Fan control system and work machine

Abstract

To provide a fan control system capable of suitably performing drive control of a fan, and a work machine equipped with the fan control system.SOLUTION: A fan control system includes a fan 32, a dust protector 31 provided in the vicinity of the fan 32, a fan drive section 33 for normally and reversely rotating the fan, a fan control section 51 for drive-controlling the fan drive section 33, a clogging degree calculating section 53 for calculating a clogging degree of the dust protector 31 on the basis of the drive behavior of the fan 32, and a reverse rotation instructing section 54 for instructing reverse rotation of the fan 32 to the fan control section 51 on the basis of the clogging degree.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a fan control system and a work machine equipped with the fan control system. [Background technology]

[0002] The working machine is provided with a structure that draws in outside air to cool thermal equipment such as a radiator and an engine by rotating a cooling fan, and a dust remover is provided to prevent grass, dust, etc. from entering the thermal equipment storage space that houses such thermal equipment together with the outside air (cooling air). However, there is a problem that dust adheres to and accumulates on the dust remover when dust removal is continued, reducing the amount of cooling air drawn in, and reducing the cooling of the thermal equipment by the cooling air. For example, in a harvester shown in Patent Document 1, as a conventional technique for solving this problem, the rotation state of the cooling fan is switched from a forward rotation state to a reverse rotation state each time a set harvesting operation time has elapsed based on a prediction of the amount of dust generated, and a reverse wind is applied to the dust remover, blowing away and removing the dust adhering to the dust remover, and restoring the amount of cooling air to the thermal equipment storage space. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-36862 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the fan control system of Patent Document 1, the cooling fan is reversed at a predetermined cycle regardless of whether the dust collector is clogged with grass, so the cooling fan may not always be driven efficiently. Also, if the cooling fan is reversed even when it is not necessary, problems such as the energy required to switch the rotation direction of the cooling fan being wasted and the durability of the rotation direction switching mechanism being reduced arise.

[0005] In view of the above circumstances, an object of the present invention is to provide a fan control system that more appropriately controls the drive of a fan, and a work machine equipped with such a fan control system. [Means for solving the problem]

[0006] A fan control system according to the present invention includes a fan, a dust guard provided around the fan, a fan drive unit that rotates the fan in forward and reverse directions, a fan control unit that drives and controls the fan drive unit, a clogging degree calculation unit that calculates the degree of clogging of the dust guard based on the driving behavior of the fan, and a reverse rotation command unit that commands the fan control unit to rotate the fan in the reverse direction based on the degree of clogging.

[0007] In addition, the term "clogging degree" in this application indicates the degree of clogging of the air circulation holes of the dust protector. For example, a clogging degree of 0% indicates a state in which the dust protector is new and the air circulation holes are not blocked at all, and a clogging degree of 100% indicates a state in which the air circulation holes of the dust protector are completely blocked. The unit of the clogging degree does not have to be %. In this application, the clogging degree is calculated based on the driving behavior of the fan. For example, the clogging degree can be calculated using a function with the driving behavior as a variable, and this function can be obtained experimentally and empirically. If the clogging degree is K, the function for deriving the clogging degree is G, and the driving behaviors are driving behavior 1: α1, driving behavior 2: α2, driving behavior 3: α3, ..., this relationship is expressed by the following formula. K = G(α1,α2,α3,...) For example, α1, α2, α3, . . . may be a fan drive time, a fan rotation speed, a difference between a target fan rotation speed and an actual fan rotation speed, a fluctuation range of the fan rotation speed, and the like. Such a function can be conveniently expressed as a look-up table. The degree of clogging can also be determined using a decision tree algorithm.

