Working machine, control method for working machine

Abstract

To provide a work machine capable of realizing a control securing cooling capacity of a cooling fan.SOLUTION: A work machine comprises: an electric power supply device; a plurality of electrical apparatuses driven by electric power supply from the electric power supply device; a sensor detecting current consumption of the electrical apparatuses; a cooling fan driven by electric power supply from the electric power supply device and generating air flow; and a controller controlling the cooling fan. The electrical apparatuses include a first apparatus provided with the sensor. The controller determines whether a total sum of the current consumption of the electrical apparatuses including current consumption of the first apparatus detected by the sensor and current consumption of the cooling fan exceeds output current of the electric power supply device.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a working machine and a control method for the working machine.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2021-50666 (Patent Document 1) describes a cooling fan control device that controls a plurality of cooling fans. The cooling fan control device includes a controller. The controller optimizes the target rotational speed of each cooling fan within a range where the power consumption of the cooling fans does not exceed the power capacity of the power supply based on the power capacity of the power supply and the total required power according to the cooling state of the cooling target for each of the plurality of cooling fans.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Even when the cooling fan and the electrical equipment are driven by the power generated by the generator, it is necessary to ensure the cooling capacity of the cooling target by the cooling fan.

[0005] The present disclosure proposes a working machine and a control method for the working machine that can realize control to ensure the cooling capacity of the cooling fan.

Means for Solving the Problems

[0006] According to an aspect of the present disclosure, a working machine is proposed, which includes a power supply device, a plurality of electrical devices driven by power supply from the power supply device, a sensor for detecting the current consumption of the electrical devices, a cooling fan driven by power supply from the power supply device to generate an air flow, and a controller for controlling the cooling fan. The electrical devices include a first device provided with a sensor for detecting the current consumption of the electrical device. The controller determines whether the sum of the current consumption of the electrical devices including the current consumption of the first device detected by the sensor and the current consumption of the cooling fan exceeds the output current of the power supply device.

Advantages of the Invention

[0007] According to the working machine and control method of the present disclosure, control for ensuring the cooling capacity of the cooling fan can be realized.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail with reference to the drawings. In the specification and drawings, the same components or corresponding components are denoted by the same reference numerals, and repeated descriptions are not repeated. Also, in the drawings, for the sake of convenience of explanation, the configuration may be omitted or simplified in some cases.

[0010] <Overall Configuration> In an embodiment, a hydraulic excavator 1 will be described as an example of a working machine. FIG. 1 is a side view schematically showing the configuration of the hydraulic excavator 1.

[0011] As shown in FIG. 1, the hydraulic excavator 1 includes a working machine 2 and a vehicle body 3. The vehicle body 3 includes a traveling body 31, a swing circle 32, a revolving body 33, and a hydraulic motor 35.

[0012] The traveling body 31 has a pair of left and right crawler devices 311. Each of the pair of left and right crawler devices 311 has a crawler. When the pair of left and right crawlers are rotationally driven, the hydraulic excavator 1 self-propels.

[0013] The swing circle 32 is connected to the hydraulic motor 35. The swing circle 32 rotates by the rotational drive of the hydraulic motor 35. The hydraulic motor 35 is driven by hydraulic oil supplied from a hydraulic source (a hydraulic pump and an oil tank not shown).

[0014] The revolving body 33 is installed on the traveling body 31 via the swing circle 32. The revolving body 33 revolves with respect to the traveling body 31 as the swing circle 32 rotates.

[0015] The revolving body 33 has a frame 331 to which the working machine 2 is attached, a cab 332, and a controller 80 (see FIG. 2) that controls the operation of the hydraulic excavator 1. The cab 332 is disposed, for example, on the front left side (front side of the vehicle) of the revolving body 33.

[0016] The working machine 2 is supported by the frame 331 on the front side of the revolving body 33 and, for example, on the right side of the cab 332. The working machine 2 has a boom 21, an arm 22, a bucket 23, a boom cylinder 211, an arm cylinder 221, a bucket cylinder 231, and the like.

[0017] The boom 21 is attached to the slewing body 33. The base end of the boom 21 is rotatably connected to the slewing body 33 by a boom foot pin (not shown).

[0018] The arm 22 is attached to the tip of the boom 21. The base end of the arm 22 is rotatably connected to the tip of the boom 21 by a boom tip pin 242.

