Construction machinery

Abstract

Provided is a construction machine comprising: an electric motor that serves as a power source; a heat exchanger; a fuel cell that generates power to be supplied to the electric motor; a cooling fan that blows cooling air to the heat exchanger; and a fan control device that controls rotation of the cooling fan. In the construction machine, a hydrogen gas detection sensor is provided in a machine room in which the heat exchanger, the fuel cell, and the cooling fan are disposed, and the fan control device increases the rotational speed of the cooling fan when the hydrogen gas detection sensor has detected hydrogen gas.

Description

[Technical Field]

[0001] The present invention relates to a construction machine equipped with a fuel cell. [Background technology]

[0002] Hydrogen is expected to be a next-generation energy source that does not emit carbon dioxide. A fuel cell is a system that generates electricity and heat from hydrogen and oxygen in the air. However, when a fuel cell is installed in a machine that people ride in, hydrogen is colorless and odorless, so if it leaks, it is difficult for people to detect it. In response to this, Patent Document 1 discloses a car equipped with a hydrogen detection device to detect hydrogen leaks.

[0003] In order to detect hydrogen leaks in automobiles equipped with fuel cells, a fuel cell box was previously required to seal elements such as fuel cells from which hydrogen could leak. In Patent Document 1, a suction means is provided to suck in atmospheric gas from a specified space from which hydrogen could leak, and a hydrogen detection device is positioned upwind of the suction means, thereby eliminating the need for a fuel cell box. Hydrogen that leaks within the specified space is sucked in by the suction means and discharged toward a storage battery that stores electricity generated by the fuel cell, where it is used to cool the storage battery. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-80655 Summary of the Invention [Problem to be solved by the invention]

[0005] In the case of a vehicle such as that in Patent Document 1, the vehicle body can take in wind while traveling, which means that hydrogen inside the vehicle body is easily expelled outside the vehicle by the wind while traveling. However, unlike machines such as automobiles that primarily move around, construction machines such as hydraulic excavators often perform work such as excavation in a fixed area without moving around much, so a system is needed to actively expel hydrogen inside the vehicle body outside the machine without relying on wind while traveling or natural wind.

[0006] An object of the present invention is to provide a construction machine that can actively discharge hydrogen around a fuel cell or its associated equipment to the outside of the machine. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a construction machine comprising an electric motor as a power source, a fuel cell that generates power to be supplied to the electric motor, a hydrogen tank filled with hydrogen gas to be supplied to the fuel cell, a hydraulic actuator driven by hydraulic oil discharged from a hydraulic pump, cooling water to cool the electric motor, cooling water to cool the fuel cell, and a heat exchanger that cools the hydraulic oil that drives the hydraulic actuator, a cooling fan that blows cooling air to the heat exchanger, and a fan control device that controls the rotation of the cooling fan, wherein a hydrogen gas detection sensor is provided in a machine room in which the heat exchanger, the fuel cell, the cooling fan, and the hydrogen tank are arranged, the fuel cell is adjacent to the cooling fan, and the fan control device increases the rotation speed of the cooling fan when the hydrogen gas detection sensor detects hydrogen gas. [Effects of the Invention]

[0008] According to the present invention, even in construction machinery in which it is difficult to take in wind generated by running into the interior of the machinery, hydrogen around the fuel cell or its associated equipment can be actively discharged outside the machinery. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a side view of a hydraulic excavator, which is an example of a construction machine according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram illustrating a part of the on-board equipment housed in the machine room of the construction machine according to the first embodiment of the present invention superimposed on a plan view of a rotating body. [Figure 3] FIG. 1 is a schematic diagram showing the main parts of a fuel cell system provided in a construction machine according to a first embodiment of the present invention. [Figure 4] 1 is a flowchart showing a control procedure for a cooling fan by a fan control device provided in a construction machine according to a first embodiment of the present invention. [Figure 5] 10 is a flowchart showing another example of the control procedure for the cooling fan by the fan control device provided in the construction machine according to the first embodiment of the present invention. [Figure 6] 10 is a flowchart showing a control procedure for a cooling fan by a fan control device provided in a construction machine according to a second embodiment of the present invention. [Figure 7] 10 is a flowchart showing a procedure for controlling a cooling fan by a fan control device provided in a construction machine according to a third embodiment of the present invention. [Figure 8] FIG. 10 is a diagram illustrating an example of a display on a monitor provided in a construction machine according to a third embodiment of the present invention. [Figure 9] 10 is a flowchart showing a control procedure for a cooling fan by a fan control device provided in a construction machine according to a fourth embodiment of the present invention. [Figure 10] 10 is a flowchart showing a procedure for controlling a cooling fan by a fan control device provided in a construction machine according to a fifth embodiment of the present invention. [Figure 11] A diagram explaining how to compare the distance between the driver's seat and each fan DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] (First embodiment) -Construction machinery- FIG. 1 is a side view of a hydraulic excavator, which is an example of a construction machine according to a first embodiment of the present invention. In this embodiment, a hydraulic excavator equipped with a bucket 23 as an attachment at the tip of a working mechanism 20 (front working machine) will be described as an example of a construction machine. However, the present invention can also be applied to hydraulic excavators equipped with attachments other than a bucket, or other types of construction machines such as wheel loaders and bulldozers. In this specification, the front of the operator's cab 16 (the right side in FIG. 1) is defined as the front of the hydraulic excavator (strictly speaking, the front of the rotating bed 12).

