WO2023063256A1

WO2023063256A1 - System for controlling cooling fan, work machine, and method for controlling cooling fan

Info

Publication number: WO2023063256A1
Application number: PCT/JP2022/037629
Authority: WO
Inventors: 厚北條
Original assignee: 株式会社小松製作所
Priority date: 2021-10-11
Filing date: 2022-10-07
Publication date: 2023-04-20
Also published as: KR20240052060A; JP7340578B2; JP2023057272A; DE112022003877T5; CN118056047A

Abstract

Provided is a system for controlling a cooling fan with which the cooling capacity of the cooling fan can be ensured. The control system includes an engine, a work apparatus driven by the engine, a cooling fan configured such that the speed thereof can be controlled independently of the speed of the engine, and a controller that controls the cooling fan. When the speed of the engine is greater than a threshold value and the frequency of the cooling fan is within a predetermined range in relation to the frequency of the engine while the work apparatus has stopped, the controller changes the frequency of the cooling fan and controls the cooling fan so that the difference in frequency between the cooling fan and the engine will be greater than when the frequency of the cooling fan was acquired.

Description

Cooling fan control system, working machine, and cooling fan control method

The present disclosure relates to a cooling fan control system, a working machine, and a cooling fan control method.

A control system for a cooling fan that blows air to cool a working fluid is described, for example, in International Publication No. 2007/026627 (Patent Document 1). This document discloses adjusting the number of revolutions of a cooling fan when a resting state of a working mechanism is detected based on an operating state of a working machine lever.

WO2007/026627

A hydraulically driven cooling fan is a waste of engine power when the cooling system does not need to cool as much, even when the engine is running at high speed. It was controlled to reduce the rotation speed of the fan. Despite the advantage of a hydraulically driven cooling fan in controlling the speed of the cooling fan when the engine is rotating at relatively high speeds, resonance can occur between the cooling fan and the engine. Yes, it was an issue.

This disclosure proposes a cooling fan control system, a working machine, and a cooling fan control method that can suppress resonance and ensure the cooling capacity of the cooling fan.

According to the present disclosure, a cooling device comprising an engine, a work machine driven by the engine, a cooling fan configured to be able to control the number of rotations independently of the number of rotations of the engine, and a controller that controls the cooling fan A fan control system is proposed. The controller obtains the engine frequency and the cooling fan frequency. The controller changes the frequency of the cooling fan when the number of revolutions of the engine is greater than a threshold value and the frequency of the cooling fan is within a predetermined range with respect to the frequency of the engine while the work machine is stopped. The cooling fan is controlled so as to increase the difference in frequency between the cooling fan and the engine from when the frequency of the cooling fan is acquired.

According to the present disclosure, resonance can be suppressed and the cooling capacity of the cooling fan can be ensured.

It is a side view showing roughly composition of a work machine based on an embodiment. 2 is a block diagram showing a schematic configuration of a system of the working machine shown in FIG. 1; FIG. 3 is a block diagram illustrating the functional configuration of a controller; FIG. 5 is a flow chart showing the flow of processing related to control of the frequency of the cooling fan; 4 is a graph showing the relationship between the operation of an operating lever and the number of rotations of a cooling fan; 4 is a graph showing the relationship between engine speed and execution or cancellation of cooling fan speed control of the embodiment. 4 is a graph showing the relationship between the engine speed and the frequencies of the engine and the cooling fan.

The embodiments will be described below based on the drawings. In the following description, the same reference numerals are given to the same parts. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<Configuration of working machine>
FIG. 1 is a side view schematically showing the configuration of a hydraulic excavator 100 as an example of a work machine based on an embodiment of the present disclosure. As shown in FIG. 1, a hydraulic excavator 100 of the present embodiment mainly has a traveling body 1, a revolving body 2, and a working machine 3. As shown in FIG. A vehicle body of the hydraulic excavator 100 is configured by the traveling body 1 and the revolving body 2 .

The traveling body 1 has a pair of left and right crawler belt devices 1a. Each of the pair of left and right crawler belt devices 1a has a crawler belt. The hydraulic excavator 100 is self-propelled by rotating the pair of left and right crawler belts.

The revolving body 2 is installed so as to be rotatable with respect to the traveling body 1. The revolving body 2 mainly has an operator's cab (cab) 2a, an operator's seat 2b, an engine room 2c, and a counterweight 2d. The driver's cab 2a is arranged, for example, on the front left side of the revolving body 2 (vehicle front side). A driver's seat 2b for an operator to sit on is arranged in the inner space of the driver's cab 2a.

The engine room 2c and the counterweight 2d are arranged on the rear side of the revolving body 2 (vehicle rear side) with respect to the driver's cab 2a. The engine room 2c accommodates an engine unit (engine, exhaust treatment structure, etc.). The upper part of the engine room 2c is covered with an engine hood. The counterweight 2d is arranged behind the engine room 2c.

The working machine 3 is pivotally supported on the front side of the revolving body 2 and, for example, on the right side of the operator's cab 2a. The working machine 3 has, for example, a boom 3a, an arm 3b, a bucket 3c, a boom cylinder 4a, an arm cylinder 4b, a bucket cylinder 4c, and the like. A base end (one end) of the boom 3a is rotatably connected to the revolving body 2 by a boom bottom pin 5a. A base end (one end) of the arm 3b is rotatably connected to a tip end (the other end) of the boom 3a by a boom top pin 5b. The bucket 3c (one end) is rotatably connected to the tip (the other end) of the arm 3b by an arm top pin 5c.

