Cooling systems for construction machinery

Abstract

To provide a cooling system of a construction machine that can stop and reverse a cooling fan quickly without increasing the load on a fan motor.SOLUTION: A radiator 18a and an oil cooler 18b in ventilation paths 17a, 17b are cooled with cooling fans 19a, 19b while the radiator ventilation path 17a and the oil cooler ventilation path 17b are made adjacent across a partition wall 21 and a movable plate 22a opening and closing the partition wall 21 is provided and held at a closing position by fixing devices 31, 33. For example, when the cooling fan 19a is reversed, the fixing devices 31, 33 are reset and the cooling fan 19a is stopped from being driven. The movable plate 22a is opened with differential pressure generated between the ventilation paths 17a, 17b, air currents Air3, Air1, Air4, and Air5 to circulate between the radiator ventilation path 17a and the oil cooler ventilation path 17b are generated, and when the air current Air5 hinders the cooling fan 19a from rotating and the cooling fan stops, the cooling fan is driven reversely.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a cooling system for a construction machine. [Background technology]

[0002] As a conventional cooling system for this type of construction machinery, for example, Patent Document 1 discloses a heat exchanger in which multiple heat exchangers are arranged facing an equipment housing room where the engine and exhaust gas purification system are installed, each equipped with a cooling fan. The rotation speed of the cooling fans is controlled individually based on the temperature of the internal fluid flowing through each heat exchanger, while the cooling fan is reversed for heat exchangers with low internal fluid temperatures, and air warmed by the exhaust gas purification system is circulated through the heat exchanger to raise its temperature.

[0003] Meanwhile, Patent Document 2 discloses a cooling device equipped with a fan for cooling electronic equipment. When the cooling fan needs to be stopped for maintenance or inspection of the electronic equipment, the power supply terminals are short-circuited to operate the motor as a generator, which generates a braking force to quickly stop the cooling fan.

[0004] Therefore, when reversing the rotation of the cooling fan in the construction machine of Patent Document 1, it is conceivable to quickly stop and reverse the rotation of the cooling fan by short-circuiting the power terminals of the fan motor that drives the cooling fan, as in the technology of Patent Document 2. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6723810 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-119078 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technology of Patent Document 2 is based on the principle of converting the rotational energy of the cooling fan into current to generate braking force, which has the drawback of causing the fan motor to heat up and shortening its lifespan.

[0007] The present invention has been made to solve these problems, and its purpose is to provide a cooling system for construction machinery that can quickly stop and reverse the rotation of the cooling fan without increasing the load on the fan motor. [Means for solving the problem]

[0008] In order to achieve the above object, the cooling system for a construction machine of the present invention comprises first and second ventilation ducts, one end of which communicates with the outside of the vehicle body and the other end of which communicates with a machine room, and which are adjacent to each other and separated by a partition wall; first and second heat exchangers, which are respectively disposed in the first and second ventilation ducts and are independently driven to rotate by first and second fan motors, which generate air currents that flow through the first and second heat exchangers to the machine room during forward rotation and generate air currents that flow from the machine room to the first and second heat exchangers during reverse rotation. A cooling system for a construction machine comprising first and second cooling fans and a controller having a motor control unit that drives and controls the first and second fan motors, respectively, to rotate the first and second cooling fans in either forward or reverse direction as desired, further comprising a movable plate that is provided on the partition and can be switched between a closed position that closes the partition and an open position that opens the partition, and the controller further comprises a movable plate control unit that opens the movable plate when a reversal condition is met to reverse the rotation of either one of the first and second cooling fans while the first and second cooling fans are rotating in the forward direction. [Effects of the Invention]

[0009] According to the cooling system for construction machinery of the present invention, the cooling fan can be stopped and reversed quickly without increasing the load on the fan motor. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a side view showing a hydraulic excavator according to an embodiment to which a cooling system of the present invention is applied. [Figure 2] FIG. 2 is a plan view showing the overall configuration of a cooling system installed in a machine room. [Figure 3] FIG. 10 is a perspective view showing a movable plate provided on a partition wall. [Figure 4] FIG. 10 is a cross-sectional plan view showing a fixing device for fixing the movable plate in a closed state. [Figure 5] 10 is a flowchart illustrating a fan reversal routine executed by the controller. [Figure 6] FIG. 10 is an explanatory diagram showing an operating state before the first cooling fan is rotated in reverse. [Figure 7] 10 is an explanatory diagram illustrating a state in which the driving of the first cooling fan is stopped and the first movable plate is opened. FIG. [Figure 8] FIG. 10 is an explanatory diagram illustrating when the first cooling fan starts to rotate in the reverse direction. [Figure 9] 10 is an explanatory view showing a state where the first movable plate is switched to a closed position after the first cooling fan has completed reverse rotation. FIG. [Figure 10] FIG. 10 is a perspective view showing a first movable plate of Modified Example 1 that is rotated and opened / closed by a motor drive. [Figure 11] FIG. 10 is a perspective view showing a first movable plate of Modified Example 2 that slides open and closed by motor drive. [Figure 12] FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment in which the present invention is embodied in a cooling system for a hydraulic excavator will be described. 1 is a side view showing a hydraulic excavator according to this embodiment, and the schematic configuration of the hydraulic excavator will be described first with reference to this drawing. In the following description, the front-rear, left-right, and up-down directions are expressed from the perspective of an operator riding on the hydraulic excavator.

