Construction machine

Abstract

To provide a construction machine capable of suppressing an unpleasant beat between a cooling fan and a periodical sound source caused by hydraulic pulsation of a hydraulic pump or engine explosion.SOLUTION: A hydraulic shovel 1 includes an engine 61, cooling fans 77o, 77r, 77i, and a vehicle body controller 51 for controlling a rotation speed of the cooling fans 77o, 77r, 77i. The vehicle body controller 51 specifies a frequency of a hydraulic pump 62 as a periodical sound source of which frequency is varied by a rotation speed of the engine 61, and sets a target rotation speed Nt of the cooling fans 77o, 77r, 77i to a rotation speed at which a beat with the specified frequency can be avoided, and the cooling fans 77o, 77r, 77i are driven at the set target rotation speed Nt.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a construction machine equipped with a cooling fan that cools a heat exchanger, and more particularly to a construction machine in which the rotation speed of the cooling fan can be set regardless of the rotation speed of the engine. [Background technology]

[0002] Cooling fans that are generally used in construction machines such as hydraulic excavators to cool heat exchangers include those that are connected to the engine crankshaft and rotate with the rotation of the engine crankshaft, and those that are separate from the engine and driven by a hydraulic motor or an electric motor so that their rotation speed can be set independently. In construction machines, the latter type of cooling fans that are driven so that their rotation speed can be set independently may be mounted, for example, facing each of a number of heat exchangers, and the rotation speed of each cooling fan may be controlled based on the temperature of the fluid flowing through each heat exchanger. In this case, when two cooling fans rotate at similar rotation speeds, the vibrations of the two fans are superimposed, generating a "beat."

[0003] In other words, when there are two sound sources with different frequencies f1 and f2, the composite sound wave repeats periodic amplification and attenuation. In this case, the time it takes for two overlapping waves in phase to become in phase again is the beat period T0, and since the difference in the number of waves in one period T0 is |f1×T0-f2×T0|, which is 1, the beat frequency f can be calculated as f=|f1-f2|. If this frequency f falls below a certain value (e.g. 7Hz), the beat can be heard by the human ear, which may cause discomfort to the operator and those around.

[0004] In order to suppress the generation of humming noise caused by multiple cooling fans, for example, Patent Document 1 describes a construction machine in which priorities are preset as the order in which target rotation speeds should be secured for all of a plurality of cooling target parts, and a controller corrects the lower-ranked target rotation speed, of two target rotation speeds set to have a difference less than a minimum rotation speed difference, so that the lower-ranked target rotation speed for the cooling target part with a lower priority becomes a rotation speed away from the higher-ranked target rotation speed for the cooling target part with a higher priority. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6432219 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in construction machines such as hydraulic excavators, in addition to the cooling fan, there are periodic sound sources caused by hydraulic pulsation of the hydraulic pump and engine explosion. The frequencies of these periodic sound sources increase and decrease with changes in engine speed, and cannot be increased or decreased independently of the engine speed. For this reason, the frequencies of the periodic sound sources are usually designed to be sufficiently far apart to prevent the occurrence of beats and resonance. On the other hand, it is also preferable to avoid beats between the cooling fan and the periodic sound source, but the above-mentioned conventional technology does not take beats between them into consideration.

[0007] The present invention has been made in consideration of the above circumstances, and its object is to provide a construction machine that can suppress beats between a cooling fan and a periodic sound source caused by hydraulic pulsation of a hydraulic pump or engine explosion. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the construction machine of the present invention is a construction machine equipped with an engine, a cooling fan, and a controller that controls the rotation speed of the cooling fan, wherein the controller identifies the frequency of a driving device that is a periodic sound source whose frequency changes depending on the rotation speed of the engine, sets the rotation speed of the cooling fan to a rotation speed that can avoid the occurrence of beats between the identified frequency and the cooling fan, and drives the cooling fan at the set rotation speed. Effect of the Invention

[0009] According to the present invention, it is possible to suppress beats between a cooling fan and a periodic sound source caused by hydraulic pulsation of a hydraulic pump or engine explosion. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a side view showing an example of the overall structure of a hydraulic excavator according to an embodiment of the present invention. [Diagram 2] 2 is a perspective view showing an example of an arrangement of equipment on a rotating body provided in the hydraulic excavator of FIG. 1, as viewed from above the rotating body. FIG. [Diagram 3] FIG. 2 is a block diagram showing an example of a configuration related to control of a cooling fan of a hydraulic excavator. [Figure 4] 13 is a flowchart showing an example of a rotation speed candidate determination process. [Diagram 5] 6 is a flowchart showing an example of a correction rotation speed setting process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] <Overall configuration of hydraulic excavator> In this embodiment, a crawler hydraulic excavator will be described as an example of a construction machine. Fig. 1 is a side view showing an example of the overall structure of the hydraulic excavator of this embodiment, and Fig. 2 is a perspective view of the rotating body from above, showing an example of an arrangement of equipment on the rotating body provided in the hydraulic excavator of Fig. 1.