In this embodiment, the positional relationship of each part of the hydraulic excavator 100 will be described with the work machine 3 as a reference.

The boom 3a of the work machine 3 rotates relative to the revolving body 2 around the boom bottom pin 5a. A specific portion of the boom 3a that rotates with respect to the revolving body 2, for example, the tip of the boom 3a moves in an arc shape, and a plane that includes the arc is specified. When the hydraulic excavator 100 is viewed from above, the plane is represented as a straight line. The direction in which this straight line extends is the front-rear direction of the vehicle body of the excavator 100 or the front-rear direction of the revolving body 2, and is hereinafter simply referred to as the front-rear direction. The left-right direction (vehicle width direction) of the excavator 100 or the left-right direction of the revolving body 2 is a direction orthogonal to the front-rear direction in a plan view, and is hereinafter simply referred to as the left-right direction. The vertical direction of the vehicle body of the hydraulic excavator 100 or the vertical direction of the revolving structure 2 is a direction orthogonal to a plane defined by the front-rear direction and the left-right direction, and is hereinafter simply referred to as the vertical direction.

In the front-rear direction, the side where the work implement 3 protrudes from the vehicle body is the front direction, and the direction opposite to the front direction is the rear direction. The right side and the left side in the horizontal direction are the right direction and the left direction, respectively, when viewed in the forward direction. In the vertical direction, the side with the ground is the lower side, and the side with the sky is the upper side.

The front-back direction is the front-back direction of the operator seated in the driver's seat 2b in the operator's cab 2a. The left-right direction is the left-right direction of the operator seated in the driver's seat 2b. The vertical direction is the vertical direction of the operator seated on the driver's seat 2b. The direction facing the operator seated on the driver's seat 2b is the front direction, and the direction behind the operator seated on the driver's seat 2b is the rearward direction. The right side and the left side when an operator sitting in the driver's seat 2b faces the front are the right direction and the left direction, respectively. The operator seated on the driver's seat 2b has the lower side at the feet and the upper side at the head side.

The boom 3a can be driven by a boom cylinder (boom hydraulic cylinder) 4a. By this drive, the boom 3a can be rotated vertically with respect to the revolving body 2 around the boom bottom pin 5a. The arm 3b can be driven by an arm cylinder (arm hydraulic cylinder) 4b. This drive allows the arm 3b to rotate vertically with respect to the boom 3a around the boom top pin 5b. The bucket (attachment) 3c can be driven by a bucket cylinder (attachment hydraulic cylinder) 4c. By this driving, the bucket 3c can be rotated vertically with respect to the arm 3b around the arm top pin 5c. The working machine 3 can be driven in this manner.

The boom bottom pin 5a is supported by the body of the excavator 100. The boom bottom pin 5 a is supported by a pair of vertical plates (not shown) of the frame of the revolving body 2 . The boom top pin 5b is attached to the tip of the boom 3a. Arm top pin 5c is attached to the tip of arm 3b. The boom bottom pin 5a, the boom top pin 5b and the arm top pin 5c all extend in the left-right direction. The boom bottom pin 5a is also called a boom foot pin.

The working machine 3 has a bucket link 3d. The bucket link 3d has a first link member 3da and a second link member 3db. The tip of the first link member 3da and the tip of the second link member 3db are connected via a bucket cylinder top pin 3dc so as to be relatively rotatable. The bucket cylinder top pin 3dc is connected to the tip of the bucket cylinder 4c. Therefore, the first link member 3da and the second link member 3db are pin-connected to the bucket cylinder 4c.

The proximal end of the first link member 3da is rotatably connected to the arm 3b by a first link pin 3dd. A base end of the second link member 3db is rotatably connected to a bracket at the root portion of the bucket 3c by a second link pin 3de.

A pressure sensor 6a may be attached to the head side of the boom cylinder 4a. The pressure sensor 6a can detect the pressure (head pressure) of hydraulic fluid in the cylinder head side oil chamber 40A of the boom cylinder 4a. A pressure sensor 6b may be attached to the bottom side of the boom cylinder 4a. The pressure sensor 6b can detect the pressure (bottom pressure) of the working oil in the cylinder bottom side oil chamber 40B of the boom cylinder 4a. The

pressure sensors

6a and 6b output working oil pressure information consisting of head pressure and bottom pressure to a controller 30, which will be described later.

A pressure sensor 6c may be attached to the head side of the arm cylinder 4b. The pressure sensor 6c can detect the pressure of hydraulic fluid (head pressure) in the cylinder head side oil chamber of the arm cylinder 4b. A pressure sensor 6d may be attached to the bottom side of the arm cylinder 4b. The pressure sensor 6d can detect the pressure (bottom pressure) of hydraulic fluid in the cylinder bottom side oil chamber of the arm cylinder 4b. The

pressure sensors

6c and 6d output working oil pressure information consisting of head pressure and bottom pressure to the controller 30, which will be described later.

A pressure sensor 6e may be attached to the head side of the bucket cylinder 4c. The pressure sensor 6e can detect the pressure (head pressure) of hydraulic fluid in the cylinder head side oil chamber of the bucket cylinder 4c. A pressure sensor 6f may be attached to the bottom side of the bucket cylinder 4c. The pressure sensor 6f can detect the pressure (bottom pressure) of hydraulic oil in the cylinder bottom side oil chamber of the bucket cylinder 4c. The

pressure sensors

6e and 6f output working oil pressure information including head pressure and bottom pressure to the controller 30, which will be described later.

