Work machine and work machine control method

Abstract

To provide a work machine capable of cleaning a heat exchanger while suppressing temperature rise of a fluid to be cooled.SOLUTION: A hydraulic excavator 1 includes a heat exchanger unit 36, multiple cooling fans 51a, 51b, 51c and a controller 66. The heat exchanger unit 36 has at least one heat exchanger. A plurality of cooling fans 51a, 51b, 51c cool the heat exchanger unit 36. When a rotation stops when the controller 66 changes the at least one cooling fan from forward rotation to reverse rotation, the controller 66 changes the rotation of the plurality of cooling fans 51a, 51b, 51c from forward rotation to reverse rotation while controlling at least one other cooling fan to rotate forward or reversely.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a work machine and a method for controlling a work machine. [Background technology]

[0002] A work machine such as a hydraulic excavator is provided with a heat exchanger unit having multiple heat exchangers for cooling various fluids (such as refrigerants), and a cooling fan for supplying cooling air to the heat exchanger unit. The heat exchanger unit is provided with, for example, a radiator through which engine cooling water flows, an oil cooler through which hydraulic oil for operating a hydraulic actuator flows, and an aftercooler through which compressed air flows (see, for example, Patent Document 1).

[0003] Since there is often a large amount of dust and dirt floating around at work sites where work machines are operating, the work machine shown in Patent Document 1 blows away the dust and dirt that has been carried to the heat exchanger unit by the rotation of the cooling fan and has adhered to it by rotating the cooling fan in the opposite direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-84520 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the cooling fan is switched from forward rotation to reverse rotation to clean the heat exchanger, the rotation of the cooling fan momentarily drops to zero, which can cause the temperature of the fluid to be cooled, such as the refrigerant or compressed air, to rise. Therefore, it is difficult to clean the heat exchanger by reverse rotation of the cooling fan while the engine is running.

[0006] An object of the present disclosure is to provide a work machine and a method for controlling a work machine that are capable of cleaning a heat exchanger while suppressing a temperature rise in a fluid to be cooled. [Means for solving the problem]

[0007] A work machine according to a first aspect of the present disclosure includes a heat exchange unit, multiple cooling fans, and a controller. The heat exchange unit has at least one heat exchanger. The multiple cooling fans cool the heat exchange unit. The controller changes the rotation of at least one cooling fan from forward to reverse while controlling at least one other cooling fan to continue rotating in forward or reverse when the rotation of at least one cooling fan stops during the change from forward to reverse rotation.

[0008] A control method for a work machine according to a second aspect of the present disclosure is a control method for a work machine equipped with a heat exchange unit having at least one heat exchanger and multiple cooling fans that cool the heat exchange unit, in which when the rotation of at least one cooling fan is changed from forward rotation to reverse rotation and the rotation of the multiple cooling fans stops, at least one other cooling fan is controlled to continue rotating in the forward or reverse direction. [Effects of the Invention]

[0009] According to aspects of the present disclosure, it is possible to provide a work machine and a method for controlling a work machine that are capable of cleaning a heat exchanger while suppressing a temperature rise in a fluid to be cooled. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view showing a hydraulic excavator according to an embodiment of the present disclosure. FIG. [Figure 2] FIG. 1 is a plan view of a hydraulic excavator according to an embodiment of the present disclosure. [Figure 3] FIG. 1 is a perspective view showing a rear portion of a hydraulic excavator according to an embodiment of the present disclosure. [Figure 4]1 is a perspective view of a cooling unit according to an embodiment of the present disclosure, viewed from the heat exchanger unit side. [Figure 5] 1 is a perspective view of a cooling unit according to an embodiment of the present disclosure, viewed from a cooling fan unit side. [Figure 6] FIG. 1 is a front view of a cooling unit according to an embodiment of the present disclosure, viewed from the left side of a hydraulic excavator. [Figure 7] FIG. 7 is a cross-sectional view taken along the arrows BB′ in FIG. 6. [Figure 8] FIG. 2 is a block diagram showing a configuration related to control of the hydraulic excavator according to an embodiment of the present disclosure. [Figure 9] FIG. 4 is a flowchart showing a control operation of the hydraulic excavator according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] A hydraulic excavator as an example of a work machine according to the present disclosure will be described below with reference to the drawings.

[0012] <Configuration> (Overview of Hydraulic Excavator 1) FIG. 1 is a schematic diagram showing the configuration of a hydraulic excavator 1 according to this embodiment.

[0013] The hydraulic excavator 1 (an example of a work machine) has a vehicle body 2 and a work implement 3. As shown in FIG. 1, the vehicle body 2 has a running body 11 and a revolving body 12. The running body 11 has a pair of running devices 11a, 11b. Each of the running devices 11a, 11b has tracks 11c, 11d. The hydraulic excavator 1 travels when a travel motor is rotated by driving force from an engine 33 (see FIG. 2 described later), driving the tracks 11c, 11d.

[0014] The rotating body 12 is placed on the running body 11. The rotating body 12 is configured to be able to rotate relative to the running body 11 around an axis along the vertical direction by a rotating device (not shown). A cab 31 serving as a driver's seat where an operator sits during operation is provided at the front left side of the rotating body 12. Inside the cab 31, the driver's seat, levers for operating the work implement 3, various display devices, etc. are arranged.

[0015] In this embodiment, unless otherwise specified, front, rear, left and right will be described based on the driver's seat in the cab 31. The direction in which the driver's seat faces directly ahead is the forward direction (see arrow Xf), and the direction opposite the forward direction is the rearward direction (see arrow Xb). The right and left sides of the driver's seat when facing directly ahead are the right direction (see arrow Yr) and the left direction (see arrow Yl), respectively. Furthermore, in this specification, the terms "height direction," "vertical direction," and "horizontal direction" refer to directions when the vehicle body 2 is horizontal and not tilted, unless otherwise specified.

