Construction machine

Abstract

The present invention is provided with a vehicle body, an electric motor as a power source, a fuel cell that generates power to be supplied to the electric motor, a battery that stores the power generated by the fuel cell, a tilt angle sensor that detects the tilt of the vehicle body, and a control device. The control device switches the supply of power to the electric motor from the fuel cell to the battery. Thus, even when the vehicle body is tilted, discharge stagnation of generated water generated during power generation by the fuel cell can be prevented.

Description

Technical Field

[0001] The present invention relates to an engineering machine equipped with a fuel cell. Background Art

[0002] Fuel cells installed in construction machinery such as hydraulic excavators are required to properly discharge water generated during power generation. As a prior art related to drainage, for example, Patent Document 1 discloses a fuel cell vehicle, which includes a fuel cell system and an exhaust structure for discharging cathode exhaust gas flowing out of the fuel cell system to the outside of the vehicle. In the fuel cell vehicle, the exhaust structure includes: a main exhaust pipe having a spanning portion arranged to span from one side to the other side in the horizontal direction above the vehicle body structure component; and a drainage bypass pipe arranged below the vehicle body structure component, branching from the main exhaust pipe at a position closer to one side in the horizontal direction than the vehicle body structure component, and connected to the main exhaust pipe at a position closer to the other side in the horizontal direction than the vehicle body structure component, and configured to be thinner than the main exhaust pipe.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-217895 Summary of the invention

[0006] Problems to be solved by the invention

[0007] The operation site of the construction machinery also includes inclined areas with various slopes and directions. Sometimes ordinary vehicles also operate in inclined areas with large slopes that are not considered for use. Therefore, in the above-mentioned prior art, it is believed that the discharge of generated water is prone to stagnation depending on the tilt of the vehicle body. However, if the drainage of the fuel cell stagnates, it may affect the operation of the fuel cell or damage the drainage mechanism due to the freezing of the generated water.

[0008] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a construction machine capable of preventing stagnation of discharge of generated water produced during power generation of a fuel cell even when the vehicle body is tilted.

[0009] Means for solving problems

[0010] The present application includes a variety of means for solving the above-mentioned problems, and as one example, includes: a vehicle body; an electric motor as a power source; a fuel cell that generates electric power to be supplied to the electric motor; a battery that stores the electric power generated by the fuel cell; a tilt angle sensor that detects the tilt of the vehicle body; and a control device that switches the power supply to the electric motor from the fuel cell to the battery when the detection result from the tilt angle sensor is above a predetermined tilt angle threshold.

[0011] Effects of the Invention

[0012] According to the present invention, even when the vehicle body is tilted, it is possible to prevent the discharge of generated water generated during the power generation of the fuel cell from being stagnant. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a side view schematically showing the appearance of a hydraulic excavator which is an example of a construction machine.

[0014] Figure 2 This is a functional block diagram that schematically shows a power supply system of a hydraulic excavator including a fuel cell and related components.

[0015] Figure 3 : is a flowchart showing the content of the power supply operation control process.

[0016] Figure 4 It is a diagram showing an example of the time changes of the charging rate of the secondary battery and the vehicle body inclination angle in the power supply operation control process. DETAILED DESCRIPTION

[0017] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. It should be noted that in this embodiment, a hydraulic excavator is described as an example of a construction machine, but the present invention can also be applied to other construction machines equipped with a fuel cell.

[0018] Figure 1 1 is a side view schematically showing the appearance of a hydraulic excavator as an example of a construction machine according to the present embodiment. Figure 2 This is a functional block diagram schematically illustrating a power supply system of a hydraulic excavator including a fuel cell together with related components.

[0019] like Figure 1 As shown, the hydraulic excavator 100 is roughly composed of a crawler-type lower traveling body 1e, a vehicle body 1B (construction machine body) composed of an upper rotating body 1d that can be arranged to rotate relative to the lower traveling body 1e, and a working device 1A (front working machine) that is arranged on the front side of the upper rotating body 1d so as to be able to pitch and move.

[0020] The working device 1A is a multi-articulated front working machine formed by connecting a plurality of driven parts (a boom 1a, an arm 1b and a bucket 1c) that rotate in the vertical direction. The base end of the boom 1a is supported on the front part of the upper rotating body 1d in a manner that allows it to rotate in the up-down direction. In addition, one end of the arm 1b is connected to the front end of the boom 1a so as to be able to rotate in the up-down direction, and the bucket 1c is connected to the other end (front end) of the arm 1b so as to be able to rotate in the up-down direction. It should be noted that the boom 1a, the arm 1b and the bucket 1c are driven by a boom cylinder, an arm cylinder and a bucket cylinder, respectively, which are hydraulic actuators not shown in the figure.