[0008] According to the configuration of the present invention, the degree of clogging of the dust protection device is calculated based on the driving behavior of the fan. For example, if the fan effect is insufficient even though the fan has been driven for a long time, the degree of clogging of the dust protection device is calculated to be high. When the degree of clogging of the dust protection device is calculated to be high, the reverse rotation command unit issues a reverse rotation command to the fan control unit, causing the fan to rotate in reverse and removing clogging from the dust protection device. In this way, the fan is reversed when the degree of clogging is calculated to be high, so that unnecessary reversal of the fan is suppressed and appropriate drive control of the fan is achieved.

[0009] The forward and reverse driving of the fan is easier to achieve by using an electric motor to transmit rotational power to the fan in a forward and reverse switchable manner than by using a mechanical transmission mechanism to transmit rotational power to the fan in a forward and reverse switchable manner. For this reason, the present invention proposes that the fan drive unit be a fan motor, and that the fan motor be drive-controlled by a drive signal from the fan control unit.

[0010] The degree of clogging of the dust protector tends to be large when the fan is driven powerfully for a long time, and tends to be small when the fan is driven weakly for a short time. Therefore, in the present invention, the driving behavior of the cooling fan is determined by the rotation speed of the fan, or the driving time of the fan, or both the rotation speed and the driving time. In this configuration, the degree of clogging of the dust protector is appropriately calculated using detection parameters that are easy to obtain.

[0011] If the fan reverse rotation time is too short, clogging of the dust protector may not be sufficiently cleared, and if the fan reverse rotation time is too long, inconvenience may occur since the fan effect cannot be obtained during that time. For this reason, a method using a value determined experimentally and empirically in advance (multiple values ​​may be determined and selected) for the fan reverse rotation time, or a method of deriving the reverse rotation time using the calculated clogging degree as a parameter, is preferable. For this reason, in one embodiment of the present invention, the fan reverse rotation time is a preset fixed time. In another embodiment of the present invention, the fan reverse rotation time is a variable time that is changed based on the clogging degree. A configuration in which these two forms can be selected may be adopted.

[0012] In one preferred embodiment of the present invention, the fan is a cooling fan that cools a thermal device through a cooling medium, and an internal temperature detection unit is provided that detects the temperature of the cooling medium or the thermal device, and the clogging degree calculation unit calculates the clogging degree of the dust protection device based on the detected temperature detected by the internal temperature detection unit and the driving behavior. Here, the fan control system of the present invention is applied to control the cooling fan of a cooling system that cools a thermal device. According to this configuration, the clogging degree of the dust protection device is calculated based on the detected temperature of the cooling medium or the thermal device by the internal temperature detection unit and the driving behavior of the cooling fan. As described above, when the function for deriving the clogging degree: K is G, in this embodiment, the temperature behavior of the thermal device: β1, β2, β3, is added to the driving behavior: α1, α2, α3, described above, and is expressed by the following formula. K=G(α1,α2,α3,...,β1,β2,β3,...) In this case, β1, β2, β3, . . . may be the temperature of the cooling medium or thermal equipment detected by the internal temperature detection unit, the outside air temperature detected by the external temperature detection unit, the temperature rise rate (temperature change in a specified time) of thermal equipment (cooling target equipment) such as a motor or inverter, etc. In particular, the temperature rise rate is effective because the temperature rise rate increases due to clogging. For example, if the detected temperature of the cooling medium or thermal equipment does not fall below a specified value even though the cooling fan has been driven for a long time, it is calculated that the degree of clogging of the dust protection device is high. If the degree of clogging of the dust protection device is calculated to be high, the reverse rotation command unit issues a reverse rotation command to the fan control unit, causing the cooling fan to reverse and removing the clogging of the dust protection device. In this way, the cooling fan is reversed when it is calculated that the degree of clogging is high, so that unnecessary reverse rotation of the cooling fan is suppressed and the drive control of the cooling fan is performed appropriately.

