circuit) for driving the hydraulic pump 31, and a control system electric circuit 42 (second electric circuit) for operating various control devices including a vehicle controller 70 (described later) for controlling the hydraulic excavator 1. The drive system electric circuit 41 is designed with a rated voltage of, for example, approximately 350 V or approximately 700 V, and is configured as a high-voltage circuit having a higher rated voltage than the control system electric circuit 42. On the other hand, the control system electric circuit 42 is designed with a rated voltage of, for example, approximately 12 V or approximately 24 V, and is configured as a low-voltage circuit having a lower rated voltage than the drive system electric circuit 41. A DC / DC converter 43 serving as a voltage conversion device is interposed between the drive system electric circuit 41 and the control system electric circuit 42. That is, the drive system electric circuit 41 and the control system electric circuit 42 are connected via a DC / DC converter 43. The DC / DC converter 43 has a converter controller 43a that controls voltage conversion.

[0025] The drive system electric circuit 41 includes an electric motor 51 that drives the hydraulic pump 31, a drive system battery 52 (hereinafter referred to as the first battery) that serves as a power source for the electric motor 51 and has a relatively high rated voltage, and an inverter 53 that is connected to the first battery 52 via a first power line 54 and adjusts the power supplied from the first battery 52 to the electric motor 51. The first battery 52 has a BMU (Battery Management Unit) 52a that controls the charging and discharging of the first battery 52. ​​The inverter 53 has a built-in inverter controller 53a that controls the driving of the inverter 53. Meanwhile, the control system electric circuit 42 includes a second battery 56 that has a lower rated voltage than the first battery 52, and a vehicle body controller 70, the BMU 52a, the inverter controller 53a, and the converter controller 43a that are connected to the second battery 56 via a second power line 57.

[0026] The first battery 52 is, for example, a lithium-ion battery pack and is configured to be charged by power supplied from an external power source. The first battery 52 is configured to electrically disconnect or connect the first battery 52 to the drivetrain electric circuit 41 by switching an internal relay (not shown). The BMU 52a is configured to electrically disconnect or connect the first battery 52 to the drivetrain electric circuit 41 by switching the internal relay of the first battery 52. ​​The BMU 52a also has the function of monitoring the status of the first battery 52 (such as the state of charge (SOC), temperature, voltage, and current) and detecting abnormalities. The BMU 52a is configured to calculate a battery supplyable power Pb, which is the power that the first battery 52 can supply, based on information about the status of the first battery 52 and whether or not there is an abnormality. The BMU 52a transmits the calculated battery supplyable power Pb and status monitoring information about the first battery 52, such as the presence or absence of an abnormality in the first battery 52, to the vehicle controller 70 via the vehicle communication network 59.

[0027] The electric motor 51 is driven by power supplied from the first battery 52 via an inverter 53. The inverter 53 converts DC power output from the first battery 52 into three-phase AC power and controls the three-phase AC power in accordance with commands from the vehicle body controller 70, thereby controlling the drive (rotation speed and torque) of the electric motor 51. The inverter 53 has an inverter circuit 53b (see FIG. 3 described below) that converts DC to generate three-phase AC. The inverter controller 53a monitors the state of the inverter 53 (inverter circuit 53b) and has the function of detecting abnormalities in the inverter 53 (inverter circuit 53b). The inverter controller 53a provides status information about the inverter 53 (e.g., information on the presence or absence of an abnormality in the inverter circuit 53b and drive information for the electric motor 51) to the vehicle body controller 70 via the vehicle body communication network 59, and controls the rotation speed of the electric motor 51 in accordance with commands from the vehicle body controller 70. The rotation speed of the electric motor 51 is controlled by the inverter 53, which changes the rotation speed of the hydraulic pump 31, thereby controlling the discharge flow rate (hydraulic output) of the hydraulic pump 31. The function of the inverter controller 53a will be described in detail later.

[0028] The second battery 56 is a relatively low-voltage battery, for example, a lead-acid battery. The second battery 56 functions as a power source for activating various control devices, such as the vehicle controller 70, the BMU 52a of the first battery 52, the inverter controller 53a, and the converter controller 43a, when the hydraulic excavator 1 is started. Therefore, the second battery 56 has a capacity sufficient to operate all of these controllers 70, 43a, 52a, and 53a, but is configured as a battery with a smaller capacity than the first battery 52. ​​The second battery 56 is not intended to be used as a power source for the above-mentioned controllers 70, 43a, 52a, and 53a during normal operation after startup of the hydraulic excavator 1. However, if an abnormality occurs in the DC / DC converter 43, limiting the drive of the DC / DC converter 43, the second battery 56 can be used as a power source for the above-mentioned controllers 70, 43a, 52a, and 53a.

[0029] The DC / DC converter 43 converts the voltage of the power input from the drive system electric circuit 41 (first power line 54) and outputs the converted voltage to the control system electric circuit 42. The DC / DC converter 43 is provided with a temperature sensor 43b (see FIG. 3 described later) that detects the temperature of the DC / DC converter 43 (voltage conversion circuit), a current sensor 43c (see FIG. 3 described later) that detects the current input to the DC / DC converter 43 (voltage conversion circuit), and a voltage sensor 43d (see FIG. 3 described later) that detects the voltage input to the DC / DC converter 43 (voltage conversion circuit). The temperature sensor 43b, the current sensor 43c, and the voltage sensor 43d each output detection signals corresponding to the detected values ​​to the converter controller 43a. The converter controller 43a monitors the status (temperature, current, voltage, etc.) of the DC / DC converter 43 and detects abnormalities in the DC / DC converter 43. The converter controller 43a is configured to, when an abnormality in the converter controller 43a is detected, restrict (including stop) the driving of the DC / DC converter 43. The converter controller 43a transmits information on the status of the DC / DC converter 43, information on the presence or absence of an abnormality, and the like to the vehicle body controller 70 via the vehicle body communication network 59. The function of the converter controller 43a will be described in detail later.

[0030] A rotation speed indicating dial 21 disposed inside the cab 10 (see FIG. 1) is electrically connected to the vehicle body controller 70. The rotation speed indicating dial 21 functions as a rotation speed indicating device that indicates the rotation speed of the hydraulic pump 31 or the electric motor 51 according to the amount of operation (dial operation amount) performed by the operator, and outputs an instruction signal according to the dial operation amount to the vehicle body controller 70.

[0031] The electric motor 51 or the hydraulic pump 31 is provided with a rotation speed sensor 23 that detects the actual rotation speed of the electric motor 51 or the hydraulic pump 31. The rotation speed sensor 23 outputs a detection signal corresponding to the detected actual rotation speed Na of the electric motor 51 or the hydraulic pump 31 to the inverter controller 53a (see FIG. 3 described later).

[0032] The hydraulic excavator 1 also includes a cooling system 60 that cools the electric motor 51 and the inverter 53 and cools the hydraulic oil circulating through the hydraulic system 30. The cooling system 60 includes components: a cooling pump 61 that circulates a coolant that cools the electric motor 51 and the inverter 53, a radiator 62 that cools the coolant by heat exchange, and a radiator fan 63 that supplies cooling air to the radiator 62. The electric motor 51, the inverter 53, and the radiator 62 are connected via a coolant line 64. The cooling system 60 further includes components: an oil cooler 67 that cools the hydraulic oil of the hydraulic system 30 by heat exchange, and an oil cooler fan 68 that supplies cooling air to the oil cooler 67. The cooling pump 61, the radiator fan 63, and the oil cooler fan 68 are each driven by a built-in electric motor and constitute electrically driven cooling equipment.