[0019] The bucket 23 is attached to the tip of the arm 22. The bucket 23 is rotatably connected to the tip of the arm 22 by an arm tip pin 243. The bucket 23 is an example of an attachment that can be attached to the tip of the working machine 2.

[0020] The boom 21 can be driven by a boom cylinder 211. The boom cylinder 211 is driven by hydraulic oil supplied from a hydraulic source. By this drive, the boom 21 can rotate vertically with respect to the slewing body 33 about a boom foot pin (not shown).

[0021] The arm 22 can be driven by an arm cylinder 221. The arm cylinder 221 is driven by hydraulic oil supplied from a hydraulic source. By this drive, the arm 22 can rotate vertically with respect to the boom 21 about a boom tip pin 242.

[0022] The bucket 23 can be driven by a bucket cylinder 231. The bucket cylinder 231 is driven by hydraulic oil supplied from a hydraulic source. By this drive, the bucket 23 can rotate vertically with respect to the arm 22 about an arm tip pin 243. Thus, the working machine 2 can be driven.

[0023] <System Configuration> Figure 2 is a schematic block diagram showing the system configuration of the hydraulic excavator 1. The engine 40 is a driving source for the operation of the hydraulic excavator 1. The engine 40 is an internal combustion engine, for example, a diesel engine. The rotational speed of the engine 40 is controlled by adjusting the amount of fuel injected into the cylinder. This adjustment is performed by the governor attached to the fuel injection pump of the engine 40 being controlled by the controller 80. The rotational speed of the engine 40 is detected by the rotational speed sensor 41. A detection signal indicating the rotational speed of the engine 40 detected by the rotational speed sensor 41 is input from the rotational speed sensor 41 to the controller 80.

[0024] The output shaft of the engine 40 is connected to the alternator 42. The alternator 42 operates as a generator that generates electricity using the driving force generated by the engine 40. The alternator 42 corresponds to the power supply device of the embodiment. The rotational speed of the alternator 42 is set according to the rotational speed of the engine 40. The higher the rotational speed of the engine 40, the higher the rotational speed of the alternator 42, and the greater the amount of electricity generated by the alternator 42.

[0025] The alternator 42 and the battery 50 are electrically connected. The electric power generated by the alternator 42 is stored in the battery 50. The battery 50 is a power storage device that stores electric power. The battery 50 is a secondary battery such as a nickel-metal hydride battery or a lithium-hydrogen battery.

[0026] The battery 50 is electrically connected to a plurality of electrical devices 51 to 53. The electric power generated by the alternator 42 is supplied to the electrical devices 51 to 53 via the battery 50. The electrical devices 51 to 53 are each driven by the power supply from the alternator 42.

[0027] The current sensor 54 detects the current consumption of the electrical device 51. The current sensor 55 detects the current consumption of the electrical device 52. The electrical device 53 is not provided with a current sensor for detecting the current consumption of the electrical device 53. The electrical devices 51 and 52 correspond to the first devices of the embodiment in which sensors for detecting the current consumption of the electrical devices 51 and 52 are provided. The electrical device 53 corresponds to the second device of the embodiment in which a sensor for detecting the current consumption of the electrical device 53 is not provided. For example, the electrical device 51 may be a light, the electrical device 52 may be an air conditioner, and the electrical device 53 may be a wiper. It is also possible to use, as the first device provided with a current sensor, an electrical device with a relatively large current consumption, and, as the second device not provided with a current sensor, an electrical device with a relatively small current consumption.

[0028] A detection signal indicating the current consumption of the electrical device 51 detected by the current sensor 54 is input from the current sensor 54 to the controller 80. A detection signal indicating the current consumption of the electrical device 52 detected by the current sensor 55 is input from the current sensor 55 to the controller 80. The controller 80 is configured to be able to grasp the current consumption of the electrical devices 51 and 52 upon receiving the input of the detection signals from the current sensors 54 and 55, and not to be able to grasp the current consumption of the electrical device 53 which is not provided with a current sensor.

[0029] The cooling device 60 of the embodiment includes a heat exchanger 70. The heat exchanger 70 of the embodiment has a radiator 71, an oil cooler 72, and a CAC (Charge Air Cooler) 73. Inside the radiator 71, the cooling water of the engine 40 circulates. Inside the oil cooler 72, the hydraulic oil supplied to hydraulic actuators such as the hydraulic motor 35, boom cylinder 211, arm cylinder 221, and bucket cylinder 231 shown in FIG. 1 circulates. Inside the CAC 73, the air supplied to the engine 40 circulates.