[0013] The cooling system described above is further provided with an external temperature detector that detects the outside air temperature (ambient temperature: environmental temperature), and the clogging degree calculator calculates the clogging degree based on the outside air temperature, the detected temperature, and the driving behavior. In this configuration, the clogging degree of the dust protection device is calculated taking into account not only the temperature of the cooling medium or thermal device detected by the internal temperature detector and the driving behavior of the cooling fan, but also the outside air temperature, so that the deviation between the detected temperature and the thermal device temperature due to the high and low outside air temperatures (summer and winter, daytime and night, etc.) is suppressed, the accuracy of the clogging degree calculation is improved, and more appropriate driving control of the cooling fan is performed.

[0014] The above-mentioned cooling system is suitable for use in harvesters in which leaves and stems fly about during harvesting, and grass cutters in which grass clippings fly about. Cooling systems in such working machines use cooling air, cooling water, cooling liquid, heat pipes, and the like as cooling media. A cooling fan creates cooling air and may either spray it directly onto the thermal equipment or onto the cooling media that exchanges heat with the thermal equipment.

[0015] An engine, an electric motor, a hybrid engine, etc. are used as a power source for a work machine. In an engine type, the main thermal equipment is a radiator and an engine, and in an electric motor type, the main thermal equipment is an electric motor, an inverter, and a battery. Therefore, in a preferred embodiment of the present invention, the thermal equipment is at least one of the radiator, the engine, the motor, the inverter, and the battery.

[0016] The above-mentioned cooling system is particularly suitable when applied to a work machine because the above-mentioned features can be utilized. Therefore, the work machine according to the present invention includes a cooling fan that cools a thermal device through a cooling medium, a dust guard provided around the cooling fan, a fan drive unit that rotates the cooling fan forward and backward, a fan control unit that drives and controls the fan drive unit, an internal temperature detection unit that detects the temperature of the cooling medium or the temperature of the thermal device, a clogging degree calculation unit that calculates the clogging degree of the dust guard based on the detected temperature detected by the internal temperature detection unit and the drive behavior of the cooling fan, and a reverse rotation command unit that commands the fan control unit to reverse the rotation of the cooling fan based on the clogging degree. [Brief description of the drawings]

[0017] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. 2 is a left side view in vertical section showing the arrangement of components of the power system. [Figure 4] FIG. 2 is a functional block diagram of a cooling system control system. [Diagram 5] FIG. 4 is a flowchart illustrating an example of cooling fan control. [Figure 6] FIG. 11 is a flowchart illustrating another example of the cooling fan control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The embodiment of the present invention will be described with reference to the drawings. In the following description, unless otherwise specified, the direction of the arrow U shown in Figures 1, 2, and 3 is "up", the direction of the arrow D is "down", the direction of the arrow F shown in Figures 1 and 3 is "front", the direction of the arrow B is "rear", the direction of the arrow R shown in Figure 2 is "right", and the direction of the arrow L is "left".

[0019] The working machine in this embodiment will be described with reference to Figures 1, 2 and 3. The right and left front wheels 1 and the right and left rear wheels 2 of the working machine are attached to a machine body 3. A bonnet 4 is provided at the front of the machine body 3, and a driver's section 5 is provided at the rear of the machine body 3. The driver's section 5 is provided with a steering wheel 6 for steering the front wheels 1, a driver's seat 7 and a rope frame 9. A plurality of manual operating tools 10 for operating the working devices provided on the working machine are arranged around the steering wheel 6.

[0020] The vehicle body 3 shown in Figures 1 and 3 is a frame structure. As shown in Figure 3, a transmission 12 having a continuously variable transmission 11 is attached to the rear of the vehicle body 3, and a front axle case 8 is attached to the front of the vehicle body 3. The front wheels 1 are supported by the front axle case 8, and the rear wheels 2 are supported by a transmission case 13 that houses the transmission 12.