[0012] A pair of left and right crawlers 3 are provided on a lower traveling structure 2 of the hydraulic excavator 1, and the crawlers 3 are driven by a hydraulic traveling motor (not shown) to travel the hydraulic excavator 1. An upper rotating structure 4 is provided on the lower traveling structure 2, and the upper rotating structure 4 is driven to rotate by a hydraulic rotating motor (not shown). A multi-jointed front work unit 5 is provided in front of the upper rotating structure 4, and the front work unit 5 is made up of a boom 6, an arm 7, and a bucket 8. The angle of the boom 6 is changed by a boom cylinder 6a, the angle of the arm 7 is changed by an arm cylinder 7a, and the angle of the bucket 8 is changed by a bucket cylinder 8a.

[0013] An operator's cab 10 for an operator is provided on the front of the frame 9 of the upper rotating body 4, and a fuel tank 11, a machine room 12, a counterweight 13, and the like are provided on the frame 9 behind the operator's cab 10. Although not shown, various operating devices that are operated by the operator are provided in the operator's cab 10, and an engine 14 (shown in FIG. 2) that functions as a power source for the hydraulic excavator 1 is disposed in the machine room 12. Although not shown, a hydraulic pump is driven by the engine 14, and the hydraulic oil discharged is switched by a hydraulic circuit in response to operation of the operating device and is supplied appropriately to the hydraulic motors for traveling or swinging and each hydraulic actuator such as each of the cylinders 6a to 8a. This allows the hydraulic excavator 1 to travel, the upper rotating body 4 to swing, the front work unit 5 to operate, and so on.

[0014] FIG. 2 is a plan view showing the overall configuration of the cooling system installed in the machine room 12. As shown in FIG. The machinery room 12 is defined facing the left side wall 4a of the upper rotating body 4, and an engine 14 is mounted on the right side of the machinery room 12, and a cooling system 16 for cooling the engine 14 is mounted on the left side. Overall, the cooling system 16 is composed of three ventilation ducts 17a to 17c that connect the outside of the left side wall 4a of the upper rotating body 4 (hereinafter simply referred to as the outside of the vehicle body) with the machinery room 12, heat exchangers 18a to 18c, cooling fans 19a to 19c, and fan motors 20a to 20c that are respectively disposed in the ventilation ducts 17a to 17c, movable plates 22 that are respectively provided on a pair of partition walls 21 that separate adjacent ventilation ducts 17a to 17c, and a controller 23 that controls the cooling system 16.

[0015] The ventilation passages 17a to 17c are arranged side by side in the front-to-rear direction and adjacent to each other while being partitioned by the above-mentioned partition wall 21. The left end of each of the ventilation passages 17a to 17c opens into the left side wall 4a of the upper rotating body 4, and heat exchangers 18a to 18c are disposed at the respective openings.

[0016] A radiator 18a serving as a heat exchanger is disposed in the foremost ventilation passage 17a, and therefore, hereinafter, this passage will be referred to as the radiator ventilation passage 17a, and the cooling fan 19a and fan motor 20a therein will also be referred to as the "radiator" to distinguish them. An oil cooler 18b serving as a heat exchanger is disposed in the middle ventilation passage 17b, and therefore, hereinafter, this passage will be referred to as the oil cooler ventilation passage 17b, and the cooling fan 19b and fan motor 20b therein will also be referred to as the "oil cooler" to distinguish them. An intercooler 18c serving as a heat exchanger is disposed in the rearmost ventilation passage 17c, and therefore, hereinafter, this passage will be referred to as the intercooler ventilation passage 17c, and the cooling fan 19c and fan motor 20c therein will also be referred to as the "intercooler" to distinguish them.

[0017] The radiator 18a is connected to a cooling circuit of the engine 14, through which engine coolant flows. The oil cooler 18b is connected to a lubrication circuit of the engine 14, through which lubricating oil flows. The intercooler 18c is connected to an intake circuit of the engine 14, through which intake air flows. In the following description, the coolant, lubricating oil, and intake air flowing through the heat exchangers 18a to 18c may be collectively referred to as internal fluids.

[0018] FIG. 3 is a perspective view showing the movable plate 22 provided on the partition wall 21, and FIG. 4 is a plan sectional view showing a fixing device for fixing the movable plate 22 in the closed state. As shown in FIGS. 2 to 4, each movable plate 22 and its corresponding fixed plate 24 constitutes a partition wall 21, with the right half of the partition wall 21 being formed by the fixed plate 24 and the left half being formed by the movable plate 22. The fixed plate 24 of each partition wall 21 is fixed so as not to displace between the adjacent ventilation passages 17a to 17c, and the movable plate 22 of each partition wall 21 is supported so as to be rotatable about the axis Lh of hinges 25 provided at three locations above and below the left end. As will be described in detail later, the movable plate 22 is normally maintained in a closed position that closes the partition wall 21, and is switched to an open position that opens the partition wall 21 when the cooling fans 19a to 19c are rotated in the reverse direction. Note that the movable plate 22 is opened by the pressure difference generated between the adjacent ventilation passages 17a to 17c, and its open position (rotation angle) changes depending on the magnitude of the pressure difference.

