JP7788334B2 - Work machinery - Google Patents

Description

The present invention relates to a work machine that allows the cooling fan to rotate forward and backward.

In addition to being used for excavating soil and sand, work machines such as hydraulic excavators are also used in dusty environments, for example, when collecting wood chips and coal on transport ships, dismantling and disposing of scrap metal, and sorting industrial waste. Work machines used in environments with a large amount of dust in the outside air are prone to dust accumulation and clogging of the heat exchanger, which can reduce the heat exchange efficiency of the heat exchanger.

To prevent a deterioration in the heat exchange efficiency of the heat exchanger, some work machines have a function that blows away and removes dust that has accumulated in the heat exchanger by rotating the cooling fan in the reverse direction. For example, the work machine described in Patent Document 1 is programmed to automatically rotate the cooling fan in the reverse direction when the fan has been rotating in the forward direction for a predetermined period of time.

Japanese Patent Application Laid-Open No. 2020-084520

However, in the work machine described in Patent Document 1, the controller automatically reverses the rotation of the cooling fan, which could result in dust and hot air being emitted from the building cover while workers are working nearby.

The present invention was made in consideration of the above-mentioned circumstances, and its purpose is to provide a work machine that can discharge dust accumulated in a heat exchanger at an appropriate time.

In order to achieve the above object, the present invention provides a work machine including a building in which a first vent and a second vent are formed to connect an internal space to the outside, a cooling fan housed in the internal space and capable of rotating in a forward direction to generate cooling air from the first vent to the second vent and rotating in a reverse direction to generate cooling air from the second vent to the first vent, a heat exchanger disposed opposite the cooling fan, a sensor that detects a person in a position facing the side wall of the building in which the first vent is formed, among the periphery of the building, and a controller that controls the rotation of the cooling fan based on the detection result of the sensor, The controller reverses the rotation of the cooling fan and starts measuring the reverse rotation time of the cooling fan when the sensor does not detect a person; stops the reverse rotation of the cooling fan and suspends measurement of the reverse rotation time when the sensor detects a person during the period when the cooling fan is rotating in reverse; resumes the reverse rotation of the cooling fan and measurement of the reverse rotation time when the sensor no longer detects a person during the period when the cooling fan is stopped in reverse; and rotates the cooling fan forward when the reverse rotation time reaches a predetermined threshold .

The present invention provides a work machine that can discharge dust accumulated in a heat exchanger at an appropriate time. Issues, configurations, and advantages other than those described above will become clear from the description of the following embodiments.

1 is a side view of a hydraulic excavator, which is a representative example of a work machine according to the present invention. FIG. 1 is a cross-sectional view of the engine building as seen from the rear, showing the flow of cooling air when the cooling fan 12 is rotated forward. 1 is a cross-sectional view of the engine building as seen from the rear, showing the flow of cooling air when the cooling fan 12 is rotated in reverse. FIG. 2 is a control block diagram of the hydraulic excavator. 10 is a flowchart of a reverse rotation control process.

Embodiments of a work machine according to the present invention will be described with reference to the drawings. Figure 1 is a side view of a hydraulic excavator 1, a representative example of a work machine according to the present invention. Note that, unless otherwise specified, the terms front, back, left, and right in this specification refer to the perspective of an operator who is riding on and operating the hydraulic excavator 1.

The hydraulic excavator 1 comprises a lower traveling body 2 and an upper rotating body 3 supported by the lower traveling body 2. The lower traveling body 2 and the upper rotating body 3 are an example of a machine body. The lower traveling body 2 comprises a pair of left and right crawlers. When the rotation of a traveling motor (not shown) is transmitted to rotate the pair of left and right crawlers, the hydraulic excavator 1 travels. However, the lower traveling body 2 may be wheeled instead of crawler-mounted.

The upper rotating body 3 is rotatably supported on the lower running body 2. The driving force of a swing motor (not shown) is transmitted to the upper rotating body 3, causing it to swing relative to the lower running body 2. The upper rotating body 3 mainly comprises a swing frame 5 serving as a base, a front work implement 4 attached to the center of the front end of the swing frame 5 so that it can swing up and down, a cab (operator's seat) 7 located on the front left side of the swing frame 5, and a counterweight 6 located at the rear end of the swing frame 5.

The front work implement 4 includes a boom 4a supported on the upper rotating body 3 so that it can be raised and lowered, an arm 4b rotatably supported at the tip of the boom 4a, a bucket 4c rotatably supported at the tip of the arm 4b, and hydraulic cylinders 4d, 4e, and 4f that drive the boom 4a, arm 4b, and bucket 4c. The counterweight 6 is used to balance the weight of the front work implement 4 and is a heavy object that has an arc shape when viewed from above.