[0012] The hydraulic excavator shown in the drawing comprises a vehicle body 10 and a working device 20. The vehicle body 10 comprises a running body 11 and a rotating body 12.

[0013] In this embodiment, the traveling body 11 is equipped with left and right crawler-type traveling devices 13 having endless track tracks, and travels by driving the left and right traveling devices 13 respectively by left and right traveling motors 14. Hydraulic motors are used as the traveling motors 14.

[0014] The rotating body 12 is mounted on the upper part of the running body 11 so as to be able to rotate via a rotation device 15. The rotation device 15, which connects the running body 11 and the rotating body 12, includes a rotation motor (not shown), which is driven to rotate the rotating body 12 around a vertical central axis relative to the running body 11. A hydraulic motor is used for the rotation motor 34. A cab 16 in which an operator sits is provided at the front of the rotating body 12 (on the front left side in this embodiment). Behind the cab 16 of the rotating body 12 is a machine room 17 which houses a hydraulic pump 41 (FIG. 2) and the like, and a counterweight 18 is mounted at the rear end of the rotating body 12 to balance the weight with the work implement 20.

[0015] The working device 20 is an articulated working arm for performing work such as excavating earth and sand, and is connected to the front of the revolving unit 12 (to the right of the cab 16 in this embodiment). The working device 20 is composed of a boom 21, an arm 22, and a bucket 23. The boom 21 is connected to a base frame of the revolving unit 12, called a revolving frame, by a pin, and rotates up and down relative to the revolving unit 12 as a boom cylinder 31 extends and retracts. Both ends of the boom cylinder 31 are rotatably connected to the boom 21 and the revolving unit 12. The arm 22 is connected to the tip of the boom 21 by a pin, and rotates back and forth relative to the boom 21 as an arm cylinder 32 extends and retracts. Both ends of the arm cylinder 32 are rotatably connected to the arm 22 and the boom 21. The bucket 23 is connected to the tip of the arm 22 by a pin, and rotates relative to the arm 22 as the bucket cylinder 33 extends and retracts. The base end of the bucket cylinder 33 is connected to the arm 22, and the tip end is connected via a link to the bucket 23. The boom cylinder 31, arm cylinder 32, and bucket cylinder 33 that drive the working device 20 are hydraulic actuators.

[0016] -Machine room- 2 is a schematic diagram showing some of the on-board equipment housed in the machinery room superimposed on a plan view (view from above) of the rotating body 12. Inside the cab 16, there is a driver's seat S where the operator sits. Between the cab 16 and the counterweight 18, there is a machinery room 17 defined by a hood.

[0017] The machinery room 17 accommodates part of the fuel cell system 40, including the fuel cell 45, devices driven by the fuel cell 45, and devices related to the operation of the fuel cell 45. Specifically, the components that make up the fuel cell system 40, such as a hydraulic pump 41, an electric motor 42, a heat exchanger (radiator) 43, a cooling fan 44, the fuel cell 45, and a hydrogen tank 46, are accommodated in the machinery room 17. As shown in FIG. 2, the fuel cell 45 is adjacent to the cooling fan 44 in the left-right direction. In the example of FIG. 2, the heat exchanger 43, the cooling fan 44, the fuel cell 45, the electric motor 42, and the hydraulic pump 41 are lined up in this order from left to right in the machinery room 17, but the arrangement of these devices may be changed as necessary.

[0018] The hydraulic pump 41 draws hydraulic oil from a hydraulic oil tank (not shown) and discharges it as pressure oil for driving each hydraulic actuator (such as the boom cylinder 31) mounted on the hydraulic excavator.

[0019] The electric motor 42 is a power source for the hydraulic excavator, and has an output shaft connected to the drive shaft of the hydraulic pump 41 to drive the hydraulic pump 41.

[0020] The heat exchanger 43 is a radiator that cools liquids such as the cooling water for the electric motor 42, fuel cell 45, etc., and the hydraulic oil returning to the hydraulic oil tank, by exchanging heat with cooling air. In other words, the heat exchanger 43 cools the cooling water that cools the electric motor 42, the cooling water that cools the fuel cell 45, and the hydraulic oil that drives each hydraulic actuator. The heat exchanger 43 may include multiple heat exchangers.

[0021] The cooling fan 44 is a blowing device that blows cooling air to the heat exchanger 43. In this embodiment, the cooling fan 44 is disposed between the heat exchanger 43 and the fuel cell 45, but the position of the cooling fan 44 can be changed as appropriate as long as the heat exchanger 43 is exposed to the flow of cooling air that the cooling fan 44 induces. The size and number of the cooling fans 44 are set according to the required amount of cooling air. If one cooling fan 44 is sufficient, one cooling fan will suffice, but this embodiment illustrates a configuration in which multiple cooling fans (two in the example of FIG. 2) (a first cooling fan 44a and a second cooling fan 44b) are provided.