[0030] The cooling water of the engine 40 is the fluid to be cooled by the radiator 71. The hydraulic oil is the fluid to be cooled by the oil cooler 72. The intake air of the engine 40 is the fluid to be cooled by the CAC 73. The temperature sensor 74 detects the temperature of the cooling water passing through the radiator 71. The temperature sensor 75 detects the temperature of the hydraulic oil passing through the oil cooler 72. The temperature sensor 76 detects the temperature of the air passing through the CAC 73. Detection signals indicating the temperatures of the fluids to be cooled detected by the temperature sensors 74 to 76 are input from the temperature sensors 74 to 76 to the controller 80.

[0031] The cooling device 60 includes a plurality of cooling fans 61 to 63. The cooling fans 61 to 63 are respectively arranged facing the heat exchanger 70. Specifically, the cooling fan 61 is arranged facing the radiator 71 and blows air to the radiator 71. The air flow generated by the cooling fan 61 cools the radiator 71. The cooling fan 61 is a fan for cooling the cooling water of the engine 40 flowing through the radiator 71.

[0032] The engine 40 generates heat and corresponds to the heat source of the embodiment to be cooled by the cooling fan 61. The engine 40 transfers the generated heat to the cooling water. Due to the heat transfer from the engine 40, the temperature of the cooling water rises. When the cooling water with the increased temperature passes through the radiator 71, it dissipates heat to the air flow generated by the cooling fan 61, so that the cooling water is cooled and the temperature of the cooling water decreases. The engine 40 is cooled by the cooled water flowing back to the engine 40.

[0033] The cooling fan 62 is arranged facing the oil cooler 72 and blows air to the oil cooler 72. The air flow generated by the cooling fan 62 cools the oil cooler 72. The cooling fan 62 is a fan for cooling the hydraulic oil flowing through the oil cooler 72. The cooling fan 63 is arranged facing the CAC 73 and blows air to the CAC 73. The air flow generated by the cooling fan 63 cools the CAC 73. The cooling fan 63 is a fan for cooling the air flowing through the CAC 73.

[0034] The cooling fans 61 to 63 are electric fans. The electric motors 64 to 66 are electrically connected to the battery 50. The cooling fan 61 is driven by the electric motor 64. The electric motor 64 is powered from the battery 50 and is driven upon receiving a control signal from the controller 80. The cooling fan 62 is driven by the electric motor 65. The electric motor 65 is powered from the battery 50 and is driven upon receiving a control signal from the controller 80. The cooling fan 63 is driven by the electric motor 66. The electric motor 66 is powered from the battery 50 and is driven upon receiving a control signal from the controller 80.

[0035] The electric power generated by the alternator 42 is supplied to the electric motors 64 to 66 via the battery 50. The cooling fans 61 to 63 are driven by the power supply from the alternator 42 to generate an air flow passing through the heat exchanger 70. The cooling fans 61 to 63 are controlled by the controller 80. The controller 80 controls the electric motors 64 to 66, for example, by PWM (Pulse Width Modulation). The controller 80 controls the respective rotational speeds of the cooling fans 61 to 63 by controlling the respective rotational speeds of the electric motors 64 to 66.

[0036] The controller 80 is a controller that controls the overall operation of the hydraulic excavator 1, and is configured to include a CPU (Central Processing Unit), a non-volatile memory, a timer, and the like. The controller 80 is electrically connected to the engine 40, the rotational speed sensor 41, the current sensors 54, 55, the electric motors 64 to 66, the temperature sensors 74 to 76, and the like.

[0037] The controller 80 stores in advance a program for controlling the cooling fans 61 to 63. The controller 80 stores in advance a table of the current value generated and output by the alternator 42 with respect to the rotational speed of the engine 40, a table of the rotational speeds of the cooling fans 61 to 63 with respect to the temperature of the fluid to be cooled detected by the temperature sensors 74 to 76, a table of the current consumption of the cooling fans 61 to 63 with respect to the rotational speeds of the cooling fans 61 to 63, and a table of the torque output by the engine 40 with respect to the rotational speed of the engine 40. Instead of the above various tables, functions may be stored in the controller 80. The controller 80 stores in advance a set value of the current consumption of the electrical equipment 53 where the current sensor is not provided.