[0021] As shown in Fig. 3, the lifting link mechanism 14 is connected to the rear part of the transmission case 13 so as to be able to swing up and down. Various working devices (not shown) can be attached to the lifting link mechanism 14. The lifting link mechanism 14 is operated to swing up and down by the lifting cylinder 15, whereby the working device is lifted and lowered. A hydraulic pump 61 and a hydraulic pump motor 62 that drives the hydraulic pump 61 are attached to the upper part of the transmission case 13. The hydraulic pump motor 62 is an electric motor 29. The lifting and lowering operation of the lifting cylinder 15 is driven by hydraulic oil from the hydraulic pump 61.

[0022] As shown in Figures 1 and 2, a front loader 17, which is one of the working devices, is attached to the front of the machine body 3. The front loader 17 has a base 18, a boom 19, a bucket 20, a hydraulic boom cylinder 21, a bucket cylinder 22, etc. The boom cylinder 21 operates to raise and lower the boom 19, and the bucket cylinder 22 operates to scoop and dump the bucket 20. Hydraulic oil from a hydraulic pump 61 is supplied to the boom cylinder 21 and the bucket cylinder 22. Hydraulic oil from the hydraulic pump 61 is also supplied to a lift cylinder (not shown) that operates to swing the lift arm 16.

[0023] Hydraulic actuators such as the lift cylinder 15, the boom cylinder 21, and the bucket cylinder 22 operate based on the operation of the manual operation tool 10.

[0024] As shown in FIGS. 1 and 2, a mower deck 24 is attached to the machine body 3 so as to be capable of ascending and descending, and is disposed between the front wheels 1 and the rear wheels 2.

[0025] The mower deck 24 has three rotating blades (not shown) that are rotated around an axis that runs vertically, and are arranged inside the mower deck 24 so that they are lined up in the left-right direction. Grass cut by the rotating blades is discharged to the right side from the right discharge section 25 of the mower deck 24.

[0026] 3, a driving battery 27, an inverter 28, an electric motor 29, a cooling fan 32 which is an example of a fan, a fan motor 33, and an electrical equipment battery 34 are provided in the front of the vehicle body 3. The driving battery 27 is stored inside the bonnet 4. The inverter 28 and the electric motor 29 are disposed below the driving battery 27. A lower cover 30 is provided below the inverter 28 and the electric motor 29 so as to cover the inverter 28 and the electric motor 29.

[0027] 3, the power of the electric motor 29 is transmitted via a transmission shaft to the continuously variable transmission 11. The continuously variable transmission 11 is configured as a hydrostatic type and is capable of continuously changing the speed between the forward and reverse sides.

[0028] The power changed in speed by the continuously variable transmission 11 is transmitted to the rear wheels 2 via an auxiliary transmission (not shown) and a rear wheel differential (not shown) provided inside the transmission 12. The power branched off just before the rear wheel differential is transmitted via a transmission shaft to a front wheel differential (not shown) provided inside the front axle case 8, and then transmitted from the front wheel differential to the front wheels 1.

[0029] A front PTO shaft 37 is provided at a lower part of the front portion of the transmission 12 facing forward, and a rear PTO shaft 38 is provided at a rear portion of the transmission 12 facing backward. Of the power transmitted by the transmission shafts, power that is not subjected to speed change by the continuously variable transmission 11 is transmitted to the front PTO shaft 37 and the rear PTO shaft 38.

[0030] The power of the front PTO shaft 37 is transmitted to the mower deck 24 via a transmission shaft (not shown). The power of the rear PTO shaft 38 is transmitted to a working device attached to the lifting link mechanism 14 via a transmission shaft (not shown).

[0031] A cooling fan 32 and a fan motor 33, which are components of a cooling system for a work machine, which is an example of a fan control system, are integrated and attached to a lower cover 30. A dust guard 31 made of a dustproof net is attached to an area of ​​the lower cover 30 facing the cooling fan 32. Outside air as cooling wind is introduced into the inside of the lower cover 30 through the dust guard 31 by the suction force of the cooling fan 32. An example of the dust guard 31 is a filter. The introduced cooling wind cools the inverter 28 and the electric motor 29, which are thermal devices. The traveling battery 27 is also included in the thermal devices, and when an engine is installed, a radiator as an engine accessory is also included in the thermal devices. In this embodiment, the fan motor 33 is a fan drive unit, and the cooling wind is a cooling medium. The cooling medium also includes a coolant, a heat pipe, and the like.