[0033] The cooling pump 61 and the radiator fan 63 are connected to the second power line 57 of the control system electric circuit 42. Similarly, the oil cooler fan 68 is connected to the second power line 57 of the control system electric circuit 42. The cooling pump 61 is configured so that its drive is controlled in response to a command from the vehicle body controller 70. The radiator fan 63 and the oil cooler fan 68 are configured so that their rotation speeds are controlled by a PWM command from the vehicle body controller 70.

[0034] The radiator 62 is provided with a coolant temperature sensor 65 that detects the temperature of the coolant. The coolant temperature sensor 65 outputs a detection signal corresponding to the detected coolant temperature St1 to the vehicle body controller 70. The oil cooler 67 is provided with a hydraulic oil temperature sensor 69 that detects the temperature of the hydraulic oil. The hydraulic oil temperature sensor 69 outputs a detection signal corresponding to the detected hydraulic oil temperature St2 to the vehicle body controller 70.

[0035] The vehicle body controller 70 is configured to monitor the status of the hydraulic excavator 1 in addition to controlling the operation of the hydraulic excavator 1. The vehicle body controller 70 is communicably connected to various control devices, such as the BMU 52a of the first battery 52, the inverter controller 53a, and the converter controller 43a, via a vehicle body communication network 59. The vehicle body controller 70 is configured to exchange information with these control devices, monitor each other, and issue commands to the various control devices. In this embodiment, the vehicle body controller 70 and the inverter controller 53a function as control devices that control the operation of the hydraulic pump 31 and the electric motor 51 by exchanging information with each other. Furthermore, the vehicle body controller 70 basically variably controls the rotation speed of the radiator fan 63, which serves as an electric cooling device, so that the coolant temperature is maintained within a set range based on a detection value St1 of the coolant temperature sensor 65, and variably controls the rotation speed of the oil cooler fan 68, which serves as an electric cooling device, so that the hydraulic oil temperature is maintained within a set range based on a detection value St2 of the hydraulic oil temperature sensor 69. The functions of the vehicle body controller 70 will be described in detail below.

[0036] In the hydraulic excavator 1 configured as above, the start-up procedure from the start-up instruction from the operator to the start-up of the electric motor 51 is as follows.

[0037] First, when the operator turns on the key switch (not shown) located inside the cab 10 (see FIG. 1), a command to start the hydraulic excavator 1 is output. This causes power to be supplied from the lead-acid battery that is the second battery 56, and various control devices are started up, such as the vehicle controller 70 of the control system electric circuit 42, the BMU 52a of the first battery 52, the inverter controller 53a, and the converter controller 43a. The controllers 70, 43a, 52a, and 53a start communication to form a vehicle communication network 59, thereby becoming capable of operating in conjunction with one another.

[0038] Next, the BMU 52 a of the first battery 52 starts up the first battery 52. ​​As a result, the electric power of the first battery 52 is output to the drive system electric circuit 41.

[0039] Next, the converter controller 43a starts up the DC / DC converter 43. As a result, the DC / DC converter 43 converts the voltage of the power supplied from the first battery 52 to the drive system electric circuit 41 and outputs the converted voltage to the control system electric circuit 42. As a result, the controllers 70, 43a, 52a, and 53a, which had previously been operated by power from the second battery 56, now operate by power from the first battery 52 supplied via the DC / DC converter 43.

[0040] Next, the vehicle body controller 70 starts the radiator fan 63 and the oil cooler fan 68 using the power supplied from the first battery 52 to the control system electric circuit 42 via the DC / DC converter 43, and also starts the cooling pump 61. This completes preparations for starting the electric motor 51 that drives the hydraulic pump 31 of the hydraulic system 30.

[0041] Thereafter, when the operator turns the key switch to start, the power output from the first battery 52 to the first power line 54 of the drive system electric circuit 41 is adjusted by the inverter 53 and supplied to the electric motor 51. This causes the electric motor 51 to rotate, which starts the hydraulic pump 31 discharging pressure oil. In other words, the start-up of the hydraulic system 30 is completed. This puts the hydraulic excavator 1 into an operable state. Note that the procedure for shutting down the operation of the hydraulic excavator 1 involves stopping the various devices in the reverse order of the start-up.

[0042] When the hydraulic excavator 1 is in operation, the electric power output from the first battery 52 to the first power line 54 of the drive system electric circuit 41 is supplied to the electric motor 51 via the inverter 53, and is also supplied to the control system electric circuit 42 via the DC / DC converter 43. The electric power supplied to the control system electric circuit 42 via the DC / DC converter 43 operates the controllers 70, 43a, 52a, 53a, and drives the electric cooling devices such as the radiator fan 63, the oil cooler fan 68, and the cooling pump 61. The electric power is also used to charge the second battery 56 of the control system electric circuit 42.

[0043] Next, the functions of the vehicle body controller, converter controller, and inverter controller during operation of the construction machine according to one embodiment will be described using Figures 3 to 10. Figure 3 is a block diagram showing the hardware configuration and functional configuration of the vehicle body controller of the construction machine according to one embodiment shown in Figure 2, together with the functions of the converter controller and inverter controller.

[0044] 3, the converter controller 43a of the DC / DC converter 43 has a DC / DC control unit that controls the voltage conversion of the DC / DC converter 43. The DC / DC control unit 43a receives a temperature Std of the DC / DC converter 43 (voltage conversion circuit) that is a detection value of a temperature sensor 43b, a current Sid of the DC / DC converter 43 (voltage conversion circuit) that is a detection value of a current sensor 43c, and a voltage Svd of the DC / DC converter 43 (voltage conversion circuit) that is a detection value of a voltage sensor 43d. The DC / DC control unit 43a monitors the state of the DC / DC converter 43 and detects abnormalities in the DC / DC converter 43 based on the detection value Std of the temperature sensor 43b, the detection value Sid of the current sensor 43c, and the detection value Svd of the voltage sensor 43d. For example, the DC / DC control unit 43a determines whether the DC / DC converter 43 is overheated based on the detection value Std of the temperature sensor 43b, whether an overcurrent is present in the DC / DC converter 43 based on the detection value Sid of the current sensor 43c, whether an overvoltage is present in the DC / DC converter 43 based on the detection value Sid of the voltage sensor 43d, and detects an abnormality in the DC / DC converter 43 from the results of circuit diagnosis. The DC / DC control unit 43a transmits information on whether the DC / DC converter 43 is in an abnormal state (normal state or abnormal state) to the vehicle body controller 70. When the converter controller 43a detects an abnormality in the DC / DC converter 43, it is configured to limit (including stop) the drive of the DC / DC converter 43 depending on the abnormal state of the DC / DC converter 43.

[0045] The converter controller 43a is also configured to calculate a DC / DC outputtable power Wdc, which is the power that can be output from the DC / DC converter 43 to the control system electric circuit 42, depending on the abnormal state of the DC / DC converter 43. Specifically, the converter controller 43a calculates the DC / DC outputtable power Wdc based on at least one of the detection value Std of the temperature sensor 43b, the detection value Sid of the current sensor 43c, and the detection value Svd of the voltage sensor 43d, or the detection result of an abnormality (failure) of the DC / DC converter 43. The calculated DC / DC outputtable power Wdc is sent to the vehicle body controller 70.

