Work machine

Abstract

A purpose of the present invention is to prevent an electric motor from entering an output limiting state.　A work machine 1 comprises: an electrical device (98) that includes a rechargeable battery (90a) and an electric motor (91) supplied with power from the battery (90a); a temperature detection device (110) that detects the temperature of the electrical device (98); and a control device (120) that controls the rotational speed of the electric motor (91). The control device (120) predicts whether the temperature detected by the temperature detection device (110) will reach a threshold temperature (Th) at which output of the electric motor (91) will be limited. If it is predicted that the threshold temperature will be reached, the control device (120) determines an upper limit of the rotational speed of the electric motor (91) to be a warning upper limit (UL3), which is a value smaller than an upper limit (UL1) under normal conditions and larger than an upper limit (UL2) when the output is limited.

Description

Work machine

[0001] The present invention relates to a work machine such as a backhoe.

[0002] In the electric work vehicle disclosed in Patent Document 1, when the battery temperature rises, the output of the electric motor is limited to a limited output value.

[0003] Japanese Patent Laid-Open Publication "JP-A-2024-27805"

[0004] However, in the electric work vehicle of Patent Document 1, when the battery temperature rises, the output of the electric motor is limited to the limited output value, so the electric motor is in a significant output limit state. Also, it may take time until the battery temperature drops, and the output limit state of the electric motor may continue, potentially prolonging the function limit state of the electric work vehicle.

[0005] The present invention has been made to solve such problems of the prior art, and an object thereof is to suppress the electric motor from entering an output limit state.

[0006] A work machine according to an aspect of the present invention includes an electric device including a rechargeable battery and an electric motor supplied with power from the battery, a temperature detection device that detects the temperature of the electric device, and a control device that controls the rotational speed of the electric motor. The control device predicts whether the detected temperature by the temperature detection device reaches a threshold temperature at which the output of the electric motor is limited, and when it is predicted that the threshold temperature will be reached, the upper limit value of the rotational speed of the electric motor is set to an upper limit value during warning, which is smaller than the normal upper limit value and larger than the upper limit value during output limitation.

[0007] According to the above work machine, it is possible to suppress the electric motor from entering an output limit state.

[0008] This is a schematic side view of the work machine in the embodiment. This is a schematic top view of the work machine in the embodiment. This is a schematic rear view of the work machine in the embodiment. This is a block diagram showing the system of the work machine in the embodiment. This is a diagram showing the water cooling path by the radiator when the exterior cover is removed and the rear room is viewed from above. This is a diagram showing an example in a conventional work machine where the upper limit of the rotation speed of the electric motor is changed to the upper limit for output limiting when the battery temperature reaches a threshold temperature. This is a block diagram showing an example of the main components of the work machine in the embodiment. This is a block diagram showing another example of the main components of the work machine in the embodiment. This is a diagram showing an example in a work machine in the embodiment where the upper limit of the rotation speed of the electric motor is changed to the upper limit for warning before the temperature of the electrical equipment reaches a threshold temperature. This is a diagram showing an example in a work machine in the embodiment where the temperature of the electrical equipment is predicted to reach a threshold temperature. This is a diagram showing an example in which the control device determines the upper limit of the rotation speed of the electric motor according to the detected temperature using a function or map. This is a flowchart showing the process of determining the upper limit of the rotation speed of the electric motor by the control device. This is a diagram showing the effect of determining the upper limit of the rotation speed of the electric motor in the embodiment compared to the conventional method. This is a diagram showing an example in a work machine in the embodiment where the temperature of the electrical equipment is predicted to reach a threshold temperature based on the ambient temperature. This figure shows an example of predicting when the average temperature of electrical equipment in a modified work machine will reach a threshold temperature. This figure also shows an example of a control device in a modified work machine that uses a function or map to determine the upper limit of the rotational speed of the electric motor according to the detected temperature.

[0009] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Figure 1 is a schematic side view of the work machine 1 in the embodiment. Figure 2 is a schematic top view of the work machine 1 in the embodiment. Figure 3 is a schematic rear view of the work machine 1 in the embodiment.

[0010] First, let's explain the overall configuration of the work machine 1. As shown in Figures 1 to 3, the work machine 1 is a rotating work machine 1A such as a backhoe, which is equipped with a slewing platform 2A (machine body 2), a lower traveling body 10, and a work device 20. The work machine 1 is also an electric work machine (electric rotating work machine 1A) that is driven by electricity. A driver's seat 8 where the operator sits is provided on the slewing platform 2A. The area around the driver's seat 8 is covered by a protective mechanism 80, such as a cabin.

[0011] In this embodiment, the direction the driver seated in the driver's seat 8 of the work machine 1 faces (direction of arrow Y1 in Figures 1 and 2, etc.) is described as the front, the opposite direction (direction of arrow Y2 in Figures 1 and 2, etc.) is described as the rear, the left side of the driver (front side in Figure 1, direction of arrow X1 in Figures 2 and 3, etc.) is described as the left, and the right side of the driver (back side in Figure 1, direction of arrow X2 in Figures 2 and 3, etc.) is described as the right. The horizontal direction, which is perpendicular to the front-rear direction Y3, is described as the width direction X3 (see Figures 2 and 3). The direction from the center of the width direction X3 of the turntable 2A toward the right or left is described as the outward width direction. An operable operating device 5 is provided around the driver's seat 8, and the work machine 1 is operated by operating the operating device 5.

[0012] The turntable 2A is rotatable around a pivot axis X (vertical axis) that extends in the vertical direction. Specifically, the turntable 2A is supported on the lower traveling body 10 via a pivot bearing 3 so as to be rotatable around the pivot axis X (rotatable to the left and right). The center of the pivot bearing 3 is the pivot axis X (center of rotation), and a pivot motor is attached to the turntable 2A. This pivot motor is a hydraulic device M driven by hydraulic fluid discharged by a hydraulic pump P, and is a motor that rotates the turntable 2A around the pivot axis X. The turntable 2A is provided with an exterior cover 70 (cover), brackets, and stays. The exterior cover 70 forms a space (rear room R shown in Figure 5, which will be described later) at the rear of the turntable 2A for arranging equipment, tanks, and other parts. The brackets, stays, etc. are members for attaching the above parts.

[0013] As shown in Figures 1 and 2, the lower traveling body 10 has a traveling frame 11 and a traveling mechanism 12. The traveling frame (track frame) 11 is a structure to which the traveling mechanism 12 is attached and which supports the turntable 2A on its upper part.

[0014] The travel mechanism 12 is, for example, a crawler type. The travel mechanism 12 includes an idler 13, a drive wheel 14, a plurality of rolling wheels 15, an endless crawler belt 16, and hydraulic equipment M (travel motors ML, MR) of the travel system driven by hydraulic fluid discharged by a hydraulic pump P. The travel motors ML, MR are composed of hydraulic motors and drive the drive wheel 14 to cause the crawler belt 16 to circumferentially move around. A dozer device 18 is mounted on the front of the lower travel body 10, which is driven up and down by the extension and retraction of a dozer cylinder C5 (M), which is a hydraulic cylinder (hydraulic actuator).

[0015] As shown in Figures 1 and 2, the work device 20 is provided on the front side of the turntable 2A. As shown in Figure 1, the work device 20 has a boom 21, an arm 22, and a bucket (working tool) 23. The base end of the boom 21 is pivotally attached to the swing bracket 24 so as to be rotatable around a horizontal axis (an axis extending in the width direction X3), and the boom 21 is able to swing up and down (vertically). The arm 22 is pivotally attached to the tip of the boom 21 so as to be rotatable around a horizontal axis, and the arm 22 is able to swing in the front-rear direction or up and down direction. The bucket 23 is provided at the tip of the arm 22 so as to be able to perform scooping and dumping operations. The work machine 1 can be fitted with other working tools (hydraulic attachments) that can be driven by hydraulic fluid in place of or in addition to the bucket 23. Other examples of work tools include hydraulic breakers, hydraulic crushers, angle brooms, earth augers, pallet forks, sweepers, mowers, and snow blowers.

