Control method of motor-driven construction machine

Abstract

To appropriately control rotation of a cooling fan in a charging mode of charging a battery.SOLUTION: A control method of a motor-driven construction machine having a cooling fan for cooling a driving system for driving a machine body by a motor-driven motor to which power is supplied from a battery, includes stopping rotation of the cooling fan, when a charging mode of charging the battery while the cooling fan rotates ends.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a control method for an electric construction machine. [Background technology]

[0002] Conventionally, electric construction machines equipped with an electric motor driven by power from an external power source have been proposed. For example, Patent Document 1 discloses a technique in which a second cooling fan is provided in addition to a first cooling fan that is driven by the electric motor to cool a heat exchanger, and the second cooling fan is driven to cool a control panel when the electric motor is stopped. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-84569 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in electric construction machinery, a configuration may be considered in which, in addition to an external power source, for example, a rechargeable battery is used as the drive source for the electric motor. In an electric construction machinery equipped with a battery, a drive system is constructed that drives the machine body with power supplied from the battery or an external power source. In addition to a drive mode in which the drive system is driven, such a drive system may have an operating mode that stops the drive system and charges the battery.

[0005] However, no proposal has been made yet, including in Patent Document 1, regarding control of the rotation of the cooling fan in the charging mode.

[0006] The present invention has been made to solve the above problems, and its object is to provide a control method for an electric construction machine that can appropriately control the rotation of the cooling fan in a charging mode in which the battery is charged. [Means for solving the problem]

[0007] A control method for an electric construction machine according to one aspect of the present invention is a control method for an electric construction machine equipped with a cooling fan that cools a drive system that drives a machine body using an electric motor powered by a battery, the control method comprising: stopping rotation of the cooling fan when a charging mode in which the cooling fan rotates to charge the battery is completed. Effect of the Invention

[0008] According to the above configuration, the rotation of the cooling fan in the charging mode can be appropriately controlled. [Brief description of the drawings]

[0009] [Figure 1] 1 is a side view showing a schematic configuration of a hydraulic excavator, which is an example of an electric construction machine according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view showing a schematic configuration of the inside of an engine room of the hydraulic excavator. [Diagram 3] FIG. 2 is an explanatory diagram showing a circulation path of cooling water in the hydraulic excavator. [Figure 4] FIG. 2 is an explanatory diagram showing a circulation path of hydraulic oil in the above-mentioned hydraulic excavator. [Diagram 5] FIG. 2 is a block diagram illustrating a schematic configuration of a control system of the hydraulic excavator. [Figure 6] 4 is a graph showing the relationship between the temperature of the cooling water and the rotation speed of the cooling fan. [Figure 7] 4 is a graph showing a relationship between the temperature of the hydraulic oil and the rotation speed of the cooling fan. [Figure 8] 5 is a graph showing a relationship between the rotation speed of an electric motor of the hydraulic excavator and the rotation speed of the cooling fan. [Figure 9] 4 is a graph showing a relationship between an output of an inverter included in the hydraulic excavator and the rotation speed of the cooling fan. [Figure 10] 5 is a flowchart showing an operation flow by controlling the rotation of the cooling fan based on the temperature of the coolant, from a drive mode to a charge mode. [Figure 11] 5 is a graph showing an example of transition of the rotation speed of the cooling fan controlled based on the temperature of the cooling water. [Figure 12] 10 is a graph showing another example of transition of the rotation speed of the cooling fan controlled based on the temperature of the cooling water. [Figure 13] 5 is a flowchart showing an operation flow by rotation control of the cooling fan based on temperatures of the coolant and hydraulic oil, from the drive mode to the charge mode. [Figure 14] 10 is a graph showing yet another example of transition of the rotation speed of the cooling fan controlled based on the temperature of the cooling water. [Figure 15] 10 is a graph showing yet another example of transition of the rotation speed of the cooling fan controlled based on the temperature of the cooling water. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The following describes an embodiment of the present invention with reference to the drawings.

[0011] [1. Electric construction machinery] 1 is a side view showing a schematic configuration of a hydraulic excavator 1, which is an example of an electric construction machine of this embodiment. Note that the electric construction machine is not limited to the hydraulic excavator 1, and may be other vehicles such as a wheel loader. The hydraulic excavator 1 includes a lower traveling body 2, a working machine 3, and an upper rotating body 4.

[0012] Here, directions in FIG. 1 are defined as follows. First, the direction in which the lower traveling body 2 moves straight is the fore-aft direction, one side of which is the "front" and the other side is the "rear". In FIG. 1, as an example, the traveling motor 22 side with respect to the blade 23 is shown as the "front". Also, the lateral direction perpendicular to the fore-aft direction is the left-right direction. In this case, the left side as seen from the operator (pilot, driver) sitting in the cockpit 41a is the "left" and the right side is the "right". Furthermore, the direction of gravity perpendicular to the fore-aft and left-right directions is the up-down direction, and the upstream side of the gravity direction is the "up" and the downstream side is the "down".

[0013] (Lower running body) The lower traveling structure 2 includes a pair of left and right crawlers 21 and a pair of left and right traveling motors 22. Each traveling motor 22 is a hydraulic motor. The left and right traveling motors 22 drive the left and right crawlers 21, respectively, to move the hydraulic excavator 1 forward and backward. The lower traveling structure 2 is provided with a blade 23 for performing ground leveling work and a blade cylinder 23a. The blade cylinder 23a is a hydraulic cylinder that rotates the blade 23 up and down.

[0014] (Work equipment) The work machine 3 includes a boom 31, an arm 32, and a bucket 33. By independently driving the boom 31, the arm 32, and the bucket 33, it is possible to perform work of excavating earth and sand, for example.

[0015] The boom 31 is rotated by a boom cylinder 31a. A base end of the boom cylinder 31a is supported on the front part of the upper rotating body 4 and is movable so as to be telescopic. The arm 32 is rotated by an arm cylinder 32a. A base end of the arm cylinder 32a is supported on the tip part of the boom 31 and is movable so as to be telescopic. The bucket 33 is rotated by a bucket cylinder 33a. A base end of the bucket cylinder 33a is supported on the tip part of the arm 32 and is movable so as to be telescopic. The boom cylinder 31a, the arm cylinder 32a, and the bucket cylinder 33a are constituted by hydraulic cylinders.