[0046] For example, if the DC / DC converter 43 detects an abnormality that disables its operation, i.e., if a failure of the DC / DC converter 43 is detected, the converter controller 43a determines that the DC / DC converter 43 is unable to output power to the control system electric circuit 42 and sets the DC / DC outputtable power Wdc to "0." At this time, the converter controller 43a controls the DC / DC converter 43 to stop driving.

[0047] The converter controller 43a also refers to the table shown in FIG. 4, for example, and calculates the DC / DC output power Wdc using the detection value Std of the temperature sensor 43b. FIG. 4 shows a table that specifies the DC / DC output power Wdc versus the temperature Tdc of the DC / DC converter. In the table shown in FIG. 4, the DC / DC output power Wdc is a constant value Wr (rated output) when the temperature Tdc of the DC / DC converter ranges from 0 to Tα. That is, the DC / DC converter 43 is in a normal state when the temperature Tdc ranges from 0 to Tα. On the other hand, when the temperature Tdc ranges from Tα to Tβ, the DC / DC output power Wdc decreases linearly from Wr to 0. That is, the DC / DC converter 43 detects an abnormal overtemperature condition when the temperature Tdc is higher than Tα. At this time, the converter controller 43a controls the drive of the DC / DC converter 43 (voltage conversion circuit) so that the output power to the control system electric circuit 42 is limited within the range of the calculated DC / DC outputtable power Wdc. In particular, when the temperature Tdc exceeds Tβ, the converter controller 43a stops the drive of the DC / DC converter 43. As a result, the output power to the control system electric circuit 42 via the DC / DC converter 43 becomes zero.

[0048] The converter controller 43a has, as its hardware configuration, a storage device (not shown) made up of RAM, ROM, etc., and a processing device (not shown) made up of CPU, MPU, etc. The storage device pre-stores programs and various information required for monitoring the status of the DC / DC converter 43 and detecting and controlling abnormalities. The processing device reads the programs and various information from the storage device as appropriate and executes processing in accordance with the programs, thereby realizing the above-mentioned functions.

[0049] The vehicle body controller 70 is configured to basically control the rotation speeds of the radiator fan 63 and the oil cooler fan 68 based on the detection values ​​St1 and St2 of the coolant temperature sensor 65 and the hydraulic oil temperature sensor 69. It is also configured to basically control the rotation speeds of the hydraulic pump 31 and the electric motor 51 based on the amount of operation of the rotation speed indicator dial 21. However, when an abnormality in the DC / DC converter 43 is detected, the vehicle body controller 70 of this embodiment is configured to limit the operation of the electric cooling devices (the radiator fan 63, the oil cooler fan 68, and the cooling pump 61) through which a relatively large current flows, so that the operation of various control devices, such as the vehicle body controller 70, the BMU 52a, the inverter controller 53a, and the converter controller 43a of the control system electric circuit 42, continues. Furthermore, the hydraulic output of the hydraulic pump 31 is limited to prevent overheating due to insufficient cooling of the cooling system 60 caused by limiting the operation of the radiator fan 63 and the oil cooler fan 68.

[0050] The vehicle body controller 70 includes, as its hardware configuration, a storage device 71 including RAM, ROM, etc., and a processing device 72 including a CPU, MPU, etc. The storage device 71 pre-stores programs necessary for controlling the radiator fan 63 and the oil cooler fan 68, as well as programs and various information necessary for controlling the hydraulic pump 31 and the electric motor 51. The processing device 72 reads the programs and various information from the storage device 71 as appropriate, receives various information from various devices, and executes processing in accordance with the programs to realize various functions. The vehicle body controller 70 includes, as functions executed by the processing device 72, a pump rotation speed calculation unit 74, an energy management unit 75, a DC / DC command calculation unit 76, a motor command calculation unit 77, a pump control unit 78, and a fan command calculation unit 79.

[0051] The pump rotation speed calculation unit 74 receives an instruction signal corresponding to the amount of rotation of the rotation speed instruction dial 21, and calculates the required rotation speed Nr of the hydraulic pump 31 based on the instruction signal (dial operation amount). The calculated required rotation speed Nr is output to the motor command calculation unit 77.

[0052] The energy management unit 75 receives the battery supplyable power Pb, which is the calculation result of the BMU 52a of the first battery 52, from the BMU 52a. Furthermore, the energy management unit 75 determines the distribution of the battery supplyable power Pb to the electrical devices connected to the drivetrain electric circuit 41 according to a preset distribution rate. Here, the input destinations (distribution destinations) of the power supplied from the first battery 52 to the drivetrain electric circuit 41 are only the inverter 53 and the DC / DC converter 43. Therefore, the energy management unit 75 distributes the battery supplyable power Pb according to set values ​​to determine the inverter inputable power Pim, which is the power that can be input to the inverter 53, and the DC / DC inputable power Pdc, which is the power that can be input to the DC / DC converter 43. The energy management unit 75 outputs the calculated inverter inputable power Pim to the motor command calculation unit 77 and outputs the calculated DC / DC inputable power Pdc to the DC / DC command calculation unit 76.

[0053] The DC / DC command calculation unit 76 receives status monitoring information (presence or absence of an abnormality) of the DC / DC converter 43 from the converter controller 43a and the DC / DC output capacity Wdc, which is the calculation result of the converter controller 43a. It also receives the DC / DC input capacity Pdc, which is the calculation result of the energy management unit 75. The DC / DC command calculation unit 76 sets a DC / DC degeneration flag corresponding to the received information (presence or absence of an abnormality) of the DC / DC converter 43, and outputs the set DC / DC degeneration flag to the motor command calculation unit 77. Furthermore, the DC / DC command calculation unit 76 calculates the fan allowable power consumption Pf, which is the allowable power consumption of the radiator fan 63 and the oil cooler fan 68, using the input DC / DC output capacity W and DC / DC input capacity Pdc, and a total required power (set value) which is the sum of the power required to operate all of the various control devices connected to the control system electric circuit 42, such as the vehicle body controller 70, the BMU 52a, the inverter controller 53a, and the converter controller 43a. The calculated fan allowable power consumption Pf is output to the fan command calculation unit 79 .

[0054] Specifically, the DC / DC command calculation unit 76 sets the DC / DC degeneration flag and calculates the fan allowable power consumption Pf, for example, according to the flowchart shown in Fig. 5. Fig. 5 is a flowchart showing an example of the processing procedure of the DC / DC command calculation unit in the vehicle body controller shown in Fig. 3.

[0055] 5, the DC / DC command calculation unit 76 first determines whether an abnormality has been detected in the DC / DC converter 43 based on the status monitoring information of the DC / DC converter 43 received from the converter controller 43a (step S10). If an abnormality has been detected in the DC / DC converter 43 (YES in step S10), the DC / DC degeneration flag is set to "1" indicating an abnormality (step S20). On the other hand, if an abnormality has not been detected in the DC / DC converter 43 (NO in step S30), the DC / DC degeneration flag is set to "0" indicating normality (step S30).

[0056] Next, the DC / DC command calculation unit 76 compares the DC / DC output power Wdc from the converter controller 43a with the DC / DC input power Pdc from the energy management unit 75, and sets the smaller value as the control system electric circuit power Pec2, which is the power output to the control system electric circuit 42 via the DC / DC converter 43 (step S40). Next, the DC / DC command calculation unit 76 calculates the allowable fan power consumption Pf of the radiator fan 63 and the oil cooler fan 68 constituting the electric cooling equipment by performing a difference calculation in which the preset on-board controller power consumption Pcon_sum is subtracted from the control system electric circuit power Pec2 set in step S40 (step S50). Note that the allowable fan power consumption Pf is set to 0 or greater. That is, if the result of the difference calculation is 0 or less, the allowable fan power consumption Pf is set to 0. On the other hand, if the result of the difference calculation is greater than 0, the result of the difference calculation is set to 0. The on-board controller power consumption Pcon_sum is the power required to operate all of the various control devices connected to the control system electric circuit 42, such as the vehicle controller 70, BMU 52a, inverter controller 53a, and converter controller 43a (the total power requirement obtained by adding up the power requirements of each control device), and is a value set based on values ​​experimentally measured in advance. The on-board controller power consumption Pcon_sum is stored in advance in the storage device 71.