[0016] As shown in Figure 1, the work machine 1 is equipped with hydraulic equipment M of a work system that is operated by hydraulic fluid discharged by a hydraulic pump P, and the work device 20 is driven by the operation of the hydraulic equipment M of the work system. In this embodiment, the hydraulic equipment M includes a swing cylinder C1, a boom cylinder C2, an arm cylinder C3, and a bucket cylinder C4. The swing cylinder C1, boom cylinder C2, arm cylinder C3, and bucket cylinder C4 are composed of hydraulic cylinders (hydraulic actuators). As shown in Figure 1, the swing bracket 24 is swingable by the extension and retraction of the swing cylinder C1, which is provided on the right side of the turntable 2A. The boom 21 is swingable by the extension and retraction of the boom cylinder C2. The arm 22 is swingable by the extension and retraction of the arm cylinder C3. The bucket 23 is capable of scooping and dumping operations by the extension and retraction of the bucket cylinder C4.

[0017] Therefore, the hydraulic equipment M provided by the work machine 1 includes a slewing motor, travel motors ML and MR, a swing cylinder C1, a boom cylinder C2, an arm cylinder C3, and a bucket cylinder C4. The hydraulic equipment M also includes a control valve V that controls the above-mentioned hydraulic cylinders and a hydraulic oil tank T. As shown in Figure 2, the hydraulic oil tank T and the control valve V are positioned in front of the hydraulic pump P.

[0018] Figure 4 is a block diagram showing the system of the work machine 1. As shown in Figure 4, the work machine 1 includes a battery unit 90, an electric motor 91, electrical components 92, a charging port 93, and a cooling unit CU. As shown in Figure 3, the battery unit 90, electric motor 91, electrical components 92, charging port 93, and cooling unit CU are installed on the turntable 2A (machine body 2).

[0019] The battery unit 90 is a device that can store electricity and output the stored power. The detailed configuration of the battery unit 90 will be described later.

[0020] The electric motor 91 is a drive source driven by the power output of the battery unit 90. The electric motor 91 is a permanent magnet embedded type three-phase AC synchronous motor. The rotational speed of the electric motor 91 is controlled, for example, by a rotational speed control device 5c. The rotational speed control device 5c can set a range of rotational speeds for the electric motor 91 when setting the motor speed of the electric motor 91 according to the current value that changes according to the operation of the operating device 5. The rotational speed control device 5c is, for example, a dial-shaped switch such as a selector switch with multiple switching positions, and target values ​​for the rotational speed of the electric motor 91 are assigned to the multiple switching positions. The rotational speed control device 5c can set the range of target values ​​for the rotational speed of the electric motor 91, for example, in the range of 1500 to 2600 rpm / min. The electric motor 91 may be a synchronous motor of another type, and may be an AC motor or a DC motor. In addition, the rotational speed of the electric motor 91 may be set based on a preset table according to the amount operated by the operating device 5.

[0021] The electric motor 91 rotates its drive shaft using power supplied from the battery unit 90, and transmits the driving force from the drive shaft to the hydraulic pump P. The hydraulic pump P is connected to the drive shaft of the electric motor 91 and is driven by the driving force transmitted from the drive shaft. In other words, the hydraulic pump P is driven by the electric motor 91 to discharge hydraulic fluid.

[0022] As shown in Figure 2, the electric motor 91 and the hydraulic pump P are arranged side by side in the front-rear direction Y3 on the other side (right side) of the center line Y in the width direction X3 of the turntable 2A, and to the side of the battery unit 90. Specifically, the electric motor 91 and the hydraulic pump P are located on the lower side (right side) of the battery unit 90.

[0023] As shown in Figure 3, the electrical components 92 are arranged in a line in the width direction X3 above the battery unit 90. As shown in Figure 4, the electrical components 92 are directly or indirectly connected to the battery unit 90 and transmit the power supplied by the battery unit 90, or are devices that operate using that power. Examples of electrical components 92 include a power distribution unit 100 (PDU), an inverter 92b, and a DC / DC converter 92c.

[0024] The power distribution device 100 is connected to the battery unit 90 and other electrical equipment 98, including the inverter 92b, and distributes power from the battery unit 90 to the other electrical equipment 98 (inverter 92b, DC / DC converter 92c, etc.) for output. The electric motor 91 is one of the electrical equipment 98. The electric motor 91 is driven by power supplied from the power distribution device 100 and supplies power to the hydraulic pump P.

[0025] The inverter 92b is installed in the power supply path 132 from the battery unit 90 to the electric motor 91 and adjusts the power output to the electric motor 91. In this embodiment, the inverter 92b is connected to the power distribution device 100 and the electric motor 91. The inverter 92b is a device that drives the electric motor 91, converting DC power to three-phase AC power and supplying the three-phase AC power to the electric motor 91. The inverter 92b can arbitrarily change the current and voltage of the power supplied to the electric motor 91.

[0026] The DC / DC converter 92c converts the voltage of the input DC current to a different voltage. In this embodiment, the DC / DC converter 92c is a step-down converter that converts the input voltage to a lower voltage. The DC / DC converter 92c is connected to the power distribution device 100 and the on-board battery 96. The DC / DC converter 92c is installed, for example, in the work machine 1 and supplies power to the on-board battery 96 that supplies power to electronic equipment.

[0027] As shown in Figures 1 to 3, the exterior cover 70 includes an upper bonnet 71, a rear bonnet 72, a left bonnet 73, and a right bonnet 74. The upper bonnet 71 is a cover member that forms the upper part of the rear room R and is detachably attached to the support frame, covering the battery unit 90 and electrical components 92. The rear bonnet 72 is a cover member that forms the rear of the rear room R and is attached to the support frame. The left bonnet 73 is a cover member that forms the left side of the rear room R and has an air intake 73a as shown in Figure 1. The air intake 73a is, for example, composed of multiple horizontally elongated openings arranged vertically, but is not limited to this configuration. The right bonnet 74 is a cover member that forms the right rear of the rear room R.

[0028] The charging port 93 shown in Figures 3 and 4 is a socket to which a cable for storing power in the battery unit 90 is connected, and power is supplied from an external source. When connecting the charging port 93 with the cable that supplies power from an external source, the charging lid 72a (cover member) attached to the rear bonnet 72 is opened, as shown in Figures 2 and 3, and the charging port 93 is exposed from the exterior cover 70. The charging lid 72a is pivotably connected to the rear bonnet 72 by a hinge or the like, and can be opened and closed around the pivot axis of the hinge.

[0029] As shown in Figure 4, the cooling unit CU includes a radiator 94 for cooling electrical equipment 98 and an oil cooler 97 for cooling the hydraulic fluid that drives the work device 20. The radiator 94 is a device for cooling the coolant (refrigerant) that cools the electric motor 91 and electrical components 92, etc. The radiator 94 is cooled (heat removed) by a radiator fan 94a. The radiator fan 94a generates cooling air by rotating, thereby removing heat from the radiator 94. The radiator fan 94a draws in air from around the radiator 94 and discharges it from inside the rear room R through the opening in the exterior cover 70 to the outside of the rear room R. As a result, the cooling air, which has exchanged heat with the radiator 94 and whose temperature has risen, is discharged to the outside.