[0016] (Upper rotating body) The upper rotating body 4 is configured to be rotatable relative to the lower traveling body 2 via a swivel bearing (not shown). A control section 41, a swivel base 42, a swivel motor 43, an engine room 44, etc. are arranged on the upper rotating body 4. The interior of the engine room 44 will be described in detail later. The upper rotating body 4 rotates via the swivel bearing by being driven by the swivel motor 43, which is a hydraulic motor.

[0017] A plurality of hydraulic pumps 71 (see FIG. 2) are disposed on the upper rotating body 4. Each hydraulic pump 71 is driven by an electric motor 63 (see FIG. 2) inside the engine room 44. Each hydraulic pump 71 supplies working oil (pressurized oil) to hydraulic motors (e.g., the left and right travel motors 22, the swing motor 43) and hydraulic cylinders (e.g., the blade cylinder 23a, the boom cylinder 31a, the arm cylinder 32a, the bucket cylinder 33a). The hydraulic motors and hydraulic cylinders that are driven by the supply of working oil from any of the hydraulic pumps 71 are collectively referred to as hydraulic actuators 73 (see FIG. 4).

[0018] A control seat 41a is disposed in the control section 41. Various levers 41b are disposed around the control seat 41a. An operator sits in the control seat 41a and operates the levers 41b to drive the hydraulic actuator 73. This allows the lower traveling body 2 to travel, the blade 23 to perform ground leveling work, the work machine 3 to perform excavation work, the upper rotating body 4 to rotate, and the like.

[0019] The upper rotating body 4 is provided with a power feed port (not shown). The above-mentioned power feed port and a commercial power source 51, which is an external power source, are connected via a power feed cable 52. This makes it possible to drive an electric motor 63 with power supplied from the commercial power source 51. In addition, it is also possible to charge a battery 53 (e.g., a lithium-ion battery) that is detachably attached to the upper rotating body 4 by supplying the power supplied from the commercial power source 51 to the battery 53.

[0020] In addition to the battery 53, a dedicated fan drive power supply 54 for driving a cooling fan F (see FIG. 2) described below is detachably attached to the upper rotating body 4. The fan drive power supply 54 is formed, for example, of a lead battery that outputs a direct current voltage of 12 V. The battery 53 and the fan drive power supply 54 (lead battery) can be replaced with new ones when their performance deteriorates due to long-term use or due to their lifespan.

[0021] The lower traveling body 2, the work machine 3 and the upper rotating body 4 may be configured to include an electric traveling motor, an electric cylinder, an electric swing motor, etc. In this case, the lower traveling body 2, the work machine 3 and the upper rotating body 4 can all be driven by electricity without using hydraulic equipment. In other words, when the lower traveling body 2, the work machine 3 and the upper rotating body 4 are collectively defined as the machine body BA, the machine body BA may be driven only by electricity (all electric), or may be driven by a combination of electricity and hydraulic equipment. Therefore, it can be said that the hydraulic excavator 1 of this embodiment is configured to include at least the machine body BA driven by electricity.

[0022] [2. Internal structure of engine room] Fig. 2 is a plan view showing a schematic outline of the internal configuration of the engine room 44. For convenience, Fig. 2 omits the illustration of the top surface of the engine room 44 and illustrates only one hydraulic pump 71. In addition to the battery 53 and hydraulic pump 71 described above, an inverter 62, an electric motor 63, a heat exchanger HE, a cooling fan F, a hydraulic oil tank 74, and the like are provided inside the engine room 44. The hydraulic oil tank 74 contains hydraulic oil for driving the hydraulic actuator 73. A power supply unit 61 (see Fig. 3) is also provided in the engine room 44.

[0023] (power supply, inverter) The power supply device 61 converts the AC voltage supplied from the commercial power supply 51 via the power supply cable 52 into a DC voltage. The inverter 62 converts the DC voltage output from the power supply device 61 or the DC voltage supplied from the battery 53 into an AC voltage and supplies it to the electric motor 63.

[0024] In a drive mode, which will be described later, an AC voltage output from the inverter 62 is supplied to the electric motor 63 to drive the electric motor 63. On the other hand, in a charge mode, which will be described later, a DC voltage output from the power supply device 61 is supplied to the battery 53 to charge the battery 53.

[0025] (Electric motor) The electric motor 63 is driven by power supplied from at least one of the commercial power source 51 and the battery 53 via the inverter 62. The electric motor 63 is disposed in the engine room 44 so that the rotation shaft of the motor is oriented in the left-right direction, for example, but is not limited to this arrangement. The battery 53 described above is disposed above the electric motor 63. Furthermore, the cockpit 41a is disposed above the battery 53 via a seat mount. The positional relationship between the electric motor 63 and the battery 53 is also not limited to the above example.

[0026] A hydraulic pump 71 is connected to a rotating shaft (output shaft) of the electric motor 63. The hydraulic pump 71 supplies hydraulic oil in a hydraulic oil tank 74 to a hydraulic actuator 73 via a hydraulic valve 72 (see FIG. 4).

[0027] (Heat exchange device) The heat exchanger HE is located in the engine room 44 on the opposite side of the hydraulic pump 71 with respect to the electric motor 63. The heat exchanger HE includes a first heat exchanger HE1 and a second heat exchanger HE2.

[0028] First heat exchange device The first heat exchanger HE1 is composed of a radiator that exchanges heat with the cooling medium. The cooling medium cools the electric motor 63 and the like by circulating in a circulation path that passes through the electric motor 63 and the like. Note that, although water (hereinafter referred to as "cooling water") is used as the cooling medium in this embodiment, a medium other than water (for example, oil) may also be used.

[0029] 3 is an explanatory diagram showing the circulation path of the cooling water. The cooling water circulates through the power supply device 61, inverter 62, electric motor 63, first heat exchange device HE1, water tank 64, and electric water pump 65 in that order. In the first heat exchange device HE1, high-temperature cooling water supplied from the electric motor 63 is cooled by heat exchange using air blown from a cooling fan F, and the cooled water is returned to the water tank 64. By circulating the cooling water, devices such as the electric motor 63 can be cooled.