[0016] The work implement 3 is attached to the front center position of the rotating body 12. As shown in FIG. 1, the work implement 3 has a boom 21, an arm 22, and an excavation bucket 23. The base end of the boom 21 is rotatably connected to the rotating body 12. The tip of the boom 21 is rotatably connected to the base end of the arm 22. The tip of the arm 22 is rotatably connected to the excavation bucket 23. The excavation bucket 23 is attached to the arm 22 so that its opening faces toward the rotating body 12 (rear). A hydraulic excavator 1 with the excavation bucket 23 attached in this orientation is called a backhoe.

[0017] Hydraulic cylinders 24 to 26 (boom cylinder 24, arm cylinder 25, and bucket cylinder 26) are arranged to correspond to the boom 21, arm 22, and excavation bucket 23, respectively. The work implement 3 is driven by driving these hydraulic cylinders 24 to 26, thereby performing work such as excavation.

[0018] An engine room 32 is disposed behind the cab 31 of the revolving structure 12. Fig. 2 is a plan view of the hydraulic excavator 1 showing the internal configuration of the engine room 32. Fig. 3 is a perspective view of the hydraulic excavator 1 as viewed from the rear. The revolving structure 12 further has an engine 33, a hydraulic pump 34, and a cooling unit 35. The engine room 32 is disposed behind the cab 31.

[0019] As shown in Figures 2 and 3, the engine room 32 accommodates an engine 33, a hydraulic pump 34, and a cooling unit 35. The cooling unit 35, the engine 33, and the hydraulic pump 34 are arranged in this order from left to right. The engine 33 generates driving force. The engine 33 is an internal combustion engine such as a diesel engine. The hydraulic pump 34 is connected to the engine 33. The hydraulic pump 34 is driven by the engine 33 and discharges hydraulic oil. The hydraulic oil discharged from the hydraulic pump 34 is supplied to hydraulic actuators such as the hydraulic cylinders 24 to 26 described above.

[0020] The cooling unit 35 cools various fluids to be cooled, such as refrigerant and compressed air. An intake port 32a is arranged in the side wall of the engine compartment 32 to the left of the cooling unit 35. A net is arranged at the intake port 32a. An exhaust port 32b is arranged in the side wall of the engine compartment 32 to the right of the hydraulic pump 34. A net is arranged at the exhaust port 32b. The cooling unit 35 has multiple cooling fans 51a, 51b, and 51c (described later). When the cooling fans 51a, 51b, and 51c rotate forward, external air is taken into the engine compartment 32 through the intake port 32a, as shown by arrow A in FIG. 2. The air taken into the engine compartment 32 passes through the engine 33 and the hydraulic pump 34 in this order, and is then discharged to the outside through the exhaust port 32b.

[0021] (Cooling unit 35) Fig. 4 is a perspective view of the cooling unit 35. Fig. 4 is a perspective view of the cooling unit 35 viewed from the left side of the hydraulic excavator 1. Fig. 5 is a perspective view of the cooling unit 35. Fig. 5 is a perspective view of the cooling unit 35 viewed from the right side of the hydraulic excavator 1.

[0022] 2 and 5, the cooling unit 35 includes a heat exchanger unit 36 ​​(an example of a heat exchange section) and a cooling fan unit 37. The heat exchanger unit 36 ​​includes a plurality of heat exchangers (described later) that cool various fluids to be cooled. The cooling unit 35 supplies cooling air to the heat exchanger unit 36.

[0023] The heat exchanger unit 36 ​​is disposed on the left side of the cooling unit 35. The heat exchanger unit 36 ​​is disposed on the intake port 32a side of the cooling unit 35. The heat exchanger unit 36, cooling fan unit 37, engine 33, and hydraulic pump 34 are disposed in this order from the intake port 32a toward the exhaust port 32b.

[0024] (Heat Exchanger Unit 36) 4, the heat exchanger unit 36 ​​has an oil cooler 41, an aftercooler 42, a radiator 43, an air conditioner condenser 44, and a fuel cooler 45. Each of the oil cooler 41, the aftercooler 42, the radiator 43, the air conditioner condenser 44, and the fuel cooler 45 is an example of a heat exchanger.

[0025] Hydraulic oil for operating hydraulic actuators such as the hydraulic cylinders 24 to 26 is supplied to the oil cooler 41. The hydraulic oil is cooled as it passes through the oil cooler 41. The oil cooler 41 is disposed in front of the heat exchanger unit 36. When viewed along the left-right direction of the hydraulic excavator 1, the oil cooler 41 has a generally rectangular shape that is long in the up-down direction.

[0026] The aftercooler 42 is supplied with compressed air that has been obtained by taking in and compressing outside air using a turbocharger (not shown). The aftercooler 42 is connected to the engine 33. The compressed air is cooled as it passes through the aftercooler 42 and is then sent to the engine 33. The aftercooler 42 is disposed behind the oil cooler 41. When viewed along the left-right direction of the hydraulic excavator 1, the aftercooler 42 has a generally rectangular shape that is long in the up-down direction. The aftercooler 42 is formed higher than the oil cooler 41.

[0027] Cooling water for the engine 33 is supplied to the radiator 43. The supplied cooling water is cooled as it passes through the radiator 43 and is then discharged toward the engine 33. The radiator 43 is disposed behind the aftercooler 42. When viewed along the left-right direction of the hydraulic excavator 1, the radiator 43 has a generally rectangular shape that is long in the vertical direction. The radiator 43 is formed at approximately the same height as the aftercooler 42.

[0028] The oil cooler 41, the aftercooler 42, and the radiator 43 are arranged in line in this order from the front side to the rear side of the hydraulic excavator 1.

[0029] The air conditioner condenser 44 is supplied with refrigerant for the air conditioner used to air-condition the cab 31. The supplied refrigerant is cooled as it passes through the air conditioner condenser 44 and is then discharged toward the air conditioner. The air conditioner condenser 44 is disposed to the left of the oil cooler 41, the aftercooler 42, and the radiator 43. The air conditioner condenser 44 is disposed on the intake port 32a side of the oil cooler 41, the aftercooler 42, and the radiator 43. The air conditioner condenser 44 is disposed approximately in the center of the oil cooler 41, the aftercooler 42, and the radiator 43 in the up-down direction. The air conditioner condenser 44 is disposed across the oil cooler 41, the aftercooler 42, and the radiator 43 in the front-rear direction.