[0030] The oil cooler 97 is a device that cools the hydraulic fluid discharged from the hydraulic pump P. The oil cooler 97 is cooled by an oil cooler fan 97a. The oil cooler fan 97a generates cooling air by rotating, draws in air around the oil cooler 97, and discharges the drawn-in air from the inside of the rear room R formed by the exterior cover 70 to the outside.

[0031] As shown in Figure 3, the radiator 94 and oil cooler 97 are positioned above the hydraulic pump P and electric motor 91. As a result, the radiator fan 94a and oil cooler fan 97a draw in the air surrounding the battery unit 90, including the air that has been heated by the battery unit 90, and the air that has been heated by the hydraulic pump P and electric motor 91 and moved upward, and discharge it to the outside of the machine body 2.

[0032] Here, the water cooling path 95 provided by the radiator 94 will be described. Figure 5 shows the water cooling path 95 provided by the radiator 94 in a plan view of the rear room R with the exterior cover 70 removed. As shown in Figure 5, the work machine 1 is equipped with a water cooling path 95 provided by the radiator 94. The water cooling path 95 connects the radiator 94, the electric motor 91, and electrical components 92 (for example, the inverter 92b and the DC / DC converter 92c), and is a path through which the refrigerant cooled by the radiator 94, as well as the refrigerant that has undergone heat exchange with the electric motor 91 and the electrical components 92, flows. The water cooling path 95 is also provided with a cooling pump 95a that discharges cooling water and circulates the cooling water as refrigerant. In this embodiment, the water cooling path 95 circulates cooling water from the radiator 94 through the cooling pump 95a, the inverter 92b, the DC / DC converter 92c, and the electric motor 91 to the radiator 94. Specifically, the water cooling path 95 includes a supply channel 95b, a return channel 95c, a first channel 95d, a second channel 95e, and a third channel 95f.

[0033] As shown in Figure 5, the supply channel 95b is a channel that sends refrigerant from the electric motor 91, etc., to the radiator 94. More specifically, the supply channel 95b connects the electric motor 91 and the radiator 94 and allows refrigerant to flow from the electric motor 91 to the radiator 94. The return channel 95c is a channel that returns refrigerant from the radiator 94 to the cooling pump 95a. More specifically, it connects the radiator 94 and the cooling pump 95a and allows refrigerant to flow from the radiator 94 to the cooling pump 95a.

[0034] The first water channel 95d connects the cooling pump 95a and the inverter 92b, allowing refrigerant to flow from the cooling pump 95a to the inverter 92b. The second water channel 95e connects the inverter 92b and the DC / DC converter 92c, allowing refrigerant to flow from the inverter 92b to the DC / DC converter 92c. The third water channel 95f connects the DC / DC converter 92c and the electric motor 91, allowing refrigerant to flow from the DC / DC converter 92c to the electric motor 91. In other words, the cooling water cooled in the radiator 94 returns to the radiator 94 through the return water channel 95c, the cooling pump 95a, the first water channel 95d, the inverter 92b, the second water channel 95e, the DC / DC converter 92c, the third water channel 95f, the electric motor 91, and the supply water channel 95b.

[0035] As shown in Figure 4, the work machine 1 includes a control device 120 and a memory unit 121. The control device 120 is composed of electrical and electronic circuits, a processor, memory, etc. The processor is, for example, a CPU (Central Processing Unit), GPU (Graphics Processing Unit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), and ASIC (Application Specific Integrated Circuit). The control device 120 controls various devices of the work machine 1 by having the processor execute a control program. For example, the control device 120 controls the rotation speed of the electric motor 91 based on the operation of a rotation speed control device 5c that is provided around the driver's seat 8 and is operable. The control device 120 also controls the starting of the work machine 1 based on the operation of a starter switch 7 that is provided around the driver's seat 8 and can start the work machine 1.

[0036] The storage unit 121 is a non-volatile memory or the like, and stores various information related to the control of the control device 120. For example, the storage unit 121 may be an HDD (Hard Disk Drive), an SSD (Solid State Drive), etc. The storage unit 121 stores information such as a table relating the rotational speed of the electric motor 91 to the amount of manipulation of the rotational speed control tool 5c.

[0037] As shown in Figure 4, the battery unit 90 includes a plurality of batteries 90a. The plurality of batteries 90a are connected in parallel to each other. The batteries 90a are rechargeable and are secondary batteries such as lithium-ion batteries or lead-acid batteries. The batteries 90a have a plurality of cells inside, and the plurality of cells are electrically connected in series and / or parallel. In this embodiment, the battery unit 90 has two batteries 90a. Note that the number of batteries 90a in the battery unit 90 is not limited to two, and does not have to be a plurality.

[0038] As shown in Figure 4, the work machine 1 is equipped with a connection switching unit 131. The connection switching unit 131 switches the power supply path 132 from the battery 90a to the electric motor 91 between a connected state and a disconnected state for each battery 90a. The connection switching unit 131 switches between the connected state and the disconnected state by, for example, performing relay opening and closing operations on at least a portion of the power supply path 132. As a result, the battery unit 90 outputs power from the battery 90a that is in the connected state and stops outputting power from the other batteries 90a that are in the disconnected state. The control unit 120 controls the connection switching unit 131, that is, sets the batteries 90a that output power from the battery unit 90.

[0039] Each battery 90a has a battery management unit (BMU) 123 that monitors and controls the battery 90a. The BMU 123 acquires the voltage, temperature, current, and terminal voltage of the internal cells of the battery 90a, and calculates the remaining capacity of the battery 90a. The BMU 123 can also control the switching of relays inside the battery 90a, and can control the start and stop of power supply to the battery 90a. Furthermore, the BMU 123 (detection unit) can determine whether the battery unit 90 is in a charging state (i.e., charging) or a discharging state (i.e., in use) by acquiring the voltage, current, etc. of the battery 90a. The BMU 123 may be built into each battery 90a or installed outside each battery 90a.

[0040] The control device 120 sets one of the multiple batteries 90a to be connected and configured as an output battery that outputs power from the battery unit 90, and sets the other batteries 90a to be disconnected and configured as shut-off batteries that do not output power. The control device 120 has a battery control unit 120a that performs switching control of the output batteries.

[0041] The battery control unit 120a is communicably connected to the connection switching unit 131 by wire or wirelessly, and controls the connection switching unit 131 by transmitting a signal. Thereby, the battery control unit 120a switches the connection state and the cut-off state of the plurality of batteries 90a, and performs switching control (switching process) of the output battery and the stop battery.

[0042] The battery control unit 120a performs switching control of the output battery and the stop battery based on a predetermined condition. Specifically, when the driving of the work device 20 is prohibited or restricted, the battery control unit 120a sets the output battery and the stop battery based on the selector 122 communicably connected to the control device 120 and the remaining capacity of each of the plurality of batteries 90a.

[0043] The battery control unit 120a sets the battery 90a selected by a selection instruction via the selector 122 as the output battery. On the other hand, the battery control unit 120a sets the battery 90a not selected by a selection instruction via the selector 122 as the stop battery. The selector 122 selects one of the plurality of batteries 90a based on the operation of the operator. That is, the selector 122 receives a selection instruction of the battery 90a to be the output battery from the operator. For example, the selector 122 is a plurality of operation switches arranged around the driver's seat 8 and capable of being pressed. The plurality of operation switches are respectively associated with the batteries 90a, and when one operation switch is operated, one battery 90a associated with the one operation switch is selected.

[0044] As shown in FIG. 4, the work machine 1 includes a first drive motor 97b that drives an oil cooler fan 97a and a second drive motor 94b that drives a radiator fan 94a. The oil cooler fan 97a and the radiator fan 94a can be driven independently of the electric motor 91. Hereinafter, the control of the oil cooler fan 97a and the radiator fan 94a will be described.