[0030] The power supply device 61, inverter 62, electric motor 63, and electric water pump 65 constitute a drive system DS that drives the machine body BA (see FIG. 1) with electricity. That is, the hydraulic excavator 1 as an electric construction machine of this embodiment is equipped with a drive system DS that drives the machine body BA with electricity. The hydraulic excavator 1 is also equipped with a heat exchanger HE (for example, a first heat exchanger HE1) that performs heat exchange of a cooling medium for cooling the drive system DS.

[0031] In this embodiment, the power supply device 61, the inverter 62, and the electric motor 63 included in the drive system DS are all water-cooled, but some of them may be air-cooled. For example, the electric motor 63 may be air-cooled and the inverter 62 may be water-cooled.

[0032] Second heat exchange device The second heat exchanger HE2 is composed of an oil cooler that performs heat exchange on the hydraulic oil used to drive the hydraulic actuator 73. The hydraulic oil also circulates through a circulation path within the hydraulic excavator 1, similar to the cooling water.

[0033] 4 is an explanatory diagram showing the circulation path of the hydraulic oil. The hydraulic oil circulates through the hydraulic pump 71, hydraulic valve 72, hydraulic actuator 73, second heat exchanger HE2, and hydraulic oil tank 74 in that order. In the second heat exchanger HE2, the high-temperature hydraulic oil supplied from the hydraulic actuator 73 is cooled by air blown from a cooling fan F and returned to the hydraulic oil tank 74. When the hydraulic oil becomes hot, its properties (e.g., viscosity) deteriorate, and its performance such as lubrication deteriorates. Therefore, by cooling the hydraulic oil in the second heat exchanger HE2, it is possible to suppress the deterioration of the performance of the hydraulic oil.

[0034] The above-mentioned hydraulic pump 71, hydraulic valve 72, and hydraulic actuator 73 are used together with the power supply device 61, inverter 62, electric motor 63, and electric water pump 65 that constitute the drive system DS. Therefore, the hydraulic pump 71, hydraulic valve 72, and hydraulic actuator 73 are also included in the above-mentioned drive system DS that drives the aircraft BA (see FIG. 1). In other words, the drive system DS includes the electric motor 63, the hydraulic pump 71 driven by the electric motor 63, and the hydraulic actuator 73 driven by the hydraulic oil supplied from the hydraulic pump 71. Then, the heat exchanger HE (second heat exchanger HE2) performs heat exchange with the hydraulic oil.

[0035] (Cooling fan) The cooling fan F is located on the electric motor 63 side with respect to the heat exchange device HE, and sends air toward the heat exchange device HE (first heat exchange device HE1, second heat exchange device HE2). Such a cooling fan F includes a motor driven by power supplied from the above-mentioned fan drive power supply 54, and a rotary fan rotated by the above-mentioned motor. The air blown by the cooling fan F toward the heat exchange device HE and warmed by heat exchange with the cooling water and hydraulic oil is discharged to the outside of the engine room 44 through slits (not shown) provided in a side wall or top surface of the engine room 44.

[0036] In this embodiment, one cooling fan F is configured to send air to both the first heat exchange device HE1 and the second heat exchange device HE2, but it may be configured to send air to only one of the first heat exchange device HE1 and the second heat exchange device HE2. For example, when the first heat exchange device HE1 and the second heat exchange device HE2 are arranged apart from each other in the engine room 44, a cooling fan F may be provided corresponding to each of the first heat exchange device HE1 and the second heat exchange device HE2, and each cooling fan F may send air separately to each of the first heat exchange device HE1 and the second heat exchange device HE2.

[0037] In other words, the heat exchanger HE to which one cooling fan F blows air may be both the first heat exchanger HE1 and the second heat exchanger HE2, may be only the first heat exchanger HE1, or may be only the second heat exchanger HE2. In this case, it can be said that the cooling fan F is only required to be configured to blow air toward the heat exchanger HE that exchanges heat with at least one of the cooling water and the hydraulic oil.

[0038] That is, the hydraulic excavator 1 as an electric construction machine of this embodiment is provided with a cooling fan F that sends air for cooling the heat exchanger HE.

[0039] The cooling method using the cooling fan F includes a suction method and a discharge method. The suction method is a method in which air is sucked in from the outside to the inside to cool the heat exchanger HE. Therefore, in the suction method, air flows in the following order: outside of the hydraulic excavator 1, cooling fan F, heat exchanger HE, inside, and outside. In contrast, the discharge method is a method in which air is sucked in from the outside and then discharged inside to the heat exchanger HE by the cooling fan F. Therefore, in the discharge method, air flows in the following order: outside of the hydraulic excavator 1, inside, cooling fan F, heat exchanger HE, and outside. In this embodiment, either the suction method or the discharge method can be adopted as the cooling method using the cooling fan F.

[0040] 3. Control System Configuration 5 is a block diagram showing a schematic configuration of a control system of the hydraulic excavator 1. The hydraulic excavator 1 further includes an operation mode selection unit 45, a control unit 80, and a parameter detection unit 90 in addition to the above configuration.

[0041] (Operation mode selection section) The operation mode selection unit 45 is provided around the cockpit 41a in Fig. 1, and is operated by an operator to select an operation mode of the electric motor 63. This operation mode selection unit 45 includes, for example, a key, a push button, a lever, a touch panel display device, etc. The operation mode of the electric motor 63 can be set and switched by turning a key, turning a push button on / off, operating a lever, inputting an instruction via the touch panel, etc.

[0042] Here, the operation modes of the electric motor 63 include a drive mode and a charge mode. The drive mode is an operation mode in which the electric motor 63 is driven to drive the drive system DS by power supply only from the battery 53 or by power supply from both the commercial power supply 51 and the battery 53. In the drive mode, the electric motor 63 is driven to drive the hydraulic pump 71 to supply hydraulic oil to the hydraulic actuator 73. This allows the hydraulic actuator 73 to be driven.

[0043] On the other hand, the charge mode is an operation mode in which the drive system DS is stopped and the battery 53 that stores electric power is charged. In the charge mode, electric power is supplied from the commercial power source 51 to the battery 53 via the power supply 61. This causes the battery 53 to be charged.

[0044] Thus, the above operation modes include a drive mode in which the drive system DS is driven, and a charge mode in which the drive system DS is stopped from being driven and the battery 53 that stores electric power is charged.

