Construction machinery
The construction machine addresses water stagnation issues in fuel cells by switching power supply to a secondary battery when the vehicle body tilts beyond a threshold, ensuring effective drainage and maintaining operation.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- HITACHI CONSTRUCTION MACHINERY CO LTD
- Filing Date
- 2023-03-30
- Publication Date
- 2026-07-01
AI Technical Summary
Construction machines operating on sloped areas face issues with water drainage from fuel cells becoming stagnant, which can affect the fuel cell's operation or damage the drainage mechanism due to freezing.
A construction machine equipped with a fuel cell, an electric motor, a secondary battery, a tilt angle sensor, and a control device that switches power supply from the fuel cell to the battery when the vehicle body tilt exceeds a predetermined angle, ensuring adequate drainage and preventing water stagnation.
Prevents water generated during fuel cell power generation from becoming stagnant, even when the vehicle body is tilted, thereby maintaining the fuel cell's operation and preventing drainage mechanism damage.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a construction machine equipped with a fuel cell.
Background Art
[0002] For fuel cells mounted on construction machines such as hydraulic excavators, it is required to appropriately drain the water generated during the power generation process. As a conventional technique related to drainage, for example, Patent Document 1 discloses a fuel cell vehicle including a fuel cell system and an exhaust structure that discharges the cathode exhaust gas flowing out of the fuel cell system to the outside of the vehicle. The exhaust structure includes a main exhaust pipe having a straddle portion provided so as to straddle above a vehicle body structural member from one side in the horizontal direction to the other side, and a drain bypass pipe provided below the vehicle body structural member, branching from the main exhaust pipe at a position on one side in the horizontal direction of the vehicle body structural member, connecting to the main exhaust pipe at a position on the other side in the horizontal direction of the vehicle body structural member, and configured to be thinner than the main exhaust pipe.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] The work sites where construction machines operate include sloped areas, and the slopes and directions are various. There are cases where work is carried out on sloped areas with large slopes that are not considered for use in general automobiles. Therefore, in the above conventional technology, it is conceivable that the drainage of the generated water may be likely to be stagnant depending on the inclination state of the vehicle body. However, if the drainage of the fuel cell is stagnant, it may affect the operating state of the fuel cell or damage the drainage mechanism due to freezing of the generated water.
[0005] The present invention has been made in view of the above, and aims to provide a construction machine that can prevent the drainage of water generated during the power generation process of a fuel cell from becoming stagnant, even when the vehicle body is tilted. [Means for solving the problem]
[0006] The present invention includes several means for solving the above problems, but to give one example, it comprises a vehicle body, an electric motor that serves as a power source, a fuel cell that generates electricity to be supplied to the electric motor, a battery that stores the electricity generated by the fuel cell, a tilt angle sensor that detects the tilt of the vehicle body, and a control device, wherein the control device 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 greater than or equal to a predetermined tilt angle threshold. [Effects of the Invention]
[0007] According to the present invention, even when the vehicle body is tilted, it is possible to prevent the drainage of water generated during the power generation process of the fuel cell from becoming stagnant. [Brief explanation of the drawing]
[0008] [Figure 1] This is a schematic side view showing the external appearance of a hydraulic excavator, an example of construction machinery. [Figure 2] This is a functional block diagram that schematically shows the power supply system of a hydraulic excavator, including a fuel cell, along with its related components. [Figure 3] This flowchart shows the details of the power supply operation control process. [Figure 4] This figure shows an example of the time-dependent changes in the secondary battery charge level and vehicle body tilt angle during power supply operation control processing. [Modes for carrying out the invention]
[0009] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In this embodiment, a hydraulic excavator will be used as an example of construction machinery, but the present invention can also be applied to other construction machinery equipped with fuel cells.
[0010] Figure 1 is a schematic side view showing the external appearance of a hydraulic excavator, which is an example of a construction machine according to this embodiment. Figure 2 is a schematic functional block diagram showing the power supply system of the hydraulic excavator, including a fuel cell, along with its related components.
[0011] As shown in Figure 1, the hydraulic excavator 100 is generally composed of a vehicle body 1B (construction machine body) which consists of a crawler-type lower traveling body 1e and an upper rotating body 1d which is rotatably mounted relative to the lower traveling body 1e, and a working device 1A (front working device) which is rotatably mounted on the front side of the upper rotating body 1d.