[0022] The fuel cell 45 is a power generation device that converts the chemical energy of hydrogen and an oxidant (typically oxygen) into electricity through an oxidation-reduction reaction, and generates power to be supplied to various electrical devices mounted on the hydraulic excavator, including the electric motor 42 and the cooling fan 44. The power generated by the fuel cell 45 is supplied to the electrical devices as power or is stored in a battery (not shown) mounted on the hydraulic excavator. The hydrogen gas supplied to the fuel cell 45 is filled in a hydrogen tank 46. High-purity hydrogen gas filled in the hydrogen tank 46 is supplied to the fuel cell 45. The hydraulic excavator is also equipped with an air compressor (not shown), and the air around the hydraulic excavator is compressed by the air compressor and supplied to the fuel cell 45. The oxygen contained in this compressed air is used as an oxidant.

[0023] In the example of FIG. 2, the hydrogen tank 46 is disposed between the fuel cell 45 and the counterweight 18, but the location of the hydrogen tank 46 can also be changed as necessary.

[0024] -Fuel cell system- 3 is a schematic diagram showing the main parts of the fuel cell system 40. As shown in FIG. 3, the hydraulic excavator of this embodiment is equipped with a light 25, a monitor 26, a hydrogen gas detection sensor 51, a fan control device 52, and a main controller 53.

[0025] The light 25 is a lighting device that illuminates the outside of the machine (the surroundings of the hydraulic excavator) when the hydraulic excavator is operated in a dark place, etc. The light 25 illustrated in FIG. 1 is a light that illuminates the area in front of the revolving unit 12, and in this embodiment is installed on the work implement 20 (boom 21), but it can also be installed on the front of the revolving frame, for example. Although not shown, there are also cases where a separate light is provided that illuminates the area behind or to the side of the revolving unit 12.

[0026] The monitor 26 is a display device that displays support information and settings related to the operation of the hydraulic excavator, and is installed in a position inside the operator's cab 16 that is easily visible from the operator's seat S (FIG. 2).

[0027] The hydrogen gas detection sensor 51 is a sensor capable of detecting hydrogen gas. Various commonly known types of hydrogen gas detection sensor 51 can be applied, such as catalytic combustion type, gas thermal conduction type, and semiconductor type. The hydrogen gas detection sensor 51 is arranged inside the machinery compartment 17 together with the fuel cell 45, the hydrogen tank 46, and the hydrogen gas piping connecting the fuel cell 45 and the hydrogen tank 46, and detects hydrogen gas in the machinery compartment 17 (under the hood). The output of the hydrogen gas detection sensor 51 is input to the main controller 53. In this embodiment, a configuration is illustrated in which the hydrogen gas detection sensor 51 is connected to the fan control device 52 via the main controller 53, but the hydrogen gas detection sensor 51 can also be connected directly to the fan control device 52 without going through the main controller 53.

[0028] While the placement of the hydrogen gas detection sensor 51 is shown schematically in FIG. 3 , a reasonable location for detecting hydrogen gas is, for example, downwind of the cooling fan 44 (downstream of the cooling fan 44 in the direction of the flow of cooling air induced by the cooling fan 44). Furthermore, because hydrogen gas is lighter than air, it is preferable to install the hydrogen gas detection sensor 51 in an upper rather than lower position within the machinery room 17. Other suitable locations for the hydrogen gas detection sensor 51 include near the joints of the hydrogen gas piping and near the hood opening. To improve the hydrogen gas detection rate, it is also preferable to install multiple hydrogen gas detection sensors 51 in these locations. For example, hydrogen gas may temporarily remain in the machinery room 17 immediately after replacing parts such as the hydrogen gas piping during maintenance. During such maintenance, improper installation of parts may occur. Furthermore, hydrogen gas may enter the machinery room 17 from outside the aircraft.

[0029] The fan control device 52 is a device (e.g., an inverter, a computer, etc.) that controls the rotation speed of the cooling fan 44, and controls the rotation speed of the cooling fan 44 based on the output of the hydrogen gas detection sensor 51. In this embodiment, the main controller 53 is interposed between the hydrogen gas detection sensor 51 and the fan control device 52, and the fan control device 52 controls the rotation speed of the cooling fan 44 in response to a signal input from the main controller 53 based on the output of the hydrogen gas detection sensor 51. The fan control device 52 may be directly connected to the hydrogen gas detection sensor 51 without going through the main controller 53, and may control the rotation speed of the cooling fan 44 in response to the output (on / off of hydrogen gas detection) input directly from the hydrogen gas detection sensor 51 (or via an A / D converter, if necessary). Furthermore, when both the fan control device 52 and the main controller 53 are configured as computers, a single computer may be configured to serve as both the fan control device 52 and the main controller 53.

[0030] Specifically, when hydrogen gas is detected by the hydrogen gas detection sensor 51, the fan control device 52 increases the rotation speed of the cooling fan 44. In this embodiment, when hydrogen gas is detected by the hydrogen gas detection sensor 51, the fan control device 52 is configured to increase the rotation speed of the cooling fan 44 from the first rotation speed N1 to the second rotation speed N2.