[0045] (Control unit) The control unit 80 is configured with an electronic control unit called an ECU (Electronic Control Unit). The control unit 80 includes a main control unit 80a, a cooling fan control unit 80b, and a storage unit 80c. The main control unit 80a and the cooling fan control unit 80b are configured with a common CPU (Central Processing Unit), for example, but may be configured with separate CPUs.

[0046] The main control unit 80a controls the operation of each unit in the hydraulic excavator 1 other than the cooling fan F. The cooling fan control unit 82 controls the rotation of the cooling fan F in accordance with the operation mode of the drive system DS. In other words, the hydraulic excavator 1 is equipped with the cooling fan control unit 82 that controls the rotation of the cooling fan F in accordance with the operation mode set (by the operation mode selection unit 45). The control of the rotation of the cooling fan F by the cooling fan control unit 82 will be described in detail later. The cooling fan control unit 82 includes a drive circuit that sends a drive signal to the cooling fan F to rotate the cooling fan F.

[0047] The storage unit 80c is a memory that stores various information such as operation programs of the main control unit 80a and the cooling fan control unit 80b, as well as tables described later. The storage unit 80c includes a RAM (Random Access Memory), a ROM (Read Only Memory), and the like.

[0048] (Parameter detection section) The parameter detection unit 90 detects parameters that change depending on the driving state of the drive system DS. The parameters include the coolant temperature, the hydraulic oil temperature, and the rotation speed of the electric motor 63. To detect these parameters, the parameter detection unit 90 includes a coolant temperature sensor 90a, a hydraulic oil temperature sensor 90b, and an electric motor rotation speed detection sensor 90c.

[0049] The coolant temperature sensor 90a is a sensor that detects the temperature of the coolant. The coolant temperature sensor 90a is installed, for example, at the inlet of the power supply device 61, but the installation position is not limited to the inlet of the power supply device 61 as long as it is installed at a position where the temperature of the coolant can be detected within the circulation path of the coolant shown in FIG.

[0050] The hydraulic oil temperature sensor 90b is a sensor that detects the temperature of the hydraulic oil. The hydraulic oil temperature sensor 90b is installed, for example, inside the hydraulic oil tank 74, but the installation position is not limited to inside the hydraulic oil tank 74 as long as it is installed at a position where the temperature of the hydraulic oil can be detected within the circulation path shown in FIG.

[0051] The coolant temperature sensor 90a and the hydraulic oil temperature sensor 90b are each constituted by, for example, a thermistor, but may also be constituted by other sensors (for example, a thermocouple, a resistance temperature detector, etc.).

[0052] The electric motor rotation speed detection sensor 90c is a sensor that detects the rotation speed itself of the electric motor 63. The electric motor rotation speed detection sensor 90c is configured using a resolver, an encoder, a Hall element, etc. The cooling fan control unit 80b calculates the rotation speed of the cooling fan F based on the value detected by the electric motor rotation speed detection sensor 90c and outputs it as a CAN (Controller Area Network) communication signal, but is not limited to this configuration.

[0053] The inverter 62 includes a sensor 62a therein, and calculates and outputs power from the voltage and current detected by the sensor 62a. The power output by the inverter 62 also constitutes a parameter that changes depending on the driving state of the drive system DS.

[0054] Here, for example, as the rotational speed of the electric motor 63 increases, the heat generation amount of the electric motor 63 increases, and the heat generation amount of the hydraulic actuator 73 using the electric motor 63 as a power source also increases. For this reason, due to the heat transfer from the electric motor 63, the temperature of the cooling water rises, and due to the heat transfer from the hydraulic actuator 73, the temperature of the hydraulic oil rises. Also, when the rotational speed of the electric motor 63 increases, the output of the inverter 62 that supplies power to the electric motor 63 naturally increases.

[0055] Therefore, by the parameter detection unit 90 detecting, as parameters, the temperature of the cooling water, the temperature of the hydraulic oil, or the rotational speed of the electric motor 63, or by the inverter 62 calculating and obtaining the output power, the cooling fan control unit 80b can determine the driving state (low load / high load, driving / stopped state) of the drive system DS (for example, the electric motor 63) based on the above parameters.

[0056] Also, as described above, the temperature of the cooling water, the temperature of the hydraulic oil, the rotational speed of the electric motor 63, and the output of the inverter 62 change according to the heat generation state of the drive system DS (for example, the electric motor 63). Therefore, it can be said that the driving state of the drive system DS is detected by parameters (the temperature of the cooling water, the temperature of the hydraulic oil, the rotational speed of the electric motor 63, the output of the inverter 62) that change according to the heat generation state of the drive system DS.

[0057] [4. Rotational Control of Cooling Fan] In the present embodiment, the above-described cooling fan control unit 80b controls the rotation of the cooling fan F based on the above parameters in each of the drive mode and the charging mode. Hereinafter, the rotational control of the cooling fan F in each operation mode will be described.

[0058] [A. Rotational Control of Cooling Fan in Drive Mode] When the operation mode selection unit 45 selects the drive mode as the operation mode of the drive system DS (for example, the electric motor 63), the cooling fan control unit 80b controls the rotation speed C of the cooling fan F in the drive mode based on a parameter detected in the drive mode (for example, any one of the coolant temperature, the hydraulic oil temperature, the rotation speed of the electric motor 63, and the output of the inverter 62). More specifically, this is as follows.

[0059] (A-1. Cooling fan rotation control based on cooling water temperature) FIG. 6 shows the relationship between the cooling water temperature D (℃) and the (target) rotation speed C (rpm: revolutions per minute, 1 rpm = 1 / 60 s) of the cooling fan F to be controlled in drive mode with respect to the cooling water temperature D. -1 6 is a graph showing the relationship between the temperature D of the cooling water and the target rotation speed C of the cooling fan F. There is a nearly linear relationship between the temperature D of the cooling water and the target rotation speed C of the cooling fan F. In this embodiment, the relationship shown in FIG. 6 is stored in advance in the form of a table in the memory unit 80c of the control unit 80.