[0045] The first drive motor 97b and the second drive motor 94b are each connected to the control device 120. The control device 120 has a fan control unit 120b that controls the driving of the first drive motor 97b and the second drive motor 94b. The fan control unit 120b independently controls the first drive motor 97b (radiator fan 94a) and the second drive motor 94b (oil cooler fan 97a).

[0046] As shown in FIG. 4, the work machine 1 includes a water temperature detection unit 126 and an oil temperature detection unit 127. The water temperature detection unit 126 is a sensor that detects the temperature of the cooling water (refrigerant) as a voltage value. The water temperature detection unit 126 is provided, for example, in the feed water passage 95b and detects the temperature of the cooling water flowing toward the radiator 94. The water temperature detection unit 126 is connected to the control device 120 by wire or wirelessly, and outputs the detected temperature information of the cooling water to the control device 120 as a signal.

[0047] The oil temperature detection unit 127 is a sensor that detects the temperature of the hydraulic oil as a voltage value. The oil temperature detection unit 127 is provided, for example, in a pipeline connected to the oil cooler 97 and detects the temperature of the hydraulic oil flowing toward the oil cooler 97. The oil temperature detection unit 127 is connected to the control device 120 by wire or wirelessly, and outputs the detected temperature information of the hydraulic oil to the control device 120 as a signal.

[0048] When the BMU 123 detects the discharge state of the battery unit 90 (during battery output, that is, during use), the fan control unit 120b (control device 120) rotates the radiator fan 94a at a predetermined first target rotational speed according to the temperature of the cooling water detected by the water temperature detection unit 126. For example, the fan control unit 120b rotates the radiator fan 94a so that the first target rotational speed gradually increases as the temperature of the cooling water rises.

[0049] When the BMU 123 detects the discharge state of the battery unit 90 (battery output, i.e., in use), the fan control unit 120b (control device 120) rotates the oil cooler fan 97a at a predetermined second target rotational speed according to the temperature of the hydraulic fluid detected by the oil temperature detection unit 127. For example, as the temperature of the hydraulic fluid rises, the fan control unit 120b rotates the oil cooler fan 97a so that the second target rotational speed increases in stages.

[0050] Furthermore, the work machine 1 is equipped with an alerting device 124 located around the driver's seat 8 to notify the operator or manager. The alerting device 124 comprises a display device 124a, such as a monitor that displays images, and an audio output device 124b (speaker) that provides audio notifications. The display device 124a is, for example, a liquid crystal display or an organic EL display. The display device 124a has a touch operation function, allowing user input via touch operation. The alerting device 124 notifies the remaining capacity of multiple batteries 90a calculated by the BMU 123. The alerting device 124 also notifies the battery unit 90 of its charging status, such as that it is charging, and that the radiator fan 94a and oil cooler fan 97a are operating.

[0051] Furthermore, if the operation of the work device 20 is prohibited or restricted, the battery control unit 120a will charge the battery unit 90 when the operator gives an instruction to start charging the selection tool 122.

[0052] Furthermore, when the BMU 123 detects that the battery unit 90 is charging, the fan control unit 120b rotates the radiator fan 94a at a predetermined first rotational speed and the oil cooler fan 97a at a predetermined second rotational speed.

[0053] Here, using Figure 6, we will explain why the functional limitation state may persist for an extended period in conventional work machines. Figure 6 shows an example in conventional work machines where the upper limit of the rotational speed of the electric motor is changed to the upper limit UL2 for output limitation when the battery temperature reaches the threshold temperature Th. The threshold temperature Th is the temperature at which the output of the electric motor is limited, and is also called the temperature protection threshold.

[0054] As shown in Figure 6, in conventional work machines, when the battery temperature, which is the equipment temperature, rises and reaches the threshold temperature Th (for example, at time t1), the output (maximum torque) of the electric motor is limited to a limiting output value (a limiting torque smaller than the maximum torque) at time t2, for example, immediately after time t1. The limiting torque is the maximum torque that is limited. In other words, the upper limit of the rotational speed of the electric motor is determined to be the upper limit UL2 during output limitation, which is smaller than the upper limit UL1 during normal operation. The upper limit UL1 during normal operation is the upper limit of rotational speed when the equipment temperature is sufficiently lower than the threshold temperature Th (the upper limit of the rotational speed of the electric motor under normal conditions). The upper limit UL2 during output limitation is the upper limit of rotational speed that has been lowered in response to the electric motor's output being limited to the limiting torque (the upper limit of the electric motor's rotational speed during output limitation). As a result, the electric motor is in a state of significant output limitation. Also, as shown in Figure 6, it may take time for the battery temperature to drop below the threshold temperature Th, and the output limitation state of the electric motor may continue, resulting in a prolonged state of functional limitation in conventional work machines.

[0055] The main components of the implement 1 in this embodiment will be described using Figure 7A. Figure 7A is a block diagram showing an example of the main components of the implement 1 in this embodiment. As shown in Figure 7A, the implement 1 includes an electrical device 98 including a battery 90a, an inverter 92b, and an electric motor 91, a temperature detection device 110 for detecting the temperature of the electrical device 98, and a control device 120 for controlling the rotational speed of the electric motor 91. Power from the battery 90a is distributed by a power distribution device 100 and input to the inverter 92b. The inverter 92b can arbitrarily change the current and voltage of the power supplied to the electric motor 91. The electric motor 91 transmits driving force to the hydraulic pump P.

[0056] As shown in Figures 4 and 7A, temperature detection devices 110 are provided for the battery 90a, inverter 92b, and electric motor 91. The temperature detection device 110 for the battery 90a is a BMU 123 that acquires the temperature of the battery 90a, but a temperature sensor may also be used. The temperature detection device 110 for the electric motor 91 is a temperature sensor that detects the temperature of the electric motor 91. The temperature detection device 110 for the inverter 92b is a temperature sensor that detects the temperature of the inverter 92b.

[0057] The work machine 1 comprises a hydraulic pump P, a control valve V, a work device 20, an operating device 5, a hydraulic detection device 105, and a control device 120. The hydraulic pump P, the operating device 5, and the hydraulic detection device 105 are connected to the control device 120. The control device 120 drives the work device 20 based on the operation of the operating device 5. The work device 20 is driven by the operation of the hydraulic equipment M of the work system (swing cylinder C1, boom cylinder C2, arm cylinder C3, and bucket cylinder C4) based on the operation of the operating device 5. The control valve V controls the hydraulic cylinders with the hydraulic fluid discharged by the hydraulic pump P. The hydraulic detection device 105 detects the pressure of the hydraulic fluid supplied from the hydraulic pump P to the control valve V and outputs it to the control device 120. The hydraulic detection device 105 is, for example, a pressure sensor or a pressure detection switch.

[0058] Now, the control of the upper limit of the rotational speed of the electric motor 91 in the work machine 1 in the embodiment will be explained using Figure 8. Figure 8 is a diagram showing an example in the work machine 1 in the embodiment in which the upper limit of the rotational speed of the electric motor 91 is changed to the warning upper limit UL3 before the temperature of the electrical equipment 98 reaches the threshold temperature Th.

[0059] As shown in Figure 8, the control device 120 predicts whether the temperature detected by the temperature detection device 110 (i.e., the equipment temperature) will reach the threshold temperature Th at which the output of the electric motor 91 will be limited.