The cab 7 defines an interior space in which the operator who operates the hydraulic excavator 1 sits. The interior space of the cab 7 contains a seat on which the operator sits and operating devices that the operator operates while seated in the seat. When the operator in the cab 7 operates the operating devices, the lower traveling body 2 travels, the upper rotating body 3 rotates, and the front working implement 4 operates.

The operating device includes a forced reverse rotation button 8 (see Figures 2 and 5). The forced reverse rotation button 8 is an example of a forced reverse rotation operating unit that accepts an instruction to reverse the rotation of the cooling fan 12, regardless of the results of human presence detection by the camera 16L, which will be described later. When the forced reverse rotation button 8 is operated (pressed) by an operator in the cab 7, it outputs a forced reverse rotation signal to the controller 30 (see Figure 5), which will be described later. Note that the forced reverse rotation operating unit is not limited to the form of a button, and may be a switch, an icon displayed on the monitor 9 with a touch panel superimposed thereon, or the like.

A monitor 9 (see Figures 2 and 5) is also installed in the cab 7. The monitor 9 is an example of a notification device that notifies the operator in the cab 7 of information. The monitor 9 displays an overhead image and various messages, which will be described later. Note that specific examples of the notification device are not limited to the monitor 9, and may also include an LED lamp, a speaker, or a combination of these.

The upper rotating body 3 also supports the engine building 10 (building). The engine building 10 is supported by the rotating frame 5 behind the front work implement 4 and cab 7 and forward of the counterweight 6. The engine building 10 has an internal space that houses the components used to operate the hydraulic excavator 1.

Figure 2 is a plan view of the upper rotating body 3. Figure 3 is a cross-sectional view of the engine building 10 seen from the rear, showing the flow of cooling air when the cooling fan 12 is rotated forward. Figure 4 is a cross-sectional view of the engine building 10 seen from the rear, showing the flow of cooling air when the cooling fan 12 is rotated reversely. As shown in Figures 2 to 4, the internal space of the engine building 10 houses the engine 11, cooling fan 12, heat exchanger 13, and other components used to operate the hydraulic excavator 1.

The engine 11 is located to the right of the cooling fan 12 and heat exchanger 13. The engine 11 generates driving force to operate the hydraulic excavator 1 by mixing and burning fossil fuel and air. Meanwhile, the engine 11 generates heat by burning the fossil fuel. As a result, the interior space of the engine building 10 becomes hot.

The cooling fan 12 is located to the left of the engine 11 and to the right of the heat exchanger 13. The cooling fan 12 is driven by a drive source (not shown), such as a hydraulic motor or an electric motor, to generate cooling air within the engine building 10. The cooling fan 12 is configured to be able to rotate forward and backward under the control of the controller 30.

The heat exchanger 13 is located to the left of the engine 11 and cooling fan 12. The heat exchanger 13 includes a radiator that exchanges heat between the coolant that cooled the engine 11 and the cooling air generated by the cooling fan 12, which rotates in the forward direction, and supplies the heat back to the engine 11. The heat exchanger 13 may also include an intercooler that cools the air compressed by the turbocharger, a hydraulic oil cooler that cools the hydraulic oil stored in the hydraulic oil tank, etc.

As shown in Figures 3 and 4, the engine building 10 is formed with a first ventilation opening 14 and a second ventilation opening 15 (hereinafter, these may be collectively referred to as "vents 14, 15"). The ventilation openings 14, 15 are openings that connect the internal space of the engine building 10 to the outside of the hydraulic excavator 1. The ventilation openings 14, 15 penetrate the outer wall that defines the internal space of the engine building 10 in the thickness direction.

The first vent 14 is formed in the left wall that defines the left side of the internal space of the engine building 10. The second vent 15 is formed to the right of the first vent 14. In this embodiment, the second vent 15 is formed in the top wall that defines the top surface of the internal space of the engine building 10 and in the bottom wall that defines the bottom surface of the internal space of the engine building 10. However, the positions of the vents 14, 15 are not limited to the examples in Figures 3 and 4. As another example, the second vent 15 may be formed in the right wall that defines the right side of the internal space of the engine building 10.

The engine 11 is positioned closer to the second vent 15 than the cooling fan 12. The heat exchanger 13 is positioned closer to the first vent 14 than the cooling fan 12. A dust-collecting net may be attached to the left surface of the heat exchanger 13 (the surface facing the first vent 14). Note that the specific arrangement of the engine 11, cooling fan 12, and heat exchanger 13 is not limited to the examples shown in Figures 2 to 4, as long as the positional relationship with the vents 14 and 15 is satisfied.