[0013] 1, the hydraulic excavator 1 includes a traveling body 2, a rotating body 3 rotatably provided on the traveling body 2, and a working device 4 attached to the rotating body 3. The working device 4 includes a boom 41 attached to the rotating body 3 so as to be capable of elevation and descent, an arm 42 attached to the tip of the boom 41 so as to be capable of elevation and descent, a bucket 43 attached to the tip of the arm 42 so as to be capable of elevation and descent, a boom cylinder 44 that operates the boom 41, an arm cylinder 45 that operates the arm 42, and a bucket cylinder 46 that operates the bucket 43.

[0014] The rotating body 3 is composed of a main frame 30, a counterweight 31, a cab 32, a building cover 33, etc. The main frame 30 is the base of the rotating body 3, and is made up of a plurality of steel plates and steel materials joined together to form a support structure extending in the front-rear and left-right directions of the vehicle body. A working device 4 is attached to the front of the main frame 30 so that it can be raised and lowered. The counterweight 31 is installed at the rear of the main frame 30 and serves as a weight to balance the weight of the working device 4. The cab 32 is mounted on the front left side of the main frame 30.

[0015] As shown in Fig. 2, the inside of the cab 32 is provided with a driver's seat 50 where an operator sits, and a vehicle controller 51 (an example of a controller). The building cover 33 is a cover that separates devices such as an engine 61 mounted on the main frame 30 and a cooling package 72. The building cover 33 is provided with an engine room 60 located at the rear center of the vehicle body, and a radiator room 70 located at the rear left side of the vehicle body. In the engine room 60, the engine 61 and the hydraulic pump 62 are arranged in a horizontal orientation with the crankshaft extended in the left-right direction. In the radiator room 70, the cooling package 72 and the like are mounted.

[0016] <Configuration related to cooling fan control> Next, a configuration relating to control of the cooling fan of the hydraulic excavator 1 will be described with reference to Fig. 3. Fig. 3 is a block diagram showing an example of a configuration relating to control of the cooling fan of the hydraulic excavator 1.

[0017] 3, the hydraulic pump 62 (an example of a driving device) is directly connected to the engine 61 and is driven by the output of the engine 61. The cooling package 72 has an oil cooler 73 (an example of a heat exchanger) that cools hydraulic oil used to drive the working device 4, a radiator 74 (an example of a heat exchanger) that cools engine coolant, an intercooler 75 (an example of a heat exchanger) that cools intake air supplied to the engine 61 by a turbocharger (not shown), cooling fans 77o, 77r, and 77i that cool the respective heat exchangers, and fan motors 76o, 76r, and 76i that drive the respective cooling fans 77o, 77r, and 77i.

[0018] A hydraulic oil temperature sensor 73s, an engine cooling water temperature sensor 74s, and an intake air temperature sensor 75s are provided in the flow paths of the hydraulic oil (one example of a fluid) flowing through the oil cooler 73, the engine cooling water (one example of a fluid) flowing through the radiator 74, and the intake air (one example of a fluid) flowing through the intercooler 75. The hydraulic oil temperature sensor 73s (one example of a temperature detector) detects the temperature of the hydraulic oil and transmits the temperature information to the vehicle body controller 51. The engine cooling water temperature sensor 74s (one example of a temperature detector) detects the temperature of the engine cooling water and transmits the temperature information to the vehicle body controller 51. The intake air temperature sensor 75s (one example of a temperature detector) detects the temperature of the intake air and transmits the temperature information to the vehicle body controller 51.

[0019] The fan motors 76o, 76r, 76i are each driven according to a rotation speed command from the vehicle body controller 51. The vehicle body controller 51 sets the rotation speed of the cooling fan 77o based on the temperature of the hydraulic oil detected by the hydraulic oil temperature sensor 73s, and blows cooling air to the oil cooler 73. The vehicle body controller 51 sets the rotation speed of the cooling fan 77r based on the temperature of the engine coolant detected by the engine coolant temperature sensor 74s, and blows cooling air to the radiator 74. The vehicle body controller 51 sets the rotation speed of the cooling fan 77i based on the temperature of the intake air detected by the intake air temperature sensor 75s, and blows cooling air to the intercooler 75.