[0032] A functional block diagram showing a control system of the cooling system is shown in Fig. 4. Here, the cooling system cools thermal devices such as an inverter 28 and an electric motor 29 using cooling air as a cooling medium.

[0033] In this embodiment, an internal temperature sensor 35 and an external temperature sensor 36 are provided as temperature sensors for detecting temperature. The internal temperature sensor 35 detects the temperature of the internal space of the aircraft body 2, such as the space covered by the bonnet 4, the space covered by the lower cover 30, and the transmission case 13. Furthermore, the internal temperature sensor 35 directly or indirectly detects the temperature of the cooling air, which is the cooling medium, or the temperature of the thermal equipment. Specifically, the internal temperature sensor 35 includes a water temperature sensor arranged in the flow path of the radiator, an oil temperature sensor arranged in the oil circuit, a temperature sensor embedded inside the electric motor 29, a temperature sensor embedded inside the battery, a temperature sensor arranged in the flow space of the cooling air flow by the cooling fan 32, and the like.

[0034] The external temperature sensor 36 detects the external temperature (ambient temperature: environmental temperature). The external temperature sensor 36 includes not only a temperature sensor that detects the external temperature (ambient temperature: environmental temperature) and is arranged in the external area of ​​the aircraft 2, but also a temperature acquirer that acquires the air temperature from a weather information service such as the Japan Meteorological Agency. Specific examples of the temperature sensor arranged in the external area of ​​the aircraft 2 include a temperature sensor arranged in the driver's section 5, a temperature sensor arranged outside the hood 4, and the like.

[0035] The core element of the control system of this cooling system is a computer-based control unit 100. The control unit 100 includes, as control function units, an internal temperature detection unit 41, an external temperature detection unit 42, a fan control unit 51, a drive behavior generation unit 52, a clogging degree calculation unit 53, and a reverse rotation command unit 54.

[0036] The internal temperature detection unit 41 detects (calculates) for example the temperature of a thermal device (the inverter 28 or the electric motor 29, or both) based on a sensor signal from the internal temperature sensor 35. The temperature detected by the internal temperature detection unit 41 is used by other control function units as the internal detected temperature. The external temperature detection unit 42 detects (calculates) the outside air temperature, for example the ambient temperature of the work machine, based on a sensor signal from the external temperature sensor 36. The temperature detected by the external temperature detection unit 42 is used by other control function units as the external detected temperature.

[0037] The fan control unit 51 provides a drive signal to the fan motor 33, which serves as a fan drive unit, to rotate the cooling fan 32 forward and backward. The drive behavior generation unit 52 reads out the rotation speed of the cooling fan 32, or the drive time of the cooling fan 32, or both the rotation speed and the drive time, based on the fan control information acquired from the fan control unit 51, performs necessary calculations to parameterize the information, and generates fan behavior parameters that indicate the drive behavior of the cooling fan 32.

[0038] The clogging degree calculation unit 53 generates a temperature parameter, for example, a value obtained by normalizing the internal detected temperature by the external detected temperature, based on the internal detected temperature and the external detected temperature. The temperature parameter may be generated using only the internal detected temperature. The clogging degree calculation unit 53 calculates the clogging degree of the dust protector 31 from the generated temperature parameter and the fan behavior parameter generated by the drive behavior generation unit 52. To calculate the clogging degree, a previously created arithmetic expression or lookup table is used, which derives the clogging degree from the temperature parameter and the fan behavior parameter. A plurality of such arithmetic expressions and lookup tables may be prepared and selected according to the work situation.