[0030] Fuel for the engine 33 is supplied to the fuel cooler 45. The fuel is cooled as it passes through the fuel cooler 45 and then supplied to the engine 33. The fuel cooler 45 is disposed to the left of the aftercooler 42 and the radiator 43. The fuel cooler 45 is disposed on the intake port 32a side of the aftercooler 42 and the radiator 43. The fuel cooler 45 is disposed from the aftercooler 42 to the radiator 43. The fuel cooler 45 is disposed below the air conditioner condenser 44.

[0031] The frame 46 supports the oil cooler 41, the aftercooler 42, and the radiator 43. The frame 46 is disposed so as to surround the peripheral portions of the oil cooler 41, the aftercooler 42, and the radiator 43, which are disposed side by side. The air conditioner condenser 44 is fixed to a front portion 46a of the frame 46, which is disposed at the front edge of the oil cooler 41, and to a rear portion 46b of the frame 46, which is disposed at the rear edge of the radiator 43. The fuel cooler 45 is fixed to the rear portion 46b of the frame 46 and to a lower portion 46c of the frame 46, which is disposed at the lower edges of the oil cooler 41, the aftercooler 42, and the radiator 43. At least one of the hydraulic oil supplied to the oil cooler 41, the compressed air supplied to the aftercooler 42, the cooling water supplied to the radiator 43, the refrigerant supplied to the air conditioner condenser 44, and the fuel supplied to the fuel cooler 45 is an example of a fluid to be cooled.

[0032] (Cooling fan unit 37) 5, the cooling fan unit 37 includes a plurality of cooling fans 51a, 51b, and 51c, and a shroud 52. The plurality of cooling fans 51a, 51b, and 51c are supported by the shroud 52 so as to be rotatable.

[0033] Fig. 6 is a view of the cooling unit 35 as viewed from the left side of the hydraulic excavator 1 (as viewed along the air suction direction). Fig. 7 is a cross-sectional view taken along the arrows B-B' in Fig. 6. In Fig. 6, in order to show the positional relationship between the oil cooler 41, aftercooler 42, and radiator 43 and the cooling fans 51a, 51b, and 51c, the air conditioner condenser 44 and fuel cooler 45 are indicated by two-dot chain lines, and the rear of the air conditioner condenser 44 and fuel cooler 45 are indicated by solid lines.

[0034] The cooling fans 51a, 51b, and 51c are electric fans and are arranged on the right side of the heat exchanger unit 36. The cooling fans 51a, 51b, and 51c are arranged to face the oil cooler 41, the aftercooler 42, and the radiator 43 at predetermined intervals.

[0035] The shroud 52 is attached to the frame 46. The shroud 52 includes a facing surface 53 and side portions 54. The facing surface 53 is disposed to face the oil cooler 41, the aftercooler 42, and the radiator 43 at a predetermined distance. Cooling fans 51a, 51b, and 51c are disposed on the facing surface 53. The side portions 54 connect the periphery of the facing surface 53 to the peripheries of the oil cooler 41, the aftercooler 42, and the radiator 43. The side portions 54 are fixed to the frame 46 provided on the peripheries of the oil cooler 41, the aftercooler 42, and the radiator 43. The side portions 54 cover the front, rear, upper, and lower sides of a space S (see FIG. 7) formed between the facing surface 53 and the oil cooler 41, the aftercooler 42, and the radiator 43. As shown in FIG. 7 , a front portion 54a of the side surface portion 54, which is formed from the front end of the opposing surface 53 toward the heat exchanger unit 36, is fixed to the front portion 46a of the frame 46. A rear portion 54b of the side surface portion 54, which is formed from the rear end of the opposing surface 53 toward the heat exchanger unit 36, is fixed to the rear portion 46b of the frame 46. As shown in FIG. 5 , a lower portion 54c of the side surface portion 54, which is formed from the lower end of the opposing surface 53 toward the heat exchanger unit 36, is fixed to the lower portion 46c of the frame 46, and an upper portion 54d of the side surface portion 54, which is formed from the upper end of the opposing surface 53 toward the heat exchanger unit 36, is fixed to the upper portion 46d of the frame 46. In this way, the side surface portion 54 surrounds the space between the opposing surface 53, on which the cooling fans 51a, 51b, and 51c are arranged, and the heat exchanger unit 36, so that cooling air generated by the rotation of the cooling fans 51a, 51b, and 51c is efficiently supplied to the heat exchanger unit 36.

[0036] As shown in Fig. 6, cooling fans 51a, 51b, and 51c are arranged in this order from top to bottom. Cooling fan 51a is arranged to face aftercooler 42 and radiator 43. Cooling fan 51b is arranged to face oil cooler 41 and aftercooler 42. Cooling fan 51c is arranged to face aftercooler 42 and radiator 43. Of cooling fans 51a, 51b, and 51c, cooling fan 51b has the largest area overlapping with aftercooler 42. The areas overlapping with aftercooler 42 of cooling fans 51a and 51c are approximately the same.

[0037] 2, external air is drawn in through intake port 32a and supplied to the inside of engine compartment 32. The air drawn in through intake port 32a passes through heat exchanger unit 36, cools the fluid to be cooled in each heat exchanger, passes through engine 33 and hydraulic pump 34, and is discharged from engine compartment 32 through outlet port 32b.

[0038] The forward rotation of cooling fans 51a, 51b, and 51c causes surrounding dust and dirt to adhere to the mesh of air intake 32a, and the dust and dirt that passes through air intake 32a adheres to heat exchanger unit 36. Reverse control is performed to rotate cooling fans 51a, 51b, and 51c in the reverse direction to blow away the dust and dirt that has adhered to air intake 32a and heat exchanger unit 36. By rotating cooling fans 51a, 51b, and 51c in the reverse direction, air intake 32a and heat exchanger unit 36 ​​are cleaned. In FIG. 7, the direction of air flow during reverse rotation is indicated by arrow C.