[0020] <How to control the cooling fan> Next, a method for controlling the cooling fans 77o, 77r, 77i will be described with reference to Figs. 4 and 5, taking as an example a method for avoiding resonance with the hydraulic pulsation frequency of the hydraulic pump 62. Fig. 4 is a flowchart showing an example of a rotation speed candidate determination process, and Fig. 5 is a flowchart showing an example of a correction rotation speed setting process. The processes in Figs. 4 and 5 are mainly performed by the vehicle body controller 51. In this embodiment, the process in Figs. 4 and 5 will be described assuming that the vehicle body controller 51 is the subject of the process.

[0021] The rotation speed candidate determination process shown in FIG. 4 is started when the temperatures of the fluids (hydraulic oil, engine coolant, and intake air) detected by the hydraulic oil temperature sensor 73s, the engine coolant temperature sensor 74s, and the intake air temperature sensor 75s are transmitted to the vehicle body controller 51.

[0022] In step S1, the vehicle body controller 51 determines the target rotation speed Nt of each of the cooling fans 77o, 77r, and 77i based on the fluid temperature. Specifically, the vehicle body controller 51 determines the target rotation speed Nt of the cooling fan 77o based on the temperature of the hydraulic oil detected by the hydraulic oil temperature sensor 73s. The vehicle body controller 51 also determines the target rotation speed Nt of the cooling fan 77r based on the temperature of the engine coolant detected by the engine coolant temperature sensor 74s. The vehicle body controller 51 also determines the target rotation speed Nt of the cooling fan 77i based on the temperature of the intake air detected by the intake air temperature sensor 75s. The method of determining each target rotation speed Nt may be, for example, a "fluid temperature-target rotation speed" table prepared in advance, or may be determined by proportional integral control based on the target temperature of the fluid. After completing the process of step S1, the vehicle body controller 51 proceeds to step S2.

[0023] In step S2, the vehicle body controller 51 determines whether or not the frequency FNt of the fan noise generated by the target rotation speed Nt of any one of the cooling fans determined in step S1 is within the beat generation range Ff (for example, frequency FNt ± 7 Hz) of the frequency FNt of the fan noise generated by the target rotation speed Nt of the other cooling fans. If it is present, the vehicle body controller 51 proceeds to step S3 (step S2: YES), and if it is not present, the vehicle body controller 51 proceeds to step S4 (step S2: NO). The frequency FNt [Hz] of the fan noise is calculated by "target rotation speed Nt [rpm] / 60 × number of fan blades".

[0024] In step S3, the vehicle body controller 51 performs a correction process for the target rotation speed Nt so that the frequency FNt of the fan noise of each of the cooling fans 77o, 77r, and 77i does not overlap within the beat generation range Ff. For example, it is assumed that the frequency FNt of the fan noise corresponding to the target rotation speed Nt of the cooling fan 77o determined based on the temperature detected by the hydraulic oil temperature sensor 73s is 250 Hz, the frequency FNt of the fan noise corresponding to the target rotation speed Nt of the cooling fan 77r determined based on the temperature detected by the engine cooling water temperature sensor 74s is 245 Hz, and the frequency FNt of the fan noise corresponding to the target rotation speed Nt of the cooling fan 77i determined based on the temperature detected by the intake air temperature sensor 75s is 240 Hz. In this case, when the highest target rotation speed Nt is used as a reference, the vehicle body controller 51 first fixes the target rotation speed Nt of the cooling fan 77o, and corrects the target rotation speed Nt of the cooling fan 77r having the next highest rotation speed so that the frequency FNt of the generated sound does not generate a beat between the cooling fan 77o. For example, the target rotation speed Nt is corrected so that the frequency FNt of the sound of the cooling fan 77r becomes 243 Hz (250 Hz-7 Hz=243 Hz). Similarly, the vehicle body controller 51 corrects the target rotation speed Nt of the cooling fan 77i so that the frequency FNt of the generated sound does not generate a beat between the cooling fan 77o and the corrected cooling fan 77r. For example, the target rotation speed Nt is corrected so that the frequency FNt of the sound of the cooling fan 77i becomes 236 Hz (243 Hz-7 Hz=236 Hz). Note that, other than the highest target rotation speed Nt, the same correction process as described above may be performed using the lowest target rotation speed Nt or an intermediate target rotation speed Nt as a reference. After completing the process of step S3, the vehicle body controller 51 proceeds to step S4.