[0021] The upper revolving body 1d is constructed by arranging various components on a revolving frame as a base, and the revolving frame is driven to rotate relative to the lower traveling body 1e by a revolving hydraulic motor as a hydraulic actuator not shown in the figure, thereby enabling the upper revolving body 1d to rotate relative to the lower traveling body 1e. The revolving frame of the upper revolving body 1d is equipped with: a fuel cell 1 for generating electric power for driving the hydraulic excavator 100; a secondary battery 6 (battery) for storing the electric power generated by the fuel cell 1; an inclination angle sensor 10 for detecting the inclination (inclination, inclination direction) of the vehicle body 1B of the hydraulic excavator 100; an electric motor 4 driven by electric power from the fuel cell 1 and the secondary battery 6; a hydraulic drive system 5 for driving various hydraulic actuators including a hydraulic pump and a pilot pump driven by the electric motor 4; and a controller 9 (control device) for controlling the overall operation of the hydraulic excavator 100.

[0022] The fuel cell 1 is a device that generates electricity from a chemical reaction between a fuel (e.g., hydrogen) and an oxidant (e.g., oxygen). In the fuel cell 1 of this embodiment, air containing oxygen (oxidant) required for the reaction with hydrogen (fuel) is fed into the interior by an electric compressor, and air in which oxygen is consumed by the reaction and water (generated water) generated by the reaction are discharged from an exhaust and drain pipe 12.

[0023] When the fuel cell 1 is driven in a normal state, for example, when generating electric power corresponding to the demand from the electric motor 4, the generated water is squeezed out from the exhaust drain pipe 12 by the discharge pressure of the air sent by the electric compressor and in which the oxygen is consumed. Since the oxygen consumption changes according to the driving condition of the fuel cell 1 (increase or decrease in the amount of power generated), the amount of air sent by the electric compressor also changes.

[0024] For example, as the amount of power generated by the fuel cell 1 increases, the amount of air fed in (and the amount of air discharged) also increases. When the fuel cell 1 is driven in a high load state that is predetermined to generate more power than the normal state, the amount of air fed in by the electric compressor is also the largest. At this time, the amount of air discharged from the exhaust and drainage pipe 12 is also the largest, and the amount of generated water generated during the power generation process of the fuel cell 1 and the drainage capacity are also the largest.

[0025] Similarly, as the amount of power generated by the fuel cell 1 decreases, the amount of air fed in (and the amount of air discharged) also decreases, and when the fuel cell 1 is driven in a low idle state (low load state) that is predetermined as a power generation standby state, the amount of air fed in by the electric compressor is also minimal. At this time, the amount of air discharged from the exhaust and drainage pipe 12 is also minimal, and the amount of generated water generated during the power generation process of the fuel cell 1 and the drainage capacity are also minimal.

[0026] Here, the power generation standby state is a state in which the fuel cell 1 is stably driven at a power generation of about 10 kW so that power generation can be immediately generated when power is required, considering that it takes a considerable time from the state in which the power generation of the fuel cell 1 is zero to the state in which sufficient power is obtained. The power generation standby state is set in advance when power supply from the fuel cell 1 is not required, so that the fuel cell 1 can immediately generate power to supply the required power in all cases where power is required from the hydraulic excavator 100, such as when there is an input from the operating lever, when a command to increase the speed is input through the motor speed adjustment dial, when the air conditioner is turned on, when charging the LIB, and when purifying the generated water of the fuel cell 1.

[0027] like Figure 2 As shown, in the power supply system of the hydraulic excavator 100 , the fuel cell 1 generates electric power according to a control signal from the controller 9 , and supplies the generated electric power to the inverter 3 and the secondary battery 6 (battery) via the DC / DC converter 2 .

[0028] The secondary battery 6 supplies the stored power to the inverter 3 through the operation of the bidirectional DC / DC converter 7 corresponding to the control signal from the controller 9, and stores the power supplied from the fuel cell 1 via the DC / DC converter 2. The secondary battery 6 is provided with a SOC sensor 8 for detecting the charge rate (SOC: State Of Charge), and the SOC sensor 8 sends the detection result to the controller 9.

[0029] The inverter 3 converts the electric power supplied from the fuel cell 1 and the secondary battery 6 in accordance with a control signal from the controller 9 to drive the electric motor 4 .