[0060] In the drive mode, the cooling fan control unit 80b determines the rotation speed C of the cooling fan F based on the table of Fig. 6 from the temperature D of the cooling water detected by the cooling water temperature sensor 90a, and rotates the cooling fan F at the determined rotation speed C. For example, in the drive mode, when the cooling water temperature sensor 90a detects the temperature D1 (°C), the cooling fan control unit 80b determines the rotation speed C11 (rpm) of the cooling fan F corresponding to the temperature D1 from the table of Fig. 6, and rotates the cooling fan F at the determined rotation speed C11. Also, for example, in the drive mode, when the cooling water temperature sensor 90a detects the temperature D2 (°C) (>D1), the cooling fan control unit 80b determines the rotation speed C12 (rpm) (>C11) of the cooling fan F corresponding to the temperature D2 from the table of Fig. 6, and rotates the cooling fan F at the determined rotation speed C12.

[0061] (A-2. Cooling fan rotation control based on hydraulic oil temperature) 7 is a graph showing the relationship between the hydraulic oil temperature G (°C) and the rotation speed C of the cooling fan F to be controlled in the drive mode with respect to the hydraulic oil temperature G. There is a nearly linear relationship between the hydraulic oil temperature G and the target rotation speed C of the cooling fan F. In this embodiment, the relationship shown in FIG. 7 is pre-stored in the form of a table in the memory unit 80c of the control unit 80.

[0062] In the drive mode, the cooling fan control unit 80b determines the rotation speed C of the cooling fan F to be controlled based on the temperature G of the hydraulic oil detected by the hydraulic oil temperature sensor 90b based on the table of FIG. 7, and rotates the cooling fan F at the determined rotation speed C. For example, in the drive mode, when the hydraulic oil temperature sensor 90b detects the temperature G1 (°C), the cooling fan control unit 80b determines the rotation speed C21 (rpm) of the cooling fan F corresponding to the temperature G1 based on the table of FIG. 7, and rotates the cooling fan F at the determined rotation speed C21. Also, for example, in the drive mode, when the hydraulic oil temperature sensor 90b detects the temperature G2 (°C) (>G1), the cooling fan control unit 80b determines the rotation speed C22 (rpm) (>C21) of the cooling fan F corresponding to the temperature G2 based on the table of FIG. 7, and rotates the cooling fan F at the determined rotation speed C22.

[0063] (A-3. Controlling the rotation of the cooling fan based on the rotation speed of the electric motor) 8 is a graph showing the relationship between the rotation speed M (rpm) of the electric motor and the rotation speed C of the cooling fan F to be controlled in the drive mode with respect to the rotation speed M. There is a nearly linear relationship between the rotation speed M of the electric motor and the target rotation speed C of the cooling fan F. In this embodiment, the relationship shown in FIG. 8 is stored in advance in the form of a table in the memory unit 80c of the control unit 80.

[0064] In the drive mode, the cooling fan control unit 80b determines the rotation speed C of the cooling fan F based on the rotation speed M of the electric motor 63 detected by the electric motor rotation speed detection sensor 90c, based on the table of Fig. 8, and rotates the cooling fan F at the determined rotation speed C. For example, in the drive mode, when the electric motor rotation speed detection sensor 90c detects the rotation speed M1 (rpm) of the electric motor 63, the cooling fan control unit 80b determines the rotation speed C31 (rpm) of the cooling fan F corresponding to the rotation speed M1 from the table of Fig. 8, and rotates the cooling fan F at the determined rotation speed C31.

[0065] (A-4. Cooling fan rotation control based on inverter output) 9 is a graph showing the relationship between the output P (W) of the inverter 62 and the rotation speed C of the cooling fan F to be controlled in the drive mode with respect to the output P. There is a nearly linear relationship between the output P of the inverter 62 and the target rotation speed C of the cooling fan F. In this embodiment, the relationship shown in FIG. 9 is pre-stored in the form of a table in the memory unit 80c of the control unit 80.

[0066] In the drive mode, the cooling fan control unit 80b determines the rotation speed C of the cooling fan F from the output P of the inverter 62 based on the table of Fig. 9, and rotates the cooling fan F at the determined rotation speed C. For example, in the drive mode, when the inverter 62 detects the output P1 (W), the cooling fan control unit 80b determines the rotation speed C41 (rpm) of the cooling fan F corresponding to the output P from the table of Fig. 9, and rotates the cooling fan F at the determined rotation speed C41.

[0067] The cooling fan control unit 80b can select one of the four parameters mentioned above (cooling water temperature D, hydraulic oil temperature G, rotation speed M of the electric motor 63, and output P of the inverter 62) and control the rotation speed C of the cooling fan F based on the selected parameter.

[0068] Thus, in the drive mode, the cooling fan control unit 80b controls the rotation speed C of the cooling fan F based on a parameter that changes according to the heat generation state of the drive system DS (for example, the electric motor 63). As a result, in the drive mode, it is possible to realize rotation control of the cooling fan F according to the drive state of the drive system DS. That is, in the drive mode, the rotation speed C of the cooling fan F is changed according to the drive state of the electric motor 63, and the cooling fan F can be rotated without causing an excess or deficiency in the rotation speed C. Therefore, it is possible to suppress the occurrence of insufficient cooling of the cooling water or insufficient cooling of the hydraulic oil in the heat exchanger HE due to insufficient rotation of the cooling fan F. As a result, it is possible to suppress the occurrence of failures caused by heat generation of the electric motor 63 and performance degradation due to high temperature of the hydraulic oil, while rotating the cooling fan F at the minimum necessary rotation speed C, thereby suppressing power consumption to the minimum necessary.

[0069] In particular, it is desirable that the cooling fan control unit 80b controls the rotation speed C of the cooling fan F in the drive mode based on the temperature of the cooling medium as a parameter. Note that the cooling medium is, for example, cooling water, but as described above, it may also be oil.

[0070] Although the rotation speed M of the electric motor 63 and the output P of the inverter 62 may change suddenly in a short time, the temperature of the cooling medium (for example, the temperature D of the cooling water) changes smoothly according to the driving state of the electric motor 63 and does not change suddenly in a short time. Therefore, in the driving mode, by controlling the rotation speed C of the cooling fan F based on the temperature of the cooling medium, it becomes relatively easy to control the rotation of the cooling fan F.