[0031] The first rotation speed N1 is a value set for blowing cooling air to the heat exchanger 43 during operation of the hydraulic excavator of this embodiment. The first rotation speed N1 may be a constant value or a variable value that changes depending on the temperature of the object to be cooled (cooling water, hydraulic oil, etc.) detected by a temperature sensor (not shown). Furthermore, in a case where the cooling fan 44 includes multiple fans (first cooling fan 44a, second cooling fan 44b) as in this embodiment, if some of the cooling fans (e.g., first cooling fan 44a) are set to stop for the purpose of blowing cooling air, the first rotation speed N1 of these cooling fans is 0. In other words, increasing the rotation speed of a cooling fan from 0 to the second rotation speed N2 is also included in the concept of "speed increase." Needless to say, the same applies when the rotation speed increases from a stopped state to the second rotation speed N2 when the first rotation speed N1 is a variable value with a minimum value of 0.

[0032] The second rotation speed N2 is a value set to exhaust hydrogen gas around the hydrogen gas pipe, fuel cell 45, or hydrogen tank 46 from the machine room 17, and is set to a value higher than the first rotation speed N1 (for example, the maximum rotation speed of the cooling fan 44). Even if the first rotation speed N1 is a variable value that changes depending on the temperature of the object to be cooled, the second rotation speed N2 is set to a value higher than the maximum value of the first rotation speed N1.

[0033] The cooling fan 44 includes a first cooling fan 44a and a second cooling fan 44b. In this embodiment, the first cooling fan 44a and the second cooling fan 44b are always driven at the same rotation speed, but they may also be configured to be driven at different rotation speeds depending on the required cooling air volume.

[0034] The main controller 53 is electrically connected to on-board electrical equipment such as the hydrogen gas detection sensor 51, the fan control device 52, the lights 25, and the monitor 26, and outputs a command signal to the fan control device 52 based on the output of the hydrogen gas detection sensor 51. Specifically, when hydrogen gas is detected by the hydrogen gas detection sensor 51, the main controller 53 outputs a command signal to the fan control device 52 to rotate the cooling fan 44 at the second rotation speed N2. Conversely, when hydrogen gas is not detected by the hydrogen gas detection sensor 51, the main controller 53 outputs a command signal to the fan control device 52 to rotate the cooling fan 44 at the first rotation speed N1. Therefore, in this embodiment, the cooling fan 44 rotates at the second rotation speed N2 only while hydrogen gas is detected by the hydrogen gas detection sensor 51. When hydrogen gas is not detected, or when hydrogen gas is no longer detected after hydrogen gas is detected and the cooling fan 44 is accelerated to the second rotation speed N2, the cooling fan 44 rotates at the first rotation speed N1.

[0035] -Cooling fan control- 4 is a flowchart showing the control procedure of the cooling fan 44 by the fan control device 52. As described above, when hydrogen gas is detected by the hydrogen gas detection sensor 51, the fan control device 52 increases the rotation speed of the cooling fan 44 from the first rotation speed N1 to the second rotation speed N2. The fan control device 52 repeatedly executes the control of FIG. 4 (the cycle from "START" to "RETURN") while the power is on. The flowchart illustrated in the figure is based on the assumption that the hydrogen gas detection sensor 51 is operating normally.

[0036] 4 when power is turned on. First, in step S10, the fan control device 52 determines whether hydrogen gas is being detected by the hydrogen gas detection sensor 51 based on the output of the hydrogen gas detection sensor 51. If hydrogen gas is not detected by the hydrogen gas detection sensor 51, the fan control device 52 proceeds from step S10 to step S30 and drives the cooling fan 44 at the first rotation speed N1. Conversely, if hydrogen gas is detected by the hydrogen gas detection sensor 51, the fan control device 52 proceeds from step S10 to step S20 and drives the cooling fan 44 at the second rotation speed N2. If the cooling fan 44 was being driven at the first rotation speed N1 immediately before (in the previous cycle), the cooling fan 44 will increase its rotation speed from the first rotation speed N1 to the second rotation speed N2 at the point when hydrogen gas is detected.

[0037] After executing the process of step S20 or S30, the fan control device 52 proceeds to step S40 to determine whether the power has been turned off, and if the power has been turned off, executes delay control and ends the control of Fig. 4. If the power is still on, the fan control device 52 returns to step S10.

[0038] By repeating this control, the fan control device 52 continues to drive the cooling fan 44 at the first rotation speed N1 until hydrogen gas is detected by the hydrogen gas detection sensor 51. Thereafter, when hydrogen gas is detected by the hydrogen gas detection sensor 51, the fan control device 52 increases the rotation speed of the cooling fan 44 from the first rotation speed N1 to the second rotation speed N2. In this embodiment, when hydrogen gas is no longer detected by the hydrogen gas detection sensor 51 as a result of driving the cooling fan 44 at the second rotation speed N2, the fan control device 52 returns the rotation speed of the cooling fan 44 from the second rotation speed N2 to the first rotation speed N1.