[0025] In step S4, the vehicle body controller 51 specifies the hydraulic pulsation frequency of the hydraulic pump 62 determined by the current engine speed, and determines whether or not the frequency FNt of the fan sound due to the target speed Nt of each of the cooling fans 77o, 77r, and 77i determined in step S1 or corrected in step S3 is within the beat generation range Fp (for example, pulsation frequency ±7 Hz) of the specified hydraulic pulsation frequency. The hydraulic pulsation frequency can be calculated by "engine speed [rpm] × number of pistons × reduction ratio ÷ 60", or a table showing the correspondence between the hydraulic pulsation frequency and the engine speed is stored in the vehicle body controller 51, and the hydraulic pulsation frequency may be specified according to the table when processing step S4. If the frequency FNt of the fan sound is within the beat generation range Fp, the vehicle body controller 51 proceeds to step S5 (step S4: YES). On the other hand, if the fan sound frequency FNt is not within the beat occurrence range Fp, the vehicle body controller 51 terminates the rotation speed candidate determination process (step S4: NO), and drives the cooling fans 77o, 77r, and 77i at the target rotation speed Nt determined in step S1 or corrected in step S3.

[0026] In step S5, the vehicle body controller 51 determines candidates for the rotation speed that can avoid beats between the hydraulic pump 62. Specifically, the vehicle body controller 51 determines the maximum value Nth (an example of a first maximum value) and the minimum value Ntl (an example of a first minimum value) of the target rotation speed Nt, which are calculated from the maximum value FNth and the minimum value FNtl of the beat generation range Fp, respectively, as the candidates for the rotation speed. If the frequency FNt of the fan sound is the maximum value FNth or the minimum value FNtl of the beat generation range Fp, no beats audible to the operator or people nearby are generated, and this process makes it possible to avoid beats caused by hydraulic pulsation. After completing the process of step S5, the vehicle body controller 51 proceeds to step S6.

[0027] In step S6, the vehicle body controller 51 determines whether or not the maximum value FNth or the minimum value FNtl of the beat generation range Fp, which corresponds to the maximum value Nth and the minimum value Ntl, respectively, that are the rotation speed candidates determined in step S5, are within the beat generation range Ff of another cooling fan. If the maximum value FNth or the minimum value FNtl is within the beat generation range Ff, the vehicle body controller 51 proceeds to step S7 (step S6: YES), and if not, proceeds to step S8 (step S6: NO).

[0028] In step S7, the vehicle body controller 51 re-determines the maximum value Nth or the minimum value Ntl of the target rotation speed Nt corresponding to the maximum value FNth or the minimum value FNtl present in the beat generation range Ff. Specifically, when the maximum value FNth is present in the beat generation range Ff, the vehicle body controller 51 sets the rotation speed converted from the maximum value of the range that combines the beat generation range Fp of the hydraulic pulsation frequency of the hydraulic pump 62 and the beat generation range Ff of the other cooling fans as the maximum value Nth (an example of the second maximum value). When the minimum value FNtl is present in the beat generation range Ff, the vehicle body controller 51 sets the rotation speed converted from the minimum value of the range that combines the beat generation range Fp of the hydraulic pulsation frequency of the hydraulic pump 62 and the beat generation range Ff of the other cooling fans as the minimum value Ntl (an example of the second minimum value). This process makes it possible to avoid both the hydraulic pulsation and the beat caused by the rotation speed of the other cooling fans. After completing the process of step S7, the vehicle body controller 51 proceeds to step S8.

[0029] In step S8, the vehicle body controller 51 determines whether the maximum value Nth and the minimum value Ntl, which are rotation speed candidates, are outside the settable range of the cooling fans 77o, 77r, and 77i. The settable range is the range of rotation speed that can be set by the hardware and software limitations determined for each of the cooling fans 77o, 77r, and 77i. That is, the vehicle body controller 51 determines whether the maximum value Nth exceeds the maximum rotation speed of the settable range of the cooling fans 77o, 77r, and 77i, and whether the minimum value Ntl is below the minimum rotation speed of the settable range of the cooling fans 77o, 77r, and 77i. If at least one of the maximum value Nth and the minimum value Ntl is outside the settable range of the cooling fans 77o, 77r, and 77i, the vehicle body controller 51 proceeds to step S9 (step S8: YES), and if it is within the settable range, the vehicle body controller 51 proceeds to step S10 (step S8: NO).