[0039] When the degree of clogging of the dust protection device 31 calculated by the clogging degree calculation unit 53 exceeds a threshold value, it is necessary to reverse the rotation of the cooling fan 32 to blow away the stalks, grass, and roots that are stuck in the dust protection device 31. When the degree of clogging exceeds the threshold value, the reverse rotation command unit 54 issues a reverse rotation command to the fan control unit 51 to reverse the rotation of the cooling fan 32. Upon receiving the reverse rotation command, the fan control unit 51 generates a reverse rotation control signal and issues it to the fan motor 33 to reverse the rotation of the cooling fan 32.

[0040] The reverse rotation time of the cooling fan 32 may be a preset fixed time or may be a variable time that is changed based on the degree of clogging. For example, when the degree of clogging is low, reverse rotation may be performed for a fixed time, and when the degree of clogging is low, reverse rotation may be performed for a time exceeding the fixed time. In addition, the higher the degree of clogging, the higher the reverse rotation speed may be, either continuously or stepwise.

[0041] An example of cooling fan control in the above-mentioned cooling system will be described with reference to the flowchart of FIG.

[0042] When cooling fan control is started, an initial setting process is performed (#01). In the initial setting process, the conditions for reverse rotation of the cooling fan 32, such as the threshold value of the clogging amount and the time for reverse rotation of the cooling fan 32, are set. Next, based on a forward rotation command received from the control management section of the control unit 100, the fan control section 51 provides the fan motor 33 with a control signal for rotating the cooling fan 32 forward (#02). This causes the cooling fan 32 to start rotating forward (#03).

[0043] Next, a parameter generation process is performed for the temperature and driving behavior required to calculate the clogging amount of the dust protector 31. With regard to temperature, the internal detected temperature is acquired from the internal temperature detection unit 41 (#11), and the external detected temperature is acquired from the external temperature detection unit 42 (#12). From the acquired internal detected temperature and external detected temperature, a temperature parameter used to determine reverse rotation of the cooling fan 32 is generated (#13). Note that acquisition of the external detected temperature is not essential, and the temperature parameter may be generated directly from the internal detected temperature. With regard to the driving behavior, the driving behavior generated by the driving behavior generation unit 52 is acquired (#21), and from the acquired driving behavior, a fan driving parameter indicating the driving behavior of the cooling fan 32 is generated (#22).

[0044] The clogging degree calculation unit 53 calculates the clogging degree of the dust protector 31 using the temperature parameters and the fan drive parameters (#31). The calculated clogging degree is compared with an initially set threshold value (#32). If the clogging degree is equal to or less than the threshold value (#32 No branch), the process returns to steps #11 and #21 to repeat the new parameter generation process.

[0045] When the degree of clogging exceeds the threshold value (Yes branch at #32), a reverse rotation command is sent by the reverse rotation command unit 54 to the fan control unit 51 (#41). As a result, a control signal for reversing the rotation of the cooling fan 32 is sent to the fan motor 33, and the cooling fan 32 rotates in the reverse direction (#42).

[0046] The reverse rotation time of the cooling fan 32 is checked (#43). The fan motor 33 continues to rotate in the reverse direction until the reverse rotation time has elapsed a predetermined reverse rotation time (#43: No branch). If the reverse rotation time has elapsed the predetermined reverse rotation time (#43: Yes branch), a forward rotation command is given to the fan control unit 51 (#51), the fan motor 33 rotates in the forward direction, and as a result, the cooling fan 32 returns to forward rotation (#52). Control returns to steps #11 and #21, and new parameter generation processing is performed.