[0039] Note that the flowchart in FIG. 4 illustrates an example in which the rotation speed of the cooling fan 44 is increased to the second rotation speed N2 and then returned to the first rotation speed N1 once hydrogen gas is no longer detected. However, this is not a limitation. For example, as shown in FIG. 5, the fan control device 52 can be configured to drive the cooling fan 44 at the first rotation speed N1 at the start of control, temporarily increase the rotation speed of the cooling fan 44 to the second rotation speed N2, and then not automatically return to the first rotation speed N1. Although not specifically shown in the example in FIG. 5, the state in which the cooling fan 44 is driven at the second rotation speed N2 may continue until the power is turned off or power is lost. Alternatively, an operation signal can be manually input to the fan control device 52 via an operation device (not shown) to stop the cooling fan 44 or slow it down to the first rotation speed N1. Even in these cases, the control in FIG. 5 is applied to the subsequent operation of the cooling fan 44.

[0040] -effect- As described above, in this embodiment, the hydrogen gas detection sensor 51 is installed inside the machine room 17, and the fan control device 52 is configured to be able to control the cooling fan 44, which blows cooling air to the heat exchanger 43, in accordance with the output of the hydrogen gas detection sensor 51. When hydrogen gas is detected by the hydrogen gas detection sensor 51, the fan control device 52 controls the rotation speed of the cooling fan 44 to increase from the first rotation speed N1 for blowing cooling air to the heat exchanger 43 to the second rotation speed N2 for exhausting hydrogen gas from the machine room 17. This makes it possible to actively exhaust hydrogen gas around the fuel cell 45 or its associated equipment (such as the hydrogen tank 46 and hydrogen gas piping) outside the machine, even in construction machines in which it is difficult to introduce wind from traveling into the machine interior.

[0041] (Second embodiment) FIG. 6 is a flowchart showing the control procedure for the cooling fan 44 by the fan control device 52 provided in a construction machine according to a second embodiment of the present invention. For processes that are the same as or correspond to those in the flowchart of the first embodiment (FIG. 4), the same step numbers as in FIG. 4 are used in FIG. 6, and explanations are omitted or simplified as appropriate. As with the first embodiment, the fan control device 52 repeatedly executes the control of FIG. 6 (the cycle from "START" to "RETURN") while the power is on. As with the first embodiment, the flowchart illustrated in the same figure assumes that the hydrogen gas detection sensor 51 is operating normally. Furthermore, the hardware configuration of this embodiment is the same as that of the first embodiment.

[0042] In this embodiment as well, when hydrogen gas is detected by the hydrogen gas detection sensor 51, the fan control device 52 increases the rotation speed of the cooling fan 44 from the first rotation speed N1 to the second rotation speed N2. This embodiment differs from the first embodiment in that, after increasing the rotation speed of the cooling fan 44 to the second rotation speed N2, the fan control device 52 returns the rotation speed of the cooling fan 44 from the second rotation speed N2 to the first rotation speed N1 after a preset time T1 has elapsed from the time when the hydrogen gas detection sensor 51 becomes non-detecting of hydrogen gas.

[0043] When the power is turned on, the fan control device 52 starts the control of Figure 6, determines whether hydrogen gas is detected (step S10), and if hydrogen gas is detected, proceeds from step S10 to step S11, sets flag F to 1, and drives the cooling fan 44 at the second rotation speed N2 (step S20).

[0044] On the contrary, when hydrogen gas is not detected, the fan control device 52 moves the procedure from step S10 to step S12 and sets the flag F to 0. At that time, when the fan control device 52 switches the setting of the flag F from 1 to 0, it records the time t in the memory. That is, when hydrogen gas was detected in the determination of step S10 in the previous cycle (the cycle immediately before the current cycle) and the determination of step S10 in the current cycle switches to a state where hydrogen gas is not detected, the time t is recorded in the memory.

[0045] After setting the flag F to 0, the fan control device 52 calculates the time from time t to the present, that is, the continuous time T until the current time in the state where hydrogen gas is not detected, and determines whether the continuous time T is equal to or greater than the set time T1 (step S13). If T≥T1, that is, if the set time T1 has elapsed since the time t when the hydrogen gas detection sensor 51 entered the non-detection state of hydrogen gas, the fan control device 52 drives the cooling fan 44 at the first rotation speed N1 (step S30). On the contrary, if T<T1, that is, if the set time T1 has not elapsed since the time t when the hydrogen gas detection sensor 51 entered the non-detection state of hydrogen gas, the fan control device 52 drives the cooling fan 44 at the second rotation speed N2 (step S20). In the control of FIG. 6, the procedure after step S20 or step S30 is the same as that in the first embodiment (FIG. 4).

[0046] Also in this embodiment, since the cooling fan 44 is speeded up when hydrogen gas is detected, the same effect as in the first embodiment can be obtained.

[0047] Also, as described above, in this embodiment, once the cooling fan 44 is driven at the second rotation speed N2, even if hydrogen gas is no longer detected thereafter, it continues to be driven at the second rotation speed N2 for the set time T1 in the state where hydrogen gas is not detected. When the cooling fan 44 is driven at the second rotation speed N2 for the set time T1 in the state where hydrogen gas is not detected, the fan control device 52 returns the rotation speed of the cooling fan 44 from the second rotation speed N2 to the first rotation speed N1. Therefore, the residual hydrogen gas in the machine room 17 can be more effectively suppressed.