[0039] (Control configuration of hydraulic excavator 1) Next, a configuration relating to the control of the hydraulic excavator 1 of this embodiment will be described. Fig. 8 is a block diagram showing a configuration relating to the control of the hydraulic excavator 1.

[0040] The hydraulic excavator 1 further includes a hydraulic oil temperature sensor 61 , an aftercooler temperature sensor 62 , a water temperature sensor 63 , an engine oil temperature sensor 64 , a reverse rotation switch 65 , and a controller 66 .

[0041] The hydraulic oil temperature sensor 61 detects the temperature of the hydraulic oil passing through the oil cooler 41 and transmits the detected value v1 to the controller 66. The hydraulic oil temperature sensor 61 detects the temperature of the hydraulic oil at the inlet of the oil cooler 41. However, this is not limiting, and the hydraulic oil temperature sensor 61 may also detect the temperature of the hydraulic oil at the outlet of the oil cooler 41, or may further detect the temperatures of the hydraulic oil at both the inlet and outlet.

[0042] The aftercooler temperature sensor 62 detects the temperature of the air passing through the aftercooler 42 and sends the detected value v2 to the controller 66. The aftercooler temperature sensor 62 detects the temperature of the air at the outlet of the aftercooler 42. However, this is not limiting, and the aftercooler temperature sensor 62 may detect the temperature of the air at the inlet of the aftercooler 42, or may further detect the temperatures of the air at both the inlet and the outlet.

[0043] The water temperature sensor 63 detects the temperature of the coolant passing through the radiator 43 and transmits the detected value v3 to the controller 66. The water temperature sensor 63 detects the temperature of the coolant at the inlet of the radiator 43. However, this is not limiting, and the water temperature sensor 63 may also detect the temperature of the coolant at the outlet of the radiator 43, or may further detect the temperatures of the coolant at both the inlet and the outlet.

[0044] The engine oil temperature sensor 64 is disposed in the oil pan of the engine 33. The engine oil temperature sensor 64 detects the temperature of the engine oil and transmits a detected value v4 to the controller 66.

[0045] The reverse rotation switch 65 is disposed inside the cab 31. The reverse rotation switch 65 may be displayed on a touch panel or may be a push button switch, for example. The reverse rotation switch 65 is operated by the driver to reverse the rotation of the cooling fans 51a, 51b, and 51c to clean the intake port 32a and the heat exchanger unit 36. When the driver operates the reverse rotation switch 65, an operation signal os is sent to the controller 66.

[0046] The controller 66 includes a processor and a storage device. The processor is, for example, a CPU (Central Processing Unit). Alternatively, the processor may be a processor different from the CPU. When the processor receives the operation signal os, it executes reverse rotation control to change the rotation of the cooling fans 51a, 51b, and 51c from forward to reverse rotation based on the detected values ​​v1 to v4 in accordance with a program.

[0047] The storage device includes a non-volatile memory such as a read-only memory (ROM) and / or a volatile memory such as a random access memory (RAM). The storage device may also include an auxiliary storage device such as a hard disk or a solid-state drive (SSD). The storage device is an example of a non-transitory computer-readable recording medium. The storage device stores a first threshold, a second threshold, a third threshold, and a fourth threshold for determining whether to perform reverse rotation control. The first threshold is set for a detection value v1 of the hydraulic oil temperature sensor 61. The second threshold is set for a detection value v2 of the aftercooler temperature sensor 62. The third threshold is set for a detection value v3 of the water temperature sensor 63. The fourth threshold is set for a detection value v4 of the engine oil temperature sensor 64. At least one of the first threshold, the second threshold, the third threshold, and the fourth threshold corresponds to an example of a predetermined value.

[0048] When the controller 66 receives the operation signal os from the operation of the reverse rotation switch 65, it determines whether or not the cooling fans 51a, 51b, and 51c can be rotated in reverse based on the temperature of each fluid to be cooled.

[0049] The controller 66 compares each detection value with a threshold value set for each detection value, and executes reverse rotation control if all detection values ​​are equal to or less than the threshold value. Specifically, the controller 66 executes reverse rotation control if the detection value v1 of the hydraulic oil temperature sensor 61 is equal to or less than a first threshold value, the detection value v2 of the aftercooler temperature sensor 62 is equal to or less than a second threshold value, the detection value v3 of the water temperature sensor 63 is equal to or less than a third threshold value, and the detection value v4 of the engine oil temperature sensor 64 is equal to or less than a fourth threshold value.

[0050] The first, second, third, and fourth thresholds are set taking into account the temperature rise caused by the reverse rotation of the cooling fans 51a, 51b, and 51c. Because the air volume when the cooling fans rotate in reverse is smaller than when they rotate in forward, the temperature of the fluid to be cooled passing through the heat exchanger unit 36 ​​rises when the cooling fans rotate in reverse compared to when they rotate in forward. The first, second, third, and fourth thresholds are set to temperatures at which the engine 33 can be driven normally even when the temperature rise caused by changing from forward rotation to reverse rotation is added to each threshold.

[0051] When the controller 66 receives the operation signal os and determines that the cooling fans 51a, 51b, and 51c can be rotated in reverse, it changes the rotation of the cooling fans 51a, 51c, and 51b from forward to reverse in this order.

[0052] Specifically, the controller 66 sends a reverse rotation command signal rs1 to the cooling fan 51a, and after a first predetermined time has elapsed, sends a reverse rotation command signal rs2 to the cooling fan 51c, and after a second predetermined time has elapsed, sends a reverse rotation command signal rs3 to the cooling fan 51b. The first predetermined time is set to be the time from when the reverse rotation command signal rs1 is sent to the cooling fan 51a until the cooling fan 51a stably rotates in the reverse direction at a constant rotation speed. The second predetermined time is set to be the time from when the reverse rotation command signal rs2 is sent to the cooling fan 51c until the cooling fan 51c stably rotates in the reverse direction at a constant rotation speed. The first predetermined time and the second predetermined time may be set to be the same or different.