As shown in FIG. 3, the cooling fan 12 rotating in the forward direction generates cooling air that flows from the first vent 14 to the second vent 15. That is, when the cooling fan 12 rotates in the forward direction, outside air containing dust flows into the internal space of the engine building 10 through the first vent 14, passes through the heat exchanger 13, the cooling fan 12, and the engine 11, and is discharged from the internal space of the engine building 10 through the second vent 15. At this time, as shown by the dotted hatching in FIG. 3, dust contained in the outside air accumulates on the left side of the heat exchanger 13. Furthermore, as the amount of dust that accumulates on the left side of the heat exchanger 13 increases, the heat exchange efficiency decreases.

As shown in FIG. 4, the cooling fan 12 rotating in the reverse direction generates cooling air that flows from the second vent 15 toward the first vent 14. That is, when the cooling fan 12 rotates in the reverse direction, outside air flows into the interior space of the engine building 10 through the second vent 15, passes through the engine 11, the cooling fan 12, and the heat exchanger 13, and is discharged from the interior space of the engine building 10 through the first vent 14. At this time, as shown by the dotted hatching in FIG. 4, dust accumulated on the left side of the heat exchanger 13 is blown away by the cooling air generated by the cooling fan 12 rotating in the reverse direction. Meanwhile, the cooling air, which has become hot due to the heat of the engine 11, is discharged from the first vent 14.

Furthermore, as shown in FIG. 2, the hydraulic excavator 1 is equipped with cameras 16L, 16R, and 16B. Cameras 16L, 16R, and 16B are attached to the outer wall of the upper rotating body 3 (more specifically, the engine building 10 or counterweight 6). Furthermore, cameras 16L, 16R, and 16B are attached facing in different directions in order to capture images of the area around the upper rotating body 3.

More specifically, camera 16L is attached to the left wall of the engine building 10 and captures the image to the left of the upper rotating body 3. Camera 16R is attached to the right wall of the engine building 10 and captures the image to the right of the upper rotating body 3. Camera 16B is attached to the counterweight 6 and captures the image to the rear of the upper rotating body 3. Cameras 16L, 16R, and 16B then output video signals indicating the captured images to controller 30.

Figure 5 is a control block diagram of the hydraulic excavator 1. As shown in Figure 5, the hydraulic excavator 1 is equipped with a controller 30 having a CPU 31 (Central Processing Unit) and memory 32. The memory 32 is configured, for example, as a ROM (Read Only Memory), a RAM (Random Access Memory), an HDD (Hard Disk Drive), or a combination of these. The controller 30 realizes the processing described below by having the CPU 31 read and execute program code stored in the memory 32.

However, the specific configuration of the controller 30 is not limited to this, and may be realized by hardware such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array).

The controller 30 controls the overall operation of the hydraulic excavator 1. Based on the forced reverse rotation signal output from the forced reverse rotation button 8 and the video signals output from the cameras 16L, 16R, and 16B, the controller 30 displays information on the monitor 9, controls the operation of the engine 11, and controls the rotation of the cooling fan 12.

First, the controller 30 generates an overhead image of the upper rotating body 3 from above based on the video signals output from each of the cameras 16L, 16R, and 16B. The controller 30 then displays the generated overhead image on the monitor 9. The controller 30 also starts or stops the engine 11 in response to the operation of a key switch (not shown) by an operator in the cab 7.

The controller 30 also determines whether or not a person is present in a position facing the first air vent 14 (i.e., to the left of the engine building 10) based on the video signal output from the camera 16L. More specifically, the controller 30 uses a known person extraction method to extract a person from the video captured by the camera 16L. The controller 30 then controls the rotation of the cooling fan 12 depending on whether or not a person has been extracted from the video captured by the camera 16L (i.e., whether or not a person has been detected by the camera 16L). Furthermore, in response to a forced reverse rotation signal being output from the forced reverse rotation button 8, the controller 30 reverses the rotation of the cooling fan 12, regardless of the result of the person detection by the camera 16L.

In other words, camera 16L is an example of a sensor for detecting a person in a position facing the left wall of the engine building 10 where the first air vent 14 is formed, within the periphery of the engine building 10. Note that in this embodiment, an example has been described in which one of cameras 16L, 16R, and 16B for generating overhead images is also used as a sensor for detecting people. However, specific examples of sensors for detecting people are not limited to camera 16L, and any sensor (e.g., LiDAR) that can distinguish between people and objects may be used.