[0071] In the above, in the driving mode, an example has been described in which the cooling fan control unit 80b controls the rotation speed C of the cooling fan F based on any one of a plurality of parameters. However, the rotation speed C of the cooling fan F may also be controlled by combining a plurality of parameters. For example, the cooling fan control unit 80b may control the rotation speed C of the cooling fan F in the driving mode based on both the temperature D of the cooling medium (e.g., cooling water) and the temperature G of the hydraulic oil as parameters. In this case, it becomes possible to set the rotation speed C of the cooling fan F that can obtain the effect of sufficiently cooling both the cooling water and the hydraulic oil.

[0072] For example, in the driving mode, assume that the temperature of the cooling water detected by the cooling water temperature sensor 90a is D1, and the temperature of the hydraulic oil detected by the hydraulic oil temperature sensor 90b is G1. And assume that the rotation speed C11 corresponding to the temperature D1 is higher than the rotation speed C21 corresponding to the temperature G1 of the hydraulic oil. At this time, the cooling fan control unit 80b controls the rotation speed C of the cooling fan F in the driving mode to the higher one (e.g., C11) among the rotation speed (C11) corresponding to the temperature of the cooling medium (e.g., D1) and the rotation speed (e.g., C21) corresponding to the temperature of the hydraulic oil (e.g., G1).

[0073] In this case, by the rotation of the cooling fan F at the rotation speed C11, both the cooling effect of the cooling water and the cooling effect of the hydraulic oil can be obtained. In particular, for the hydraulic oil, since the cooling fan F rotates at a rotation speed C11 higher than the rotation speed C21 required for cooling, the cooling effect is more promoted. However, when prioritizing the cooling effect of the hydraulic oil (the effect of suppressing the performance degradation due to the high temperature of the hydraulic oil) over the power consumption reduction effect, such rotation control of the cooling fan F becomes very effective.

[0074] <B. Rotation Control of Cooling Fan in Charging Mode> Next, the rotation control of the cooling fan F in the charging mode will be described. Here, the description includes the transition of the operation mode from the driving mode to the charging mode.

[0075] (B-1. Rotation Control Based on Temperature of Cooling Water) 10 is a flowchart showing the flow of operation by the rotation control of the cooling fan F based on the coolant temperature D, from the drive mode to the charge mode. When the electric motor 63 starts to be driven (S1), the rotation control of the cooling fan F is performed in the drive mode, for example, based on the coolant temperature D. This causes the cooling fan F to rotate at a rotation speed according to the drive state of the electric motor 63 (S2). If the charge mode is not selected by the operation mode selection unit 45 (No in S3), the rotation control of the cooling fan F in S2 continues.

[0076] When a predetermined time (e.g., t11 (min)) has elapsed since the electric motor 63 started to be driven and the charging mode is selected by the operation mode selection unit 45 (Yes in S3), the driving of the electric motor 63 is stopped and the charging mode is entered. Then, the parameter detection unit 90 (e.g., the coolant temperature sensor 90a) detects the coolant temperature D (S4), similar to the driving mode. The detection timing of the coolant temperature D in the charging mode may be immediately after entering the charging mode, or may be a timing when a predetermined time (e.g., several seconds) has elapsed since entering the charging mode.

[0077] Then, the cooling fan control unit 80b determines whether the coolant temperature D detected by the coolant temperature sensor 90a is equal to or lower than a predetermined threshold value (coolant threshold value Dth (° C.)) (S5).

[0078] For example, when the temperature of the cooling water detected in the charging mode is D1, and the temperature D1 is equal to or lower than the cooling water threshold value Dth as shown in FIG. 6 (Yes in S5), the cooling fan control unit 80b sets the rotation speed C of the cooling fan F to a lower rotation speed (e.g., C13 (rpm)) than the rotation speed controlled in the driving mode (e.g., the rotation speed C11 corresponding to the temperature D1), and rotates the cooling fan F at the rotation speed C13 (S6). That is, when the parameter (detected by the parameter detection unit 90) is equal to or lower than the threshold value, the cooling fan control unit 80b sets the rotation speed of the cooling fan F in the driving mode (the rotation speed corresponding to the value of the parameter in the driving mode) as the charging mode rotation speed. Note that the charging mode rotation speed means the rotation speed of the cooling fan F in the charging mode (hereinafter, the same applies).

[0079] If the coolant temperature D1 is a low temperature equal to or lower than the coolant threshold Dth, the cooling fan control unit 80b can determine that the electric motor 63 was driven at a relatively low load in the drive mode before entering the charging mode. When the electric motor 63 is driven at a low load, the amount of heat generated by the electric motor 63 is small, so that even if the rotation speed of the cooling fan F is reduced in the charging mode, a failure due to heat generated by the electric motor 63 is unlikely to occur. Therefore, in this case, the cooling fan control unit 80b determines that the rotation speed of the cooling fan F can be changed from the drive mode. Based on such a determination, the rotation speed of the cooling fan F in the charging mode is reduced below that in the drive mode, thereby making it possible to reduce the power consumed by the rotation of the cooling fan F.

[0080] On the other hand, if the coolant temperature detected in the charging mode is, for example, D2 and this temperature D2 exceeds the coolant threshold value Dth (No in S5), the cooling fan control unit 80b rotates the cooling fan F at the same rotation speed as the rotation speed controlled in the driving mode (for example, the rotation speed C12 corresponding to the temperature D2) (S7). That is, when the parameter (detected by the parameter detection unit 90) exceeds the threshold value, the cooling fan control unit 80b sets the rotation speed of the cooling fan F in the driving mode as the charging mode rotation speed. In other words, when the above parameter exceeds the threshold value, the cooling fan control unit 80b maintains the rotation speed of the cooling fan F in the charging mode at the rotation speed of the cooling fan (corresponding to the value of the above parameter) in the driving mode.

[0081] If the coolant temperature D2 is high and exceeds the coolant threshold Dth, the cooling fan control unit 80b can determine that the electric motor 63 is driven under high load in the drive mode. When the electric motor 63 is driven under high load, a breakdown due to heat generated by the electric motor 63 is likely to occur. Therefore, in this case, the cooling fan control unit 80b determines that the rotation speed of the cooling fan F should not be changed from that in the drive mode, and based on this determination, rotates the cooling fan F at the same rotation speed in the charge mode as in the drive mode.