[0019] The right ends of the ventilation passages 17a to 17c open into the machinery compartment 12 and face the engine 14, and cooling fans 19a to 19c and fan motors 20a to 20c are disposed at the respective openings. Each of the fan motors 20a to 20c individually drives and rotates the corresponding cooling fan 19a to 19c, and when each of the cooling fans 19a to 19c rotates forward, an airflow Air1 is generated in each of the ventilation passages 17a to 17c, flowing from the outside of the vehicle body through the heat exchangers 18a to 18c to the machinery compartment 12. When each of the cooling fans 19a to 19c rotates reversely, an airflow Air2 (shown in FIGS. 8 and 9) is generated in each of the ventilation passages 17a to 17c, flowing from the machinery compartment 12 through the heat exchangers 18a to 18c to the outside of the vehicle body. Each of the cooling fans 19a to 19c is provided with a rotation speed sensor 26 (corresponding to a "rotation speed detector" of the present invention) that detects the rotation speed. Except for the areas of the cooling fans 19a to 19c, the openings of the ventilation passages 17a to 17c in the machine room 12 are closed by shrouds 27.

[0020] 2, the positional relationship between the cooling system 16 and the engine 14 is set as follows. First, the axis Lf of the radiator cooling fan 19a is located slightly rearward of the front end of the engine 14, and the axis Lf of the intercooler cooling fan 19c is located slightly forward of the rear end of the engine 14. As a result, the axes Lf of all of the cooling fans 19a to 19c are located within the region in the fore-and-aft direction of the engine 14 (corresponding to the "direction in which the cooling fans are arranged side by side" in this specification). Therefore, when each of the cooling fans 19a to 19c rotates forward, most of the generated airflows Air1 and Air2 impinge on the engine 14. Furthermore, the shrouds 27 of each of the ventilation passages 17a to 17c and the engine 14 are spaced apart in the left-right direction, forming a space extending in the front-and-rear direction between them. As described below, this space functions as a circulation ventilation passage 28.

[0021] Next, the movable plate 22 of each partition wall 21 will be described in detail with reference to Figures 3 and 4. In the following explanation, the movable plate 22 (hereinafter referred to as the first movable plate 22a) of the partition wall 21 between the radiator ventilation passage 17a and the oil cooler ventilation passage 17b will be mainly described, but the other movable plate 22 (hereinafter referred to as the second movable plate 22b) has the same configuration and operates in the same way.

[0022] First movable plate 22a is provided in anticipation of the case where radiator cooling fan 19a rotating in the forward direction is rotated in the reverse direction, and is designed to be opened by rotating from a closed position toward oil cooler ventilation passage 17b around hinge 25. Within radiator ventilation passage 17a, tip fixing devices 31 are supported via brackets 30 at three positions above and below the left end of fixed plate 24. Also within radiator ventilation passage 17a, base end fixing devices 33 are supported via brackets 32 at two positions above and below the left end (on the hinge 25 side) of first movable plate 22a.

[0023] The distal and proximal end fixing devices 31, 33 are formed by winding coils 31b, 33b around permanent magnets 31a, 33a, respectively, and when the first movable plate 22a rotates to the closed position, one side of the plate abuts against the end of the permanent magnets 31a, 33a of each fixing device 31, 33. When the coils 31b, 33b of each fixing device 31, 33 are not energized, a magnetic field is formed in the permanent magnets 31a, 33a, generating a magnetic force, and when the coils 31b, 33b are energized, the magnetic field of the permanent magnets 31a, 33a is obstructed and the magnetic force is released.

[0024] Therefore, when the first movable plate 22a rotates to the closed position while the coils 31b, 33b of the fixing devices 31, 33 are not energized, the metallic first movable plate 22a is attracted to the coils 31b, 33b of the fixing devices 31, 33 and maintained in the closed position. Furthermore, the magnetic force of the base end fixing device 33 located close to the hinge 25 acts even when the first movable plate 22a is in the open position, rotating the first movable plate 22a from the open position to the closed position. On the other hand, when the coils 31b, 33b of the fixing devices 31, 33 are energized, the first movable plate 22a is released from the magnetic force and becomes freely rotatable. As described below, the first movable plate 22a rotates to the open position due to the differential pressure between the radiator ventilation passage 17a and the oil cooler ventilation passage 17b.

[0025] In addition, second movable plate 22b is designed to rotate toward intercooler ventilation passage 17c and open in anticipation of the case where oil cooler cooling fan 19b is rotated in the reverse direction. Therefore, each of fixing devices 31, 33 of second movable plate 22b is disposed in oil cooler ventilation passage 17b and operates in the same manner as described above.