Figure 6 is a flowchart of the reverse rotation control process. The reverse rotation control process rotates the cooling fan 12 in reverse to blow away dust accumulated on the left surface of the heat exchanger 13. In this embodiment, at the start of the reverse rotation control process, the engine 11 is running, the cooling fan 12 is rotating forward, and the undercarriage 2, upper revolving body 3, and front implement 4 are stopped.

First, in step S11, the controller 30 waits to execute the processes from step S12 onwards until a predetermined reverse rotation condition is met (S11: No). The reverse rotation condition is a condition for specifying the timing to start reverse rotation of the cooling fan 12 in order to blow away dust accumulated on the heat exchanger 13.

As one example, the reverse rotation condition may be that the elapsed time since the most recent end of the reverse rotation control process has reached a threshold value. As another example, the reverse rotation condition may be that the elapsed time since the most recent end of the reverse rotation control process during which the cooling fan 12 has been rotating forward has reached a threshold value. The elapsed time can be measured, for example, by a system clock mounted on the controller 30. Furthermore, the reverse rotation condition may include the engine 11 being driven, the hydraulic excavator 1 being stopped, etc., in addition to the elapsed time reaching the threshold value.

If the reverse rotation condition is met in step S11 (S11: Yes), then in the next step S12, the controller 30 determines whether or not a person has been detected by the camera 16L. If a person has been detected by the camera 16L in step S12 (S12: Yes), the controller 30 waits for the execution of the processes from step S13 onwards. Furthermore, the controller 30 repeatedly determines whether or not a person has been detected by the camera 16L at predetermined time intervals until no more people are detected by the camera 16L.

If no person is detected by the camera 16L in step S12 (S12: No), in the next step S13, the controller 30 rotates the cooling fan 12 in reverse and starts a timer set to a predetermined time (e.g., 30 seconds). "Starting the timer" is an example of starting to measure the reverse rotation time that the cooling fan 12 is rotating in reverse.

In the next steps S14 and S15, the controller 30 continues to rotate the cooling fan 12 in the reverse direction while repeatedly determining at predetermined time intervals whether a person is detected by the camera 16L (S14) and whether the timer has timed out (S15). A period in which no person is detected by the camera 16L (S14: No) and the timer has not timed out (S15: No) is an example of a period in which the cooling fan 12 is rotating in the reverse direction.

If the timer times out without the camera 16L detecting a person (S15: Yes), the controller 30 rotates the cooling fan 12 forward in the next step S16, and ends the reverse rotation control process. "The timer times out" is an example of the reverse rotation time reaching a predetermined threshold (e.g., 30 seconds).

On the other hand, if a person is detected by the camera 16L before the timer times out (S14: Yes), the controller 30 stops the cooling fan 12 and the timer in the next step S17. "Stopping the timer" is an example of suspending measurement of the reverse rotation time. The controller 30 also displays a message on the monitor 9 indicating that the reverse rotation of the cooling fan 12 has been suspended.

In the next steps S18 and S19, the controller 30, with the cooling fan 12 stopped, repeatedly determines at predetermined time intervals whether a person is detected by the camera 16L (S18) and whether the forced reverse rotation button 8 has been pressed (S19). A period during which a person is detected by the camera 16L (S18: Yes) and the forced reverse rotation button 8 has not been pressed (S19: No) is an example of a period during which the cooling fan 12 is stopped.

When a person is no longer detected by the camera 16L (S18: No), the controller 30 resumes the reverse rotation of the cooling fan 12 and restarts the timer stopped in step S17 (S13). "Restarting the timer" is an example of restarting the measurement of the reverse rotation time that was interrupted in step S17. The controller 30 then executes the processing from step S14 onwards.

On the other hand, when the forced reverse rotation button 8 is pressed while a person is detected by the camera 16L (S19: Yes), the controller 30 resumes the reverse rotation of the cooling fan 12 and restarts the timer stopped in step S17 in step S20, the next step after step S19. In the next step S21, the controller 30 continues the reverse rotation of the cooling fan 12 without detecting a person with the camera 16L until the timer times out (S21: No). Then, when the timer times out (S21: Yes), the controller 30 performs the process of rotating the cooling fan 12 in the forward direction in step S16, and ends the reverse rotation control process.

The above embodiment provides the following advantages, for example:

In the above embodiment, when a person is detected by the camera 16L (S12: Yes/S14: Yes/S18: Yes), the cooling fan 12 is not reversed, preventing the hot air discharged from the first ventilation opening 14 from hitting the worker. As a result, dust accumulated in the heat exchanger 13 can be discharged at the appropriate time.