The boom 3a, the arm 3b, and the bucket 3c may be provided with position sensors for obtaining information on their respective positions and attitudes. The position sensor outputs boom information, arm information and attachment information for obtaining respective positions of the boom 3a, the arm 3b and the bucket 3c to the controller 30, which will be described later.

A stroke sensor 7a may be attached to the boom cylinder 4a as a position sensor. The stroke sensor 7a detects the amount of displacement of the cylinder rod 4ab with respect to the cylinder 4aa in the boom cylinder 4a as boom information. A stroke sensor 7b may be attached to the arm cylinder 4b as a position sensor. The stroke sensor 7b detects the amount of displacement of the cylinder rod in the arm cylinder 4b as arm information. A stroke sensor 7c may be attached to the bucket cylinder 4c as a position sensor. The stroke sensor 7c detects the amount of displacement of the cylinder rod in the bucket cylinder 4c as attachment information.

The position sensor may be an angle sensor. An angle sensor 9a may be attached around the boom bottom pin 5a. An angle sensor 9b may be attached around the boom top pin 5b. An angle sensor 9c may be attached around the arm top pin 5c. The

angle sensors

9a, 9b, 9c may be potentiometers or rotary encoders. The

angle sensors

9a, 9b, and 9c output rotation angle information (boom information, arm information, and attachment information) of the boom 3a and the like to the controller 30, which will be described later.

As shown in FIG. 1, when viewed from the side, a straight line passing through the boom bottom pin 5a and the boom top pin 5b (indicated by a two-dot chain line in FIG. 1) and a straight line extending in the vertical direction (a dashed line in FIG. 1) ) is defined as the boom angle θb. Boom angle θb is usually an acute angle. The boom angle θb represents the angle of the boom 3a with respect to the revolving body 2. As shown in FIG. The boom angle θb can be calculated from the detection result of the stroke sensor 7a, and can be calculated from the measurement value of the angle sensor 9a.

When viewed from the side, the angle between a straight line passing through the boom bottom pin 5a and the boom top pin 5b and a straight line passing through the boom top pin 5b and the arm top pin 5c (indicated by a chain double-dashed line in FIG. 1) is Let the arm angle be θa. The arm angle θa represents the angle of the arm 3b with respect to the boom 3a in the area where the arm 3b rotates when viewed from the side. The arm angle θa can be calculated from the detection result of the stroke sensor 7b, and can be calculated from the measurement value of the angle sensor 9b.

When viewed from the side, the angle formed by a straight line passing through the boom top pin 5b and the arm top pin 5c and a straight line passing through the arm top pin 5c and the cutting edge of the bucket 3c (indicated by a chain double-dashed line in FIG. 1) is Let the bucket angle be θk. The bucket angle θk represents the angle of the bucket 3c with respect to the arm 3b in the region where the bucket 3c rotates when viewed from the side. The bucket angle θk can be calculated from the detection result of the stroke sensor 7c, and can be calculated from the measurement value of the angle sensor 9c.

<System configuration>
Next, a schematic configuration of the working machine system will be described with reference to FIG. FIG. 2 is a block diagram showing a schematic configuration of the system of the work machine shown in FIG. 1. As shown in FIG.

The system in this embodiment is a system for controlling the cooling fan 21 . A system according to the embodiment includes a hydraulic excavator 100 as an example of a working machine shown in FIG. 1 and a controller 30 shown in FIG. The controller 30 may be mounted on the hydraulic excavator 100 . The controller 30 may be installed outside the excavator 100 . The controller 30 may be placed at the work site of the excavator 100 or at a remote location away from the work site of the excavator 100 .

The engine 15 is mounted on the revolving body 2. The engine 15 is accommodated in the engine room 2c. Engine 15 is, for example, a diesel engine. By controlling the injection amount of fuel to the engine 15, the output of the engine 15 is controlled. The engine 15 is a drive source for operating the hydraulic excavator 100 . The driving force generated by the engine 15 causes the traveling body 1 to travel, the revolving body 2 to revolve with respect to the traveling body 1, and the working machine 3 to operate. In the embodiment, the engine 15 is an in-line 6-cylinder.

A hydraulic pump 23 is connected to the engine 15 . The rotation of the engine 15 rotates the hydraulic pump 23 . When the hydraulic pump 23 is operated, hydraulic oil is supplied from the hydraulic pump 23 to the hydraulic motor 22 via the electromagnetic proportional control valve 24, and the hydraulic motor 22 is rotated. The hydraulic motor 22 is a motor for rotating the cooling fan 21 . In the embodiment, the cooling fan 21 has six blades. A cooling fan 21 , a hydraulic motor 22 and a hydraulic pump 23 are mounted on the revolving body 2 .

The cooling fan 21 is rotationally driven by a hydraulic motor 22 . The cooling fan 21 is a hydraulically driven fan that is driven using hydraulic oil as a power transmission medium. The cooling fan 21 is not directly connected to the output shaft of the engine 15 , so that the rotation speed of the cooling fan 21 can be freely controlled independently of the rotation speed of the engine 15 . Specifically, the number of revolutions of the cooling fan 21 is controlled according to the flow rate of hydraulic oil supplied from the hydraulic pump 23 to the hydraulic motor 22 .

The intake air cooler 25 cools the air drawn into the engine 15 . The oil cooler 26 cools hydraulic oil circulating through the hydraulic motor 22 and the hydraulic pump 23 . The radiator 27 cools cooling water for the engine 15 . Intake air cooler 25 , oil cooler 26 and radiator 27 are arranged to face cooling fan 21 . Cooling fan 21 is rotated by hydraulic motor 22 to blow cooling air to intake air cooler 25 , oil cooler 26 and radiator 27 .