[0026] As shown in FIG. 2, the controller 23 includes a motor control unit 23a and a movable plate control unit 23b. Various types of detected information, such as the rotation speeds of the cooling fans 19a to 19c detected by the respective rotation speed sensors 26, and the coolant temperature, oil temperature, and intake air temperature of the engine 14, are input to the controller 23. Based on this information, the controller 23 sets target rotation speeds for the cooling fans 19a to 19c during normal rotation in order to maintain the coolant temperature, oil temperature, intake air temperature, and the like of the engine 14 at appropriate temperatures during operation.

[0027] Furthermore, when it is necessary to remove debris adhering to the heat exchangers 18a to 18c or to raise the temperature of the internal fluid, the controller 23 reverses the rotation of the cooling fans 19a to 19c of the corresponding heat exchangers 18a to 18c. If debris adheres to the heat exchangers 18a to 18c, the cooling efficiency of the internal fluid deteriorates, making it necessary to remove the debris. Furthermore, if the temperature of the internal fluid is excessively low, smooth operation of the engine 14 that drives the hydraulic pump cannot be expected, and as a result, there is a possibility that the hydraulic excavator 1, which is driven by the hydraulic oil from the hydraulic pump, will not operate normally, so it is necessary to raise the temperature of the internal fluid.

[0028] If dust adheres to the heat exchangers 18a-18c, the temperature of the heat exchangers 18a-18c rises at the same fan rotation speed, and the power consumption of the fan motors 20a-20c increases. Therefore, whether or not dust needs to be removed is determined based on the correlation between these factors (corresponding to the reversal condition described below). By reversing the rotation of the cooling fans 19a-19c, the dust can be expelled to the outside of the vehicle along with the airflow Air2 that flows through the heat exchangers 18a-18c and out of the vehicle.

[0029] Regarding whether or not the internal fluid needs to be heated, it is determined that the temperature needs to be increased when a temperature sensor (not shown) detects that the temperature of the internal fluid is equal to or lower than a predetermined threshold (corresponding to a reversal condition described below). For example, even immediately after starting the engine 14, the air in the machinery compartment 12 is heated by heat received from the engine surface, and is also heated by the inflow of air that has passed through any of the heat exchangers 18a-18c whose temperature has risen earlier. This air in the machinery compartment 12 flows as airflow Air2 through the heat exchangers 18a-18c that need to be heated by reversing the rotation of the cooling fans 19a-19c, thereby facilitating the temperature increase of the internal fluid.

[0030] As described above, when rotating the cooling fans 19a to 19c in the reverse direction, shorting the power terminals of the fan motors as described in Patent Document 2 can quickly stop the rotation. However, this can cause the fan motors to generate heat and shorten their lifespan. Therefore, in this embodiment, when rotating either the radiator cooling fan 19a or the oil cooler cooling fan 19b in the reverse direction, a measure is taken to prevent the rotation (forward rotation) of the cooling fan 19a, 19b that is to be rotated in the reverse direction by utilizing the airflow Air1 from the adjacent cooling fans 19b, 19c. To implement this measure, it is necessary to open the movable plates 22a, 22b between the adjacent cooling fans 19b, 19c. The movable plate control unit 23b of the controller 23 controls the fixing devices 31, 33 for this purpose.

[0031] Furthermore, the motor control unit 23a normally controls the fan motors 20a to 20c based on the target rotation speed, but when any of the cooling fans 19a to 19c rotates in the reverse direction, it controls the cooling fans 19a to 19c to stop or reverse the power supply to the cooling fans 19a to 19c.

[0032] The control situation when the radiator cooling fan 19a or the oil cooler cooling fan 19b is rotated in the reverse direction will be described below. As a premise for the explanation, it is assumed that first and second movable plates 22a, 22b are kept in the closed position and all cooling fans 19a to 19c are driven to rotate in the normal direction, and the case where radiator cooling fan 19a is rotated in the reverse direction in this state will be described.

[0033] In this control state, the radiator ventilation passage 17a and the oil cooler ventilation passage 17b correspond to the "first and second ventilation passages" of the present invention, the radiator 18a and the oil cooler 18b correspond to the "first and second heat exchangers" of the present invention, the radiator cooling fan 19a and the oil cooler cooling fan 19b correspond to the "first and second cooling fans" of the present invention, the radiator fan motor 20a and the oil cooler fan motor 20b correspond to the "first and second fan motors" of the present invention, and the first movable plate 22a corresponds to the "movable plate" of the present invention.

[0034] When the radiator cooling fan 19a is reversed, the control state on the intercooler ventilation passage 17c side (the airflow flow state within the intercooler ventilation passage 17c, the driving state of the intercooler cooling fan 19c, the opening / closing state of the second movable plate 22b, etc.) does not change, so these control states will not be mentioned and the explanation will be based on Figures 6 to 9, in which the intercooler ventilation passage 17c is not shown.

[0035] FIG. 5 is a flowchart showing a fan reversal routine executed by controller 23, FIG. 6 is an explanatory diagram showing the operating state before radiator cooling fan 19a is reversed, FIG. 7 is an explanatory diagram when the drive of radiator cooling fan 19a is stopped and first movable plate 22a is opened, FIG. 8 is an explanatory diagram when reverse rotation of radiator cooling fan 19a is started, and FIG. 9 is an explanatory diagram when reverse rotation of radiator cooling fan 19a is completed and first movable plate 22a is switched to the closed position.