[0053] When a third predetermined time has elapsed since the controller 66 sent the reverse rotation command signal rs3 to the cooling fan 51b, the controller 66 switches the cooling fan 51b, 51c, and 51a back from reverse rotation to forward rotation in this order. This third predetermined time is set to at least the time from when the reverse rotation command signal rs3 is sent to the cooling fan 51b until the cooling fan 51b stably rotates in reverse at a constant rotation speed. The time during which all the cooling fans 51a, 51b, and 51c rotate in reverse can be adjusted by changing the third predetermined time. For example, by lengthening the third predetermined time, the time during which all the cooling fans 51a, 51b, and 51c rotate in reverse can be lengthened. The reverse rotation command signals rs1, rs2, and rs3 correspond to examples of control signals.

[0054] When returning cooling fans 51a, 51b, and 51c from reverse rotation to forward rotation, controller 66 transmits forward rotation command signal ps1 to cooling fan 51b, and after a fourth predetermined time has elapsed, transmits forward rotation command signal ps2 to cooling fan 51c. Subsequently, controller 66 transmits forward rotation command signal ps3 to cooling fan 51a after a fifth predetermined time has elapsed since transmitting forward rotation command signal ps2.

[0055] The fourth predetermined time is set to the time from when the forward rotation command signal ps1 is sent to the cooling fan 51a until the cooling fan 51a rotates in the reverse direction and stably rotates in the forward direction at a constant rotation speed. The fifth predetermined time is set to the time from when the forward rotation command signal ps2 is sent to the cooling fan 51c until the cooling fan 51c rotates in the reverse direction and stably rotates in the forward direction at a constant rotation speed.

[0056] As described above, cooling fan 51b, which has the largest area facing aftercooler 42, is changed from forward rotation to reverse rotation latest among the multiple cooling fans 51a, 51b, and 51c. Here, since aftercooler 42 takes in and compresses outside air, its temperature is more likely to rise when cooling fans 51a, 51b, and 51c are stopped than refrigerant that forms a closed circuit such as radiator 43 or oil cooler 41. Therefore, by suppressing the temperature rise of the air passing through aftercooler 42, it is possible to perform cleaning by reverse rotation of cooling fans 51a, 51b, and 51c even when engine 33 is running.

[0057] Therefore, in this embodiment, the cooling fan 51a, which sends a larger amount of air to the aftercooler 42, rotates in the forward direction until the end compared to the other cooling fans 51a and 51c, thereby suppressing the temperature rise of the compressed air passing through the aftercooler 42.

[0058] In addition, when returning cooling fans 51a, 51b, and 51c from forward rotation to reverse rotation, by returning cooling fan 51b to forward rotation first, the amount of air sent to aftercooler 42 can be increased at an early stage, thereby further suppressing the temperature rise of the compressed air passing through aftercooler 42.

[0059] <Operation> Next, a description will be given of the reverse rotation control operation of the hydraulic excavator 1 of this embodiment. Fig. 9 is a flow chart showing the reverse rotation control operation of the hydraulic excavator 1 of this embodiment.

[0060] When the driver operates the reverse rotation switch 65, the controller 66 receives an operation signal os transmitted from the reverse rotation switch 65 in step S10.

[0061] Next, in step S20, the controller 66 determines whether the detection value v1 of the hydraulic oil temperature sensor 61 is equal to or less than a first threshold value. If it is determined in step S20 that the detection value v1 is not equal to or less than the first threshold value, the control ends. If it is determined in step S20 that the detection value v1 is equal to or less than the first threshold value, the control proceeds to step S30.

[0062] In step S30, the controller 66 determines whether the detected value v2 of the aftercooler temperature sensor 62 is equal to or less than the second threshold. If it is determined in step S30 that the detected value v2 is not equal to or less than the second threshold, the control ends. If it is determined in step S30 that the detected value v2 is equal to or less than the second threshold, the control proceeds to step S40.

[0063] In step S40, the controller 66 determines whether the detected value v3 of the water temperature sensor 63 is equal to or less than the third threshold. If it is determined in step S40 that the detected value v3 is not equal to or less than the third threshold, the control ends. If it is determined in step S40 that the detected value v3 is equal to or less than the third threshold, the control proceeds to step S50.

[0064] In step S50, the controller 66 determines whether the detection value v4 of the engine oil temperature sensor 64 is equal to or less than a fourth threshold value. If it is determined in step S50 that the detection value v4 is not equal to or less than the fourth threshold value, the control ends. If it is determined in step S50 that the detection value v4 is equal to or less than the fourth threshold value, the control proceeds to step S60.

[0065] In step S60, the controller 66 transmits a reverse rotation command signal rs1 to the cooling fan 51a. Upon receiving the reverse rotation command signal rs1, the cooling fan 51a changes its rotation direction from forward to reverse.

[0066] After a first predetermined time has elapsed since the transmission of the reverse rotation command signal rs1, in step S70, the controller 66 transmits a reverse rotation command signal rs2 to the cooling fan 51c. Upon receiving the reverse rotation command signal rs2, the cooling fan 51c changes its rotation direction from forward to reverse.

[0067] After a second predetermined time has elapsed since the transmission of the reverse rotation command signal rs2, in step S80, the controller 66 transmits a reverse rotation command signal rs3 to the cooling fan 51b. Upon receiving the reverse rotation command signal rs3, the cooling fan 51b changes its rotation direction from forward to reverse.

[0068] Next, after a third predetermined time has elapsed since the transmission of the reverse rotation command signal rs3, in step S90, the controller 66 transmits a forward rotation command signal ps1 to the cooling fan 51b. Upon receiving the forward rotation command signal ps1, the cooling fan 51b changes its rotation direction from reverse rotation to forward rotation.

[0069] Next, after a fourth predetermined time has elapsed since the forward rotation command signal ps1 was sent, in step S100, the controller 66 sends a forward rotation command signal ps2 to the cooling fan 51c. Upon receiving the forward rotation command signal ps2, the cooling fan 51c changes its rotation direction from reverse rotation to forward rotation.