The hydraulic oil for operating the hydraulic motor 22, the cooling water for cooling the engine 15, and the air supplied to the engine 15 are examples of the working fluid involved in the operation of the engine 15. The cooling fan 21 blows air to cool the working fluid.

A water temperature sensor 28 is provided in the cooling water path. An oil temperature sensor 29 is provided in the hydraulic oil path. An engine speed sensor 31 is attached to the engine 15 . When the engine 15 rotates, the water temperature sensor 28 detects the temperature of the cooling water, the oil temperature sensor 29 detects the temperature of the working oil, and the engine speed sensor 31 detects the speed of the engine 15 . These detection results are output to the controller 30 .

A fan speed sensor 32 is attached to the cooling fan 21 . When the cooling fan 21 rotates, the rotation speed of the cooling fan 21 is detected by the fan rotation speed sensor 32 . This detection result is output to the controller 30 .

The hydraulic excavator 100 includes an operating device 33 operated by an operator. The operating device 33 is arranged, for example, in the driver's cab 2a. The operating device 33 includes a working machine operating device operated to operate the working machine 3 , a swing operating device operated to swing the swing body 2 , and a swing operating device operated to operate the traveling body 1 . and a travel control device. The work machine operating device and the turning operating device are, for example, operating levers. The travel operation device is, for example, an operation pedal.

The operation detection unit 33A detects the amount of operation of the operation device 33. When the operation device 33 is an operation lever, the operation detection section 33A detects the direction and angle of inclination from the neutral position of the operation lever. When the operation device 33 is an operation pedal, the operation detection unit 33A detects the depression amount of the operation pedal. This detection result is output to the controller 30 .

The operation detection unit 33A may be, for example, a displacement sensor such as a potentiometer. The operating device 33 is not limited to an electric operating device, and may be a pilot hydraulic operating device. In this case, the operation detection section 33A may be a hydraulic sensor that detects the pressure of the pilot oil.

The controller 30 has a CPU (Central Processing Unit) and a storage unit 34 (not shown). The storage unit 34 stores a program for controlling the operation of the cooling fan 21 and various data necessary for executing the program. The storage unit 34 also temporarily stores working data generated as the work is executed.

FIG. 3 is a block diagram illustrating the functional configuration of the controller 30. As shown in FIG. As shown in FIG. 3, the controller 30 based on the embodiment includes a working machine state determination section 30A, an engine frequency acquisition section 30B, a fan frequency acquisition section 30C, a resonance frequency setting section 30D, and an arithmetic processing section 30E. , a fan control command section 30F and a timer 30T.

The work machine state determination unit 30A determines whether the work machine 3 is operating or stopped. The engine frequency acquisition unit 30B acquires the frequency of the engine 15 based on the rotation speed of the engine 15 detected by the engine rotation speed sensor 31 . Fan frequency acquisition unit 30</b>C acquires the frequency of cooling fan 21 based on the rotation speed of cooling fan 21 detected by fan rotation speed sensor 32 . The resonance frequency setting unit 30D sets a range of frequencies in which resonance can occur with respect to the frequency of the engine 15. FIG.

The computation processing unit 30E executes various computations related to control of the frequency of the cooling fan 21. Fan control command unit 30F outputs a control signal to cooling fan 21 . The timer 30T measures time. The arithmetic processing unit 30E can read the current time from the timer 30T.

<Control of Cooling Fan 21>
Control of the cooling fan 21 by the controller 30 in the hydraulic excavator 100 of the embodiment having the above configuration will be described below. FIG. 4 is a flow chart showing the flow of processing related to control of the frequency of the cooling fan 21. As shown in FIG.

As shown in FIG. 4, in step S1, it is determined whether or not the operating lever operated to operate the working machine 3 is in the neutral state. The tilt from the neutral position of the operation lever detected by the operation detection section 33A is input to the controller 30 . 30 A of work machine state determination parts discriminate|determine the state of the work machine 3 based on the detection result of 33 A of operation detection parts. Specifically, based on the detection result that the operation lever is tilted from the neutral state, the work machine state determination unit 30A determines that the operation lever is being operated, and the operator's request to operate the work machine 3 is determined. It is determined that a command has been given and therefore the working machine 3 is operating. Further, based on the detection result that the operation lever is in the neutral state, the work machine state determination unit 30A determines that the operation lever is not operated and therefore the work machine 3 is stopped.

When it is determined that the control lever is in the neutral state (YES in step S1), it is then determined in step S2 whether or not a predetermined time has elapsed. FIG. 5 is a graph showing the relationship between the operation of the control lever and the rotation speed of the cooling fan 21. As shown in FIG. The horizontal axis of FIG. 5 indicates time, and the vertical axis of FIG. 5 indicates the target rotational speed of cooling fan 21 .

The arithmetic processing unit 30E reads the time from the timer 30T. The arithmetic processing unit 30E calculates the elapsed time from the time when it was first determined in step S1 that the operation lever was in the neutral state to the current time. The arithmetic processing unit 30E reads a threshold (predetermined time T1) for the passage of time from the storage unit 34 . The arithmetic processing unit 30E determines whether or not the time elapsed with the control lever in the neutral state has exceeded the predetermined time T1. Predetermined time T1 is, for example, 4 seconds.