[0036] 5 at predetermined control intervals while the cooling system 16 is in operation. First, in step 1, it is determined whether the reverse rotation condition is met for the cooling fans 19a to 19c. If the determination is No (negative), the processing of step 1 continues. The reverse rotation condition is determined based on whether the above-mentioned removal of debris or an increase in the temperature of the internal fluid is required. If it is determined that any of the cooling fans 19a to 19c should be reversed, the subsequent processing is performed for that cooling fan 19a to 19c. Therefore, in this case, in step 1, it is determined that either the removal of debris adhering to the radiator 18a or an increase in the temperature of the engine coolant is required, and the radiator cooling fan 19a is reversed.

[0037] 6, in cooling system 16 at this point, radiator cooling fan 19a and oil cooler cooling fan 19b (and also intercooler cooling fan 19c) are rotating forward, generating a large negative pressure on their respective suction sides (heat exchanger 18a-18c sides) and a large positive pressure on their respective discharge sides (machine compartment 12 sides). As a result, airflows Air1 are generated in radiator ventilation passage 17a and oil cooler ventilation passage 17b, respectively, flowing from the outside of the vehicle toward machine compartment 12. These airflows Air1 cool radiator 18a or oil cooler 18b, and then impinge on engine 14 in machine compartment 12, thereby providing a cooling effect.

[0038] If the controller 23 judges "Yes" in step 1, it proceeds to step 2, where it stops driving the radiator cooling fan 19a. Then, in step 3, it energizes the coils 31b, 33b of the distal and proximal fixing devices 31, 33 of the first movable plate 22a. In the closed position, the first movable plate 22a is released from the magnetic force and becomes freely rotatable. The radiator cooling fan 19a experiences air resistance, gradually slowing down its rotational speed. As the rotation speed decreases, the flow rate of the airflow Air1 generated by the radiator cooling fan 19a decreases, and the negative pressure on its intake side and the positive pressure on its discharge side gradually decrease. This creates a pressure difference between the radiator ventilation passage 17a and the oil cooler ventilation passage 17b. As shown in Figure 7, in response to this pressure difference, the first movable plate 22a rotates around the hinge 25 to the open position, thereby connecting the radiator ventilation passage 17a and the oil cooler ventilation passage 17b, and generating an airflow Air3 that flows from the radiator ventilation passage 17a to the oil cooler ventilation passage 17b.

[0039] A pressure difference also occurs between the discharge side of radiator cooling fan 19a and the discharge side of oil cooler cooling fan 19b, both of which open into machinery compartment 12. As a result, a portion of airflow Air1 discharged from oil cooler cooling fan 19b and impinging on engine 14 flows as airflow Air4 along circulation air passage 28 toward radiator cooling fan 19a, generating airflow Air5 that flows backward through radiator cooling fan 19a. As a result, a portion of airflow Air1 discharged from oil cooler cooling fan 19b circulates between radiator air passage 17a and oil cooler air passage 17b as airflow Air4, airflow Air5, and airflow Air3. Airflow Air5, which flows backward through radiator cooling fan 19a, acts in a direction that impedes its rotation (forward rotation), accelerating a reduction in rotation. Therefore, radiator cooling fan 19a rapidly reduces its rotational speed and stops at an early timing.

[0040] The flow rate of the generated airflow Air5 gradually increases as the rotation speed of radiator cooling fan 19a slows down. That is, the initially generated airflow Air5 merely flows backward through a narrow region above radiator cooling fan 19a, mainly on the lower side in FIG. 7 (the oil cooler cooling fan 19b side). However, as the rotation speed of radiator cooling fan 19a slows down, the flow rate of the original airflow Air1 gradually decreases, and accordingly the flow region of airflow Air5 gradually expands toward the upper side in FIG. 7, and by the time radiator cooling fan 19a stops, airflow Air5 reaches the entire radiator cooling fan 19a.

[0041] Returning to the routine of Figure 5, after completing the processing of step 3, controller 23 proceeds to step 4, where it determines whether rotation speed Nf of radiator cooling fan 19a detected by rotation speed sensor 26 is equal to or less than 0. If radiator cooling fan 19a stops and the determination in step 4 becomes Yes, it proceeds to step 5, where it drives radiator fan motor 20a in the reverse direction. Note that the timing for starting reverse driving is not limited to this; for example, it is also possible to start reverse driving of radiator fan motor 20a before radiator cooling fan 19a stops.

[0042] As shown in Figure 8, radiator cooling fan 19a starts rotating in the reverse direction from a stopped state, which reverses the suction side (negative pressure) and discharge side (positive pressure), generating airflow Air2 that flows from engine compartment 12 to the outside of the vehicle via radiator 18a. Radiator cooling fan 19a gradually increases its rotation speed, and the flow rate of airflow Air2 increases accordingly.