[0060] Figure 9 shows an example of predicting whether the temperature of the electrical equipment 98 in the work machine 1 in the embodiment will reach a threshold temperature Th. As shown in Figures 8 and 9, the control device 120 predicts whether the detected temperature will reach the threshold temperature Th at predetermined judgment cycles (e.g., several tens of seconds, 1 second, etc.) based on the rate of change (ΔT / Δt) of the temperature detected by the temperature detection device 110 per unit time. The rate of change (ΔT / Δt) is the amount of change in the detected temperature from the previous time t10 to the current time t11, as shown in Figure 9.

[0061] For example, as shown in Figure 8, the control device 120 calculates whether the predicted temperature (shown by the predicted line L1) that would occur if the temperature change continued at a rate of change (ΔT / Δt) from the detected temperature at the current time (time t11) could become the predicted target temperature at which the threshold temperature Th is expected to be reached. Subsequently, the control device 120 determines that the temperature of the electrical equipment 98 can become the predicted target temperature (when the predicted line L1 intersects with the line L2 of the threshold temperature Th), and that the predicted time to reach the predicted target temperature (time t13) from the current time (time t11) is within a predetermined period (for example, a few minutes, a few tens of minutes, etc.).

[0062] On the other hand, the control device 120 determines that the temperature will not be reached if the predicted temperature cannot be reached (if the predicted line L1 does not intersect with the threshold temperature line L2), or if the predicted arrival time is outside a predetermined period. Note that the arrival prediction may be made using methods other than those described above.

[0063] As shown in Figure 9, the control device 120 individually predicts the temperatures of the battery 90a, the electric motor 91, and the inverter 92b. For example, in Figure 9, the control device 120 predicts that the temperature of the battery 90a will reach the threshold temperature Th, and predicts that the temperatures of the electric motor 91 and the inverter 92b will not reach the threshold temperature Th.

[0064] As shown in Figure 8, when the temperature detected by the temperature detection device 110 is predicted to reach a threshold temperature Th, the control device 120 sets the upper limit of the rotation speed of the electric motor 91 to a warning upper limit UL3, which is smaller than the upper limit UL1 under normal conditions and larger than the upper limit UL2 under output limiting conditions.

[0065] As shown in Figure 8, the upper limit UL3 during the warning period is the upper limit of the rotational speed of the electric motor 91 at which the electric motor 91 can operate with maximum torque or maximum output. In other words, as shown in Figure 8, even if the upper limit of the rotational speed of the electric motor 91 is determined (changed) to the upper limit UL3 during the warning period (the upper limit is UL3 at time t12), the maximum torque of the electric motor 91 remains constant (it remains constant even after time t11). That is, the maximum torque does not decrease. The upper limit UL3 during the warning period is a value that allows the maximum torque of the electric motor 91 to be maintained.

[0066] Figure 10 shows an example of how the control device 120 determines the upper limit of the rotational speed of the electric motor 91 according to the detected temperature using a function or map. As shown in Figure 10, the control device 120 determines the upper limit of the rotational speed of the electric motor 91 according to the detected temperature using a function or map that shows the relationship between the detected temperature and the upper limit of the rotational speed of the electric motor 91. For example, the control device 120 uses a function or map to determine the upper limit to the normal value UL1 until it is predicted that the detected temperature will reach the threshold temperature Th, and then changes it to the warning upper limit UL3 when it is predicted that the temperature will reach the threshold temperature Th. If the detected temperature does reach the threshold temperature Th, the control device 120 changes it to the output limit upper limit UL2.

[0067] Here, we will describe the case where it is predicted whether the temperature of at least one of the battery 90a and the electric motor 91 will reach a threshold temperature Th. The threshold temperature Th is set for the battery 90a and the electric motor 91, respectively. For example, the threshold temperature Th of the battery 90a and the threshold temperature Th of the electric motor 91 may be the same value or may be different values. When it is predicted that the temperature of either the battery 90a or the electric motor 91 will reach a threshold temperature Th, the control device 120 sets the upper limit of the rotational speed of the electric motor 91 to the upper limit UL3 during alert mode for the battery 90a or the electric motor 91 that is predicted to reach the corresponding threshold temperature Th.

[0068] The memory unit 121 stores the above-mentioned function or map for each battery 90a and electric motor 91. In other words, the memory unit 121 stores a function or map showing the relationship between the detected temperature of the battery 90a and the upper limit of the rotational speed of the electric motor 91, and a function or map showing the relationship between the detected temperature of the electric motor 91 and the upper limit of the rotational speed of the electric motor 91. When the control device 120 predicts that the temperature of the battery 90a will reach the threshold temperature Th, it uses the function or map for the battery 90a to determine the upper limit UL3 for the warning period. On the other hand, when the control device 120 predicts that the temperature of the electric motor 91 will reach the threshold temperature Th, it uses the function or map for the electric motor 91 to determine the upper limit UL3 for the warning period. Note that the upper limit UL3 for the warning period for the battery 90a and the electric motor 91 may be the same value or may be different values.

[0069] When the control device 120 predicts that the temperatures of both the battery 90a and the electric motor 91 will reach their respective threshold temperatures Th, it prioritizes determining the upper limit of the rotational speed of the electric motor 91 based on the upper limit UL3 of the battery 90a during warning. For example, since the battery 90a takes longer to cool than the electric motor 91, the upper limit UL3 of the battery 90a during warning is prioritized to prevent the temperature of the battery 90a from reaching the threshold temperature Th.

[0070] Next, we will describe the case in which it is predicted whether the temperature of at least one of the battery 90a, electric motor 91, and inverter 92b will reach a threshold temperature Th. The control device 120 determines the upper limit of the rotational speed of the electric motor 91 to the upper limit UL3 during the warning period of the battery 90a, electric motor 91, and inverter 92b that is predicted to reach.

[0071] The memory unit 121 stores the above-mentioned function or map for each of the battery 90a, electric motor 91, and inverter 92b. Specifically, the memory unit 121 stores a function or map showing the relationship between the detected temperature of the battery 90a and the upper limit of the rotational speed of the electric motor 91, a function or map showing the relationship between the detected temperature of the electric motor 91 and the upper limit of the rotational speed of the electric motor 91, and a function or map showing the relationship between the detected temperature of the inverter 92b and the upper limit of the rotational speed of the electric motor 91. A threshold temperature Th is set for each of the battery 90a, electric motor 91, and inverter 92b. When the control device 120 predicts that the temperature of the battery 90a will reach the threshold temperature Th, it uses the function or map for the battery 90a to determine the upper limit UL3 for the warning period. On the other hand, when the control device 120 predicts that the temperature of the electric motor 91 will reach the threshold temperature Th, it uses the function or map for the electric motor 91 to determine the upper limit UL3 for the warning period. On the other hand, when the control device 120 predicts that the temperature of the inverter 92b will reach a threshold temperature Th, it determines the upper limit value UL3 for the warning period using a function or map for the electric motor 91. The upper limit value UL3 for the warning period for the battery 90a, the electric motor 91, and the inverter 92b may be the same value or may be different values.

[0072] When the control device 120 predicts that the temperature of the battery 90a and at least one of the electric motor 91 and inverter 92b will reach a threshold temperature Th, it prioritizes determining the upper limit of the rotational speed of the electric motor 91 by using the upper limit UL3 of the battery 90a when it is under alert. For example, the cooling time may be in the following order: battery 90a (e.g., 2 hours) > electric motor 91 (e.g., 30 minutes) > inverter 92b (e.g., 15 minutes). In this case, in order to prevent the temperature of the battery 90a from reaching the threshold temperature Th, the upper limit UL3 of the battery 90a when it is under alert is prioritized. However, if the temperature of the battery 90a is not predicted to reach the threshold temperature Th, but the temperature of at least one of the electric motor 91 and inverter 92b is predicted to reach the threshold temperature Th, the upper limit of the rotational speed of the electric motor 91 may also prioritize determining the upper limit UL3 of the electric motor 91 when it is under alert.