[0047] The flowchart of FIG. 6 shows a cooling fan control in a different form from that of FIG. 5. In this form, the cooling fan 32 is returned from reverse rotation to normal rotation not when a predetermined time has passed, but when it is determined that the clogging of the dust protector 31 has been removed through calculation of the clogging degree. The flowchart of FIG. 6 is the same as the flowchart of FIG. 5 from step #01 to step #32. Furthermore, similar to the flowchart of FIG. 5, in step #32 where the clogging degree of the dust protector 31 is checked, if the clogging degree exceeds a threshold value (#32 Yes branch), a reverse rotation command is given to the fan control unit 51 by the reverse rotation command unit 54 (#41). As a result, a control signal for reversing the cooling fan 32 is given to the fan motor 33, and the cooling fan 32 is reversed (#42). In this embodiment, the condition for determining that the clogging has been removed is when the clogging degree calculated by the clogging degree calculation unit 53 using the above-mentioned temperature parameters and fan drive parameters (such as the rotation behavior by the rotation speed sensor) becomes equal to or less than a threshold value. Alternatively, it may be determined that the clogging has been cleared when the measured value falls below the threshold value by a predetermined value.

[0048] However, in the flowchart of FIG. 6, if the degree of clogging is equal to or lower than the threshold (No branch at #31), a check is made as to whether the cooling fan 32 is in a reverse rotation state or a forward rotation state (#50). If the cooling fan 32 is in a forward rotation state (No branch at #50), the process returns to steps #11 and #21, and new parameter generation processing is performed. If the cooling fan 32 is in a reverse rotation state (Yes branch at #50), a forward rotation command is given to the fan control unit 51 (#51), the fan motor 33 rotates forward, and as a result, the cooling fan 32 returns to forward rotation (#52). Thereafter, the process returns to steps #11 and #21, and new parameter generation processing is performed.

[0049] In the above-described embodiment, the fan control system of the present invention is applied to the cooling system of a work vehicle, but it can also be applied to the cooling systems of vehicles other than work vehicles and stationary machinery and equipment. Furthermore, the fan control system of the present invention can also be applied to a heating system or heating system using a fan, and an air circulation system or air cleaning system using a fan.

[0050] [Another embodiment] (1) In the above-described embodiment, the fan drive unit is the fan motor 33 whose drive is controlled by the fan control unit 51. Instead of such electrically controlled rotation control of the cooling fan 32, a mechanical rotation direction switching mechanism using a belt transmission mechanism or a gear transmission mechanism may be employed.

[0051] (2) In the above-described embodiment, the working machine is an electric vehicle using the electric motor 29 as a driving source for traveling, but instead of this, it may be a conventional vehicle using an internal combustion engine (engine) as a driving source for traveling, or a hybrid vehicle using the electric motor 29 and an internal combustion engine as a driving source for traveling. In this case, if the engine is an air-cooled type, the engine is directly cooled by cooling air (a type of cooling medium) from the cooling fan 32, and if the engine is a liquid-cooled type, the radiator that circulates coolant (a type of cooling medium) within the engine and the coolant are cooled by cooling air.

[0052] (3) Furthermore, if it is not possible to blow cooling air directly onto the thermal device, a configuration may be adopted in which cooling air is blown onto a heat pipe (a type of cooling medium) connected to the thermal device.

[0053] (4) In the above embodiment, the clogging degree of the dust protection device 31 is calculated using the temperature parameters generated from the acquired internal detected temperature and external detected temperature, and the fan drive parameters generated from the drive behavior generated by the drive behavior generating unit 52. That is, the clogging degree: K is calculated using the following relational expression (the lookup table is an example of this): K=G(α1,α2,α3,...,β1,β2,β3,...) In this case, the fan drive parameters α1, α2, α3,... include the fan drive time, the fan rotation speed, the difference between the actual rotation speed and the target rotation speed of the fan, the fan rotation speed fluctuation range, etc., and the temperature parameters β1, β2, β3,... include the temperature detected by the internal temperature detector 41 of the cooling medium or the thermal equipment, the outside air temperature detected by the external temperature detector 42, the temperature rise rate (temperature change in a predetermined time) of the thermal equipment (cooling target) such as the electric motor 29 and the inverter 28, etc. Alternatively, the clogging degree K may be calculated using only the fan drive parameters.