[0043] After completing the process of step 5, the controller 23 proceeds to step 6, where it determines whether the rotation speed Nf of the radiator cooling fan 19a has reached the target rotation speed Nftgt. For example, the target rotation speed Nftgt is preset to values ​​suitable for removing dust and increasing the temperature of the internal fluid, and one of these values ​​is selected depending on the purpose of reversing the rotation of the radiator cooling fan 19a (based on the reversal conditions) and applied to the process of step 6.

[0044] If the determination in step 6 is Yes, the routine proceeds to step 7, where energization of the coil 33b of the proximal end fixing device 33 is stopped, and then in the following step 8, energization of the coil 31b of the distal end fixing device 31 is stopped, after which the routine ends. As shown in FIG. 9, when energization of the coil 33b of the proximal end fixing device 33 is stopped, its magnetic force acts on the first movable plate 22a, causing it to rotate to the closed position. Note that the processing of steps 7 and 8 may be performed simultaneously. Then, when energization of the coil 31b of the distal end fixing device 31 is stopped, the first movable plate 22a is attracted to the permanent magnet 31a and maintained in the closed position.

[0045] When the first movable plate 22a is in the open position, the flow rate of the airflow Air2 passing through the radiator 18a is reduced by an amount corresponding to the airflow Air3 flowing from the radiator ventilation passage 17a to the oil cooler ventilation passage 17b. However, once the first movable plate 22a has completely rotated to the closed position, all of the airflow Air2 generated by the reverse rotation of the radiator cooling fan 19a flows through the radiator 18a. Therefore, when the rotation is reversed to remove debris, debris adhering to the radiator 18a is expelled to the outside of the vehicle, and when the rotation is reversed to heat the internal fluid, the temperature of the engine coolant in the radiator 18a is raised.

[0046] As described above, when the radiator cooling fan 19a is rotated in the reverse direction, the airflow Air1 generated by the adjacent oil cooler cooling fan 19b is used to generate the airflow Air5 that flows backward through the radiator cooling fan 19a, preventing its rotation. This allows the radiator cooling fan 19a to quickly stop rotating and, ultimately, quickly reverse its rotation. Furthermore, unlike the technology of Patent Document 1, the fan motor is not heated by shorting the power terminals, which prevents adverse effects such as a shortened lifespan of the radiator fan motor 20a. As a result, this embodiment allows for the removal of debris and the warming of the internal fluid to be completed at an early stage, allowing the radiator 18a to quickly resume cooling the engine coolant.

[0047] At some point, radiator cooling fan 19a is returned from reverse rotation to forward rotation, and in this embodiment, the rotation speed Nf of oil cooler cooling fan 19b is temporarily reduced at this time. When radiator cooling fan 19a is returned to forward rotation, it increases its rotation speed to the target rotation speed, but at that time, airflow Air4 flowing through ventilation passage 28 acts in a direction that prevents the increase in rotation. Because the reduction in rotation of oil cooler cooling fan 19b weakens airflow Air4, the effect is achieved that radiator cooling fan 19a can be returned to forward rotation more quickly.

[0048] While the above description has been given for the case where the radiator cooling fan 19a is rotated in the reverse direction, the control content is similar when the oil cooler cooling fan 19b is rotated in the reverse direction. Therefore, without repeating the description, the processing of steps 2 and 3 in the routine of Fig. 5 may be applied to the oil cooler fan motor 20b instead of the radiator fan motor 20a, and the processing of steps 3, 7, and 8 may be applied to the fixing devices 31 and 33 of the second movable plate 22b instead of the fixing devices 31 and 33 of the first movable plate 22a.

[0049] This makes it possible to remove dirt adhering to oil cooler 18b or to raise the temperature of the engine lubricating oil. Furthermore, through the same process as described above, the pressure difference opens second movable plate 22b, generating airflow Air3 that flows from oil cooler ventilation passage 17b to intercooler ventilation passage 17c, and also generating airflow Air5 that interferes with the rotation of oil cooler cooling fan 19b, allowing oil cooler cooling fan 19b to be quickly stopped and reversed.

[0050] In this control state, the oil cooler ventilation passage 17b and the intercooler ventilation passage 17c correspond to the "first and second ventilation passages" of the present invention, the oil cooler 18b and the intercooler 18c correspond to the "first and second heat exchangers" of the present invention, the oil cooler cooling fan 19b and the intercooler cooling fan 19c correspond to the "first and second cooling fans" of the present invention, the oil cooler fan motor 20b and the intercooler fan motor 20c correspond to the "first and second fan motors" of the present invention, and the second movable plate 22b corresponds to the "movable plate" of the present invention.

[0051] Furthermore, in this embodiment, although it is possible to reverse the rotation of the intercooler cooling fan 19c, it is not possible to quickly stop and reverse the rotation of the intercooler cooling fan 19c using the airflow Air1 generated by the adjacent oil cooler cooling fan 19b. In the structure shown in FIG. 4, the second movable plate 22b cannot rotate toward the oil cooler ventilation passage 17b, so even if the operation of the intercooler cooling fan 19c is stopped, the airflow Air3 flowing from the intercooler ventilation passage 17c to the oil cooler ventilation passage 17b cannot be generated. However, if the second movable plate 22b is configured to be rotatable toward the oil cooler ventilation passage 17b, it would also be possible to quickly stop and reverse the rotation of the intercooler cooling fan 19c, so the second movable plate 22b may be configured in this manner.