[0048] (Third embodiment) FIG. 7 is a flowchart showing the control procedure for the cooling fan 44 by the fan control device 52 provided in a construction machine according to a third embodiment of the present invention. For processes that are the same as or correspond to those in the flowchart of the first embodiment (FIG. 4), the same step numbers as in FIG. 4 are used in FIG. 7, and explanations are omitted or simplified as appropriate. As with the first embodiment, the fan control device 52 repeatedly executes the control of FIG. 7 (the cycle from "START" to "RETURN") while the power is on. As with the first embodiment, the flowchart illustrated in the same figure assumes that the hydrogen gas detection sensor 51 is operating normally. Furthermore, the hardware configuration of this embodiment is the same as that of the first embodiment.

[0049] In this embodiment as well, when hydrogen gas is detected by the hydrogen gas detection sensor 51, the fan control device 52 increases the rotation speed of the cooling fan 44 from the first rotation speed N1 to the second rotation speed N2. This embodiment differs from the first embodiment in that the main controller 53 has a function of controlling the display on the monitor 26 based on the output of the hydrogen gas detection sensor 51, and when hydrogen gas is detected by the hydrogen gas detection sensor 51, the main controller 53 displays a message on the monitor 26 (FIG. 8) urging personnel in the driver's cab 16 to exit the vehicle.

[0050] When power is applied, the fan control device 52 starts the control shown in FIG. 7. Similar to the first embodiment (FIG. 4), the fan control device 52 drives the cooling fan 44 at the first rotation speed N1 or the second rotation speed N2 depending on whether hydrogen gas is detected (steps S10-S30). In this embodiment, if hydrogen gas is detected, the fan control device 52 drives the cooling fan 44 at the second rotation speed N2 and displays a warning message on the monitor 26, such as that shown in FIG. 8 (step S21), before proceeding to step S40. The order of steps S20 and S21 may be reversed or performed simultaneously. In FIG. 8, the message displayed on the monitor 26 in step S21 is, for example, "Please dismount and move away from the excavator immediately." In the control shown in FIG. 7, the transition procedure of step S40 is the same as that of the first embodiment (FIG. 4).

[0051] The control of this embodiment illustrated in FIG. 7 is equivalent to adding a warning display process (step S21) to the process of step S20 in the flowchart of FIG. 4 of the first embodiment, but the control shown in the flowchart of FIG. 5 or FIG. 6 can also be executed in conjunction with step S20 of the warning display process (step S21).

[0052] In this embodiment as well, the cooling fan 44 is controlled to increase its speed when hydrogen gas is detected, so that the same effect as in the first embodiment can be obtained.

[0053] Furthermore, as described above, in this embodiment, when hydrogen gas is detected, the cooling fan 44 is controlled to increase its speed, and a display such as that shown in FIG. 8 is displayed on the monitor 26, thereby encouraging personnel in the cab 16 to actively exit the vehicle.

[0054] (Fourth embodiment) FIG. 9 is a flowchart showing the control procedure for the cooling fan 44 by the fan control device 52 provided in a construction machine according to a fourth embodiment of the present invention. For processes that are the same as or correspond to those in the flowchart of the first embodiment (FIG. 4), the same step numbers as in FIG. 4 are used in FIG. 9, and explanations are omitted or simplified as appropriate. As in the first embodiment, the fan control device 52 repeatedly executes the control of FIG. 9 (the cycle from "START" to "RETURN") while the power is on. As in the first embodiment, the flowchart illustrated in the same figure assumes that the hydrogen gas detection sensor 51 is operating normally. Furthermore, the hardware configuration of this embodiment is the same as that of the first embodiment.

[0055] In the present embodiment, too, when hydrogen gas is detected by the hydrogen gas detection sensor 51, the fan control device 52 increases the rotation speed of the cooling fan 44 from the first rotation speed N1 to the second rotation speed N2. This embodiment differs from the first embodiment in that the main controller 53 has a function of controlling the power supply to on-board electric devices including the electric motor 42, the cooling fan 44, and the light 25 based on the output of the hydrogen gas detection sensor 51, and when hydrogen gas is detected by the hydrogen gas detection sensor 51, the main controller 53 stops the power supply to the on-board electric devices except for the cooling fan 44 and supplies power only to the cooling fan 44. The on-board electric devices typically refer to electrical devices mounted on a hydraulic excavator whose main purpose is to convert electrical energy into mechanical work, heat, or light, and do not include electrical devices of detection systems or calculation / control systems such as sensors and computers.

[0056] Furthermore, in this embodiment, a case is described in which power is supplied only to the cooling fan 44 when hydrogen gas is detected, but it is also possible to configure the system so that power supply to on-board electric devices other than the cooling fan 44 and the light 25 is stopped and power is supplied only to the cooling fan 44 and the light 25.

[0057] When power is applied, the fan control device 52 starts the control of FIG. 9. As in the first embodiment (FIG. 4), the fan control device 52 drives the cooling fan 44 at the first rotation speed N1 or the second rotation speed N2 depending on whether hydrogen gas is detected (steps S10-S30). In this embodiment, if hydrogen gas is detected, the fan control device 52 drives the cooling fan 44 at the second rotation speed N2 and cuts off the supply of power to the onboard electric devices (such as the electric motor 42) other than the cooling fan 44 (step S22), and then proceeds to step S40. The order of steps S20 and S22 may be reversed, or steps S20 and S22 may be performed simultaneously. As described above, the power supply to the light 25 may be continued. In the control of FIG. 9, the transition procedure of step S40 is the same as that of the first embodiment (FIG. 4).