[0038] The controller 80 is mounted on the hydraulic excavator 1. The controller 80 may not be mounted on the hydraulic excavator 1. The controller 80 may be arranged outside the hydraulic excavator 1. The controller 80 may be arranged at the work site of the hydraulic excavator 1 or at a remote location away from the work site of the hydraulic excavator 1. The hydraulic excavator 1 and the controller 80 arranged outside the hydraulic excavator 1 may constitute a control system of the hydraulic excavator 1.

[0039] <Control of Cooling Fans 61 to 63> Regarding the control of the cooling fans 61 to 63 by the controller 80 in the hydraulic excavator 1 of the embodiment having the above configuration, it will be described below. FIG. 3 is a flowchart showing an example of the control of the cooling fans 61 to 63.

[0040] As shown in FIG. 3, in step S1, the rotation speeds of the cooling fans 61 to 63 are set according to the oil and water temperature table. FIG. 4 is a diagram showing an example of a table of the rotation speed of the cooling fan 61 with respect to the temperature of the cooling water of the engine 40. The horizontal axis of FIG. 4 indicates the temperature of the cooling water of the engine 40. The temperature of the cooling water of the engine 40 is detected by the temperature sensor 74. The vertical axis of FIG. 4 indicates the rotation speed of the cooling fan 61, that is, the rotation speed of the electric motor 64. The table shown in FIG. 4 is stored in the controller 80.

[0041] As shown in FIG. 4, when the temperature of the cooling water of the engine 40 is equal to or lower than a predetermined first temperature threshold, the rotation speed of the cooling fan 61 is made constant at a predetermined first rotation speed. When the temperature of the cooling water of the engine 40 rises and exceeds the first temperature threshold, the rotation speed of the cooling fan 61 increases. In the range where the temperature of the cooling water of the engine 40 is equal to or higher than the first temperature threshold and equal to or lower than a predetermined second temperature threshold, the rotation speed of the cooling fan 61 increases linearly with respect to the temperature of the cooling water of the engine 40. When the temperature of the cooling water of the engine 40 is equal to or higher than the second temperature threshold, the rotation speed of the cooling fan 61 is made constant at a predetermined second rotation speed.

[0042] The controller 80 receives a detection signal of the temperature of the cooling water of the engine 40 from the temperature sensor 74. The controller 80 sets the rotation speed of the cooling fan 61 required to cool the engine 40 corresponding to the temperature of the cooling water of the engine 40, which is the detected value of the temperature sensor 74, according to the table shown in FIG. 4.

[0043] FIG. 5 is a diagram showing an example of a table of the current consumption of the cooling fan 61 with respect to the rotation speed of the cooling fan 61. The horizontal axis of FIG. 5 indicates the rotation speed of the cooling fan 61, and the vertical axis indicates the current consumption of the cooling fan 61. As shown in FIG. 5, the current consumption of the cooling fan 61 may be in a relationship of increasing linearly with respect to the rotation speed of the cooling fan 61. According to the table shown in FIG. 5, the controller 80 obtains the current consumption of the cooling fan 61 corresponding to the rotation speed of the cooling fan 61 set by the table of FIG. 4.

[0044] Regarding the temperature of the hydraulic oil and the rotation speed of the cooling fan 62 as well, a table similar to FIG. 4 is set. Regarding the rotation speed of the cooling fan 62 and the power consumption current of the cooling fan 62 as well, a table similar to FIG. 5 is set. Regarding the temperature of the intake air of the engine 40 and the rotation speed of the cooling fan 63 as well, a table similar to FIG. 4 is set. Regarding the rotation speed of the cooling fan 63 and the power consumption current of the cooling fan 63 as well, a table similar to FIG. 5 is set. The controller 80 sets the rotation speeds of the cooling fans 62 and 63 and obtains the power consumption currents of the cooling fans 62 and 63.

[0045] Returning to FIG. 3, next, in step S2, it is determined whether or not the set values of the rotation speeds of the cooling fans 61 to 63 exceed the power consumption current shortage line. As shown in FIG. 4, a power consumption current shortage line corresponding to a predetermined rotation speed between the first rotation speed and the second rotation speed is set. In the present embodiment, the power consumption current shortage line is the current value obtained by subtracting the power consumption currents of the electrical devices other than the electric motors 64 to 66 (for example, the electrical devices 51 to 53 shown in FIG. 2) from the current generated and output by the alternator 42 when the power consumption currents of all the electrical devices other than the electric motors 64 to 66 are maximum, and is assigned to each of the cooling fans 61 to 63, and indicates the rotation speeds of the respective cooling fans 61 to 63 corresponding to the assigned current values.