[0073] As shown in Figure 10, the memory unit 121 stores the above-mentioned function or map for each of the battery 90a, electric motor 91, and inverter 92b, but it may also store a single function or map common to these.

[0074] Here, the process by which the control device 120 determines the upper limit of the rotational speed of the electric motor 91 will be explained using Figure 11. Figure 11 is a flowchart showing the process by which the control device 120 determines the upper limit of the rotational speed of the electric motor 91.

[0075] The control device 120 determines whether or not it is the judgment timing, that is, whether or not it is the timing of the aforementioned judgment cycle (for example, several tens of seconds, one second, etc.) (S11). If it is not the judgment timing (No in S11), the control device 120 returns to S11 and waits until the judgment timing arrives. On the other hand, if it is the judgment timing (Yes in S11), the control device 120 proceeds to the process in S12.

[0076] The control device 120 determines whether the temperature detected by the temperature detection device 110 has reached the threshold temperature Th (S12). If the detected temperature has reached the threshold temperature Th (Yes in S12), the control device 120 determines (changes) the upper limit of the rotational speed of the electric motor 91 to the upper limit UL2 during output limiting (S17). For example, the control device 120 determines whether the temperature of the battery 90a, the electric motor 91, and the inverter 92b has reached the threshold temperature Th. If at least one of these temperatures has reached the threshold temperature Th, the control device 120 determines (changes) the upper limit of the rotational speed of the electric motor 91 to the upper limit UL2 during output limiting.

[0077] On the other hand, if the detected temperature has not reached the threshold temperature Th (No in S12), the control device 120 performs a temperature arrival prediction process (S13). As described above with reference to Figures 8 and 9, the control device 120 predicts whether the detected temperature will reach the threshold temperature Th based on the rate of change (ΔT / Δt) of the temperature detected by the temperature detection device 110 per unit time.

[0078] If the control device 120 predicts that the threshold temperature Th will be reached (Yes in S14), it determines (changes) the upper limit of the rotational speed of the electric motor 91 to the upper limit UL3 for the warning state (S15).

[0079] On the other hand, if the control device 120 predicts that the threshold temperature Th will not be reached (No in S14), it sets the upper limit of the rotational speed of the electric motor 91 to the normal upper limit UL1 (S16). In other words, the normal upper limit UL1 is maintained.

[0080] The work machine 1 of the above-described embodiment includes a temperature detection device 110 for detecting the temperature of electrical equipment 98 (battery 90a, electric motor 91, inverter 92b, etc.) and a control device 120 for controlling the rotational speed of the electric motor 91. The control device 120 predicts whether the temperature detected by the temperature detection device 110 will reach a threshold temperature Th at which the output of the electric motor 91 is limited. If it is predicted that the threshold temperature will be reached, the control device 120 sets the upper limit of the rotational speed of the electric motor 91 to a warning upper limit UL3, which is smaller than the upper limit UL1 under normal conditions and larger than the upper limit UL2 when the output is limited.

[0081] Figure 12 shows the effect of determining the upper limit of the rotational speed of the electric motor 91 in the embodiment compared to the conventional method. As shown by the dashed line in Figure 12, conventionally, when the temperature of the electrical equipment 98 reaches the threshold temperature Th, the upper limit of the rotational speed of the electric motor 91 is determined to the upper limit UL2 during output limiting, which limits the torque to a limiting torque smaller than the maximum torque, resulting in a significant functional limitation.

[0082] In contrast, according to the work machine 1 of the above-described embodiment, as shown by the solid line in Figure 12, when it is predicted that the temperature of the electrical equipment 98 will reach the threshold temperature Th, the upper limit of the rotational speed of the electric motor 91 is set to the warning upper limit UL3, which is smaller than the normal upper limit UL1 and larger than the upper limit UL2 when the output is limited. Therefore, before the temperature of the electrical equipment 98 reaches the threshold temperature Th, the upper limit of the rotational speed of the electric motor 91 can be lowered to the warning upper limit UL3, which does not limit the output. As a result, as shown by the solid line in Figure 12, the temperature rise of the electrical equipment 98 can be suppressed or the temperature can be lowered (cooled), and the temperature of the electrical equipment 98 can be prevented from reaching the threshold temperature Th. Therefore, it is possible to prevent the electric motor 91 from entering an output-limited state due to the temperature of the electrical equipment 98 reaching the threshold temperature Th. Thus, it is possible to suppress the occurrence of unintended behavior such as system shutdown due to overheating of the electrical equipment 98.

[0083] Figure 7B is a block diagram showing another example of the main components of the work machine 1 in the embodiment. The work machine 1 may also include an ambient temperature detection device 115 for detecting the ambient temperature, as shown in Figure 7B. Figure 13 is a diagram showing an example of predicting whether the temperature of an electrical device 98 will reach a threshold temperature Th in the work machine 1 in the embodiment, based on the ambient temperature. As shown in Figure 13, the control device 120 may predict whether the detected temperature will reach the threshold temperature Th based on the rate of change of the detected temperature per unit time, based on the ambient temperature. The rate of change (ΔT / Δt) shown in Figure 13 is the amount of change in the detected temperature based on the ambient temperature during the time from the previous time t10 to the current time t11. In this case, it is possible to predict whether the detected temperature will reach the threshold temperature Th by taking the ambient temperature into consideration, so a more favorable prediction can be made.

[0084] <Modified Examples> In the above-described embodiment, as shown in Figure 9, it is predicted whether the temperature of at least one of the battery 90a, electric motor 91, and inverter 92b will reach a threshold temperature Th, but it is not limited to this. Figure 14 shows an example of predicting whether the average temperature of the electrical equipment 98 will reach a threshold temperature Th in the work machine 1 in a modified example. As shown in Figure 14, in the modified example, it is predicted whether the average temperature of at least two or more temperatures of the battery 90a, electric motor 91, and inverter 92b will reach a threshold temperature Th. In the modified example, a configuration different from the above embodiment will be described, and the same configuration will not be described here.

[0085] The control device 120 determines the upper limit of the rotational speed of the electric motor 91 to the upper limit UL3 during alert mode when it is predicted that the average temperature obtained by averaging the temperatures of the battery 90a, electric motor 91, and inverter 92b will reach a threshold temperature Th.

[0086] As shown in Figure 7B, the work machine 1 is equipped with an ambient temperature detection device 115 for detecting the ambient temperature. As shown in Figure 14, the control device 120 predicts whether the average temperature will reach a threshold temperature Th based on the rate of change of the average temperature per unit time, with the ambient temperature as the reference. The rate of change (ΔT / Δt) shown in Figure 14 is the amount of change in the average temperature with respect to the ambient temperature from the previous time t10 to the current time t11.

[0087] Figure 15 shows an example in which the control device 120 of the work machine 1 in a modified example determines the upper limit of the rotational speed of the electric motor 91 according to the detected temperature using a function or map. As shown in Figure 15, the control device 120 determines the upper limit of the rotational speed of the electric motor 91 according to the average temperature using a function or map that shows the relationship between the average temperature and the upper limit of the rotational speed of the electric motor 91. For example, the control device 120 uses a function or map to determine the upper limit to the normal value UL1 until the average temperature is predicted to reach the threshold temperature Th, and then determines the upper limit to the warning value UL3 once it is predicted to reach the threshold temperature. If the average temperature does reach the threshold temperature Th, the control device 120 determines the upper limit to the output limit value UL2.