[0070] Next, after a fifth predetermined time has elapsed since the forward rotation command signal ps2 was sent, in step S120, the controller 66 sends a forward rotation command signal ps3 to the cooling fan 51c, and the control ends. In response to the forward rotation command signal ps3, the cooling fan 51a changes its rotation direction from reverse to forward. As described above, by changing the rotation of the cooling fans 51a, 51b, and 51c from forward to reverse, the heat exchanger unit 36 ​​can be cleaned and dust and dirt can be blown away.

[0071] (Features) (1) The hydraulic excavator 1 (an example of a work machine) of this embodiment includes a heat exchanger unit 36 ​​(an example of a heat exchange section), multiple cooling fans 51a, 51b, 51c, and a controller 66. The heat exchanger unit 36 ​​has at least one heat exchanger. The multiple cooling fans 51a, 51b, 51c cool the heat exchanger unit 36. When at least one cooling fan stops rotating when changing from forward rotation to reverse rotation, the controller 66 changes the rotation of the multiple cooling fans 51a, 51b, 51c from forward rotation to reverse rotation while controlling at least one other cooling fan to continue rotating forward or reverse.

[0072] In this way, when at least one of the cooling fans 51a, 51b, and 51c stops rotating to change from forward rotation to reverse rotation, all of the cooling fans 51a, 51b, and 51c are changed from forward rotation to reverse rotation while controlling the other cooling fans to continue rotating forward or reverse.

[0073] This allows all of the cooling fans 51a, 51b, and 51c to be changed from forward rotation to reverse rotation without stopping simultaneously, thereby suppressing a temperature rise in the fluid to be cooled in the heat exchanger unit 36. Therefore, the heat exchanger can be cleaned while suppressing a temperature rise in the fluid to be cooled. Furthermore, because a temperature rise in the fluid to be cooled can be suppressed, the heat exchanger can be cleaned even while the engine 33 is running.

[0074] (2) In the hydraulic excavator 1 of this embodiment, the cooling fans 51a, 51b, and 51c are electric fans.

[0075] By using an electric fan in this way, it is possible to easily change the direction of rotation from forward to reverse. Furthermore, because electric fans are relatively small, multiple fans can be installed. Therefore, by controlling multiple electric fans when cleaning the heat exchanger, it is possible to prevent the cooling air from stopping at any time.

[0076] (3) In the hydraulic excavator 1 of this embodiment, the controller 66 transmits a reverse rotation command signal rs1 to at least one cooling fan 51a to change the rotation from forward to reverse, and then, after a first predetermined time (an example of a predetermined time) has elapsed, transmits a reverse rotation command signal rs2 to at least one other cooling fan 51c to change the rotation from forward to reverse. Also, after transmitting a reverse rotation command signal rs2 to at least one cooling fan 51b to change the rotation from forward to reverse, and after a second predetermined time (an example of a predetermined time) has elapsed, transmits a reverse rotation command signal rs3 to at least one other cooling fan 51b to change the rotation from forward to reverse.

[0077] For example, the first predetermined time can be set to the time it takes for cooling fan 51a to rotate in the reverse direction stably at a constant rotation speed from the forward direction, and the second predetermined time can be set to the time it takes for cooling fan 51c to rotate in the reverse direction stably at a constant rotation speed from the forward direction.

[0078] This prevents all cooling fans from stopping at the same time because the timing for stopping other cooling fans occurs after a specific cooling fan starts rotating in the reverse direction and the rotation speed stabilizes.

[0079] (4) In the hydraulic excavator 1 of this embodiment, the controller 66 changes the rotation direction of the plurality of cooling fans 51a, 51b, 51c from forward to reverse one by one in sequence.

[0080] This allows all of the cooling fans 51a, 51b, and 51c to be changed from forward rotation to reverse rotation one by one in order.

[0081] (5) The hydraulic excavator 1 of this embodiment further includes a hydraulic oil temperature sensor 61, an aftercooler temperature sensor 62, a water temperature sensor 63, and an engine oil temperature sensor 64. The hydraulic oil temperature sensor 61 detects the temperature of the fluid to be cooled that is heat exchanged in the oil cooler 41. The aftercooler temperature sensor 62 detects the temperature of the fluid to be cooled that is heat exchanged in the aftercooler 42. The water temperature sensor 63 detects the temperature of the fluid to be cooled that is heat exchanged in the radiator 43. The controller 66 changes the rotation of the multiple cooling fans 51a, 51b, 51c from forward to reverse when the detection value v1 of the hydraulic oil temperature sensor 61 is equal to or less than a first threshold, the detection value v2 of the aftercooler temperature sensor 62 is equal to or less than a second threshold, the detection value v3 of the water temperature sensor 63 is equal to or less than a third threshold, and the detection value v4 of the engine oil temperature sensor 64 is equal to or less than a fourth threshold.

[0082] When all cooling fans 51a, 51b, and 51c are rotated in reverse, the amount of cooling air is less than when all cooling fans 51a, 51b, and 51c are rotated in forward direction. As a result, the temperature of the fluid to be cooled rises. By setting each threshold value to a temperature that takes this temperature rise into consideration, it is possible to determine whether the temperature of the fluid to be cooled in the heat exchanger unit 36 ​​is in a state that allows for reverse rotation, and then control the change from forward rotation to reverse rotation.

[0083] (6) In the hydraulic excavator 1 of this embodiment, the heat exchanger unit 36 ​​has an aftercooler 42 as a heat exchanger.

[0084] Because the aftercooler 42 cools the compressed air that is taken in and compressed with outside air, its temperature is more likely to rise when the cooling fans 51a, 51b, and 51c are stopped than when the cooling fluids that form closed circuits, such as the radiator 43 and the oil cooler 41, are cooled. In the hydraulic excavator 1 of this embodiment, when the cooling fans 51a, 51b, and 51c are changed from forward rotation to reverse rotation, there is no timing when all of the cooling fans stop at the same time, so it is possible to suppress a rise in the temperature of the compressed air passing through the aftercooler 42. This makes it possible to clean the aftercooler 42 even while the engine 33 is running.