[0030] In step S9, the vehicle body controller 51 excludes the maximum value Nth or the minimum value Ntl determined to be outside the settable range of the cooling fans 77o, 77r, and 77i in step S8 from the rotation speed candidates. For example, if the maximum value Nth exceeds the maximum rotation speed of the cooling fans 77o, 77r, and 77i, the vehicle body controller 51 excludes the maximum value Nth from the rotation speed candidates. Also, if the minimum value Ntl is below the minimum rotation speed of the cooling fans 77o, 77r, and 77i, the vehicle body controller 51 excludes the minimum value Ntl from the rotation speed candidates. If both the maximum value Nth and the minimum value Ntl are outside the settable range, both may be excluded from the rotation speed candidates. After completing the process of step S9, the vehicle body controller 51 proceeds to step S10.

[0031] In step S10, the vehicle body controller 51 judges whether or not the temperature T of the fluid flowing through the heat exchanger to be cooled by each of the cooling fans 77o, 77r, and 77i exceeds a specified value Th (an example of a specified temperature). Specifically, the vehicle body controller 51 judges whether or not the temperature T of the hydraulic oil detected by the hydraulic oil temperature sensor 73s exceeds the specified value Th. The vehicle body controller 51 also judges whether or not the temperature T of the engine cooling water detected by the engine cooling water temperature sensor 74s exceeds the specified value Th. The vehicle body controller 51 also judges whether or not the temperature T of the intake air detected by the intake air temperature sensor 75s exceeds the specified value Th. The specified value Th is set to an appropriate value for each type of fluid. If the temperature T of the fluid exceeds the specified value Th, the vehicle body controller 51 proceeds to step S11 (step S10: YES), and if the temperature T of the fluid is equal to or lower than the specified value Th, the vehicle body controller 51 proceeds to a correction rotation speed setting process (step S10: NO).

[0032] In step S11, the vehicle body controller 51 excludes the lower rotation speed among the rotation speed candidates determined in step S5 from the rotation speed candidates. For example, if the minimum value Ntl, which is a rotation speed candidate, remains without being excluded in the processing up to this point, the vehicle body controller 51 excludes the minimum value Ntl from the candidates. The processing in step S10 and this step S11 is intended to avoid negative correction of the target rotation speed Nt (correction that reduces the target rotation speed Nt) when the temperature T of the fluid is high. For this reason, the specified value Th in step S10 is set in advance to a value close to the target temperature, for example. For example, when the target temperature is 90°C, the specified value Th may be set to 85°C, for example. After completing the processing in step S11, the vehicle body controller 51 proceeds to a correction rotation speed setting processing.

[0033] In the corrected rotation speed setting process shown in FIG. 5, the rotation speed candidates in the rotation speed candidate determination process shown in FIG. 4 are carried over.

[0034] In step S12, the vehicle body controller 51 judges whether the remaining number of rotation speed candidates is 0 or not. If the remaining number of rotation speed candidates is 0, the vehicle body controller 51 ends the corrected rotation speed setting process and returns to the flowchart of FIG. 4 (step S12: YES). In this case, the vehicle body controller 51 drives the cooling fans 77o, 77r, and 77i at the target rotation speed Nt determined in the above-mentioned step S1 or corrected in step S3. On the other hand, if the remaining number of rotation speed candidates is not 0 (if it is 1 or 2), the vehicle body controller 51 proceeds to step S13 (step S12: NO).

[0035] In step S13, the vehicle body controller 51 determines whether the remaining number of rotation speed candidates is 1. If the remaining number of rotation speed candidates is 1, the process proceeds to step S14 (step S13: YES), and if the remaining number is 2, the process proceeds to step S15 (step S13: NO).

[0036] In step S14, the vehicle body controller 51 sets the remaining candidate rotation speed as the target rotation speed Nt. After completing the process of step S14, the vehicle body controller 51 returns to the flowchart of FIG.

[0037] In step S15, the vehicle body controller 51 judges whether the temperature gradient St of the temperature T of the fluid flowing through the heat exchanger to be cooled by the cooling fans 77o, 77r, and 77i is positive or not. That is, the vehicle body controller 51 judges whether the fluid temperature is rising or falling. If the temperature gradient St is greater than 0, the process proceeds to step S16 (step S15: YES), and if the temperature gradient St is equal to or less than 0, the process proceeds to step S17 (step S15: NO).