[0057] The calculation of the allowable fan power consumption Pf by the DC / DC command calculation unit 76 is intended to limit the drive of the radiator fan 63 and the oil cooler fan 68 so that, when the converter controller 43a detects an abnormality in the DC / DC converter 43 and limits the output power to the control system electric circuit 42 via the DC / DC converter 43, the drive of the radiator fan 63 and the oil cooler fan 68 will not draw power from the second battery 56. In other words, the intention is to use the power supplied to the control system electric circuit 42 via the DC converter 43 to cover all the power consumption of various control devices such as the vehicle body controller 70, BMU 52a, inverter controller 53a, and converter controller 43a, and then drive the radiator fan 63 and the oil cooler fan 68 with the remaining power while avoiding power supply from the second battery 56. However, if an abnormality occurs in the DC / DC converter 43 and the power supplied to the control system electrical circuit 42 via the DC converter 43 is not enough to cover all the power consumption of the various control devices 70, 43a, 52a, 53a of the control system electrical circuit 42 (if the difference calculation is 0 or less), the radiator fan 63 and the oil cooler fan 68 are stopped (the fan allowable power consumption Pf is set to 0).

[0058] 3 , the motor command calculation unit 77 receives the required rotation speed Nr calculated by the pump rotation speed calculation unit 74, the inverter input allowable power Pim calculated by the energy management unit 75, and information on the DC / DC retraction flag set by the DC / DC command calculation unit 76, and also receives from the inverter controller 53a the actual rotation speed Na of the electric motor 51 and information on the presence or absence of abnormalities in the inverter 53 and the electric motor 51. Furthermore, based on the received information, the motor command calculation unit 77 calculates a rotation speed command Nc of the electric motor 51 and an allowable motor torque Tmax of the electric motor 51. The calculated rotation speed command Nc is sent to the inverter controller 44a. The calculated allowable motor torque Tmax is output to the pump control unit 78.

[0059] Specifically, the motor command calculation unit 77 calculates the rotation speed command Nc and the motor allowable torque Tmax of the electric motor 51 according to the flowchart shown in Fig. 6. Fig. 6 is a flowchart showing an example of the processing procedure of the motor command calculation unit of the vehicle body controller shown in Fig. 3.

[0060] 6, the motor command calculation unit 77 first substitutes the inverter inputtable power Pim calculated by the energy management unit 75 into Pmax (step S110), and then substitutes the required rotation speed Nr calculated by the pump rotation speed calculation unit 74 into the rotation speed command Nc of the electric motor 51 (step S120).

[0061] Next, the motor command calculation unit 77 calculates the motor allowable torque Tmax by multiplying the substitution result Pmax of S110 by the efficiency value Eim stored in advance in the storage device 71 and dividing the result by the actual rotation speed Na, which is the value detected by the rotation speed sensor 23 (step S130). The efficiency value Eim is determined by the loss that occurs when the electric power output to the first power line 54 of the drive system electric circuit 41 is supplied to the electric motor 51 via the inverter 53 to drive the electric motor 51, and is set, for example, from the performance specifications of the electric motor 51 and the inverter 53.

[0062] Next, the motor command calculation unit 77 determines whether the DC / DC degeneration flag from the DC / DC command calculation unit 76 is "0 (normal)" (step S140). If the DC / DC degeneration flag is "0" (YES in step S140), the rotation speed command Nc of the electric motor 51 remains set to the required rotation speed Nr, and the allowable motor torque Tmax of the electric motor 51 is maintained as the calculation result of step S130, and the process returns to START. On the other hand, if the DC / DC degeneration flag is "1 (abnormal)" (NO in step S150), the rotation speed command Nc of the electric motor 51 is reset to the minimum motor rotation speed Nmin pre-stored in the storage device 71, and the allowable motor torque Tmax is reset to the minimum motor torque Tmin pre-stored in the storage device 71 (step S150). The minimum motor rotation speed Nmin and minimum motor torque Tmin are set values ​​obtained by calculating in advance the minimum rotation speed and torque of the electric motor 51 required to drive the hydraulic pump 31 from the design specification values.

[0063] Returning to Fig. 3, the pump control unit 78 calculates a tilt angle command for the hydraulic pump 31 based on the motor allowable torque Tmax from the motor command calculation unit 77. For example, a table showing the correspondence relationship between the absorption torque that rotationally drives the hydraulic pump 31 and the tilt angle of the hydraulic pump 31 is set in advance. This table is set based on design specifications, experimental data, etc., and is stored in advance in the storage device 71. The pump control unit 78 refers to this table and calculates the tilt angle corresponding to the motor allowable torque Tmax as the tilt angle command Ac. When the motor allowable torque Tmax is the motor minimum torque Tmin, the tilt angle command Ac is set so that the pump displacement of the hydraulic pump 31 becomes the minimum value in the specifications.

[0064] The calculated tilt angle command Ac is sent to the regulator of the hydraulic pump 31. This makes it possible to control the load torque that the hydraulic pump 31 applies to the electric motor 51 to be equal to or less than the motor allowable torque Tmax. This makes it possible to keep the power consumed by the inverter 53 and the electric motor 51 equal to or less than the inverter input allowable power Pim.

[0065] The fan command calculation unit 79 receives detection signals St1, St2 from the coolant temperature sensor 65 and the hydraulic oil temperature sensor 69, and also receives the fan allowable power consumption Pf from the DC / DC command calculation unit 76. Furthermore, based on the received detection values ​​St1, St2 from the coolant temperature sensor 65 and the hydraulic oil temperature sensor 69 and the fan allowable power consumption Pf, the fan command calculation unit 79 calculates a PWM command PWMwt for the radiator fan 63 and a PWM command PWMol for the oil cooler fan 68 so that the power consumption of the radiator fan 63 and the oil cooler fan 68 does not exceed the fan allowable power consumption Pf. The PWM command PWMwt for the radiator fan 63 and the PWM command PWMol for the oil cooler fan 68 are output to the radiator fan 63 and the oil cooler fan 68, respectively.

[0066] Specifically, the fan command calculation unit 79 calculates the PWM command PWMwt for the radiator fan 63 and the PWM command PWMol for the oil cooler fan 68, for example, in accordance with the flowchart shown in Fig. 7. Fig. 7 is a flowchart showing an example of the processing procedure of the fan command calculation unit of the vehicle body controller shown in Fig. 3.

[0067] In FIG. 7 , the fan command calculation unit 79 first refers to the table shown in FIG. 8 and calculates the PWM command PWMwt for the radiator fan 63 using the detection value St1 (coolant temperature) of the coolant temperature sensor 65 (step S210). FIG. 8 shows a table (characteristics diagram) that defines the PWM command for the radiator fan relative to the coolant temperature Twt. The PWM command (pulse width relative to the PWM period) is set within a range from 0 (stop) to 100% (rated value). The table shown in FIG. 8 defines the PWM command as 0% when the coolant temperature Twt is lower than TL1. In other words, this indicates that cooling of the coolant is unnecessary when the coolant temperature Twt is lower than TL1. The PWM command is defined to increase linearly from 0% to 100% when the coolant temperature Twt ranges from TL1 to TH1. That is, the rotation speed of the radiator fan 63 is controlled to increase as the coolant temperature Twt increases. The table shown in FIG.