[0082] As a result, in the charging mode, the cooling fan F maintains the same blowing strength as in the driving mode, and heat exchange with the coolant in the heat exchanger HE is promoted. Therefore, the cooling effect on the coolant can be improved in the charging mode. As a result, it is possible to reduce the occurrence of breakdowns in the electric motor 63 due to heat generated in the driving mode, and the safety of the equipment can be ensured.

[0083] In addition to electric motor 63, power supply device 61 and inverter 62 are also present in the circulation path of the cooling water (see FIG. 3). Like electric motor 63, power supply device 61 and inverter 62 generate heat due to electric power. In particular, like electric motor 63, inverter 62 increases its heat temperature as the workload increases. Therefore, improving the cooling effect of the cooling water as described above also leads to a reduction in failures caused by heat generated by power supply device 61 and inverter 62.

[0084] Furthermore, in a configuration in which the heat exchanger HE includes the second heat exchanger HE2, the heat exchange of the hydraulic oil is also promoted by ensuring the blowing strength of the cooling fan F. This enhances the cooling effect on the hydraulic oil in the charging mode, and also suppresses performance degradation due to high temperatures of the hydraulic oil.

[0085] When charging of the battery 53 is completed and the charging mode ends (S8) after a predetermined time (e.g., t21 (min)) has elapsed since the electric motor 63 started to be driven, the cooling fan control unit 80b stops the rotation of the cooling fan F (S9) and ends the rotation control of the cooling fan F. As a result, when the rotation control of S6 is performed, the transition of the rotation speed C of the cooling fan F will be as shown in FIG. 11. On the other hand, when the rotation control of S7 is performed, the transition of the rotation speed C of the cooling fan F will be as shown in FIG. 12 (no change in rotation speed).

[0086] As described above, the cooling fan control unit 80b sets the rotation speed of the cooling fan F in the charge mode to the charge mode rotation speed that corresponds to the drive state (in the drive mode) of the drive system DS (S6, S7).

[0087] This makes it possible to obtain an effect according to the driving state of the drive system DS. For example, when the drive system DS (electric motor 63) is driven under high load in the drive mode, the charging mode rotation speed of the cooling fan F can be set to be equal to the rotation speed in the drive mode, thereby reducing failure of the drive system DS caused by heat generated in the drive mode. On the other hand, when the drive system DS is driven under low load in the drive mode, for example, the charging mode rotation speed of the cooling fan F can be set to a lower rotation speed than the rotation speed in the drive mode, thereby reducing power consumption.

[0088] In particular, in S6, the charge mode rotation speed is lower than the rotation speed of the cooling fan F in the drive mode. Therefore, when the drive system DS is driven under low load, it is possible to obtain the effect of reducing power consumption.

[0089] Furthermore, in the charging mode, when a parameter (for example, the temperature of the cooling water) is equal to or lower than a threshold value, the cooling fan control unit 80b sets a rotation speed of the cooling fan F lower than the rotation speed in the driving mode as the charging mode rotation speed (S6). This makes it possible to reduce the power consumed by the rotation of the cooling fan F.

[0090] On the other hand, in the charging mode, if the parameter exceeds the threshold value, the cooling fan control unit 80b sets the rotation speed of the cooling fan F in the driving mode as the charging mode rotation speed (S7). In this case, in the charging mode, strong airflow is maintained to the heat exchanger HE, and heat exchange with the coolant is promoted. This improves the cooling effect of the coolant, and can reduce equipment failures or suppress deterioration of the hydraulic oil performance.

[0091] Moreover, the cooling fan control unit 80b controls the rotation speed of the cooling fan F in the charging mode based on the temperature of the cooling medium (for example, the temperature D of the cooling water) as a parameter (S5 to S7).

[0092] As described in the rotation control of the cooling fan F in the drive mode, the temperature of the cooling medium changes smoothly according to the drive state of the electric motor 63, and does not change suddenly in a short period of time. The same is true in the charge mode, where the temperature of the cooling medium changes smoothly (for example, decreases) after the electric motor 63 stops. For this reason, in the charge mode, the control becomes easier by controlling the rotation speed of the cooling fan 61 based on the temperature of the cooling medium.

[0093] (B-2. Rotation control based on cooling water temperature and hydraulic oil temperature) The rotation control of the cooling fan F in the charging mode described above may be performed using the temperature G of the hydraulic oil in addition to the temperature D of the cooling water as a parameter.

[0094] Fig. 13 is a flowchart showing the flow of operation by the rotation control of the cooling fan F based on the coolant temperature and the hydraulic oil temperature G, from the drive mode to the charge mode. In Fig. 13, the process after No in S5 is slightly different from that in Fig. 10. The points different from Fig. 10 will be described below.

[0095] If the result of S5 is No, that is, if the coolant temperature detected in charging mode is, for example, D2 and this temperature D2 exceeds the coolant threshold value Dth, the cooling fan control unit 80b determines whether the hydraulic oil temperature G detected by the hydraulic oil temperature sensor 90b is below a predetermined threshold value (hydraulic oil threshold value Gth (°C)) (S5-1).

[0096] For example, if the temperature of the hydraulic oil detected in the charging mode is G1, and as shown in FIG. 7, the temperature G1 is equal to or lower than the hydraulic oil threshold value Gth (Yes in S5-1), the cooling fan control unit 80b rotates the cooling fan F at the same rotation speed as that controlled in the drive mode (for example, a rotation speed corresponding to the coolant temperature (for example, rotation speed C12 corresponding to coolant temperature D2)) (S7-1), and then proceeds to S8 as in FIG. 10. Note that the processing of S7-1 is substantially the same as S7 in FIG. 10.

[0097] On the other hand, for example, when the temperature of the hydraulic oil detected in the charging mode is G2 and the temperature G2 exceeds the hydraulic oil threshold value Gth (No in S5-1), the cooling fan control unit 80b rotates the cooling fan F at the same rotation speed as the rotation speed controlled in the driving mode (for example, the rotation speed C22 corresponding to the temperature G2) (S7-2), and then proceeds to S8 as in FIG. 10. That is, in FIG. 7-2, when the hydraulic oil temperature G2 as a parameter exceeds the hydraulic oil threshold value Gth as a threshold value, the cooling fan control unit 80b sets the rotation speed C22 of the cooling fan F according to the hydraulic oil temperature G2 in the driving mode as the charging mode rotation speed. That is, the cooling fan control unit 80b maintains the rotation speed of the cooling fan F at the rotation speed (for example, C22) according to the hydraulic oil temperature (for example, G2) in the driving mode.