[0012] The work device 1A is a multi-jointed front work device composed of multiple driven members (boom 1a, arm 1b, and bucket 1c) that rotate vertically. The base end of the boom 1a is supported on the front of the upper slewing body 1d so as to be rotatable in the vertical direction. One end of the arm 1b is connected to the tip of the boom 1a so as to be rotatable in the vertical direction, and the bucket 1c is connected to the other end (tip) of the arm 1b so as to be rotatable in the vertical direction. The boom 1a, arm 1b, and bucket 1c are driven by hydraulic actuators, a boom cylinder, an arm cylinder, and a bucket cylinder, respectively (not shown).
[0013] The upper rotating body 1d is constructed by arranging each component on a rotating frame that serves as the base. The rotating frame is driven to rotate relative to the lower traveling body 1e by a rotating hydraulic motor, which is a hydraulic actuator (not shown), thereby enabling the upper rotating body 1d to rotate relative to the lower traveling body 1e. The rotating frame of the upper rotating body 1d is equipped with a fuel cell 1 that generates electricity to drive the hydraulic excavator 100, a secondary battery 6 that stores the electricity generated by the fuel cell 1, a tilt angle sensor 10 that detects the inclination (slope, direction of inclination) of the body 1B of the hydraulic excavator 100, an electric motor 4 driven by electricity from the fuel cell 1 and the secondary battery 6, a hydraulic drive system 5 for driving each hydraulic actuator, including a hydraulic pump and a pilot pump, which are driven by the electric motor 4, and a controller 9 that controls the overall operation of the hydraulic excavator 100.
[0014] Fuel cell 1 is a device that generates electricity from a chemical reaction between a fuel (e.g., hydrogen) and an oxidizer (e.g., oxygen). In this embodiment of fuel cell 1, air containing oxygen (oxidizer) necessary for the reaction with hydrogen (fuel) is supplied to the interior by an electric compressor, and the air from which oxygen has been consumed by the reaction, along with the water produced by the reaction (generated water), is discharged from the exhaust drain pipe 12.
[0015] When the fuel cell 1 is operating under normal conditions, for example, when generating electricity in response to a request from the electric motor 4, the generated water is pushed out of the exhaust drain pipe 12 by the exhaust pressure of the air supplied by the electric compressor, from which oxygen has been consumed. Since the amount of oxygen consumed changes according to the operating status of the fuel cell 1 (increase or decrease in power generation), the amount of air supplied by the electric compressor is also changed.
[0016] For example, as the amount of power generated by fuel cell 1 increases, the amount of air supplied (and the amount of air discharged) also increases. When fuel cell 1 is operating under a predetermined high-load state, which is a state where the amount of power generated is greater than normal, the amount of air supplied by the electric compressor is also at its maximum. At this time, the amount of air discharged from the exhaust drain pipe 12 is also at its maximum, and the amount of water generated during the power generation process of fuel cell 1 and the drainage capacity are also at their maximum.
[0017] Similarly, as the amount of power generated by the fuel cell 1 decreases, the amount of air supplied (and the amount of air discharged) also decreases. When the fuel cell 1 is operating in a predetermined low-idle state (low-load state) as a power generation standby state, the amount of air supplied by the electric compressor is also minimized. At this time, the amount of air discharged from the exhaust drain pipe 12 is also minimized, and the amount of water generated during the power generation process of the fuel cell 1 and its drainage capacity are also minimized.
[0018] Here, the power generation standby state is a state in which the fuel cell 1 is steadily driven at a power generation output of about 10 kW, taking into consideration that it takes a considerable amount of time for the fuel cell 1 to go from a state where it generates zero power to a state where it generates a sufficient amount of power, so that it can generate power immediately when power is requested. By keeping the fuel cell 1 in the power generation standby state when power supply from the fuel cell 1 is not required, the fuel cell 1 can immediately generate power and supply the requested power in all cases where the hydraulic excavator 100 requests power, such as when there is input from the operating lever, when a command to increase the rotation speed is input using the motor rotation speed adjustment dial, when the air conditioner is turned on, when the LIB is charged, or when the water generated by the fuel cell 1 is purged.
[0019] As shown in Figure 2, in the power supply system of the hydraulic excavator 100, the fuel cell 1 generates power in response to a control signal from the controller 9 and supplies the generated power to the inverter 3 and secondary battery 6 (battery) via the DC / DC converter 2.
[0020] The secondary battery 6 supplies the stored power to the inverter 3 by the operation of the bidirectional DC / DC converter 7 according 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 that detects the state of charge (SOC), and the SOC sensor 8 transmits the detection result to the controller 9.
[0021] The inverter 3 converts the power supplied from the fuel cell 1 and the secondary battery 6 according to the control signal from the controller 9 and drives the electric motor 4.