[0068] Next, the fan command calculation unit 79 refers to the table shown in FIG. 9 and calculates a PWM command PWMol for the oil cooler fan 68 using the detection value St2 (hydraulic oil temperature) of the hydraulic oil temperature sensor 69 (step S220). FIG. 9 shows a table (characteristics diagram) that defines the PWM command for the oil cooler fan relative to the hydraulic oil temperature Tol. The PWM command (pulse width relative to the PWM period) is set within a range from 0 (stop) to 100% (rated value). The table shown in FIG. 9 defines the PWM command as 0% when the hydraulic oil temperature Tol is lower than TL2. This indicates that hydraulic oil cooling is unnecessary when the hydraulic oil temperature Tol is lower than TL2. The PWM command is defined to increase linearly from 0% to 100% when the hydraulic oil temperature Tol is in the range from TL2 to TH2. This indicates that the rotational speed of the oil cooler fan 68 is controlled to increase as the hydraulic oil temperature Tol increases. The table shown in FIG. 9 is stored in advance in the storage device 71.

[0069] Next, the fan command calculation unit 79 refers to the table shown in Fig. 10 and calculates the maximum PWM command value PWMmax for the radiator fan 63 and the oil cooler fan 68 using the fan allowable power consumption Pf (step S230). Fig. 10 shows a table (characteristics diagram) that specifies the maximum PWM command value PWMmax for the radiator fan and the oil cooler fan relative to the fan allowable power consumption Pf. The table shown in Fig. 10 sets PWM commands so that the power consumption of the radiator fan 63 and the oil cooler fan 68 corresponds to the allowable power consumption Pf.

[0070] Next, the fan command calculation unit 79 determines whether the PWM command PWMwt of the radiator fan 63, which is the result of the calculation in step S210, is smaller than the maximum PWM command PWMmax, which is the result of the calculation in step S230 (step S240). If the PWM command PWMwt of the radiator fan 63 is smaller than the maximum PWM command PWMmax (YES in step S240), the process proceeds to step S260. On the other hand, if the PWM command PWMwt of the radiator fan 63 is equal to or greater than the maximum PWM command PWMmax (NO in step S250), the PWM command PWMwt of the radiator fan 63 is reset to the maximum PWM command PWMmax (step S250), and the process proceeds to step S260.

[0071] In step S260, the fan command calculation unit 79 determines whether the PWM command PWMol for the oil cooler fan 68, which is the result of the calculation in step S220, is smaller than the maximum PWM command PWMmax, which is the result of the calculation in step S230. If the PWM command PWMol for the oil cooler fan 68 is smaller than the maximum PWM command PWMmax (YES in step S260), the PWM command PWMol for the oil cooler fan 68 is maintained as the result of the calculation in step S220, and the process returns to start. On the other hand, if the PWM command PWMol for the oil cooler fan 68 is equal to or greater than the maximum PWM command PWMmax (NO in step S270), the PWM command PWMol for the oil cooler fan 68 is reset to the maximum PWM command PWMmax.

[0072] 5 , in step S50 of the flowchart, the allowable fan power consumption Pf is limited based on the result of a difference calculation in which the power (set value) required to operate the control devices 70, 43a, 52a, and 53a other than the electric cooling devices 61, 63, and 68 in the control system electric circuit 42 is subtracted from the allowable DC / DC output power Wdc. The maximum PWM command value PWMmax for the radiator fan 63 and the oil cooler fan 68 is limited in accordance with this limited allowable fan power consumption Pf. The allowable fan power consumption Pf limits the power consumption (drive) of the radiator fan 63 and the oil cooler fan 68 so that driving the radiator fan 63 and the oil cooler fan 68 does not draw power from the second battery 56. The operation of the radiator fan 63 and the oil cooler fan 68 is limited according to the fan allowable power consumption Pf calculated using this calculation formula. Therefore, even if an abnormality in the DC / DC converter 43 is detected and the power supply to the control system electrical circuit 42 via the DC / DC converter 43 is limited, the operation of the radiator fan 63 and the oil cooler fan 68 is prevented from drawing power from the second battery 56, thereby prioritizing the continued operation of the vehicle body controller 70, BMU 52a, inverter controller 53a, and converter controller 43a of the control system electrical circuit 42.

[0073] Returning to FIG. 3 , the inverter controller 53a includes, as its hardware configuration, a storage device (not shown) including RAM, ROM, etc., and a processing device (not shown) including a CPU, MPU, etc. The storage device pre-stores programs and various information necessary for monitoring the status of the inverter circuit 53b and for detecting and controlling abnormalities. The processing device reads the programs and various information from the storage device as needed, receives commands from the vehicle body controller 70, and executes processing in accordance with the programs and commands, thereby realizing the functions of monitoring the status of the inverter circuit 53b and for detecting and controlling abnormalities. The inverter controller 53a includes, for example, a motor control unit 531 and a current control unit 532 as functions executed by the processing device.

[0074] The motor control unit 531 receives the detection signal (actual rotation speed Na of the electric motor 51 or hydraulic pump 31) from the rotation speed sensor 23 at a predetermined cycle and transmits it to the vehicle body controller 70, while also transmitting information on the presence or absence of an abnormality in the inverter circuit 53b to the vehicle body controller 70. The motor control unit 531 also calculates a motor torque command Tc that performs feedback control such that the actual rotation speed Na converges to the rotation speed command Nc, based on the deviation between the rotation speed command Nc received from the vehicle body controller 70 and the actual rotation speed Na detected by the rotation speed sensor 23. The motor control unit 531 outputs the motor torque command Tc obtained as a result of the calculation to the current control unit 532.

[0075] The current control unit 532 calculates a current value corresponding to the motor torque command Tc calculated by the motor control unit 531 , and controls the inverter circuit 53 b so that the calculated current value is output to the electric motor 51 .

[0076] As described above, the vehicle body controller 70 of this embodiment basically performs feedback control of the electric motor 51 via the inverter controller 53a so that the electric motor 51 follows the rotation speed corresponding to the rotation speed command Nc (see step S120 shown in FIG. 6 ) according to the amount of operation of the rotation speed indicating dial 21. In addition, when an abnormality in the DC / DC converter 43 is detected, the hydraulic output of the hydraulic pump 31 is limited by limiting the rotation speed of the electric motor 51 to, for example, a preset minimum rotation speed.

[0077] Next, the operation when an abnormality in the DC / DC converter is detected in the construction machine according to one embodiment will be described with reference to Figures 2 to 10. First, a case where an abnormality (failure) occurs that makes the DC / DC converter unable to be driven will be described.

[0078] 2 fails while the hydraulic excavator 1 is in operation, it becomes impossible to supply power from the drive system electric circuit 41 to the control system electric circuit 42 via the DC / DC converter 43. In this case, the converter controller 43a shown in Fig. 3 transmits information indicating that an abnormality has been detected in the DC / DC converter 43 to the vehicle body controller 70, and also transmits the DC / DC outputtable power Wdc to the vehicle body controller 70 as "0".