When it is determined that the time elapsed while the operating lever is in the neutral state and the working machine 3 is stopped does not exceed the predetermined time T1 (NO in step S2), the process returns to step S1. Then, the determination of whether or not the operating lever is in the neutral state in step S1 and the determination of whether or not the predetermined time T1 has elapsed in step S2 are repeated.

When it is determined that the predetermined time T1 has elapsed while the operating lever is in the neutral position and the working machine 3 has stopped, and therefore the working machine 3 has been stopped for the predetermined time (YES in step S2). Then, in step S3, the frequency of the engine 15 is obtained. The rotation speed of the engine 15 detected by the engine rotation speed sensor 31 is input to the controller 30 . The engine frequency acquisition unit 30B calculates the frequency of the engine 15 based on the number of rotations of the engine 15 . This calculation is performed based on the following formula, where Fe is the frequency of the engine 15, Ne is the rotation speed of the engine 15, and C is the number of cylinders of the engine 15.

Fe=Ne×C/2×60
Next, in step S4, it is determined whether or not the rotation speed Ne of the engine 15 is greater than the first threshold value. FIG. 6 is a graph showing the relationship between the rotation speed of the engine 15 and execution or cancellation of frequency control of the cooling fan 21 of the embodiment. The horizontal axis of FIG. 6 indicates the rotation speed of the engine 15 . On the vertical axis of FIG. 6, logic ON when the lever is neutral indicates a setting for executing frequency control of the cooling fan 21 of the embodiment. In the vertical axis of FIG. 6, logic OFF when the lever is neutral indicates a setting for canceling the frequency control of the cooling fan 21 of the embodiment.

The arithmetic processing unit 30E reads the first threshold value TH1 related to the rotation speed Ne of the engine 15 from the storage unit 34. The arithmetic processing unit 30E compares the rotation speed Ne of the engine 15 detected by the engine rotation speed sensor 31 with the first threshold TH1 to determine whether the rotation speed Ne of the engine 15 is greater than the first threshold TH1. to judge. The first threshold TH1 is, for example, 1400 rpm.

When it is determined that the rotation speed Ne of the engine 15 is greater than the first threshold TH1 (YES in step S4), the frequency of the cooling fan 21 is obtained in step S5. Fan frequency acquisition unit 30</b>C calculates the frequency of cooling fan 21 based on the rotation speed of cooling fan 21 . This calculation is performed based on the following formula, where Ff is the frequency of the cooling fan 21, Nf is the rotation speed of the cooling fan 21, and B is the number of blades of the cooling fan 21.

Ff=Nf×B/60
Cooling fan 21 blows air to intake air cooler 25 , oil cooler 26 and radiator 27 for cooling. A target rotation speed Nf of the cooling fan 21 according to the temperature of the air that is the working fluid of the intake air cooler 25, the temperature of the hydraulic oil that is the working fluid of the oil cooler 26, or the temperature of the cooling water that is the working fluid of the radiator 27 is set. The fan frequency acquisition unit 30C calculates the target frequency Ff of the cooling fan 21 corresponding to the target rotational speed Nf of the cooling fan 21 using the above formula.

FIG. 7 is a graph showing the relationship between the rotational speed Ne of the engine 15, the frequency Fe of the engine 15, and the frequency Ff of the cooling fan 21. FIG. The horizontal axis of FIG. 7 indicates the rotational speed Ne of the engine 15, and the vertical axis of FIG. 7 indicates the frequency Fe of the engine 15 and the frequency Ff of the cooling fan 21.

According to the above formula, the number of cylinders of the engine 15 is constant, so the frequency Fe of the engine 15 is proportional to the rotation speed Ne of the engine 15. The frequency Ff of the cooling fan 21 can be set independently of the frequency Fe of the engine 15 to a value equal to or lower than the maximum value shown in FIG. If the difference between the frequency Ff of the cooling fan 21 and the frequency Fe of the engine 15 is small, resonance may occur between the cooling fan 21 and the engine 15 .

The resonance frequency setting unit 30D sets a predetermined frequency range in which resonance can occur with respect to the frequency Fe of the engine 15. Resonance frequency setting unit 30D sets an upper limit value and a lower limit value of frequency Ff of cooling fan 21 at which resonance can occur, as shown in FIG. For example, the resonance frequency setting unit 30D may set a range within the frequency Fe of the engine 15±10 Hz as a range in which resonance may occur. That is, the upper limit of the range in which resonance can occur indicated by the broken line in FIG. 7 may be the frequency Fe of the engine 15+10 Hz. The lower limit of the range in which resonance can occur, indicated by the dashed line in FIG. 7, may be the frequency Fe of the engine 15-10 Hz.

In step S6, the arithmetic processing unit 30E determines whether or not the frequency Ff of the cooling fan 21 is greater than the upper limit of the range of frequencies in which resonance with respect to the frequency Fe of the engine 15 can occur. In step S7, the arithmetic processing unit 30E determines whether the frequency Ff of the cooling fan 21 is higher than the lower limit of the range of frequencies in which resonance can occur with respect to the frequency Fe of the engine 15 or not. That is, in steps S6 and S7, it is determined whether or not the frequency Ff of the cooling fan 21 is within a range where resonance with the frequency Fe of the engine 15 can occur.