[0058] The control of this embodiment illustrated in FIG. 9 is equivalent to adding a warning display process (step S21) to the process of step S20 in the flowchart of FIG. 4 of the first embodiment, but the control shown in the flowchart of FIG. 5, FIG. 6 or FIG. 7 can also be executed in conjunction with step S20 of the power supply limit process (step S22).

[0059] In this embodiment as well, the cooling fan 44 is controlled to increase its speed when hydrogen gas is detected, so that the same effect as in the first embodiment can be obtained.

[0060] Furthermore, as described above, in this embodiment, when hydrogen gas is detected, power is supplied only to the cooling fan 44 (or the cooling fan 44 and the light 25), thereby making it possible to prevent a shortage of power supplied to the cooling fan 44 (or the cooling fan 44 and the light 25). By ensuring the power supply to the cooling fan 44, it is possible to ensure the continuous discharge of hydrogen gas from the machine room 17. Furthermore, by ensuring the power supply to the light 25, when the hydraulic excavator is operated in a dark place or at night, the light 25 can illuminate the area around the hydraulic excavator, thereby facilitating the movement of an operator who has dismounted.

[0061] (Fifth embodiment) FIG. 10 is a flowchart showing the control procedure for the cooling fan 44 by the fan control device 52 provided in a construction machine according to a fifth embodiment of the present invention. For processes that are the same as or correspond to those in the flowchart of the first embodiment (FIG. 4), the same step numbers as in FIG. 4 are used in FIG. 10, and explanations are omitted or simplified as appropriate. As with the first embodiment, the fan control device 52 repeatedly executes the control of FIG. 10 (the cycle from "START" to "RETURN") while the power is on. As with the first embodiment, the flowchart illustrated in the same figure assumes that the hydrogen gas detection sensor 51 is operating normally. Furthermore, the hardware configuration of this embodiment is the same as that of the first embodiment.

[0062] In this embodiment, too, when hydrogen gas is detected by the hydrogen gas detection sensor 51, the fan control device 52 increases the rotation speed of the cooling fan 44 from the first rotation speed N1 to the second rotation speed N2. This embodiment differs from the first embodiment in that a difference is made between the rotation speeds of the first cooling fan 44a and the second cooling fan 44b included in the cooling fan 44. Specifically, when hydrogen gas is detected by the hydrogen gas detection sensor 51, the fan control device 52 increases the rotation speed of the first cooling fan 44a, which is relatively close to the driver's seat S, to the second rotation speed N2, and drives the second cooling fan 44b at a third rotation speed N3, which is lower than the second rotation speed N2. The third rotation speed N3 may be any rotation speed lower than the second rotation speed N2. For example, the third rotation speed N3 may be set to the same value as the first rotation speed N1, or may be set to 0 (stopped) (however, a negative value (i.e., reverse rotation) is excluded).

[0063] When power is supplied, the fan control device 52 starts the control shown in FIG. 10, and controls the rotation speed of the cooling fan 44 according to whether hydrogen gas is detected or not in the same manner as in the first embodiment (FIG. 4) (steps S10 - S30), and then proceeds to step S40. In this embodiment, when hydrogen gas is detected, in step S20, the fan control device 52 drives the first cooling fan 44a relatively close to the driver's seat S at the second rotation speed N2, and drives the second cooling fan 44b relatively far from the driver's seat S at the third rotation speed N3 (<N2). In the control of FIG. 10, the procedure for transitioning to step S40 is the same as that in the first embodiment (FIG. 4).

[0064] Note that the control of this embodiment illustrated in FIG. 10 is equivalent to applying individual fan control to the process of step S20 in the flowchart of FIG. 4 of the first embodiment. However, individual fan control can be applied to step S20 of the control represented in the flowcharts of FIGS. 5, 6, 7, or 9.

[0065] Here, FIG. 11 is a diagram for explaining a method of comparing the distances between the driver's seat S and each fan. FIG. 11 corresponds to a view of the hydraulic excavator seen from the left side of the revolving body 12. When the cooling fan 44 includes a plurality of fans, the layout of these fans may vary depending on the model and the like. In FIG. 11, the case where the cooling fans are arranged in the front - rear direction is illustrated, but they may also be arranged side - by - side. In any case, the distance between each fan and the driver's seat S is compared by, for example, the respective distances L from the reference point P of the driver's seat S to the rotation center of each fan. The reference point P can be arbitrarily set with respect to the driver's seat S, and in FIG. 11, an example of setting it at a specific position of the headrest is shown. In the example shown in FIG. 11, since the distance L1 between the first cooling fan 44a and the driver's seat S is shorter than the distance L2 between the second cooling fan 44b and the driver's seat S, the fan relatively close to the driver's seat S is the first cooling fan 44a.