[0079] The vehicle body controller 70 (DC / DC command calculation unit 76) sets the DC / DC degeneration flag to "1" (step S20 in the flowchart shown in FIG. 5), and because the DC / DC outputtable power Wdc is "0", sets the fan allowable power consumption Pf to "0" (steps S40 to S50 in the flowchart shown in FIG. 5).

[0080] Furthermore, because the fan allowable power consumption Pf is "0," the vehicle body controller 70 (fan command calculation unit 79) references the table shown in FIG. 10 and sets the maximum PWM command values ​​PWMmax for the radiator fan 63 and the oil cooler fan 68 to 0% (step S230 in the flowchart shown in FIG. 7 ). Therefore, the vehicle body controller 70 (fan command calculation unit 79) sets the PWM command PWMwt for the radiator fan 63 to 0% (step S250 in the flowchart shown in FIG. 7 ), and also sets the PWM command PWMol for the oil cooler fan 68 to 0% (step S270 in the flowchart shown in FIG. 7 ). That is, the vehicle body controller 70 (fan command calculation unit 79) controls the radiator fan 63 and the oil cooler fan 68 to stop driving.

[0081] When the radiator fan 63 and the oil cooler fan 68 are stopped, their power consumption becomes "0." Therefore, even if the DC / DC converter 43 fails and power cannot be supplied from the drive system electric circuit 41 to the control system electric circuit 42, the radiator fan 63 and the oil cooler fan 68 do not draw power from the second battery 56. Meanwhile, the various control devices in the control system electric circuit 42 (the vehicle body controller 70, the BMU 52a, the inverter controller 53a, and the converter controller 43a) can continue to operate using power supplied from the second battery 56, which functions as the power source for the control system electric circuit 42 during the DC / DC converter 43 failure. At this time, unlike the radiator fan 63 and the oil cooler fan 68, the control devices 70, 52a, 53a, and 43a do not draw a large current from the power source, and therefore a sudden voltage drop in the second battery 56 is unlikely to occur.

[0082] Furthermore, because the DC / DC degeneration flag is "1" (NO in step S140 of the flowchart shown in FIG. 6), the vehicle body controller 70 (motor command calculation unit 77) sets the rotation speed command Nc of the electric motor 51 to the minimum motor rotation speed Nmin and sets the allowable motor torque Tmax to the minimum motor torque Tmin (step S150 of the flowchart shown in FIG. 6). As a result, the vehicle body controller 70 (pump control unit 78) controls the pump displacement of the hydraulic pump 31 to a minimum value corresponding to the minimum motor torque Tmin. Furthermore, the inverter controller 53a controls the rotation speed of the electric motor 51 so that the actual rotation speed of the electric motor 51 follows the minimum motor rotation speed Nmin. As a result, the hydraulic pump 31 is driven with minimum power. Therefore, driving the hydraulic pump 31 with minimum power suppresses temperature increases of the coolant and hydraulic oil in the cooling system 60, making it possible to prevent overheating of the cooling system 60 even when the radiator fan 63 and the oil cooler fan 68 are stopped.

[0083] Second, a case where an abnormality such as an overtemperature of the DC / DC converter is detected will be described. When the DC / DC converter reaches an abnormal overtemperature state, it is necessary to suppress the temperature rise of the DC / DC converter by reducing the power supplied to the control system electric circuit via the DC / DC converter in order to suppress heat generation in the DC / DC converter.

[0084] Therefore, the converter controller 43a shown in FIG. 3 uses the table shown in FIG. 4 to limit the output power of the DC / DC converter 43 to the control system electric circuit 42 within a range of the DC / DC output power Wdc corresponding to the detection value Std of the temperature sensor 43b. When the detection value Std of the temperature sensor 43b exceeds Tα in the table shown in FIG. 4, an overtemperature abnormality of the DC / DC converter 43 is detected. In particular, when the detection value Std of the temperature sensor 43b exceeds Tβ in the table shown in FIG. 4, the converter controller 43a stops driving the DC / DC converter 43 and sets the output power of the DC / DC converter 43 to "0" to the control system electric circuit 42. When the converter controller 43a shown in FIG. 3 controls the drive limit of the DC / DC converter 43 upon detecting an overtemperature abnormality, it transmits information about the abnormality detection of the DC / DC converter 43 to the vehicle body controller 70 and also transmits to the vehicle body controller 70 the DC / DC output power Wdc corresponding to the detection value Std of the temperature sensor 43b.

[0085] The vehicle controller 70 (DC / DC command calculation unit 76) sets the DC / DC degeneration flag to "1" based on the abnormality detection information from the converter controller 43a (step S20 in the flowchart shown in FIG. 5). The vehicle controller 70 also compares the DC / DC output power Wdc from the converter controller 43a with the DC / DC input power Pdc from the energy management unit 75, and sets the smaller value as the control system electric circuit power Pec2 (step S40 in the flowchart shown in FIG. 5). The DC / DC input power Pdc varies depending on whether or not an abnormality is present in the first battery 52. ​​If no abnormality is detected in the first battery 52, the DC / DC output power Wdc, which is limited by the detection of an overtemperature abnormality in the DC / DC converter 43, is smaller than the DC / DC input power Pdc. In this case, the fan allowable power consumption Pf is set to a value obtained by subtracting the on-board controller power consumption Pcon_sum from the DC / DC output power Wdc (step S50 in the flowchart shown in FIG. 5). In other words, the power consumption of the radiator fan 63 and the oil cooler fan 68 is determined after securing the power (total required power added up of the required power of the various control devices) required to operate all of the various control devices (vehicle body controller 70, BMU 52a, inverter controller 53a, converter controller 43a) connected to the control system electrical circuit 42 from the DC / DC output power Wdc, which is limited due to the abnormal detection of an overtemperature in the DC / DC converter 43.

[0086] Furthermore, the vehicle controller 70 (fan command calculation unit 79) sets the maximum PWM command value PWMmax for the radiator fan 63 and the oil cooler fan 68 based on the calculated fan allowable power consumption Pf by referring to the table shown in FIG. 10 (step S230 of the flowchart shown in FIG. 7). If the detection value St1 of the coolant temperature sensor 65 corresponds to a high value (%) of the PWM command PWMwt of the radiator fan 63 in the table shown in FIG. 8, or if the detection value St2 of the hydraulic oil temperature sensor 69 corresponds to a high value (%) of the PWM command PWMol of the oil cooler fan 68 in the table shown in FIG. 9, the PWM command PWMwt of the radiator fan 63 is reduced to the maximum PWM command value PWMmax set based on the fan allowable power consumption Pf (step S250 of the flowchart shown in FIG. 7), and the PWM command PWMol of the oil cooler fan 68 is reduced to the maximum PWM command value PWMmax set based on the fan allowable power consumption Pf (step S270 of the flowchart shown in FIG. 7). That is, in response to the limitation of the output power of the DC / DC converter 43 to the control system electric circuit 42 due to an abnormality in the overtemperature of the DC / DC converter 43, the vehicle controller 70 (fan command calculation unit 79) prioritizes securing the power consumption of each controller 70, 43a, 52a, 53a of the control system electric circuit 42, and performs control to limit the operation (power consumption) of the radiator fan 63 and the oil cooler fan 68 so that power is not drawn from the second battery 56 of the control system electric circuit 42 by driving the radiator fan 63 and the oil cooler fan 68.

[0087] As a result, each of the controllers 70 , 43 a , 52 a , and 53 a can continue to operate using the power supplied from the drive system electric circuit 41 to the control system electric circuit 42 via the DC / DC converter 43 .