[0085] (7) In the hydraulic excavator 1 of this embodiment, the heat exchanger unit 36 ​​further includes a radiator 43 and an oil cooler 41 as a plurality of heat exchangers.

[0086] This allows cleaning of the radiator 43 and the oil cooler 41 while suppressing a rise in the temperature of the fluid to be cooled.

[0087] (8) In the hydraulic excavator 1 of this embodiment, the controller 66 changes the cooling fan 51b, which has the largest area overlapping the aftercooler 42 when viewed along the air suction direction, from forward rotation to reverse rotation the slowest among the multiple cooling fans 51a, 51b, and 51c.

[0088] Since the temperature of the fluid to be cooled in the aftercooler 42 is more likely to rise than in the radiator 43 and the oil cooler 41, the temperature rise in the aftercooler 42 can be suppressed by lastly reversing the rotation of the cooling fan 51b, which sends most of the air to the aftercooler 42.

[0089] (9) The hydraulic excavator 1 of this embodiment further includes a reverse rotation switch 65. The reverse rotation switch 65 is operated by the operator and transmits an operation signal os to the controller 66. Upon receiving the operation signal os, the controller 66 changes the rotation of the multiple cooling fans 51a, 51b, 51c from forward rotation to reverse rotation. This allows the driver to clean the heat exchanger unit 36 ​​at a timing desired by the driver. (10) The control method for a hydraulic excavator of this embodiment is a control method for a hydraulic excavator equipped with a heat exchanger unit 36 ​​having at least one heat exchanger and multiple cooling fans 51a, 51b, 51c that cool the heat exchanger unit 36, and in steps S60 to S80, when the rotation of at least one cooling fan stops when changing from forward rotation to reverse rotation, the multiple cooling fans 51a, 51b, 51c are changed from forward rotation to reverse rotation while controlling at least one other cooling fan to continue rotating forward or reverse.

[0090] In this way, when at least one cooling fan stops rotating when changing from forward rotation to reverse rotation, all the cooling fans 51a, 51b, and 51c are changed from forward rotation to reverse rotation while controlling so that at least one other cooling fan continues rotating forward or reverse.

[0091] This allows all of the cooling fans 51a, 51b, and 51c to be changed from forward rotation to reverse rotation without stopping simultaneously, thereby making it possible to suppress a temperature rise in the fluid to be cooled in the heat exchanger unit 36. Therefore, the heat exchanger can be cleaned while suppressing a temperature rise in the fluid to be cooled. Furthermore, because a temperature rise in the fluid to be cooled can be suppressed, the heat exchanger can be cleaned even while the engine 33 is running.

[0092] (Other embodiments) Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0093] (A) In the hydraulic excavator 1 of the above embodiment, the cooling fans 51a, 51c, and 51b are changed from forward rotation to reverse rotation one by one in sequence, but this is not limited to this. For example, two cooling fans may be changed from forward rotation to reverse rotation simultaneously, and then the remaining cooling fan may be changed from forward rotation to reverse rotation. Specifically, for example, by simultaneously sending a reverse rotation command signal to cooling fans 51a and 51c, cooling fans 51a and 51c are changed from forward rotation to reverse rotation simultaneously. Then, after the reverse rotation of cooling fans 51a and 51c reaches a certain rotation speed and stabilizes, a reverse rotation command signal is sent to cooling fan 51b, thereby changing cooling fan 51b from forward rotation to reverse rotation.

[0094] Alternatively, one cooling fan may be changed from forward rotation to reverse rotation, and then the remaining two cooling fans may be changed from forward rotation to reverse rotation simultaneously. Specifically, for example, a reverse rotation command signal is sent to cooling fan 51a, causing cooling fan 51a to change from forward rotation to reverse rotation. Then, after the reverse rotation of cooling fan 51a reaches a certain rotation speed and stabilizes, a reverse rotation command signal is sent simultaneously to cooling fans 51b and 51c, causing cooling fans 51b and 51c to change from forward rotation to reverse rotation simultaneously.

[0095] (B) In the hydraulic excavator 1 of the above embodiment, three cooling fans 51a, 51b, 51c are arranged, but the number is not limited to three, and two or four or more cooling fans may be provided.

[0096] If four or more cooling fans are provided, the cooling fans may be divided into multiple groups, and the rotation of each group may be changed from forward to reverse in turn. The number of cooling fans included in each group may be the same or different. Also, a group does not necessarily have to include multiple cooling fans, and may include only one cooling fan.

[0097] (C) In the hydraulic excavator 1 of the above embodiment, the cooling fan 51a is rotated in reverse before the cooling fan 51c, but either of the cooling fans 51a and 51c may be rotated in reverse first because the cooling fans 51a and 51c have approximately the same area overlapping the aftercooler 42. Furthermore, when returning to forward rotation, either of the cooling fans 51a and 51c may be rotated first.

[0098] (D) In the hydraulic excavator 1 of the above embodiment, reverse rotation control is performed to change the rotation of the cooling fans 51a, 51b, and 51c from forward to reverse when the detection value v1 of the hydraulic oil temperature sensor 61 is equal to or less than the first threshold, the detection value v2 of the aftercooler temperature sensor 62 is equal to or less than the second threshold, the detection value v3 of the water temperature sensor 63 is equal to or less than the third threshold, and the detection value v4 of the engine oil temperature sensor 64 is equal to or less than the fourth threshold. However, this is not limiting. For example, it is not necessary to determine whether the detection value v4 of the engine oil temperature sensor 64 is equal to or less than the fourth threshold. Furthermore, it is not necessary to perform all of the above-described temperature detection values ​​to determine whether they are equal to or less than the thresholds. However, it is preferable to at least determine whether the detection value v2 of the aftercooler temperature sensor 62 is equal to or less than the second threshold. Because the aftercooler 42 takes in and compresses external air to cool the compressed air, stopping the cooling fans 51a, 51b, and 51c significantly increases the temperature. For this reason, it is preferable to detect the temperature of the compressed air, which is the fluid to be cooled by the aftercooler 42, and determine whether or not it is equal to or higher than a threshold value.