[0038] In step S16, the vehicle body controller 51 sets the target rotation speed Nt to the minimum value Ntl, which is the lower side of the rotation speed candidates. By setting the rotation speed low in step S16 when the fluid temperature is rising, the fluid temperature is further encouraged to rise, and it becomes possible to pass through the beat generation range quickly. After completing the process of step S16, the vehicle body controller 51 returns to the flowchart of FIG.

[0039] In step S17, the vehicle body controller 51 sets the target rotation speed Nt to the maximum value Nth, which is the higher side of the rotation speed candidates. By setting the rotation speed higher in step S17 when the fluid temperature is decreasing, the fluid temperature is further encouraged to decrease, and it becomes possible to pass through the beat generation range quickly. After completing the process of step S17, the vehicle body controller 51 returns to the flowchart of FIG. 4.

[0040] 4 and 5 are merely examples, and at least some of the steps may be deleted or changed, or steps other than those described above may be added. In addition, the order of at least some of the steps may be changed, or multiple steps may be combined into a single step.

[0041] In addition, although the above describes an example of a method for avoiding resonance between the cooling fan and the hydraulic pulsation frequency of the hydraulic pump 62, the target for resonance avoidance is not limited to the hydraulic pump 62. For example, beats can be avoided for other driving equipment that is a periodic sound source whose frequency changes depending on the rotation speed of the engine 61, such as the explosion frequency of the engine 61, by applying a method similar to the processes shown in Figs. 4 and 5.

[0042] <Effects of the embodiment> As described above, according to the hydraulic excavator 1 of the embodiment, the vehicle controller 51 specifies the frequency of the hydraulic pump 62, which is a periodic sound source whose frequency changes depending on the rotation speed of the engine 61, sets the target rotation speed Nt of the cooling fans 77o, 77r, 77i to a rotation speed that can avoid the occurrence of humming between the specified frequency, and drives the cooling fans 77o, 77r, 77i at the set target rotation speed Nt. This makes it possible to control the target rotation speed Nt of the cooling fans 77o, 77r, 77i so as to avoid a certain range from the frequency of the hydraulic pulsation of the hydraulic pump 62 and the frequency of the engine explosion, whose frequency cannot be changed independently of the engine rotation speed. Therefore, it is possible to suppress unpleasant humming between the cooling fans 77o, 77r, 77i and the periodic sound source caused by the hydraulic pulsation of the hydraulic pump 62 and the engine explosion. As a result, it is possible to reduce the discomfort of the operator and those around caused by the humming.

[0043] In addition, each periodic sound source is usually designed to have a frequency that is sufficiently far apart to avoid the occurrence of beats or resonance. Therefore, in the method of the present invention, it is unlikely that different periodic sound sources will simultaneously affect the setting of the target rotation speed Nt of one cooling fan, or that beats will occur between cooling fans after the rotation speed correction. Therefore, the method of the present invention makes it possible to set an appropriate fan rotation speed regardless of the number of periodic sound sources or cooling fans.

[0044] Furthermore, particularly in this embodiment, the vehicle body controller 51 specifies the frequency of the sound generated by the hydraulic pump 62 based on a calculation based on the specifications and engine speed of the engine 61 or a table of engine speed and frequency. As a result, even if the frequency of the sound generated by the hydraulic pump 62 changes due to fluctuations in the engine speed, the rotation speeds of the cooling fans 77o, 77r, and 77i are also changed each time, thereby minimizing the occurrence of humming.

[0045] In particular, in this embodiment, the vehicle body controller 51 sets a plurality of rotation speed candidates that can avoid humming between the cooling fans 77o, 77r, 77i and the hydraulic pump 62, and drives the cooling fans 77o, 77r, 77i at a rotation speed selected from the plurality of rotation speed candidates. This makes it possible to set a rotation speed that satisfies some other condition in addition to avoiding humming with the hydraulic pump 62.

[0046] In particular, in this embodiment, the vehicle body controller 51 determines the target rotation speed Nt of the cooling fans 77o, 77r, and 77i based on the fluid temperatures detected by the hydraulic oil temperature sensor 73s, the engine cooling water temperature sensor 74s, and the intake air temperature sensor 75s, and when the determined target rotation speed Nt is within a range in which humming occurs between the hydraulic pump 62, the maximum value Nth and the minimum value Ntl of the range of the target rotation speed Nt that can avoid humming between the hydraulic pump 62 are set as rotation speed candidates, and the cooling fans 77o, 77r, and 77i are driven at a rotation speed selected from the maximum value Nth and the minimum value Ntl. This makes it possible to set a rotation speed that avoids humming between the hydraulic pump 62 and meets some other conditions.