[0088] According to the modified work machine 1 described above, it is possible to predict whether or not the average temperature will reach the threshold temperature Th by taking the ambient temperature into consideration, thus enabling a more favorable prediction of the temperature reaching the threshold.

[0089] In the embodiment described above, the control device 120 predicts whether the detected temperature of the electrical equipment 98 will reach the threshold temperature Th. However, in making this prediction, or instead of making this prediction, a predetermined warning temperature may be used. When the detected temperature falls below the threshold temperature Th to a predetermined warning temperature, the control device 120 sets the upper limit of the rotational speed of the electric motor 91 to the upper limit UL3 during warning.

[0090] In the modified configuration described above, the control device 120 predicts whether the average temperature will reach the threshold temperature Th. However, a predetermined warning temperature may be used for this prediction, or instead of this prediction. When the average temperature falls below the threshold temperature Th to a predetermined warning temperature, the control device 120 sets the upper limit of the rotational speed of the electric motor 91 to the upper limit UL3 during warning.

[0091] The main characteristic features and effects of the work machine 1 in the embodiments described above are as follows.

[0092] (Item A1) An electrical device 1 comprising an electrical device 98 including a rechargeable battery 90a and an electric motor 91 supplied with power from the battery 90a, a temperature detection device 110 for detecting the temperature of the electrical device 98, and a control device 120 for controlling the rotational speed of the electric motor 91, wherein the control device 120 predicts whether the temperature detected by the temperature detection device 110 will reach a threshold temperature Th at which the output of the electric motor 91 is limited, and if it is predicted that the threshold temperature will reach a threshold temperature Th, the upper limit of the rotational speed of the electric motor 91 is set to a warning upper limit UL3 which is smaller than the upper limit UL1 under normal conditions and larger than the upper limit UL2 when the output is limited.

[0093] With this configuration, when it is predicted that the temperature of the electrical equipment 98 will reach the threshold temperature Th, the upper limit of the rotational speed of the electric motor 91 is set to a warning upper limit UL3, which is smaller than the normal upper limit UL1 and larger than the upper limit UL2 when the output is limited. Therefore, before the temperature of the electrical equipment 98 reaches the threshold temperature Th, the upper limit of the rotational speed of the electric motor 91 can be lowered to the warning upper limit UL3, which does not limit the output. This suppresses the temperature rise of the electrical equipment 98 or lowers (cools) the temperature, and prevents the temperature of the electrical equipment 98 from reaching the threshold temperature Th. Therefore, it is possible to prevent the electric motor 91 from entering an output-limited state due to the temperature of the electrical equipment 98 reaching the threshold temperature Th. Thus, it is possible to suppress the occurrence of unintended behavior such as system shutdown due to overheating of the electrical equipment 98.

[0094] (Item A2) The work machine 1 according to Item A1, wherein the temperature detection device 110 is provided on the battery 90a and the electric motor 91, the threshold temperature Th is set for the battery 90a and the electric motor 91 respectively, and the control device 120 determines the upper limit of the rotational speed of the electric motor 91 to the upper limit UL3 during the warning period for the battery 90a and the electric motor 91 that is expected to reach the corresponding threshold temperature Th.

[0095] With this configuration, when it is predicted that the temperature of the battery 90a or the electric motor 91 will reach a threshold temperature Th, the upper limit of the rotational speed of the electric motor 91 can be set to the upper limit UL3 during the warning period for the battery 90a or the electric motor 91 that is predicted to reach the threshold temperature Th. In other words, the upper limit of the rotational speed of the electric motor 91 can be set to the upper limit UL3 during the warning period corresponding to the electrical equipment 98 that is predicted to reach the threshold temperature Th. Therefore, it is possible to suppress the occurrence of unintended behavior such as system shutdown due to overheating of the battery 90a or the electric motor 91.

[0096] (Item A3) The work machine 1 according to Item A2, wherein when the control device 120 predicts that the temperatures of both the battery 90a and the electric motor 91 will reach the corresponding threshold temperature Th, it prioritizes determining the upper limit of the rotational speed of the electric motor 91 by setting the upper limit of the battery 90a during the warning period, UL3.

[0097] With this configuration, if it is predicted that the temperature of both the battery 90a or the electric motor 91 will reach a threshold temperature Th, the upper limit of the rotational speed of the electric motor 91 is determined by prioritizing the upper limit UL3 of the battery 90a during warning, thereby suppressing output limitations caused by the battery 90a, which takes time to cool down.

[0098] (Item A4) The work machine 1 according to Item A2, wherein the electrical equipment 98 includes an inverter 92b that adjusts the power output from the battery 90a to the electric motor 91, the temperature detection device 110 is further provided on the inverter 92b, the threshold temperature Th is set for the battery 90a, the electric motor 91, and the inverter 92b respectively, and the control device 120 determines the upper limit of the rotational speed of the electric motor 91 to the upper limit UL3 during the warning period for the battery 90a, the electric motor 91, and the inverter 92b that is expected to reach the corresponding threshold temperature Th.

[0099] With this configuration, if it is predicted that the temperature of any of the battery 90a, electric motor 91, or inverter 92b will reach a threshold temperature Th, the upper limit of the rotational speed of the electric motor 91 can be set to the upper limit UL3 during the warning period for the battery 90a, electric motor 91, or inverter 92b that is predicted to reach the threshold temperature Th. In other words, the upper limit of the rotational speed of the electric motor 91 can be set to the upper limit UL3 during the warning period corresponding to the electrical equipment 98 that is predicted to reach that temperature. Therefore, it is possible to suppress the occurrence of unintended behavior such as system shutdown due to overheating of the battery 90a, electric motor 91, and inverter 92b.

[0100] (Item A5) An implement 1 according to any one of items A1 to A4, comprising an ambient temperature detection device 115 for detecting ambient temperature, wherein the control device 120 predicts whether the detected temperature will reach the threshold temperature Th based on the rate of change of the detected temperature per unit time with respect to the ambient temperature.

[0101] With this configuration, it is possible to predict whether the detected temperature will reach the threshold temperature Th, taking into account the ambient temperature, thus enabling a more favorable prediction of temperature arrival.

[0102] (Item A6) The work machine 1 according to Item A1, wherein the electrical equipment 98 includes an inverter 92b that adjusts the power output from the battery 90a to the electric motor 91, the temperature detection device 110 is provided on the battery 90a, the electric motor 91, and the inverter 92b, and the control device 120 determines the upper limit of the rotation speed of the electric motor 91 to the upper limit UL3 during warning when it is predicted that the average temperature obtained by averaging the temperatures of the battery 90a, the electric motor 91, and the inverter 92b will reach the threshold temperature Th.

[0103] With this configuration, it is possible to predict whether or not a threshold temperature Th will be reached based on the average temperature obtained by averaging the detected temperatures of the battery 90a, the electric motor 91, and the inverter 92b.

[0104] (Item A7) The work machine 1 according to Item A6, which is equipped with an ambient temperature detection device 115 for detecting ambient temperature, and the control device 120 predicts whether the average temperature will reach the threshold temperature Th based on the rate of change of the average temperature per unit time with respect to the ambient temperature.

[0105] With this configuration, it is possible to predict whether the average temperature will reach the threshold temperature Th, taking the ambient temperature into consideration, thus enabling a more favorable prediction of temperature arrival.

[0106] (Item A8) The upper limit UL3 during the warning period is the upper limit of the rotational speed of the electric motor 91 at which the electric motor 91 can operate with maximum torque or maximum output, as described in any one of Items A1 to A7.

[0107] With this configuration, the upper limit UL3 during the warning period is the upper limit of the rotational speed at which the electric motor 91 can operate with maximum torque or maximum output, thus ensuring the maximum torque or maximum output of the electric motor 91. For this reason, the electric motor 91 can be used without any functional limitations.