[0088] Furthermore, because the DC / DC degeneration flag is "1" (NO in step S140 of the flowchart shown in FIG. 6), the vehicle body controller 70 (motor command calculation unit 77) sets the rotation speed command Nc of the electric motor 51 to the minimum motor rotation speed Nmin and sets the allowable motor torque Tmax to the minimum motor torque Tmin (step S150 of the flowchart shown in FIG. 6). As a result, the vehicle body controller 70 (pump control unit 78) controls the pump displacement of the hydraulic pump 31 to a minimum corresponding to the minimum motor torque Tmin. Furthermore, the inverter controller 53a controls the rotation speed of the electric motor 51 so that the actual rotation speed of the electric motor 51 follows the minimum motor rotation speed Nmin. As a result, the hydraulic pump 31 operates with minimum power, which suppresses temperature increases in the coolant and hydraulic oil in the cooling system 60. This makes it possible to prevent overheating of the cooling system 60 even when the operation of the radiator fan 63 and the oil cooler fan 68 is restricted.

[0089] As described above, the hydraulic excavator 1 (construction machine) according to one embodiment includes the hydraulic pump 31, the drive system electric circuit 41 (first electric circuit) having the electric motor 51 that drives the hydraulic pump 31, the control system electric circuit 42 (second electric circuit) having a lower rated voltage than the drive system electric circuit 41 (first electric circuit), and the DC / DC converter 43 as a voltage conversion device that is interposed between the drive system electric circuit 41 (first electric circuit) and the control system electric circuit 42 (second electric circuit) and converts the voltage of electric power input from the drive system electric circuit 41 (first electric circuit) and outputs the converted electric power to the control system electric circuit 42 (second electric circuit). The drive system electric circuit 41 (first electric circuit) includes the first battery 52 that is a power source for the electric motor 51, and the inverter 53 that is connected to the first battery 52 via the first power line 54 and adjusts the electric power supplied from the first battery 52 to the electric motor 51. The control system electric circuit 42 (second electric circuit) includes a second battery 56 having a lower rated voltage than the first battery 52, an oil cooler fan 68 connected to the second battery 56 via a second power line 57 and serving as an electric cooling device that cools the hydraulic oil discharged by the hydraulic pump 31, and a vehicle controller 70 and an inverter controller 53a connected to the second battery 56 via the second power line 57 and serving as control devices that control the oil cooler fan 68 (electric cooling device) and the electric motor 51. The hydraulic excavator 1 (construction machine) further includes a converter controller 43a (conversion device abnormality detection device) that detects an abnormality in the DC / DC converter 43 (voltage conversion device) and limits the operation of the DC / DC converter 43 (voltage conversion device) when an abnormality in the DC / DC converter 43 (voltage conversion device) is detected. The vehicle controller 70 and the inverter controller 53a (control device) are configured to limit the operation of the oil cooler fan 68 (electric cooling equipment) when an abnormality in the DC / DC converter 43 (voltage conversion device) is detected by the converter controller 43a (conversion device abnormality detection device).

[0090] According to this configuration, if an abnormality is detected in the DC / DC converter 43 (voltage conversion device), the operation of the oil cooler fan 68 (electric cooling device) is limited, thereby preventing a sudden voltage drop in the second battery 56. Therefore, even if the power supply to the control system electric circuit 42 (second electric circuit) via the DC / DC converter 43 (voltage conversion device) is limited, normal operation of the vehicle body controller 70 and the inverter controller 53a (control device) can be maintained, allowing the hydraulic excavator 1 (construction machine) to continue operating. In other words, even if an abnormality occurs in the DC / DC converter 43 (voltage conversion device), the hydraulic excavator 1 (construction machine) can be prevented from stopping operation.

[0091] In this embodiment, the first battery 52 is a lithium ion battery, and the second battery 56 is a lead storage battery.

[0092] With this configuration, a battery with a high energy density that can withstand repeated charging and discharging can be used as the first battery 52, and an inexpensive battery that is both durable and reliable can be used as the second battery 56.

[0093] In addition, in this embodiment, the vehicle body controller 70 and the inverter controller 53a (control device) stop the oil cooler fan 68 (electric cooling device) when the power supplied to the control system electrical circuit 42 (second electrical circuit) via the DC / DC converter 43 (voltage conversion device) falls below the power required to operate the vehicle body controller 70 and the inverter controller 53a (control device).

[0094] According to this configuration, even in a situation where power is drawn from the second battery 56 as a power source for the control system electrical circuit 42 (second electrical circuit) to continue operating the vehicle body controller 70 and the inverter controller 53a (control device), a sudden voltage drop in the second battery 56 can be prevented by stopping the oil cooler fan 68 (electric cooling device) through which a large current flows.

[0095] In this embodiment, the converter controller 43a (conversion device abnormality detection device) calculates a DC / DC outputtable power Wdc (conversion device outputtable power), which is power that can be output from the DC / DC converter 43 (voltage conversion device) to the control system electric circuit 42 (second electric circuit), in accordance with an abnormal state of the DC / DC converter 43 (voltage conversion device). Furthermore, the vehicle body controller 70 and the inverter controller 53a (control device) limit the drive of the oil cooler fan 68 (electric cooling equipment) based on the DC / DC outputtable power Wdc (conversion device outputtable power) calculated by the converter controller 43a (conversion device abnormality detection device) and the power required by the vehicle body controller 70 and the inverter controller 53a (control device).

[0096] According to this configuration, the operation of the oil cooler fan 68 (electric cooling equipment) is limited taking into consideration the power consumption of the vehicle body controller 70 and inverter controller 53a (control device) of the control system electrical circuit 42 (second electrical circuit), so that the output power to the control system electrical circuit 42 (second electrical circuit) limited by the converter controller 43a (conversion device abnormality detection device) can be preferentially allocated to the continued operation of the vehicle body controller 70 and inverter controller 53a (control device) of the control system electrical circuit 42 (second electrical circuit).

[0097] Furthermore, in this embodiment, the vehicle body controller 70 and the inverter controller 53a (control device) stop the oil cooler fan 68 (electric cooling device) when the required power is equal to or greater than the DC / DC outputtable power Wdc (outputtable power of the conversion device), and when the required power is less than the DC / DC outputtable power Wdc (outputtable power of the conversion device), control the drive of the oil cooler fan 68 (electric cooling device) so that the power does not exceed the allowable power consumption Pf, which is the difference between the DC / DC outputtable power Wdc (outputtable power of the conversion device) and the required power.

[0098] According to this configuration, when the power required by the vehicle body controller 70 and inverter controller 53a (control device) of the control system electric circuit 42 (second electric circuit) exceeds the output power to the control system electric circuit 42 (second electric circuit) limited by the converter controller 43a (conversion device abnormality detection device), the oil cooler fan 68 (electric cooling device) is stopped, thereby reliably preventing the oil cooler fan 68 (electric cooling device) from drawing power from the second battery 56. Furthermore, in other cases, the oil cooler fan 68 (electric cooling device) is driven so as not to exceed the allowable power consumption Pf, thereby reliably preventing the oil cooler fan 68 (electric cooling device) from drawing power from the second battery 56.

[0099] In addition, in this embodiment, the converter controller 43a (conversion device abnormality detection device) is connected to the second battery 56 via the second power line 57, and the vehicle body controller 70 and the inverter controller 53a (control device) can limit the driving of the oil cooler fan 68 (electric cooling equipment) based on the DC / DC output power Wdc (conversion device output power) and the total required power obtained by adding together the required power of the vehicle body controller 70 and the inverter controller 53a (control device) and the required power of the converter controller 43a (conversion device abnormality detection device).