[0046] If the rotation speed of the cooling fan 61 is in the range below the power consumption current shortage line shown in FIG. 4 and the rotation speeds of the cooling fans 62 and 63 are similarly in the range below the power consumption current shortage line, even if all the electrical devices other than the electric motors 64 to 66 are in use, the total sum of the power consumption currents of the electrical devices and the power consumption currents of the cooling fans 61 to 63 does not exceed the generated current by the alternator 42. On the other hand, if the rotation speed of any one or more of the cooling fans 61 to 63 exceeds the power consumption current shortage line, when all the electrical devices other than the electric motors 64 to 66 are in use, the total sum of the power consumption currents of the electrical devices other than the electric motors 64 to 66 and the power consumption currents of the cooling fans 61 to 63 may exceed the current generated and output by the alternator 42.

[0047] Therefore, when it is determined that the set value of the rotation speed of any of the cooling fans 61 to 63 exceeds the current consumption shortage line (YES in step S2), next in step S3, the current consumption of electrical equipment other than the electric motors 64 to 66 is calculated. The controller 80 receives a detection signal of the current consumption of the electrical equipment 51 from the current sensor 54. The controller 80 receives a detection signal of the current consumption of the electrical equipment 52 from the current sensor 55. The controller 80 calculates the sum of the current consumption of the electrical equipment 51 detected by the current sensor 54, the current consumption of the electrical equipment 52 detected by the current sensor 55, and the set value of the current consumption of the electrical equipment 53 stored in the controller 80 in advance, as the current consumption of the electrical equipment other than the electric motors 64 to 66.

[0048] Next, in step S4, it is determined whether the sum of the current consumption of the electrical equipment other than the electric motors 64 to 66 calculated in step S3 and the current consumption of the cooling fans 61 to 63 obtained in step S1 exceeds the generated current by the alternator 42.

[0049] The controller 80 receives a detection signal of the rotation speed of the engine 40 from the rotation speed sensor 41. The controller 80 calculates the generated current of the alternator 42 from the rotation speed of the engine 40 detected by the rotation speed sensor 41 according to the table of the generated current by the alternator 42 with respect to the rotation speed of the engine 40 stored in the controller 80 in advance. The controller 80 compares the calculated generated current of the alternator 42 with the sum of the current consumption of the electrical equipment and the cooling fans 61 to 63, and determines whether the current consumption of the electrical equipment and the cooling fans 61 to 63 exceeds the generated current of the alternator 42.

[0050] As a result of the determination in step S4, when it is determined that the sum of the current consumption of the electrical equipment and the current consumption of the cooling fans 61 to 63 exceeds the generated current of the alternator 42 (YES in step S4), the process proceeds to step S5, and the rotation speeds of the cooling fans 61 to 63 are reset.

[0051] The controller 80 changes the settings of the cooling fans 61 to 63. Specifically, the controller 80 reduces the rotational speeds of the cooling fans 61 to 63. Typically, the controller 80 sets the rotational speeds of the cooling fans 61 to 63 to values below the current consumption shortage line respectively. When the rotational speeds of the cooling fans 61 to 63 decrease, as shown in FIG. 5, the current consumption of the cooling fans 61 to 63 decreases. Thereby, the controller 80 ensures that the sum of the current consumption of the electrical equipment and the current consumption of the cooling fans 61 to 63 does not exceed the generated current of the alternator 42.

[0052] In step S5, the output of the engine 40 is also restricted. By reducing the rotational speed of the cooling fan 61, the ability of the cooling fan 61 to cool the cooling water of the engine 40 decreases. To prevent the engine 40 from overheating, the controller 80 restricts the output of the engine 40. The controller 80 restricts the heat generation amount of the engine 40 to suppress the heat transfer from the engine 40 to the cooling water. The controller 80 suppresses the temperature rise of the cooling water in the engine 40 so that the cooling water of the engine 40 is sufficiently cooled while passing through the radiator 71 by the cooling fan 61 with a reduced rotational speed and thus a reduced cooling capacity.

[0053] FIG. 6 is a diagram showing an example of an engine torque curve. The horizontal axis of FIG. 6 indicates the rotational speed of the engine 40. The vertical axis of FIG. 6 indicates the output torque of the engine 40. The engine torque curve TC1 shown by the solid line in FIG. 6 indicates the upper limit value of the torque that the engine 40 can output according to the rotational speed, as defined by the characteristics of the engine 40. The engine torque curve TC1 defines the relationship between the rotational speed of the engine 40 and the upper limit value of the output torque of the engine 40. Normally, the controller 80 controls the governor so as to control the output torque of the engine 40 according to the engine torque curve TC1.