[0047] In particular, in this embodiment, the vehicle controller 51 selects the minimum value Ntl from among the rotation speed candidates when the fluid temperature detected by the hydraulic oil temperature sensor 73s, the engine cooling water temperature sensor 74s, and the intake air temperature sensor 75s is rising, and selects the maximum value Nth from among the rotation speed candidates when the fluid temperature is falling. As a result, when the fluid temperature is rising, the rotation speed is set low to further encourage the fluid temperature to rise, and it becomes possible to pass through the beat generation range quickly. Also, when the fluid temperature is falling, the rotation speed is set high to further encourage the fluid temperature to fall, and it becomes possible to pass through the beat generation range quickly.

[0048] In particular, in this embodiment, when the maximum value Nth or minimum value Ntl of the target rotation speed Nt corresponding to the maximum value FNth and minimum value FNtl of the beat generation range Fp is within the range in which beat occurs with other cooling fans, the vehicle body controller 51 resets the maximum value Nth and minimum value Ntl in the range that combines the rotation speed range in which beat can be avoided with the hydraulic pump 62 and the rotation speed range in which beat can be avoided with other cooling fans as rotation speed candidates, and drives the cooling fans 77o, 77r, and 77i at the rotation speed selected from the reset maximum value Nth or minimum value Ntl. This makes it possible to avoid both the hydraulic pulsation of the hydraulic pump 62 and the beat caused by the rotation speed of the other cooling fans.

[0049] In particular, in this embodiment, the vehicle body controller 51 excludes a rotation speed candidate that is outside the range of settable rotation speeds of the cooling fans 77o, 77r, and 77i. This makes it possible to exclude from the rotation speed candidates rotation speeds that cannot be set due to hardware and software limitations set for the cooling fans themselves.

[0050] In particular, in this embodiment, when the fluid temperature T detected by the hydraulic oil temperature sensor 73s, the engine cooling water temperature sensor 74s, and the intake air temperature sensor 75s is higher than a predetermined specified value Th, the vehicle body controller 51 excludes the lower one of the rotation speed candidates from the rotation speed candidates. This makes it possible to avoid negative correction of the target rotation speed Nt (correction that reduces the target rotation speed Nt) when the fluid temperature T is higher than the target temperature, for example, and to control the rotation speed of the cooling fan so that the fluid temperature T follows the target temperature.

[0051] In particular, in this embodiment, when there are no rotation speed candidates due to the exclusion processing in steps S9 and S11, the vehicle body controller 51 drives the cooling fans 77o, 77r, and 77i based on the target rotation speed Nt set based on the fluid temperatures detected by the hydraulic oil temperature sensor 73s, the engine cooling water temperature sensor 74s, and the intake air temperature sensor 75s. As a result, when the rotation speed candidates satisfy a predetermined condition, the correction processing of the target rotation speed Nt is stopped, and the cooling fans 77o, 77r, and 77i can be driven using the target rotation speed Nt based on the original fluid temperature.

[0052] <Modification> The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit and technical concept of the present invention.

[0053] For example, in the above embodiment, the case where the multiple heat exchangers are cooled by separate cooling fans has been described, but the present invention is not limited to this. For example, a single cooling fan may be used to cool the multiple heat exchangers (oil cooler 73, radiator 74, and intercooler 75). In this case, it is only necessary to set a target rotation speed Nt that can avoid humming between the cooling fan and the hydraulic pump 62, and it is not necessary to prevent humming between the cooling fans. That is, steps S2, S3, S6, and S7 in FIG. 4 are not required. In this case, the fluid temperature in step S1 may be any one of the temperatures of the hydraulic oil, the engine cooling water, or the intake air.

[0054] In the above embodiment, the construction machine is described taking the crawler type hydraulic excavator 1 as an example, but the application of the present invention is not limited to this. For example, the present invention can be widely applied to other construction machines such as hydraulic cranes and wheel loaders that have periodic sound sources caused by hydraulic pulsation of a hydraulic pump or engine explosion.