[0100] According to this configuration, the operation of the oil cooler fan 68 (electric cooling equipment) is limited taking into account the total power consumption of the vehicle body controller 70, inverter controller 53a (control device), and converter controller 43a (conversion device abnormality detection device) in the control system electrical circuit 42 (second electrical circuit), so that the output power to the control system electrical circuit 42 (second electrical circuit) limited by the converter controller 43a (conversion device abnormality detection device) can be preferentially allocated to the continued operation of the vehicle body controller 70, inverter controller 53a (control device), and converter controller 43a (conversion device abnormality detection device) in the control system electrical circuit 42 (second electrical circuit).

[0101] Furthermore, in this embodiment, the vehicle body controller 70 and the inverter controller 53 a (control device) can stop the oil cooler fan 68 (electric cooling device) when the total required power is equal to or greater than the DC / DC outputtable power Wdc (outputtable power of the conversion device), and can control the drive of the oil cooler fan 68 (electric cooling device) so that the power consumption does not exceed the allowable power consumption Pf, which is the difference between the DC / DC outputtable power Wdc (outputtable power of the conversion device) and the total required power, when the total required power is less than the DC / DC outputtable power Wdc (outputtable power of the conversion device).

[0102] According to this configuration, when the total power required by the vehicle body controller 70, inverter controller 53a (control device), and converter controller 43a (conversion device abnormality detection device) in the control system electric circuit 42 (second electric circuit) exceeds the output power to the control system electric circuit 42 (second electric circuit) limited by the converter controller 43a (conversion device abnormality detection device), the oil cooler fan 68 (electric cooling device) is stopped, thereby reliably preventing the oil cooler fan 68 (electric cooling device) from drawing power from the second battery 56. Furthermore, in other cases, the oil cooler fan 68 (electric cooling device) is driven so as not to exceed the allowable power consumption Pf, thereby reliably preventing the oil cooler fan 68 (electric cooling device) from drawing power from the second battery 56.

[0103] In addition, in this embodiment, if the converter controller 43a (conversion device abnormality detection device) detects an abnormality in the DC / DC converter 43 (voltage conversion device), the vehicle controller 70 and the inverter controller 53a (control device) limit the hydraulic output of the hydraulic pump 31 driven by the electric motor 51.

[0104] According to this configuration, by limiting the hydraulic output of the hydraulic pump 31 driven by the electric motor 51, the temperature rise of the hydraulic oil is suppressed, so that even if the operation of the oil cooler fan 68 that cools the hydraulic oil is limited, overheating of the hydraulic oil can be avoided.

[0105] In the present embodiment, the hydraulic pump 31 is a variable displacement pump whose pump volume is variable, and the vehicle body controller 70 (control device) controls the pump volume of the hydraulic pump 31. The limitation of the hydraulic output of the hydraulic pump 31 by the vehicle body controller 70 and the inverter controller 53a (control device) limits the pump volume of the hydraulic pump 31 to a predetermined minimum volume and also limits the rotation speed of the hydraulic pump 31 driven by the electric motor 51 to a predetermined minimum rotation speed.

[0106] According to this configuration, by minimizing the power of the hydraulic pump 31, it is possible to reliably suppress the temperature rise of the hydraulic oil, so that even if the operation of the oil cooler fan 68 that cools the hydraulic oil is restricted, overheating of the hydraulic oil can be avoided.

[0107] Other Embodiments Although the above-described embodiment shows an example in which the present invention is applied to the hydraulic excavator 1, the present invention can be widely applied to various types of battery-powered construction machinery.

[0108] Furthermore, the present invention is not limited to the above-described embodiment, but includes various modifications. The above-described embodiment has been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. It is also possible to add, delete, or replace part of the configuration of the present embodiment with other configurations.

[0109] For example, in the above-described embodiment, the cooling system 60 is configured to cool the hydraulic oil circulating through the hydraulic system 30, and also cool the coolant that cools the electric motor 51 and the inverter 53. However, if the heat generation amounts of the electric motor 51 and the inverter 53 are relatively small, the cooling system may be configured to cool only the hydraulic oil circulating through the hydraulic system 30, without the radiator fan 63 and the like.

[0110] REFERENCE SIGNS LIST 1...hydraulic excavator (construction machinery), 31...hydraulic pump, 41...drive system electric circuit (first electric circuit), 42...control system electric circuit (second electric circuit), 43...DC / DC converter (voltage conversion device), 43a...converter controller (conversion device abnormality detection device), 51...electric motor, 52...first battery, 53...inverter, 53a...inverter controller (control device), 54...first power line, 56...second battery, 57...second power line, 68...oil cooler fan (electric cooling device), 70...vehicle controller (control device)

Claims

1. A construction machine comprising a hydraulic pump, a first electric circuit having an electric motor for driving the hydraulic pump, a second electric circuit having a rated voltage lower than that of the first electric circuit, and a voltage conversion device interposed between the first electric circuit and the second electric circuit for converting the voltage of the power input from the first electric circuit and outputting the converted voltage to the second electric circuit. The first electric circuit includes a first battery which is a power source of the electric motor, and an inverter connected to the first battery via a first power line for adjusting the power supplied from the first battery to the electric motor. The second electric circuit includes a second battery having a rated voltage lower than that of the first battery, an electric cooling device connected to the second battery via a second power line for cooling the hydraulic oil discharged by the hydraulic pump, and a control device connected to the second battery via the second power line for controlling the electric cooling device and the electric motor. The construction machine further comprises a conversion device abnormality detection device for detecting an abnormality of the voltage conversion device and restricting the drive of the voltage conversion device when the abnormality of the voltage conversion device is detected. The control device restricts the drive of the electric cooling device when the abnormality of the voltage conversion device is detected by the conversion device abnormality detection device.

2. The construction machine according to claim 1, wherein the first battery is a battery composed of a lithium ion battery, and the second battery is a battery composed of a lead storage battery.

3. The construction machine according to claim 1, wherein the control device stops the electric cooling device when the power supplied to the second electric circuit through the voltage conversion device is lower than the power required to operate the control device.

4. The construction machine according to claim 1, wherein the conversion device abnormality detection device calculates a conversion device outputtable power which is the power outputtable from the voltage conversion device to the second electric circuit according to the abnormal state of the voltage conversion device, and the control device restricts the drive of the electric cooling device based on the conversion device outputtable power calculated by the conversion device abnormality detection device and the required power of the control device.

5. In the construction machine according to claim 4, when the required power is equal to or greater than the output-capable power of the conversion device, the control device stops the electric cooling equipment, and when the required power is less than the output-capable power of the conversion device, the control device controls the driving of the electric cooling equipment so as not to exceed the allowable power consumption, which is the difference between the output-capable power of the conversion device and the required power. A construction machine characterized by this.

6. In the construction machine according to claim 1, when an abnormality of the voltage conversion device is detected by the conversion device abnormality detection device, the control device limits the hydraulic output of the hydraulic pump driven by the electric motor. A construction machine characterized by this.

7. In the construction machine according to claim 6, the hydraulic pump is a variable displacement pump whose pump volume is variable, the control device controls the pump volume of the hydraulic pump, and the limitation of the hydraulic output of the hydraulic pump by the control device is to limit the pump volume of the hydraulic pump to a predetermined minimum volume and limit the rotational speed of the hydraulic pump driven by the electric motor to a predetermined minimum rotational speed. A construction machine characterized by this.

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