[0022] The controller 9 performs a power operation control process for controlling the operation of the power supply system including the fuel cell 1 and the secondary battery 6 (that is, the bidirectional DC / DC converter 7) according to the operation signal from the operation panel 11 such as the lever and key switch provided in the cab in front of the upper swing body 1d, the detection results from the SOC sensor 8 and the tilt angle sensor 10, etc.
[0023] FIG. 3 is a flowchart showing the content of the power operation control process.
[0024] In FIG. 3, the controller 9 first determines whether or not the detection result of the tilt angle sensor 10, that is, the tilt angle θ of the vehicle body 1B is smaller than a predetermined tilt angle threshold θth (step S100). The tilt angle threshold θth is a threshold for determining whether or not the tilt angle of the vehicle body 1B, that is, the tilt angle of the fuel cell 1, is an angle at which the generated water can be sufficiently drained by the drainage capacity in the power generation standby state.
[0025] If the determination result in step S100 is YES, the fuel cell is driven with a normal load (step S101). That is, in the series of processes of steps S100 and S101, when the fuel cell 1 is in a state (tilt angle) where the generated water can be sufficiently drained, the hydraulic excavator 100 is controlled to be driven by the power generation by the normal driving of the fuel cell 1.
[0026] Furthermore, if the result of the determination in step S100 is NO, that is, if it is determined that the angle of inclination is such that the generated water cannot be sufficiently drained by the drainage capacity in the power generation standby state, then it is determined whether the charge level of the secondary battery 6 is greater than a predetermined lower limit SOC (charge level threshold) (step S110). The lower limit SOC is the determination criterion for determining whether the charge level is such that there is no impediment to the power supply from the secondary battery 6 to each part of the hydraulic excavator 100.
[0027] If the result of the determination in step S110 is YES, the system switches to a state in which the electric motor 4 is driven by power from the secondary battery 6, i.e., to a battery-driven state (step S120), and further switches the fuel cell 1 to a power generation standby state (low load state) (step S130). In other words, in the series of processes in steps S100, S110, S120, and S130, when the fuel cell 1 is in a state (inclination angle) where it cannot sufficiently drain the generated water, the fuel cell 1 is driven in a low load state to minimize the amount of generated water, thereby reducing the need for drainage, and the hydraulic excavator 100 is controlled to be driven by the power of the secondary battery 6 with a sufficient charge level.
[0028] Furthermore, if the result of the determination in step S110 is NO, the fuel cell 1 is driven in a high-load state (step S111). In other words, in the series of processes in steps S100, S110, and S111, if the fuel cell 1 is in a state (inclination angle) where it is not possible to sufficiently drain the generated water and the hydraulic excavator 100 cannot be driven by the power of the secondary battery 6, the fuel cell 1 is driven in a high-load state to maximize its drainage capacity, thereby ensuring sufficient drainage of the generated water and charging the secondary battery 6.
[0029] Figure 4 shows an example of the time change in the secondary battery charge rate and vehicle body tilt angle during power supply operation control processing.
[0030] As shown in Figure 4, when the vehicle body's tilt angle is smaller than the tilt angle threshold θth, the hydraulic excavator 100 is driven by the electricity generated by the normal operation of the fuel cell 1. At this time, the charge level of the secondary battery 6 is maintained at its maximum value (upper limit SOC).
[0031] When the tilt angle of the vehicle body gradually increases and exceeds the tilt angle threshold θth, the fuel cell 1 is switched to a power generation standby state to suppress water generation, and the system switches to driving the hydraulic excavator 100 with power from the secondary battery 6.
[0032] Even when the vehicle's tilt angle increases further and reaches the maximum tilt angle θmax, the fuel cell 1 remains in a power generation standby state, and the hydraulic excavator 100 is driven by the power from the secondary battery 6. Here, the maximum tilt angle θmax is the maximum tilt angle of the vehicle body that is required to be operational in construction machinery, and is, for example, 35 degrees in all directions of the vehicle body.
[0033] The hydraulic excavator 100 continues to operate when the vehicle body is tilted at its maximum tilt angle θmax. When the charge level of the secondary battery 6 reaches its lower limit (lower limit SOC), the hydraulic excavator 100 is switched to be driven by electricity generated by the fuel cell 1 under high load, and the secondary battery 6 is charged. When the charge level of the secondary battery 6 reaches a predetermined intermediate SOC, the fuel cell 1 is switched back to the power generation standby state to suppress water generation, and the hydraulic excavator 100 is switched back to be driven by the electricity of the secondary battery 6.
[0034] The effects of this embodiment, configured as described above, will now be explained.