[0108] (Item A9) The control device 120 determines the upper limit of the rotational speed of the electric motor 91 according to the detected temperature using a function or map that shows the relationship between the detected temperature and the upper limit of the rotational speed of the electric motor 91, as described in any one of items A1 to A4 and A8.

[0109] With this configuration, the upper limit of the rotation speed of the electric motor 91 is determined appropriately according to the detected temperature. This is because the upper limit is set to the normal value until the detection temperature is predicted to reach the threshold temperature Th, and then set to the warning upper limit once the threshold temperature is predicted to be reached.

[0110] (Item A10) The control device 120 determines the upper limit of the rotational speed of the electric motor 91 according to the average temperature using a function or map that shows the relationship between the average temperature and the upper limit of the rotational speed of the electric motor 91, as described in Item A6 or A7.

[0111] With this configuration, the upper limit of the rotation speed of the electric motor 91 is determined appropriately according to the average temperature. This is because the upper limit is set to the normal value until the average temperature is predicted to reach the threshold temperature Th, and then set to the warning upper limit once the threshold temperature is predicted to be reached.

[0112] (Item A11) The work machine 1 according to any one of items A1 to A4, A8, wherein the control device 120 determines the upper limit of the rotation speed of the electric motor 91 to the upper limit UL3 during the warning period when the detected temperature falls below a predetermined warning temperature that is lower than the threshold temperature Th.

[0113] With this configuration, when the temperature of the electrical equipment 98 falls below a predetermined warning temperature, which is lower than the threshold temperature Th, the upper limit of the rotational speed of the electric motor 91 is set to a warning upper limit UL3, which is between the normal upper limit UL1 and the upper limit UL2 when the output is limited. Therefore, before the temperature of the electrical equipment 98 reaches the threshold temperature Th, the upper limit of the rotational speed of the electric motor 91 can be lowered to a warning upper limit UL3, which does not limit the output. This suppresses the temperature rise of the electrical equipment 98 or lowers (cools) the temperature, and prevents the temperature of the electrical equipment 98 from reaching the threshold temperature Th. As a result, it is possible to prevent the electric motor 91 from entering an output limit state due to the temperature of the electrical equipment 98 reaching the threshold temperature Th.

[0114] (Item A12) The work machine 1 according to item A6 or A7, wherein when the average temperature falls below a predetermined warning temperature that is lower than the threshold temperature Th, the control device 120 determines the upper limit of the rotation speed of the electric motor 91 to the upper limit UL3 during the warning period.

[0115] With this configuration, when the average temperature of the electrical equipment 98 falls below a predetermined warning temperature, which is lower than the threshold temperature Th, the upper limit of the rotational speed of the electric motor 91 is set to a warning upper limit UL3, which is between the normal upper limit UL1 and the upper limit UL2 when the output is limited. Therefore, before the average temperature of the electrical equipment 98 reaches the threshold temperature Th, the upper limit of the rotational speed of the electric motor 91 can be lowered to a warning upper limit UL3, which does not limit the output. This suppresses the temperature rise of the electrical equipment 98 or lowers (cools) the temperature, and prevents the average temperature of the electrical equipment 98 from reaching the threshold temperature Th. As a result, it is possible to prevent the electric motor 91 from entering an output-limited state due to the average temperature of the electrical equipment 98 reaching the threshold temperature Th.

[0116] In the embodiments and modifications described above, the work machine 1 is an electric slewing work machine 1A such as an electric backhoe, but it is not limited to this. The work machine 1 may be an electric construction work machine such as an electric loader work machine (electric wheel loader, electric compact truck loader, electric skid steer loader, etc.), an electric tractor, an electric utility vehicle (multipurpose work vehicle), or other electric work vehicle.

[0117] Having described the present invention above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope of equivalents of the claims are intended to be included.

[0118] 1. Work equipment 90a. Battery 91. Electric motor 92b. Inverter 98. Electrical equipment 110. Temperature detection device 115. Ambient temperature detection device 120. Control device Th. Threshold temperature UL1. Upper limit under normal conditions UL2. Upper limit under output limit UL3. Upper limit under alert

Claims

1. An electrical device comprising: a rechargeable battery and an electric motor supplied with power from the battery; a temperature detection device for detecting the temperature of the electrical device; and a control device for controlling the rotational speed of the electric motor, wherein the control device predicts whether the temperature detected by the temperature detection device will reach a threshold temperature at which the output of the electric motor is limited, and if it is predicted that the threshold temperature will reach a threshold temperature, it sets the upper limit of the rotational speed of the electric motor to a warning upper limit that is smaller than the upper limit under normal conditions and larger than the upper limit at the time of output limitation.

2. The work machine according to claim 1, wherein the temperature detection device is provided on the battery and the electric motor, the threshold temperature is set for the battery and the electric motor respectively, and the control device determines the upper limit of the rotational speed of the electric motor to the upper limit of the warning period for the battery and the electric motor, which are expected to reach the corresponding threshold temperature.

3. The work machine according to claim 2, wherein the control device, when it is predicted that the temperatures of both the battery and the electric motor will reach the corresponding threshold temperatures, determines the upper limit of the rotational speed of the electric motor by prioritizing the upper limit of the battery during the warning period.

4. The work machine according to claim 2, wherein the electrical equipment includes an inverter that adjusts the power output from the battery to the electric motor, the temperature detection device is further provided on the inverter, the threshold temperature is set for the battery, the electric motor, and the inverter, and the control device determines the upper limit of the rotational speed of the electric motor to the upper limit of the warning period for which the threshold temperature corresponding to the battery, the electric motor, and the inverter is expected to be reached.

5. The work machine according to any one of claims 1 to 4, comprising an ambient temperature detection device for detecting ambient temperature, wherein the control device predicts whether the detected temperature will reach the threshold temperature based on the rate of change of the detected temperature per unit time with respect to the ambient temperature.

6. The work machine according to claim 1, comprising an inverter as the electrical equipment which adjusts the power output from the battery to the electric motor, the temperature detection device which is provided on the battery, the electric motor and the inverter, and the control device which determines the upper limit of the rotational speed of the electric motor to the upper limit of the warning state when it is predicted that the average temperature obtained by averaging the temperatures of the battery, the electric motor and the inverter will reach the threshold temperature.

7. The work machine according to claim 6, comprising an ambient temperature detection device for detecting ambient temperature, wherein the control device predicts whether the average temperature will reach the threshold temperature based on the rate of change of the average temperature per unit time with respect to the ambient temperature.

8. The work machine according to claim 1, wherein the upper limit during the warning period is the upper limit of the rotational speed of the electric motor that can operate at maximum torque or maximum output.

9. The work machine according to any one of claims 1 to 4, 8, wherein the control device determines the upper limit of the rotation speed of the electric motor according to the detected temperature as the upper limit during the warning period, using a function or map that shows the relationship between the detected temperature and the upper limit of the rotation speed of the electric motor.

10. The work machine according to claim 6 or 7, wherein the control device uses a function or map showing the relationship between the average temperature and the upper limit of the rotational speed of the electric motor to determine the upper limit of the rotational speed of the electric motor according to the average temperature as the upper limit during the warning period.

11. The work machine according to any one of claims 1 to 4, 8, wherein the control device determines the upper limit of the rotation speed of the electric motor to the upper limit of the warning state when the detected temperature falls below a predetermined warning temperature.

12. The work machine according to claim 6 or 7, wherein the control device determines the upper limit of the rotation speed of the electric motor to the upper limit during the warning period when the average temperature falls below a predetermined warning temperature.

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