When it is determined that the frequency Ff of the cooling fan 21 is equal to or less than the upper limit (NO in step S6) and greater than the lower limit (YES in step S7), that is, the frequency Ff of the cooling fan 21 becomes equal to the frequency Fe of the engine 15. is within the predetermined range where resonance can occur, the frequency Ff of the cooling fan 21 is changed in step S8. In order to suppress resonance between the cooling fan 21 and the engine 15, the arithmetic processing unit 30E increases the frequency Ff of the cooling fan 21 and the frequency Fe of the engine 15 from the time when the frequency Ff of the cooling fan 21 is acquired in step S5. is increased so that the frequency Ff of the cooling fan 21 is out of the range in which resonance can occur.

For example, the arithmetic processing unit 30E can change the frequency Ff of the cooling fan 21 to below the lower limit of the range in which resonance can occur, which is indicated by the dashed line in FIG. Typically, the arithmetic processing unit 30E may change the frequency Ff of the cooling fan 21 to the lower limit of the range in which resonance can occur.

If the frequency Ff of the cooling fan 21 is greater than the upper limit (YES in step S6) or if the frequency Ff of the cooling fan 21 is equal to or less than the lower limit (NO in step S7), the frequency Ff of the cooling fan 21 cannot be changed. not done. The frequency Ff of the cooling fan 21 calculated in step S5 is used as it is.

In step S9, the cooling fan 21 is controlled according to the frequency Ff calculated in step S5 or the frequency Ff changed in step S8. When the frequency Ff of the cooling fan 21 is changed in step S8, the target rotational speed Nf of the cooling fan 21 is calculated from the changed frequency Ff using the above formula. A control signal is transmitted from the fan control command unit 30F to the electromagnetic proportional control valve 24 to change the flow rate of hydraulic oil supplied from the hydraulic pump 23 to the hydraulic motor 22 . The supplied hydraulic oil causes the hydraulic motor 22 to rotate. In this manner, the cooling fan 21 is controlled to rotate at the target rotation speed Nf.

Next, in step S10, it is determined whether or not the rotation speed Ne of the engine 15 is greater than the second threshold value. As shown in FIG. 6, the second threshold TH2 is smaller than the first threshold TH1. The second threshold TH2 is, for example, 1350 rpm. Control for changing the frequency Ff of the cooling fan 21 according to the embodiment is executed when the rotational speed Ne of the engine 15 is greater than the first threshold TH1. Even if the rotational speed Ne of the engine 15 drops below the first threshold TH1, if the rotational speed Ne of the engine 15 is greater than the second threshold TH2, the control to change the frequency Ff of the cooling fan 21 is continued. . When the rotational speed Ne of the engine 15 drops below the second threshold TH2, the control for changing the frequency Ff of the cooling fan 21 is released.

The arithmetic processing unit 30E reads the second threshold TH2 related to the rotation speed Ne of the engine 15 from the storage unit 34. The arithmetic processing unit 30E compares the target rotational speed Ne of the engine 15 set according to the temperature of the working fluid with the second threshold TH2 to determine whether the rotational speed Ne of the engine 15 is greater than the second threshold TH2. to judge whether

When it is determined that the rotation speed Ne of the engine 15 is greater than the second threshold TH2 (YES in step S10), then in step S11 it is determined whether or not the control lever is in the neutral state. This determination is made in the same manner as in step S1.

When it is determined that the operation lever is in the neutral state (YES in step S11), the process returns to step S3. When it is determined that the operation lever is out of the neutral state because the operator has operated the operation device 33 to move the hydraulic excavator 100 (NO in step S11), the control to change the frequency Ff of the cooling fan 21 is canceled. to end the process (END).

If it is determined in step S1 that the operating lever is tilted from the neutral state, the operating lever is being operated, and therefore the working machine 3 is operating (NO in step S1), the cooling fan 21 No control to change the frequency Ff of is executed. When it is determined in step S4 that rotation speed Ne of engine 15 is equal to or lower than first threshold value TH1 (NO in step S4), control to change frequency Ff of cooling fan 21 is not executed. When it is determined in step S10 after it is determined in step S4 that the rotation speed Ne of the engine 15 is greater than the first threshold TH1 (step S10 NO), the control for changing the frequency Ff of the cooling fan 21 is released.

In a state where the control for changing the frequency Ff of the cooling fan 21 is not executed, the cooling fan 21 is controlled so as to rotate at the target rotation speed Nf set according to the temperature of the working fluid.

In FIG. 5, the target rotation speed of the cooling fan 21 is reduced after a predetermined time T1 has elapsed with the control lever in the neutral state, and the frequency Ff of the cooling fan 21 is changed by operating the control lever thereafter. Behavior is shown in which the control is canceled and the target rotation speed of the cooling fan 21 returns to the speed before it was lowered. At this time, the target number of revolutions of the cooling fan 21 is gradually increased over a predetermined period of time T2. Predetermined time T2 is, for example, 2 to 3 seconds. As a result, the pressure of the hydraulic fluid supplied to the hydraulic motor 22 is prevented from suddenly increasing, causing malfunctions in the flow path of the hydraulic fluid and each hydraulic device.

<Action and effect>
Although there are some descriptions that partially overlap with the above description, the characteristic configurations and effects of the embodiment will be described collectively as follows.

As shown in FIG. 4, the controller 30 sets the rotation speed Ne of the engine 15 to be greater than the first threshold TH1 and the frequency Ff of the cooling fan 21 to match the frequency Fe of the engine when the work implement 3 is stopped. On the other hand, when it is within the predetermined range, the frequency Ff of the cooling fan 21 is changed so that the frequency difference between the cooling fan 21 and the engine 15 becomes larger than when the frequency of the cooling fan 21 was acquired. 21.