[0035] Construction sites where machinery operates include slopes, but the degree and direction of these slopes vary, and work may be performed on slopes with steep inclines that would not be suitable for use with conventional automobiles. Therefore, with conventional technology, depending on the incline of the vehicle, it is conceivable that the drainage of generated water may become stagnant. However, if the drainage of fuel cell water is stagnant, it may affect the operation of the fuel cell, or the drainage mechanism may be damaged due to the freezing of the generated water.
[0036] In contrast, this embodiment includes a vehicle body 1B, an electric motor 4 that serves as a power source, a fuel cell 1 that generates electricity for the electric motor 4, a secondary battery 6 that stores the electricity 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). 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 greater than or equal to a predetermined tilt angle threshold θth. Therefore, when the vehicle body is tilted, the amount of water generated in conjunction with the power generation by the fuel cell 1 can be suppressed, and even when the vehicle body is tilted, the drainage of water generated during the power generation process of the fuel cell can be prevented from becoming stagnant.
[0037] In this embodiment, the example described is one in which the hydraulic excavator 100 is immediately switched from being driven by the fuel cell 1 to being driven by the secondary battery 6 when the detection result of the tilt angle sensor 10 is greater than or equal to the tilt angle threshold θth. However, the embodiment is not limited to this, and for example, the system may be configured to immediately switch to being driven by the secondary battery 6 after a predetermined time has elapsed since the detection result of the tilt angle sensor 10 reached the tilt angle threshold θth.
[0038] Furthermore, a dead zone may be set for the determination based on the inclination angle threshold θth and the charge threshold (lower limit SOC).
[0039] Furthermore, although this embodiment illustrates and explains the case where a tilt angle threshold θth is used for all directions of the vehicle body, it is not limited to this, and the system may be configured to set and use different tilt angle thresholds depending on the direction of tilt.
[0040] <Note> It should be noted that the present invention is not limited to the embodiments described above, and includes various modifications and combinations that do not depart from the spirit of the invention. Furthermore, the present invention is not limited to having all the configurations described in the embodiments described above, and includes configurations in which some of the configurations are omitted. In addition, some or all of the above configurations, functions, etc. may be realized by designing, for example, an integrated circuit. Furthermore, each of the above configurations, functions, etc. may be realized in software by having a processor interpret and execute a program that realizes each function. [Explanation of Symbols]
[0041] 1A…Working device, 1B…Vehicle body, 1a…Boom, 1b…Arm, 1c…Bucket, 1d…Upper slewing body, 1e…Lower traveling 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…Control panel, 12…Exhaust drain pipe, 100…Hydraulic excavator
Claims
1. The car body and, The electric motor serves as the power source, A fuel cell that generates electricity to supply to the electric motor, A battery for storing the electricity generated by the fuel cell, An inclination angle sensor for detecting the tilt of the vehicle body, A control device is provided, The control device 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 greater than or equal to a predetermined tilt angle threshold and the charge level of the battery is greater than a predetermined charge level threshold, and drives the fuel cell at a high load when the detection result from the tilt angle sensor is greater than or equal to a predetermined tilt angle threshold and the charge level of the battery is less than or equal to a predetermined charge level threshold.
2. A vehicle body and, The electric motor serves as the power source, A fuel cell that generates electricity to supply to the electric motor, A battery for storing the electricity generated by the fuel cell, An inclination angle sensor for detecting the tilt of the vehicle body, A control device is provided, If the detection result from the tilt angle sensor is greater than or equal to a predetermined tilt angle threshold, the control device switches the power supply to the electric motor from the fuel cell to the battery. A construction machine characterized in that, even if the detection result from the tilt angle sensor is greater than or equal to a predetermined tilt angle threshold, if the charge level of the battery is less than or equal to a predetermined charge level threshold, the fuel cell is driven at a high load and the power supply to the electric motor is switched from the battery to the fuel cell.
3. In the construction machine described in claim 1, The control device is characterized in that, if the detection result from the tilt angle sensor is greater than or equal to a predetermined tilt angle threshold, it switches the power supply to the electric motor from the fuel cell to the battery after a predetermined time has elapsed.
4. In the construction machine according to claim 1 or 2, A construction machine characterized in that a dead zone is set for the determination based on the inclination angle threshold and the charge level threshold.
5. In the construction machine described in claim 1, The construction machine is characterized in that the tilt angle threshold is the limit angle at which operation is permitted as predetermined in the specifications of the fuel cell, or the angle at which the generated water cannot be sufficiently drained when the fuel cell is operated at a low load.