[0055] In addition to the above, the methods according to the above embodiments and their modifications may be used in appropriate combination. Although not specifically illustrated, the present invention can be implemented with various modifications without departing from the spirit and scope of the present invention.

[0056] Furthermore, the problems to be solved by the invention and the effects of the invention are not limited to those described above. In other words, the present invention may solve problems or achieve effects that are not described above, or may solve only some of the problems or achieve only some of the effects that are described. [Explanation of symbols]

[0057] 1. Hydraulic excavator (an example of construction machinery) 51 Vehicle controller (an example of a controller) 61 Engine 62 Hydraulic pump (an example of a driving device) 73 Oil cooler (an example of a heat exchanger) 73s Hydraulic oil temperature sensor (an example of a temperature detector) 74 Radiator (an example of a heat exchanger) 74s Engine coolant temperature sensor (an example of a temperature detector) 75 Intercooler (an example of a heat exchanger) 75s Intake air temperature sensor (an example of a temperature detector) 77i Cooling Fan 77o Cooling fan 77r Cooling fan Nt Target RPM Nth maximum value (an example of the first maximum value and the second maximum value) Ntl minimum value (example of the first minimum value and the second minimum value) St temperature gradient T temperature Th Specified value (example of specified temperature)

Claims

1. The engine, A cooling fan, A construction machine equipped with a controller that controls the rotation speed of the cooling fan, The controller identifies a frequency of a driving device that is a periodic sound source whose frequency changes depending on the rotation speed of the engine, sets the rotation speed of the cooling fan to a rotation speed that can avoid occurrence of a beat between the identified frequency and the frequency, and drives the cooling fan at the set rotation speed. A construction machine characterized by:

2. 2. The construction machine according to claim 1, The controller: The frequency of the sound generated by the driving device is determined based on a calculation based on the engine specifications and the engine speed or based on a correspondence table between the engine speed and the frequency. A construction machine characterized by:

3. The construction machine according to claim 2, a heat exchanger cooled by the cooling fan; A temperature detector for detecting a temperature of a fluid flowing through the heat exchanger, The controller: setting a rotation speed of the cooling fan based on the temperature of the fluid detected by the temperature detector; When the set rotation speed is within a rotation speed range in which a beat occurs between the driving device and the driving equipment, a first maximum value and a first minimum value in the rotation speed range in which the beat occurs are set as rotation speed candidates; The cooling fan is driven at a rotation speed selected from the first maximum value or the first minimum value. A construction machine characterized by:

4. The construction machine according to claim 3, The controller: When the temperature of the fluid is increasing, the first minimum value is selected from the rotation speed candidates; When the temperature of the fluid is decreasing, the first maximum value is selected from the rotation speed candidates. A construction machine characterized by:

5. The construction machine according to claim 3, The controller: When the first maximum value or the first minimum value is within a rotation speed range in which a beat occurs between the cooling fan and another cooling fan different from the cooling fan, a second maximum value and a second minimum value in a range including a rotation speed range in which the beat occurs between the driving device and the other cooling fan, the second maximum value and the second minimum value being set as the rotation speed candidates; The cooling fan is driven at a rotation speed selected from the second maximum value or the second minimum value. A construction machine characterized by:

6. The construction machine according to claim 5, The controller: When the temperature of the fluid is increasing, the second minimum value is selected from the rotation speed candidates; When the temperature of the fluid is decreasing, the second maximum value is selected from the rotation speed candidates. A construction machine characterized by:

7. The construction machine according to any one of claims 3 to 6, The controller: If the rotation speed candidate falls outside a range of settable rotation speeds of the cooling fan, the corresponding rotation speed candidate is excluded from the rotation speed candidates. A construction machine characterized by:

8. The construction machine according to any one of claims 3 to 6, The controller: If the temperature of the fluid detected by the temperature detector is higher than a predetermined specified temperature, a lower one of the rotation speed candidates is excluded from the rotation speed candidates. A construction machine characterized by:

9. The construction machine according to any one of claims 3 to 6, The controller: If the rotation speed candidate falls outside a range of settable rotation speeds of the cooling fan, the corresponding rotation speed candidate is excluded from the rotation speed candidates; If the temperature of the fluid detected by the temperature detector is higher than a predetermined specified temperature, a lower one of the rotation speed candidates is excluded from the rotation speed candidates; When the rotation speed candidate does not exist due to the exclusion, the cooling fan is driven based on the rotation speed set based on the temperature of the fluid detected by the temperature detector. A construction machine characterized by:

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