[0066] 11, if the first cooling fan 44a and the second cooling fan 44b are positioned differently in the vertical direction, even if the first cooling fan 44a is relatively closer in the horizontal direction from the driver's seat S (that is, the first cooling fan 44a appears closer in a plan view), the second cooling fan 44b may be closer in absolute distance in three-dimensional space. In such a case, in this embodiment, the second cooling fan 44b is considered to be the fan closest to the driver's seat S, and the second cooling fan 44b is increased in speed to the second rotation speed N2 when hydrogen gas is detected.

[0067] Furthermore, if the cooling fan 44 includes three or more cooling fans, when hydrogen gas is detected, the cooling fan closest to the driver's seat S is driven at the second rotation speed, and the remaining cooling fans are driven at a rotation speed equal to or lower than the second rotation speed N2. The remaining cooling fans may all be driven at the third rotation speed, or the rotation speeds of the remaining cooling fans may be differentiated, such as the rotation speed of the cooling fan farther from the driver's seat S being lower. Furthermore, one or some of the remaining cooling fans closest to the driver's seat S may be driven at the second rotation speed N2, the same as the cooling fan closest to the driver's seat S among all the cooling fans.

[0068] In this embodiment as well, the cooling fan 44 is controlled to increase its speed when hydrogen gas is detected, so that the same effect as in the first embodiment can be obtained.

[0069] Furthermore, as described above, in this embodiment, by driving the first cooling fan 44a close to the driver's seat S at a higher rotation speed (second rotation speed N2) than the other second cooling fan 44b, when hydrogen gas is detected inside the machinery compartment 17, the hydrogen gas near the driver's seat S is preferentially discharged. This makes it possible to actively discharge hydrogen gas from the machinery compartment 17 while moving the area where hydrogen gas exists away from the driver's seat S. [Explanation of symbols]

[0070] 10...body, 16...operator's cab, 17...machine room, 20...working device, 25...light, 26...monitor, 31...boom cylinder (hydraulic actuator), 32...arm cylinder (hydraulic actuator), 33...bucket cylinder (hydraulic actuator), 41...hydraulic pump, 42...electric motor, 43...heat exchanger, 44...cooling fan, 44a...first cooling fan, 44b...second cooling fan, 45...fuel cell, 51...hydrogen gas detection sensor, 52...fan control device, 53...main controller (controller), N1...first rotation speed, N2...second rotation speed, T1...set time, S...operator's seat

Claims

1. an electric motor as a power source; a fuel cell that generates power to be supplied to the electric motor; a hydrogen tank filled with hydrogen gas to be supplied to the fuel cell; a hydraulic actuator driven by hydraulic oil discharged from a hydraulic pump; a heat exchanger that cools cooling water for cooling the electric motor, cooling water for cooling the fuel cell, and the hydraulic oil that drives the hydraulic actuator; a cooling fan that blows cooling air to the heat exchanger; a fan control device that controls the rotation of the cooling fan, a hydrogen gas detection sensor is provided in a machine room in which the heat exchanger, the fuel cell, the cooling fan, and the hydrogen tank are arranged; the fuel cell is adjacent to the cooling fan, The construction machine is characterized in that the fan control device increases the rotation speed of the cooling fan when the hydrogen gas detection sensor detects hydrogen gas.

2. The construction machine according to claim 1, The construction machine is characterized in that, when the hydrogen gas detection sensor detects hydrogen gas, the fan control device increases the rotation speed of the cooling fan from a first rotation speed to a second rotation speed that is set higher than the first rotation speed.

3. The construction machine according to claim 2, After increasing the rotation speed of the cooling fan to the second rotation speed, the fan control device returns the rotation speed of the cooling fan from the second rotation speed to the first rotation speed after a preset time has elapsed since the hydrogen gas detection sensor went into a non-detecting state of hydrogen gas. Construction machinery characterized by:

4. The construction machine according to claim 1, The driver's cab and a monitor installed in the driver's cab; a controller for controlling the display on the monitor, When hydrogen gas is detected by the hydrogen gas detection sensor, the controller displays a message on the monitor encouraging the passenger to get off the vehicle. Construction machinery characterized by:

5. The construction machine according to claim 1, a controller for controlling power supply to the on-board electric devices including the electric motor and the cooling fan, When the hydrogen gas detection sensor detects hydrogen gas, the controller stops the supply of power to the on-board electric devices except for the cooling fan. Construction machinery characterized by:

6. The construction machine according to claim 1, Lights to illuminate the exterior of the aircraft, a controller for controlling power supply to the on-board electric devices including the electric motor, the cooling fan, and the light; When the hydrogen gas detection sensor detects hydrogen gas, the controller stops the supply of power to the on-board electric devices excluding the cooling fan and the lights. Construction machinery characterized by:

7. The construction machine according to claim 2, Further provided with a driver's cab, the cooling fan that blows cooling air to the heat exchanger that cools the cooling water that cools the electric motor, the cooling water that cools the fuel cell, and the hydraulic oil that drives the hydraulic actuator includes a first cooling fan and a second cooling fan that is farther away from the operator's cab than the first cooling fan; When hydrogen gas is detected by the hydrogen gas detection sensor, the fan control device increases the rotation speed of the first cooling fan to the second rotation speed and reduces the rotation speed of the second cooling fan to less than the second rotation speed. Construction machinery characterized by:

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