[0098] There is a concern that the performance of hydraulic oil may decrease when it becomes hot. In the charging mode, when the temperature of the hydraulic oil exceeds the hydraulic oil threshold value Gth, the rotation speed of the cooling fan F is maintained at a rotation speed corresponding to the temperature of the hydraulic oil in the drive mode, thereby increasing the cooling effect of the hydraulic oil and suppressing the decrease in performance due to the high temperature of the hydraulic oil.

[0099] In the charging mode, the driving of the electric motor 63 is stopped, and the rotation speed M of the electric motor 63 and the output P of the inverter 62 become zero. Therefore, in the charging mode, the rotation control of the cooling fan F based on the rotation speed M of the electric motor 63 or the output P of the inverter 62, as performed in the driving mode, is not performed.

[0100] In the above, the rotation control of the cooling fan F in the charging mode has been described as being based on the same parameters (e.g., the coolant temperature D and the hydraulic oil temperature G) as those used in the rotation control in the driving mode, but the rotation speed C of the cooling fan F may be controlled based on different parameters in the driving mode and the charging mode. For example, in the driving mode, the rotation speed C of the cooling fan F may be controlled based on the rotation speed M of the electric motor 63, and in the charging mode, the rotation speed C of the cooling fan F may be controlled based on the coolant temperature D.

[0101] In the above, an example has been described in which the cooling fan control unit 80b controls the rotation speed of the cooling fan F to a constant value in the charging mode, but the rotation speed of the cooling fan F may be changed stepwise or continuously during the charging mode. For example, as shown in FIG. 14, in the charging mode, if the temperature of the coolant has dropped sufficiently before charging of the battery 53 is completed, the rotation of the cooling fan F may be completely stopped at that point (for example, the point when a predetermined time (for example, t15 (min)) has elapsed since the start of driving the electric motor 63), or the rotation speed of the cooling fan F may be reduced stepwise as shown in FIG. 15. In these cases, the effect of reducing power consumption by stopping the rotation of the cooling fan F can be further enhanced compared to the control in FIGS. 11 and 12.

[0102] In this embodiment, the rotation of the cooling fan F is stopped at the end of the charging mode. However, if charging of the battery 53 is completed in a short time and the charging mode is ended early, and the cooling effect of the coolant or the like is considered to be insufficient, the cooling fan F may continue to rotate for a predetermined time even after the charging mode is ended, and the rotation of the cooling fan F may be stopped after the predetermined time has elapsed.

[0103] In the present embodiment, an example has been described in which the cooling fan control unit 80b controls the rotation speed of the cooling fan F based on the parameters detected by the parameter detection unit 90 and a preset table, but the control of the rotation of the cooling fan F is not limited to this example. For example, the cooling fan control unit 80b may control the rotation speed of the cooling fan F while performing feedback control (e.g., PID control) so that the value (detected value) of the parameter actually detected by the parameter detection unit 90 approaches a target value.

[0104] In this embodiment, in the rotation control of the cooling fan F based on Fig. 6 etc., the rotation speed C of the cooling fan F is controlled by placing a one-to-one correspondence between the temperature D of the cooling water and the rotation speed C of the cooling fan F, but it is not necessary to control in a one-to-one correspondence. For example, one rotation speed C of the cooling fan F may be assigned to a predetermined temperature range (multiple temperatures) of the cooling water, and the cooling fan F may be controlled to rotate at the common rotation speed C for temperatures within the predetermined temperature range of the cooling water.

[0105] In this embodiment, an example has been described in which a table showing the relationships in Fig. 6 and the like is stored in the memory unit 80c (see Fig. 5) of the control unit 80, but the above table may be stored in a memory different from the control unit 80 within the hydraulic excavator 1. Also, the above table may be stored in a server (e.g., a cloud server) external to the hydraulic excavator 1, and the cooling fan control unit 80b may communicate with the server to obtain information on the rotation speed of the cooling fan F according to the parameters, and control the rotation of the cooling fan F at the obtained rotation speed.

[0106] Although the embodiment of the present invention has been described above, the scope of the present invention is not limited to this, and the invention can be expanded or modified without departing from the spirit of the invention. [Industrial Applicability]

[0107] The present invention can be used in electric construction machines, such as hydraulic excavators, that have an electric motor driven by a battery. [Explanation of symbols]

[0108] 1. Hydraulic excavator (electric construction machine) 53 Battery 63 Electric Motor 71 Hydraulic Pump 73 Hydraulic Actuator 80b Cooling fan control unit 90 Parameter detection section BA aircraft DS Drive System F Cooling fan HE heat exchange equipment

Claims

1. A control method for an electric construction machine equipped with a cooling fan that cools a drive system that drives a machine body using an electric motor supplied with power from a battery, comprising: and stopping the rotation of the cooling fan when a charging mode in which the battery is charged while the cooling fan rotates is completed.

2. The method for controlling an electric construction machine according to claim 1 , wherein the charging mode is terminated when charging of the battery is completed.

3. 3. The control method for an electric construction machine according to claim 2, wherein in the charging mode, the rotation speed of the cooling fan includes a drive mode rotation speed that drives the drive system, and a charging mode rotation speed that is a rotation speed lower than the drive mode rotation speed.

4. 4. The method for controlling an electric construction machine according to claim 3, wherein in the charging mode, the rotation speed of the cooling fan is set to the charging mode rotation speed in accordance with a temperature of cooling water of a power supply device.

5. 5. The method for controlling an electric construction machine according to claim 4, wherein, in the charging mode, when the temperature of the cooling water is equal to or lower than a threshold value, the rotation speed of the cooling fan is set to the charging mode rotation speed.

6. A control method for an electric construction machine, comprising: selecting a charging mode to switch the display state of a display device; and rotating a cooling fan, which cools a drive system that drives the machine body using an electric motor powered by a battery, at a predetermined rotation speed.

Images