[0054] (5) The degree of clogging: K can also be estimated by performing image recognition on the dust protection equipment 31. For example, a photographed image of the filter part of the dust protection equipment 31 may be recognized by performing image recognition on the captured image of the filter part, and the degree of clogging may be calculated based on the recognition result. The camera used for the image recognition may also be a camera for detecting obstacles, or a dedicated camera may be prepared. The result of the calculation of the degree of clogging using such image recognition may be used in combination with the result of the calculation of the degree of clogging using fan drive parameters and temperature parameters.

[0055] In addition, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, provided no contradiction arises. Furthermore, the embodiments disclosed in this specification are illustrative, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0056] The present invention can be used in various fan control systems that control fans that operate in cooperation with dust prevention devices, and in devices and facilities that include such fan control systems. [Explanation of symbols]

[0057] 28: Inverter (thermal equipment) 29: Electric motors (thermal equipment) 30: Lower cover 31: Dust protection equipment 32: Cooling fan (fan) 33: Fan motor (fan drive section) 34: Battery for electrical equipment 35: Internal temperature sensor 36: External temperature sensor 41: Internal temperature detection unit 42: External temperature detector 51: Fan control unit 52: Driving behavior generation unit 53: Clogging degree calculation unit 54: Reverse control unit 100: Control unit

Claims

1. 1. A fan control system comprising: With fans, A dust protector provided around the fan; a fan drive unit that rotates the fan in a forward and reverse direction; a fan control unit that controls the driving of the fan drive unit; a clogging degree calculation unit that calculates a clogging degree of the dust prevention device based on a driving behavior of the fan; a reverse rotation command unit that commands the fan control unit to reverse the rotation of the fan based on the degree of clogging.

2. 2. The fan control system according to claim 1, wherein the fan drive unit is a fan motor, and the fan motor is controlled by a drive signal from the fan control unit.

3. The fan control system according to claim 1 , wherein the drive behavior is determined by a rotation speed of the fan, or a drive time of the fan, or both the rotation speed and the drive time.

4. 2. The fan control system according to claim 1, wherein the fan reversal time is a preset constant time.

5. 2. The fan control system of claim 1, wherein the fan reversal time is a variable time that is changed based on the degree of clogging.

6. 2. The fan control system according to claim 1, wherein the fan is a cooling fan that cools a thermal device through a cooling medium, and an internal temperature detection unit is provided that detects the temperature of the cooling medium or the temperature of the thermal device, and the clogging degree calculation unit calculates the clogging degree of the dust protector based on the detected temperature detected by the internal temperature detection unit and the driving behavior.

7. 7. The fan control system according to claim 6, further comprising an external temperature detector that detects an external temperature, and the clogging degree calculator calculates the clogging degree based on the external temperature, the detected temperature, and the driving behavior.

8. The fan control system according to claim 6 , wherein the cooling medium is at least one of cooling air, a cooling liquid, and a heat pipe.

9. 7. The fan control system according to claim 6, wherein the thermal equipment is at least one of a radiator, an engine, an electric motor, an inverter, and a battery.

10. A cooling fan that cools a thermal device through a cooling medium; A dust protector provided around the cooling fan; a fan drive unit that rotates the cooling fan in a forward and reverse direction; a fan control unit that controls the driving of the fan drive unit; an internal temperature detection unit that detects a temperature of the cooling medium or a temperature of the thermal device; A clogging degree calculation unit that calculates a clogging degree of the dust protector based on the detected temperature detected by the internal temperature detection unit and the driving behavior of the cooling fan; and a reverse rotation command unit that commands the fan control unit to reverse the rotation of the cooling fan based on the degree of clogging.

11. The work machine according to claim 10 , wherein the drive behavior is determined by a rotation speed of the cooling fan, or a drive time of the cooling fan, or both the rotation speed and the drive time.

Images