While the work implement 3 is in operation, it is necessary to give priority to the cooling capacity of the cooling fan 21 for cooling the working fluid (working oil). resonance is less likely to occur. If the rotational speed Ne of the engine 15 is equal to or lower than the first threshold TH1, resonance between the engine 15 and the cooling fan 21 is unlikely to occur. If the frequency Ff of the cooling fan 21 is not within the range where resonance can occur with respect to the frequency Fe of the engine 15, there is no need to perform control to suppress resonance. Therefore, control to change the frequency Ff of the cooling fan 21 is not executed. The cooling capacity of the cooling fan 21 can be ensured because the time during which the cooling capacity is reduced by decreasing the rotational speed Nf of the cooling fan 21 is shortened.

If the work implement 3 is stopped, the rotational speed Ne of the engine 15 is greater than the first threshold TH1, and the frequency Ff of the cooling fan 21 is within a range where resonance can occur with respect to the frequency Fe of the engine 15 , control to change the frequency Ff of the cooling fan 21 is executed. As a result, resonance between the engine 15 and the cooling fan 21 can be avoided, and vibration and abnormal noise can be prevented.

As shown in FIG. 4, the controller 30 may change the frequency Ff of the cooling fan 21 to below the lower limit of the predetermined range. Resonance between the engine 15 and the cooling fan 21 can be reliably avoided by setting the frequency Ff of the cooling fan 21 to be equal to or lower than the lower limit of the range in which resonance can occur with respect to the frequency Fe of the engine 15 . Further, by reducing the rotational speed Nf of the cooling fan 21 to reduce the power used to drive the cooling fan 21, fuel efficiency can be improved.

As shown in FIG. 4, the controller 30 may change the frequency Ff of the cooling fan 21 to the lower limit of the predetermined range. By rotating the cooling fan 21 at the maximum number of revolutions Nf within a range where the resonance between the engine 15 and the cooling fan 21 can be reliably avoided, the cooling performance of the cooling fan 21 can be suppressed from decreasing.

As shown in FIGS. 4 and 6, the controller 30 cancels the control to change the frequency Ff of the cooling fan 21 when the rotational speed Ne of the engine 15 drops below a second threshold TH2 which is smaller than the first threshold TH1. You may The first threshold TH1 for executing the control for changing the frequency Ff of the cooling fan 21 and the second threshold TH2 for canceling the control for changing the frequency Ff of the cooling fan 21 are made different. and the second threshold TH2. As a result, it is possible to avoid frequent switching between the execution and cancellation of the control for changing the frequency Ff of the cooling fan 21 due to variations in the rotation speed Ne of the engine 15, thereby preventing the occurrence of unnecessary errors. .

As shown in FIGS. 1 and 2, the cooling fan 21 is mounted on the hydraulic excavator 100. As shown in FIG. 4 , the controller 30 may release the control to change the frequency Ff of the cooling fan 21 when a command is given from the operator to operate the excavator 100 . While the work implement 3 is operating, there is no need to execute control for suppressing resonance. The cooling capacity of the cooling fan 21 can be ensured by reducing the rotation speed Nf of the cooling fan 21 to shorten the time during which the cooling capacity is lowered.

In the above-described embodiment, when it is determined in steps S1 and S2 that the working machine 3 has been stopped for the predetermined time T1, the control for changing the frequency Ff of the cooling fan 21 is executed. . As a condition for executing the control to change the frequency Ff of the cooling fan 21, it is determined that the rotation speed Ne of the engine 15 detected by the engine rotation speed sensor 31 is constant for a predetermined time. may When the rotation speed Ne of the engine 15 fluctuates, resonance between the engine 15 and the cooling fan 21 is less likely to occur, and even if resonance occurs, it is eliminated in a short period of time, so resonance rarely becomes a problem. By determining that the work implement 3 is stopped, it is estimated that the rotation speed Ne of the engine 15 is constant. It can be determined more accurately that the number Ne is constant.

Control for not executing control to change the frequency Ff of the cooling fan 21 when the work implement 3 is relatively stopped with respect to the revolving body 2 but the hydraulic excavator 100 is self-propelled by the drive of the traveling body 1. may be In the hydraulic excavator 100, even if resonance between the engine 15 and the cooling fan 21 occurs during self-propelled travel, the frequency of self-propelled travel is low, so the resonance rarely poses a problem. Further, when the working machine 3 is stopped relative to the revolving body 2 but the revolving body 2 is revolving with respect to the traveling body 1, the control for changing the frequency Ff of the cooling fan 21 is not executed. It may be used as a control. In the hydraulic excavator 100, even if resonance occurs between the engine 15 and the cooling fan 21 while the revolving body 2 is revolving, the revolving angle is often 90° and the revolving ends in a short period of time, so the resonance becomes a problem. Less is. The cooling capacity of the cooling fan 21 can be ensured by reducing the rotation speed Nf of the cooling fan 21 to shorten the time during which the cooling capacity is lowered.

In the above embodiment, an example was explained in which the control for changing the frequency Ff of the cooling fan 21 is canceled when it is determined in step S11 that the operation lever has been operated to operate the working machine 3. In addition to this determination, the control for changing the frequency Ff of the cooling fan 21 is also canceled when the turning operation device for turning the turning body 2 or the traveling operation device for moving the traveling body 1 is operated. You may Resonance between the engine 15 and the cooling fan 21 during turning or running rarely becomes a problem. , the cooling capacity of the cooling fan 21 can be ensured.