[0030] The controller 9 performs power operation control processing to control the operation of the power supply system including the fuel cell 1 and the secondary battery 6 (i.e., the bidirectional DC / DC converter 7) based on the operation signal from the operating panel 11 such as the lever and push switch set in the cab in front of the upper rotating body 1d, the detection results from the SOC sensor 8 and the tilt angle sensor 10, etc.

[0031] Figure 3 : is a flowchart showing the content of the power supply operation control process.

[0032] exist Figure 3 In the process, the controller 9 first determines whether the inclination angle θ of the vehicle body 1B, which is the detection result of the inclination angle sensor 10, is less than a predetermined inclination angle threshold value θth (step S100). The inclination angle threshold value θth is a threshold value for determining whether the inclination angle of the vehicle body 1B (in other words, the inclination angle of the fuel cell 1) is an angle at which the generated water can be sufficiently discharged based on the drainage capacity in the power generation standby state.

[0033] If the result of determination in step S100 is yes, the fuel cell is driven with normal load (step S101). That is, in a series of processes of steps S100 and S101, the hydraulic excavator 100 is controlled to be driven by the power generation of the fuel cell 1 based on normal driving in a state (tilt angle) where the fuel cell 1 can fully discharge the generated water.

[0034] If the result of the determination in step S100 is negative, that is, if it is determined that the inclination angle is such that the generated water cannot be sufficiently discharged based on the drainage capacity in the power generation standby state, it is then determined whether the charging rate of the secondary battery 6 is greater than a predetermined lower limit SOC (charging rate threshold) (step S110). The lower limit SOC is a criterion for determining whether the power supply from the secondary battery 6 to each part of the hydraulic excavator 100 is a storage rate that does not cause a hindrance.

[0035] If the result of determination in step S110 is yes, the state in which the electric motor 4 is driven by the electric power from the secondary battery 6, i.e., the battery driven state (step S120), is switched to the power generation standby state (low load state) of the fuel cell 1 (step S130). That is, in the series of processes of steps S100, S110, S120, and S130, the necessity of drainage is reduced by driving the fuel cell 1 in the low load state and setting the amount of generated water to the minimum in the state (tilt angle) in which the fuel cell 1 cannot sufficiently discharge generated water, and the hydraulic excavator 100 is driven by the electric power of the secondary battery 6 with a sufficient charge rate.

[0036] In addition, if the result of the determination in step S110 is negative, the fuel cell 1 is driven in a high-load state (step S111). That is, in a series of processes of steps S100, S110, and S111, control is performed so that, in a state (tilt angle) in which the fuel cell 1 cannot sufficiently discharge the generated water, and in a case in which the hydraulic excavator 100 cannot be driven by the electric power of the secondary battery 6, the generated water is sufficiently discharged by driving the fuel cell 1 in a high-load state and setting the drainage capacity to the maximum, and the secondary battery 6 is charged.

[0037] Figure 4 It is a diagram showing an example of the time changes of the charging rate of the secondary battery and the vehicle body inclination angle in the power supply operation control process.

[0038] like Figure 4 As shown, when the inclination angle of the vehicle body is less than the inclination angle threshold value θth, the hydraulic excavator 100 is driven by the electric power generated by the normal driving of the fuel cell 1. At this time, the charging rate of the secondary battery 6 is maintained at the maximum value (upper limit SOC).

[0039] When the inclination angle of the vehicle body gradually increases and exceeds the inclination angle threshold value θth, the fuel cell 1 is switched to the power generation standby state to suppress the generation of water, and the hydraulic excavator 100 is switched to be driven by the electric power of the secondary battery 6 .

[0040] Even when the inclination angle of the vehicle body further increases and reaches the maximum inclination angle θmax, the fuel cell 1 is in the power generation standby state, and the hydraulic excavator 100 is driven by the power of the secondary battery 6. Here, the maximum inclination angle θmax is the maximum value of the inclination angle of the vehicle body required to be operable in the construction machine, for example, 35 degrees in all directions of the vehicle body.

[0041] The hydraulic excavator 100 is continuously driven in a state where the inclination angle of the vehicle body is the maximum inclination angle θmax, and when the charging rate of the secondary battery 6 reaches the lower limit value (lower limit SOC), the hydraulic excavator 100 is switched to driving based on the electric power generated by the fuel cell 1 in the high load state, and the secondary battery 6 is charged. Furthermore, when the charging rate of the secondary battery 6 reaches a predetermined intermediate SOC, the fuel cell 1 is switched to the power generation standby state again to suppress the generation of water, and the hydraulic excavator 100 is switched to driving by the electric power of the secondary battery 6.

[0042] The effects of the present embodiment configured as described above will be described.