[0052] The first and second movable plates 22a, 22b are not limited to being configured to open using the differential pressure generated between adjacent ventilation passages 17a-17c. For example, the movable plates 22a, 22b may be driven to open and close by an opening / closing motor, as described below as Alternative Examples 1 and 2. Components that are common to the embodiment are given the same component numbers and will not be described again, with the differences being emphasized. Since the first and second movable plates 22a, 22b have the same configuration, the following description will focus on the first movable plate 22a.

[0053] [Example 1] FIG. 10 is a perspective view showing a first movable plate 22a of Modified Example 1 that is rotated and opened / closed by a motor drive. An opening / closing motor 41 is fixed to the outer upper surface between the ventilation passages 17a and 17b, and its output shaft 41a is located on the axis Lh of the hinge 25 and connected to the first movable plate 22a. As a result, the first movable plate 22a rotates between a closed position and an open position in response to the forward and reverse rotation of the opening / closing motor 41.

[0054] 5, instead of energizing the coils 31b, 33b of the fixing devices 31, 33, the opening / closing motor 41 is operated to rotate the first movable plate 22a to the open position. Also, in steps 7 and 8, instead of stopping the energization of the coils 31b, 33b of the fixing devices 31, 33, the opening / closing motor 41 is operated to rotate the first movable plate 22a to the closed position. As a result, similar to the above embodiment, the airflow Air3 can be generated in response to the opening and closing of the first movable plate 22a.

[0055] According to this modification 1, in addition to the effects of the above embodiment, the cooling fans 19a, 19b can be rotated in the reverse direction more quickly. More specifically, in the embodiment, even if the driving of the cooling fans 19a, 19b is stopped, the movable plates 22a, 22b are not opened until a pressure difference is generated, which causes a corresponding delay in the generation of the airflow Air3. In contrast, in modification 1, the movable plates 22a, 22b can be opened without delay as soon as the driving of the cooling fans 19a, 19b is stopped, so the airflow Air3 can be generated more quickly. As a result, the timing of stopping the rotation of the cooling fans 19a, 19b and therefore of reversing the rotation can be accelerated.

[0056] [Example 2] FIG. 11 is a perspective view showing a first movable plate 22a of Modified Example 2 that slides open and closed by motor drive, and FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. Guide rails 51 (corresponding to the "guide members" of the present invention, only the upper side is shown in FIG. 12) are provided at the top and bottom of the oil cooler ventilation passage 17b, extending along the fixed plate 24 of the partition wall 21. The upper and lower ends of the first movable plate 22a are fitted into the respective guide rails 51 and are guided by the guide rails 51 so as to be slidable between a closed position where the adjacent ventilation passages 17a, 17b are blocked and an open position where the ventilation passages 17a, 17b communicate with each other.

[0057] An opening / closing motor 52 is fixed to the external upper surface between the ventilation passages 17a and 17b, and a pinion 53 fixed to the output shaft 52a of the opening / closing motor 52 is engaged with a rack 54 provided along the upper edge of the first movable plate 22a. The rotational motion of the output shaft 52a of the opening / closing motor 52 is converted into linear motion via the pinion 53 and the rack 54, so that the first movable plate 22a slides between the closed position and the open position while being guided by the guide rail 51 in accordance with the forward and reverse rotation of the opening / closing motor 52.

[0058] The operation timing of the opening / closing motor 52 is the same as in the first modified example, whereby the airflow Air3 can be generated in response to the opening and closing of the first movable plate 22a. Although a redundant explanation will not be given, in this second modified example as well, the movable plates 22a and 22b can be opened without delay regardless of the occurrence of a pressure difference, so that the cooling fans 19a and 19b can be reversed more quickly.

[0059] This concludes the description of the embodiment, but the aspects of the present invention are not limited to this embodiment. For example, in the above embodiment, the cooling system 16 was embodied in a hydraulic excavator 1, but the construction machine to which the present invention is applied is not limited to this, and the present invention can be applied to any construction machine equipped with a cooling system in which a heat exchanger and a cooling fan are disposed in adjacent ventilation ducts. Therefore, the present invention may also be embodied as a cooling system for a wheel loader, a tire roller, a dump truck, etc.

[0060] In the above embodiment, the cooling fans 19a-19c are disposed downstream of the heat exchangers 18a-18c, and the cooling system 16 is embodied as a so-called pull-in type in which the cooling fans 19a-19c draw in air from outside the vehicle body and cause it to flow through the heat exchangers 18a-18c. However, the present invention is not limited to this. For example, the cooling system may be embodied as a so-called push-in type in which the cooling fans 19a-19c are disposed upstream of the heat exchangers 18a-18c, and the cooling fans 19a-19c force air from outside the vehicle body into the heat exchangers 18a-18c and cause it to flow through. In this case, the various effects described in the above embodiment can also be achieved. [Explanation of symbols]