[0054] The dilated engine torque curve TC2 shown by the dashed-dotted line in Fig. 6 defines an upper limit value of the output torque lower than that of the engine torque curve TC1. When restricting the output of the engine 40, the controller 80 controls the output of the engine 40 according to the dilated engine torque curve TC2. Since the generated current of the alternator 42 is set according to the rotational speed of the engine 40, when restricting the output of the engine 40, the controller 80 does not reduce the rotational speed of the engine 40, but performs control to cut off the output torque of the engine 40 by torque dilation.

[0055] In step S6, the controller 80 determines the rotational speeds of the cooling fans 61 to 63. If it is determined in the determination of step S2 that the set values of the rotational speeds of the cooling fans 61 to 63 are below the current consumption shortage line (NO in step S2), regardless of the usage status of the electrical equipment other than the electric motors 64 to 66, the sum of the current consumption of the electrical equipment and the current consumption of the cooling fans 61 to 63 does not exceed the generated current of the alternator 42. Therefore, the controller 80 determines the rotational speed set in step S1 as the rotational speeds of the cooling fans 61 to 63.

[0056] If it is determined in the determination of step S4 that the sum of the current consumption of the electrical equipment and the current consumption of the cooling fans 61 to 63 does not exceed the generated current of the alternator 42 (NO in step S4), the controller 80 determines the rotational speed set in step S1 as the rotational speeds of the cooling fans 61 to 63. The controller 80 can monitor the current consumption of the electrical equipment 51, 52 provided with the current sensors 54, 55 by the detection signals from the current sensors 54, 55. By constantly monitoring the usage status of the electrical equipment and diverting the surplus current not used by the electrical equipment as the current consumption of the cooling fans 61 to 63, it is possible to operate the cooling fans 61 to 63 at a rotational speed exceeding the current consumption shortage line.

[0057] When the rotation speeds of the cooling fans 61 to 63 are reset in the process of step S5, the controller 80 determines the reset rotation speeds as the rotation speeds of the cooling fans 61 to 63. Based on the determined rotation speeds, the controller 80 controls the cooling fans 61 to 63. The controller 80 outputs a control signal to the electric motors 64 to 66 so that the cooling fans 61 to 63 operate at the determined rotation speeds. Then, the process ends (END).

[0058] <Operation and Effect> Although there is also a description that partially overlaps with the above description, the characteristic configurations, operations, and effects of the present embodiment will be summarized as follows.

[0059] As shown in FIG. 2, the electrical equipment driven by the power supply from the alternator 42 includes the first equipment provided with a sensor for detecting the current consumption of the electrical equipment. As shown in FIG. 3, the controller 80 determines whether the sum of the current consumption of the electrical equipment including the current consumption of the first equipment detected by the sensor and the current consumption of the cooling fans 61 to 63 exceeds the output current of the alternator 42.

[0060] The electrical equipment and the cooling fans 61 to 63 are driven by the generated current of the alternator 42. By monitoring the current used by the electrical equipment and making the surplus current not used by the electrical equipment available for the cooling fans 61 to 63, and increasing the current available for the cooling fans 61 to 63, it becomes possible to operate the cooling fans 61 to 63 at a higher rotation speed. Typically, it becomes possible to rotate the cooling fans 61 to 63 at a rotation speed equal to or higher than the current consumption shortage line shown in FIG. 4. It becomes possible to continuously operate the cooling fans 61 to 63 at the maximum current, and control can be realized to ensure the cooling capacity of the fluid to be cooled by the cooling fans 61 to 63.

[0061] As shown in FIG. 3, when the sum of the current consumption of the electrical equipment and the current consumption of the cooling fans 61 to 63 exceeds the output current of the alternator 42, the controller 80 changes the settings of the cooling fans 61 to 63 so that the sum of the current consumption of the electrical equipment and the current consumption of the cooling fans 61 to 63 does not exceed the output current of the alternator 42. If the generated current of the alternator 42 is insufficient and the current shortage is supplied from the battery 50, the battery 50 may be over-discharged and the power storage function of the battery 50 may deteriorate. By changing the settings of the cooling fans 61 to 63, more specifically, by limiting the rotational speeds of the cooling fans 61 to 63 and reducing the current consumption of the cooling fans 61 to 63, it becomes possible to continue operating both the electrical equipment and the cooling fans 61 to 63 with the power supplied from the alternator 42.