[0099] (E) In the hydraulic excavator 1 of the above embodiment, while the cooling fans 51a, 51b, and 51c are rotating in reverse, temperature rise is not monitored using the detection values ​​of the hydraulic oil temperature sensor 61, the aftercooler temperature sensor 62, the water temperature sensor 63, and the engine oil temperature sensor 64, but temperature rise may be monitored.

[0100] For example, a fifth threshold is set for the detection value v1 of the hydraulic oil temperature sensor 61, a sixth threshold is set for the detection value v2 of the aftercooler temperature sensor 62, a seventh threshold is set for the detection value v3 of the water temperature sensor 63, and an eighth threshold is set for the detection value v4 of the engine oil temperature sensor 64.

[0101] Furthermore, even during steps S60 to S80, if the detection value of the hydraulic oil temperature sensor 61 becomes equal to or greater than the fifth threshold, if the detection value of the aftercooler temperature sensor 62 becomes equal to or greater than the sixth threshold, if the detection value of the water temperature sensor 63 becomes equal to or greater than the seventh threshold, or if the detection value of the engine oil temperature sensor 64 becomes equal to or greater than the fourth threshold, the controller 66 may change the reverse rotation of the cooling fans 51a, 51b, 51c back to forward rotation.

[0102] (F) In the above embodiment, when the controller 66 receives an operation signal transmitted by the driver operating the reverse rotation switch 65, the controller 66 determines the temperature and then controls the cooling fans 51a, 51b, and 51c to rotate in reverse, so that the operation of the reverse rotation switch 65 is the trigger, but this is not limited to this. For example, a timer may be provided within the controller 66 or separately, and the controller 66 may determine at predetermined time intervals whether the detected values ​​v1 to v4 are equal to or less than the respective threshold values, and if they are equal to or less than the threshold values, execute the reverse rotation control.

[0103] (G) In the hydraulic excavator 1 of the above embodiment, the cooling fans 51a, 51b, and 51c are changed from forward rotation to reverse rotation and then returned to forward rotation, but this is not limited to this. For example, when the engine 33 is stopped after the cooling fans 51a, 51b, and 51c are rotated in reverse, the cooling fans 51a, 51b, and 51c may be stopped without being rotated in reverse.

[0104] (H) In the above embodiment, a hydraulic excavator has been used as an example of a work machine, but the present invention is not limited to this and may be a bulldozer, a wheel loader, a dump truck, a forklift, or the like. [Industrial Applicability]

[0105] According to the present disclosure, it is possible to clean a heat exchanger while suppressing a temperature rise of a fluid to be cooled, and is useful for work machines and the like. [Explanation of symbols]

[0106] 1: Hydraulic excavator 36: Heat exchanger unit 51a: Cooling fan 51b: Cooling fan 51c: Cooling fan 66: Controller

Claims

1. a heat exchange section having at least one heat exchanger; a plurality of cooling fans for cooling the heat exchange unit; The engine and a controller that changes all of the cooling fans from forward rotation to reverse rotation while controlling at least one other cooling fan to continue rotating in forward or reverse rotation when the rotation of at least one of the cooling fans stops when changing from forward rotation to reverse rotation, and maintains all of the cooling fans in reverse rotation for a predetermined time; the heat exchange unit is disposed upstream of the plurality of cooling fans in the air flow when the cooling fans are rotated forward, the engine is disposed downstream of the plurality of cooling fans in the air flow when the cooling fans are rotated in the forward direction, the heat exchange unit, the plurality of cooling fans, and the engine are arranged in a direction perpendicular to the front-rear direction of the vehicle body. Work machinery.

2. The cooling fan is an electric fan.

2. The work machine according to claim 1.

3. the controller transmits a control signal to at least one of the cooling fans to change the rotation direction from forward to reverse, and then, after a predetermined time has elapsed, transmits a control signal to at least another of the cooling fans to change the rotation direction from forward to reverse; 2. The work machine according to claim 1.

4. the controller changes the rotation of the cooling fans from forward to reverse one by one in sequence; 4. The work machine according to claim 3.

5. a temperature sensor for detecting the temperature of a fluid to be cooled that is subjected to heat exchange in the heat exchanger; the controller changes the rotation of the cooling fans from forward to reverse when the value of the temperature sensor is equal to or less than a predetermined value; 2. The work machine according to claim 1.

6. The heat exchange unit has an aftercooler as the heat exchanger.

2. The work machine according to claim 1.

7. The heat exchange unit further includes a radiator and an oil cooler as the plurality of heat exchangers.

7. The work machine according to claim 6.

8. the controller changes the rotation of the cooling fan having the largest area overlapping with the aftercooler when viewed along the air suction direction from the forward rotation to the reverse rotation the slowest among the plurality of cooling fans.

7. The work machine according to claim 6.

9. A reverse rotation switch is further provided which is operated by the driver and transmits an operation signal to the controller, When the controller receives the operation signal, it changes the rotation of the cooling fans from forward to reverse.

2. The work machine according to claim 1.

10. A control method for a work machine including a heat exchange unit having at least one heat exchanger, a plurality of cooling fans that cool the heat exchange unit, and an engine, comprising: when at least one of the cooling fans stops rotating from forward rotation to reverse rotation, all of the plurality of cooling fans are changed from forward rotation to reverse rotation while controlling at least one other of the cooling fans to continue rotating forward or reverse, and all of the plurality of cooling fans are maintained in reverse rotation for a predetermined time; the heat exchange unit is disposed upstream of the plurality of cooling fans in the air flow when the cooling fans are rotated forward, the engine is disposed downstream of the plurality of cooling fans in the air flow when the cooling fans are rotated in the forward direction, the heat exchange unit, the plurality of cooling fans, and the engine are arranged in a direction perpendicular to the front-rear direction of the vehicle body. A method for controlling a work machine.

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