[0061] 1. Hydraulic excavator 12 Machine room 14 Engine 17a Radiator ventilation duct (first and second ventilation ducts) 17b Oil cooler ventilation passage (first and second ventilation passages) 17c Intercooler ventilation ducts (first and second ventilation ducts) 18a Radiator (first and second heat exchangers) 18b Oil cooler (first and second heat exchangers) 18c Intercooler (first and second heat exchangers) 19a Radiator cooling fan (first and second cooling fans) 19b Oil cooler cooling fan (first and second cooling fans) 19c Intercooler cooling fan (first and second cooling fans) 20a Radiator fan motor (first and second fan motors) 20b Oil cooler fan motor (first and second fan motors) 20c Intercooler fan motor (first and second fan motors) 21 Bulkhead 22a First movable plate (movable plate) 22b Second movable plate (movable plate) 23 Controller 23a Motor control unit 23b Movable plate control section 26 Rotational speed sensor (rotational speed detection section) 31 Tip fixation device (fixation device) 33 Proximal fixation device (fixation device) 41,52 Opening and closing motor 41a, 52a Output shaft 51 Guide rail (guide member) 53 Pinion 54 racks

Claims

1. first and second ventilation passages, one end of which communicates with the exterior of the vehicle body and the other end of which communicates with the machinery compartment, adjacent to each other and separated by a partition wall; first and second heat exchangers disposed in the first and second ventilation channels, respectively; first and second cooling fans, which are disposed in the first and second ventilation passages, respectively, and are rotationally driven by first and second fan motors, and which, when rotating in a forward direction, generate an air current that flows through the first and second heat exchangers and into the machinery chamber, and, when rotating in a reverse direction, generate an air current that flows from the machinery chamber to the first and second heat exchangers; a controller having a motor control unit that drives and controls the first and second fan motors to rotate the first and second cooling fans in a forward or reverse direction; In a cooling system for a construction machine equipped with a movable plate provided on the partition wall and switchable between a closed position for closing the partition wall and an open position for opening the partition wall, a movable plate control unit that opens the movable plate when a reverse condition for rotating either one of the first and second cooling fans in the reverse direction while the first and second cooling fans are rotating in the forward direction is met.

2. When a reverse rotation condition for reversing the one cooling fan is satisfied, the controller switches the movable plate to an open position using the movable plate control unit and stops driving the one cooling fan using the motor control unit. When the rotation speed of the one cooling fan decreases, the motor control unit drives the one cooling fan in the reverse direction. When the rotation speed of the one cooling fan increases due to the reverse rotation, the controller switches the movable plate to a closed position using the movable plate control unit.

2. The cooling system for a construction machine according to claim 1.

3. a rotation speed detection unit that detects the rotation speed of the one cooling fan, When the rotation speed of the one cooling fan detected by the rotation speed detection unit drops to 0, the controller drives the one cooling fan in the reverse direction using the motor control unit.

3. The cooling system for a construction machine according to claim 2.

4. When returning one of the cooling fans that has been rotated in reverse to a normal rotation, the controller controls the motor control unit to reduce the rotation speed of the other cooling fan.

4. The cooling system for a construction machine according to claim 2 or 3.

5. The movable plate is supported so as to be rotatable about an axis between the closed position and the open position, and is attracted by the magnetic force of a fixing device at the closed position, while when released from the magnetic force of the fixing device, the movable plate rotates to the open position due to a pressure difference between the first ventilation path and the second ventilation path.

5. The cooling system for a construction machine according to claim 1.

6. The movable plate is supported so as to be rotatable about an axis between the closed position and the open position, and an output shaft of an opening / closing motor disposed on the axis is connected to the movable plate, so that the movable plate rotates between the closed position and the open position in response to forward and reverse rotation of the opening / closing motor.

5. The cooling system for a construction machine according to claim 1.

7. The movable plate is guided by a guide member and is slidable between the closed position and the open position. A pinion of an opening / closing motor is engaged with a rack provided on one side of the movable plate, and the movable plate slides between the closed position and the open position in response to forward and reverse rotation of the opening / closing motor via the rack and the pinion.

5. The cooling system for a construction machine according to claim 1.

8. The movable plate control unit of the controller releases the magnetic force of the fixing device when a reverse rotation condition for rotating one of the cooling fans is met, and generates a magnetic force in the fixing device when the one of the cooling fans rotates in the reverse direction and increases in rotation.

6. The cooling system for a construction machine according to claim 5.

9. The movable plate control unit of the controller, when a reverse rotation condition for rotating one of the cooling fans in the reverse direction is satisfied, activates the open / close motor to switch the movable plate to an open position, and when the one of the cooling fans reverses and rotates upward, activates the open / close motor to switch the movable plate to a closed position.

8. The cooling system for a construction machine according to claim 6 or 7.

10. an engine that functions as a power source for the construction machine is disposed in the machine room; When the first and second cooling fans are rotating in the normal direction, the engine is cooled by the airflow that has passed through the first and second ventilation paths.

10. The cooling system for a construction machine according to claim 1.

11. In the direction in which the first and second cooling fans are arranged side by side, the axis of each cooling fan is located within the area of ​​the engine.

11. The cooling system for a construction machine according to claim 10.

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