[0062] As shown in FIG. 3, when the sum of the current consumption of the electrical equipment and the current consumption of the cooling fans 61 to 63 exceeds the output current of the alternator 42, the controller 80 restricts the output of the engine 40. When the rotational speeds of the cooling fans 61 to 63 are decreased, the cooling capacity of the cooling target fluid by the cooling fans 61 to 63 decreases. If the cooling of the cooling water of the engine 40 is insufficient, overheating of the engine 40 occurs. By restricting the output of the engine 40 as the rotational speeds of the cooling fans 61 to 63 are decreased and reducing the heat generation amount of the engine 40, overheating of the engine 40 can be prevented.

[0063] As shown in FIG. 3, when the sum of the current consumption of the electrical equipment and the current consumption of the cooling fans 61 to 63 does not exceed the output current of the alternator 42, the controller 80 controls the cooling fans 61 to 63 based on the rotational speeds corresponding to the current consumption of the cooling fans 61 to 63. By enabling the cooling fans 61 to 63 to use the surplus current not used by the electrical equipment, it becomes possible to rotate the cooling fans 61 to 63 at rotational speeds above the current consumption shortage line shown in FIG. 4, and control can be realized to ensure the cooling capacity of the cooling target fluid by the cooling fans 61 to 63.

[0064] As shown in FIG. 2, the electrical equipment driven by the power supply from the alternator 42 includes a second device provided with no sensor for detecting the current consumption of the electrical equipment. As shown in FIG. 3, the controller 80 calculates the sum of the current consumption of the first device detected by the sensor and the set value of the current consumption of the second device stored in advance as the current consumption of the electrical equipment. By doing so, the controller 80 can calculate the current consumption of the electrical equipment more accurately.

[0065] As shown in FIGS. 3 and 4, the controller 80 sets the rotation speeds of the cooling fans 61 to 63 based on the temperature of the fluid to be cooled obtained as the detected values of the temperature sensors 74 to 76. As shown in FIG. 5, the controller 80 obtains the current consumption of the cooling fans 61 to 63 from the set rotation speeds of the cooling fans 61 to 63. Thereby, the controller 80 can accurately acquire the current consumption of the cooling fans 61 to 63. The controller 80 can accurately determine whether the sum of the current consumption of the electrical equipment and the current consumption of the cooling fans 61 to 63 exceeds the output current of the alternator 42 by using the acquired current consumption of the cooling fans 61 to 63.

[0066] In the above embodiment, the control for reducing the rotation speeds of the cooling fans 61 to 63 and restricting the output of the engine 40 when the generated current of the alternator 42 is insufficient for the current consumption of the electrical equipment and the cooling fans 61 to 63 has been described. Not limited to this example, when it is determined that the generated current of the alternator 42 is insufficient for the current consumption of the electrical equipment and the cooling fans 61 to 63, it may be configured such that an alarm issues an alarm. The alarm may be sound, visual, tactile, or a combination thereof. The operator of the hydraulic excavator 1 who recognizes the alarm can, for example, temporarily stop the air conditioner in the cab 332 to reduce the current consumption of the electrical equipment and increase the current available for the cooling fans 61 to 63. In this way, it becomes possible to continue the work without restricting the output of the engine 40.

[0067] The cooling device 60 of the embodiment includes three heat exchangers 70, namely, a radiator 71, an oil cooler 72, and a CAC 73. The number of heat exchangers may be two or less, or may be four or more. Examples of heat exchangers are not limited to the above three, and may be, for example, a condenser of an air conditioner, a fuel cooler, etc.

[0068] In the embodiment, an example in which the cooling device 60 has three cooling fans 61 to 63 has been described. The cooling device 60 may have two or less electric cooling fans, or may have four or more electric cooling fans. The number of heat exchangers and the number of cooling fans may be different. Two or more cooling fans may cool one heat exchanger. One cooling fan may cool two or more heat exchangers. Two or more heat exchangers cooled by one cooling fan may be arranged side by side along the air flow generated by the cooling fan.