[0043] The work site where construction machinery is operated also includes inclined areas, but the inclination and direction thereof vary, and there are also cases where ordinary vehicles are operated in inclined areas with large inclinations that are not considered for use. Therefore, in the prior art, it is believed that the discharge of generated water is prone to stagnation due to the inclination of the vehicle body. However, if the drainage of the fuel cell stagnates, it may affect the operating state of the fuel cell or damage the drainage mechanism due to the freezing of the generated water.

[0044] In this regard, the present embodiment includes: a vehicle body 1B; an electric motor 4 as a power source; a fuel cell 1 that generates electric power to be supplied to the electric motor 4; a secondary battery 6 (battery) that stores the electric power generated by the fuel cell 1; a tilt angle sensor 10 that detects the tilt of the vehicle body 1B; and a controller 9 (control device), wherein the controller 9 is configured to switch the power supply to the electric motor 4 from the fuel cell 1 to the secondary battery 6 when the detection result from the tilt angle sensor 10 is above a predetermined tilt angle threshold value θth. Therefore, when the vehicle body is tilted, the amount of generated water generated in conjunction with the power generation of the fuel cell 1 can be suppressed, and even when the vehicle body is tilted, the discharge of the generated water generated during the fuel cell power generation process can be prevented from stagnation.

[0045] It should be noted that in the present embodiment, an example is given of a case where the hydraulic excavator 100 is instantly switched from being driven by the fuel cell 1 to being driven by the secondary battery 6 when the detection result of the inclination angle sensor 10 is above the inclination angle threshold value θth, but the present invention is not limited to this. For example, it may also be configured such that after the detection result of the inclination angle sensor 10 reaches the inclination angle threshold value θth, it is instantly switched to being driven by the secondary battery 6 after a predetermined time.

[0046] In addition, a configuration may be adopted in which a dead zone is set in the determination based on the tilt angle threshold value θth and the charge rate threshold value (lower limit SOC).

[0047] In the present embodiment, the case where the tilt angle threshold value θth is used for all directions of the vehicle body is described as an example, but the present invention is not limited thereto, and a configuration in which different tilt angle threshold values ​​are set according to the tilt direction may be adopted.

[0048] <Note>

[0049] It should be noted that the present invention is not limited to the above-mentioned embodiments, and includes various modifications and combinations within the scope of the gist thereof. In addition, the present invention is not limited to all the configurations described in the above-mentioned embodiments, and also includes configurations in which a part of the configuration is deleted. In addition, the above-mentioned configurations, functions, etc. may also be partially or completely implemented by, for example, integrated circuit design. In addition, the above-mentioned configurations, functions, etc. may also be implemented by software by interpreting and executing programs that implement the functions by a processor.

[0050] Description of Reference Numerals

[0051] 1A…Working device, 1B…Car body, 1a…Boom, 1b…Arm, 1c…Bucket, 1d…Upper swing body, 1e…Lower travel body, 1…Fuel cell, 2…DC / DC converter, 3…Inverter, 4…Electric motor, 5…Hydraulic drive system, 6…Secondary battery, 7…Bidirectional DC / DC converter, 8…SOC sensor, 9…Controller, 10…Tilt angle sensor, 11…Operation panel, 12…Exhaust and drain pipe, 100…Hydraulic excavator

Claims

1. A construction machine, characterized in that: include: Car body; An electric motor as a power source; a fuel cell that generates electric power to be supplied to the electric motor; a battery that stores the electricity generated by the fuel cell; a tilt angle sensor for detecting the tilt of the vehicle body; as well as Control device, The control device switches the power supply to the electric motor from the fuel cell to the battery when the detection result from the inclination angle sensor is equal to or greater than a predetermined inclination angle threshold value.

2. The construction machinery according to claim 1, characterized in that: Even if the detection result from the inclination angle sensor is above a predetermined inclination angle threshold and the charging rate of the battery is below a predetermined charging rate threshold, the control device drives the fuel cell at a high load and switches the power supply to the electric motor from the battery to the fuel cell.

3. The construction machine according to claim 1, characterized in that: When the detection result from the inclination angle sensor is equal to or greater than a predetermined inclination angle threshold value, the control device switches the power supply to the electric motor from the fuel cell to the battery after a predetermined time has elapsed.

4. The construction machinery according to claim 1 or 2, characterized in that: A dead zone is set in the determination based on the tilt angle threshold and the charge rate threshold.

5. The construction machine according to claim 1, characterized in that: The tilt angle threshold is an angle of a limit of permissible operation that is preset as a specification of the fuel cell, or an angle at which generated water cannot be sufficiently discharged when the fuel cell is operated at a low load.

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