In the above embodiment, it is determined whether the work machine 3 is operating or stopped by detecting whether or not the operation lever operated to operate the work machine 3 is in the neutral state. Not limited to this example, operation or stop of work implement 3 may be determined based on detection results of position sensors for obtaining information on the positions and attitudes of boom 3a, arm 3b and bucket 3c. The position sensors may be any one or a combination of the

stroke sensors

7a, 7b, 7c and the

angle sensors

9a, 9b, 9c described with reference to FIG. 1, for example. The attitudes of work implement 3 detected by the position sensor at different times may be compared, and if the attitudes of work implement 3 differ, it may be determined that work implement 3 is operating.

Alternatively, when the hydraulic pressure information detected by the

pressure sensors

6a, 6b, 6c, 6d, 6e, and 6f described with reference to FIG. may be judged. It may be determined that the work implement 3 is operating when it is detected that the discharge pressure of the hydraulic pumps that supply hydraulic oil to the boom cylinder 4a, the arm cylinder 4b, and the bucket cylinder 4c is fluctuating. Hydraulic excavator 100 may include an imaging device for imaging work implement 3. In this case, by analyzing the image captured by the imaging device, it is determined whether work implement 3 is operating or stopped. good too.

In the above embodiment, the cooling fan 21 is a hydraulically driven fan, but it is not limited to this, and it is sufficient if the rotation speed Nf of the cooling fan 21 can be freely controlled with respect to the rotation speed Ne of the engine 15 . For example, cooling fan 21 may be an electric fan. An alternator connected to the output shaft of the engine 15 may generate power using the driving force generated by the engine 15 , and the power generated by the alternator may drive the electric motor to rotate the cooling fan 21 .

The working machine to which the idea of the present disclosure can be applied is not limited to the hydraulic excavator 100, but can be any other type of working machine having an engine and a cooling fan, such as a bulldozer, wheel loader, motor grader, or engine-type forklift. good.

Although the embodiments have been described as above, the embodiments disclosed this time are illustrative in all respects and should be considered not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all changes within the scope and meaning equivalent to the scope of the claims.

1 traveling body, 2 rotating body, 3 work machine, 3a boom, 3b arm, 3c bucket, 4a boom cylinder, 4b arm cylinder, 4c bucket cylinder, 6a, 6b, 6c, 6d, 6e, 6f pressure sensor, 7a, 7b , 7c stroke sensor, 9a, 9b, 9c angle sensor, 15 engine, 21 cooling fan, 22 hydraulic motor, 23 hydraulic pump, 24 electromagnetic proportional control valve, 25 intake air cooler, 26 oil cooler, 27 radiator, 28 water temperature sensor, 29 Oil temperature sensor, 30 Controller, 30A Work machine state determination unit, 30B Engine frequency acquisition unit, 30C Fan frequency acquisition unit, 30D Resonance frequency setting unit, 30E Arithmetic processing unit, 30F Fan control command unit, 30T Timer, 31 Engine rotation number sensor, 32 fan speed sensor, 33 operation device, 33A operation detection unit, 34 storage unit, 100 hydraulic excavator, T1, T2 predetermined time, TH1 first threshold, TH2 second threshold.

Claims

engine and
a work machine driven by the engine;
a cooling fan configured to be able to control the number of revolutions independently of the number of revolutions of the engine;
a controller that controls the cooling fan;
the controller obtains the frequency of the engine and the frequency of the cooling fan;
When the number of rotations of the engine is greater than a threshold value and the frequency of the cooling fan is within a predetermined range with respect to the frequency of the engine, the controller controls the operation of the cooling fan. A control system for a cooling fan that controls the cooling fan so as to change the frequency to increase the frequency difference between the cooling fan and the engine compared to when the frequency of the cooling fan is obtained.
The cooling fan control system according to claim 1, wherein the controller changes the frequency of the cooling fan to a lower limit or less of the predetermined range.
The cooling fan control system according to claim 2, wherein the controller changes the frequency of the cooling fan to the lower limit of the predetermined range.
4. The controller according to any one of claims 1 to 3, wherein the controller cancels the control to change the frequency of the cooling fan when the rotation speed of the engine drops to a second threshold that is lower than the threshold. A control system for the described cooling fan.
The cooling fan is mounted on the working machine,
5. The cooling according to any one of claims 1 to 4, wherein the controller cancels the control of changing the frequency of the cooling fan when an operator's command to operate the work machine is given. fan control system.
engine and
a work machine driven by the engine;
a cooling fan configured to be able to control the number of revolutions independently of the number of revolutions of the engine;
a controller that controls the cooling fan;
the controller obtains the frequency of the engine and the frequency of the cooling fan;
When the number of rotations of the engine is greater than a threshold value and the frequency of the cooling fan is within a predetermined range with respect to the frequency of the engine, the controller controls the operation of the cooling fan. A working machine that controls a cooling fan by changing a frequency to increase the difference between the frequencies of the cooling fan and the engine compared to when the frequency of the cooling fan is obtained.
A method for controlling a cooling fan in a work machine comprising an engine, a work machine driven by the engine, and a cooling fan configured to be able to control the number of revolutions independently of the number of revolutions of the engine, comprising: ,
determining whether the work machine is operating;
obtaining the frequency of the engine;
obtaining the frequency of the cooling fan;
When the number of revolutions of the engine is greater than a threshold value and the frequency of the cooling fan is within a predetermined range with respect to the frequency of the engine while the work machine is stopped, the frequency of the cooling fan is changed. and controlling the cooling fan so as to increase the difference in frequency between the cooling fan and the engine after obtaining the frequency of the cooling fan.