[0069] In the embodiment, a temperature sensor is provided for each heat exchanger, but there may be a heat exchanger without a temperature sensor. For example, a temperature sensor for detecting the temperature of the fluid to be cooled of one of two or more heat exchangers cooled by one cooling fan is provided, and the rotation speed of the cooling fan may be controlled based on the detection value of the temperature sensor. In this case, the other heat exchangers among the two or more heat exchangers may not be provided with temperature sensors.

[0070] In the embodiment, a hydraulic excavator 1 has been described as an example of a working machine. However, the idea of the present disclosure may be applied not only to the hydraulic excavator 1 but also to other types of working machines, such as bulldozers, wheel loaders, dump trucks, etc.

[0071] Although the embodiment has been described as above, it should be considered that the disclosed embodiment is illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all changes within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0072] 1 Hydraulic excavator, 2 Working machine, 3 Vehicle body, 21 Boom, 22 Arm, 23 Bucket, 31 Travel unit, 32 Swing circle, 33 Slewing body, 35 Hydraulic motor, 40 Engine, 41 Rotation speed sensor, 42 Alternator, 50 Battery, 51, 52, 53 Electrical equipment, 54, 55 Current sensor, 60 Cooling device, 61, 62, 63 Cooling fan, 64, 65, 66 Electric motor, 70 Heat exchanger, 71 Radiator, 72 Oil cooler, 73 CAC, 74, 75, 76 Temperature sensor, 80 Controller, 211 Boom cylinder, 221 Arm cylinder, 231 Bucket cylinder, 242 Boom tip pin, 243 Arm tip pin, 311 Crawler device, 331 Frame, 332 Cab, TC1 Engine torque curve, TC2 Delayed engine torque curve.

Claims

1. A power supply device, A plurality of electrical devices driven by power supplied from the power supply device, A sensor for detecting the current consumption of the electrical device, A cooling fan driven by power supplied from the power supply device to generate an air flow, An electric motor that is supplied with power from the power supply device and drives the cooling fan, A controller for controlling the cooling fan, and The electrical device includes a first device provided with the sensor and a second device not provided with the sensor, and the current consumption of the first device is greater than the current consumption of the second device. The controller calculates, as the current consumption of the electrical device, the sum of the current consumption of the first device detected by the sensor and a set value of the current consumption of the second device stored in advance, and determines whether the sum of the current consumption of the electrical device and the current consumption of the cooling fan exceeds the output current of the power supply device. A working machine.

2. When the result of the determination is that the sum of the current consumption of the electrical device and the current consumption of the cooling fan exceeds the output current of the power supply device, the controller changes the setting of the cooling fan so that the sum of the current consumption of the electrical device and the current consumption of the cooling fan does not exceed the output current of the power supply device, and controls the cooling fan based on the rotation speed corresponding to the changed current consumption. The working machine according to claim 1.

3. Further comprising a heat source that generates heat and is cooled by the cooling fan, When the result of the determination is that the sum of the current consumption of the electrical device and the current consumption of the cooling fan exceeds the output current of the power supply device, the controller restricts the output of the heat source. The working machine according to claim 2.

4. When the result of the determination is that the sum of the current consumption of the electrical device and the current consumption of the cooling fan does not exceed the output current of the power supply device, the controller controls the cooling fan based on the rotation speed corresponding to the current consumption. The working machine according to any one of claims 1 to 3.

5. A heat exchanger through which a cooling target fluid flows inside, Further comprising a temperature sensor for measuring the temperature of the cooling target fluid, The air flow generated by the cooling fan cools the heat exchanger, The controller sets the rotation speed of the cooling fan based on the detected value of the temperature sensor, and obtains the current consumption of the cooling fan from the set rotation speed. The working machine according to any one of claims 1 to 4.

6. A power supply device, a plurality of electrical devices driven by power supply from the power supply device, a sensor for detecting the current consumption of the electrical devices, a cooling fan driven by power supply from the power supply device to generate an air flow, and an electric motor that is powered by the power supply device and drives the cooling fan. A control method for a working machine, comprising: the electrical devices include a first device provided with the sensor and a second device not provided with the sensor, and the current consumption of the first device is greater than the current consumption of the second device, detecting the current consumption of the first device by the sensor, calculating, as the current consumption of the electrical devices, the sum of the current consumption of the first device detected by the sensor and a set value of the current consumption of the second device stored in advance, calculating the sum of the current consumption of the electrical devices and the current consumption of the cooling fan, and determining whether the calculated total current consumption exceeds the output current of the power supply device. A control method for a working machine.

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