Furthermore, according to the above embodiment, if a person is detected by camera 16L while cooling fan 12 is rotating in reverse, the timer is stopped (S14: Yes → S17), and if a person is no longer detected by camera 16L, the timer is restarted (S18: No → S13). This makes it possible to average out the reverse rotation time compared to resetting the timer every time a person is detected.

Furthermore, according to the above embodiment, by pressing the forced reverse rotation button 8, the cooling fan 12 can continue to rotate in reverse regardless of the results of human detection by the camera 16L. This prevents the reverse rotation of the cooling fan 12 from being interrupted due to a false detection by the camera 16L (for example, determining that an obstacle such as a tree or wall is a human).

In the above embodiment, an example was described in which the cooling fan 12 is literally "stopped" in step S17. However, the control method in step S17 is not limited to the above example.

As another example, the controller 30 may rotate the cooling fan 12 in the forward direction in step S17. That is, if the reverse rotation of the cooling fan 12 is stopped during steps S17 to S19, the controller 30 may rotate the cooling fan 12 in the forward direction. This allows cooling air to be supplied to the heat exchanger 13 during the period when the reverse rotation of the cooling fan 12 is stopped, thereby preventing overheating.

As yet another example, the controller 30 may slow the reverse rotation speed of the cooling fan 12 in step S17. That is, the controller 30 may rotate the cooling fan 12 in reverse at a first speed during steps S13 to S15 and S20 to S21, and rotate the cooling fan 12 in reverse at a second speed slower than the first speed during steps S17 to S19. In this case, the timer may measure the reverse rotation time during which the cooling fan 12 rotates in reverse at the first speed. In other words, the above-described embodiment describes a case where the second speed is 0 (zero). Depending on the distance between the work machine and a person, hot air may not reach the person even if the cooling fan is not completely stopped. Therefore, using this control method can simultaneously prevent a deterioration in the heat exchange efficiency of the heat exchanger and ensure the safety of people around the work machine.

Furthermore, in the above-described embodiment, a hydraulic excavator 1 equipped with a crawler-type undercarriage 2 has been described as an example of a work machine. However, the present invention is not limited to this and may be applied to, for example, a hydraulic excavator equipped with a wheel-type undercarriage. It can also be widely applied to other work machines such as wheel loaders, dump trucks, and hydraulic cranes.

The above-described embodiments are illustrative examples of the present invention and are not intended to limit the scope of the present invention to these embodiments. Those skilled in the art may implement the present invention in various other forms without departing from the spirit of the present invention.

1 Hydraulic excavator 2 Lower traveling body 3 Upper rotating body 4 Front working machine 4a Boom 4b Arm 4c Bucket 4d, 4e, 4f Hydraulic cylinder 5 Swing frame 6 Counterweight 7 Cab 8 Forced reverse rotation button (forced reverse rotation operating unit)
9 Monitor 10 Engine building (building)
11 Engine 12 Cooling fan 13 Heat exchanger 14 First ventilation port 15 Second ventilation port 16B, 16L, 16R Camera (sensor for detecting a person)
30 Controller 31 CPU
32 memory

Claims (3)

a building having a first vent and a second vent formed therein that connect an interior space to the outside;
a cooling fan accommodated in the internal space and capable of rotating forward to generate cooling air from the first vent port to the second vent port and rotating backward to generate cooling air from the second vent port to the first vent port;
a heat exchanger disposed opposite the cooling fan;
a sensor that detects a person in a position facing a side wall of the building in which the first ventilation opening is formed, among the periphery of the building;
a controller that controls rotation of the cooling fan based on the detection result of the sensor,
The controller
In response to the detection of no human by the sensor, the cooling fan is rotated in reverse and a measurement of the reverse rotation time during which the cooling fan is rotated in reverse is started .
In response to the detection of a person by the sensor during the period in which the cooling fan is rotated in reverse, the reverse rotation of the cooling fan is stopped and measurement of the reverse rotation time is interrupted;
restarting the reverse rotation of the cooling fan and measuring the reverse rotation time in response to the sensor no longer detecting a person during the period in which the reverse rotation of the cooling fan is stopped;
When the reverse rotation time reaches a predetermined threshold, the cooling fan is rotated forward.
A work machine characterized by: The work vehicle according to claim 1 ,
The controller
A work machine characterized in that the cooling fan is rotated in a forward direction during a period in which the reverse rotation of the cooling fan is stopped. The work vehicle according to claim 1 ,
a forced reverse rotation operation unit for instructing the cooling fan to forcibly rotate in reverse,
The controller
a work machine configured to resume reverse rotation of the cooling fan in response to operation of the forced reverse rotation operating unit while the reverse rotation of the cooling fan is stopped, regardless of the detection result of the sensor.