Earthmoving machinery

Abstract

To provide an earthwork machine which achieves high insulation resistance while equipped with a fuel battery.SOLUTION: An earthwork machine includes a vehicle body, a fuel battery, a housing, and a refrigerant pipe. The housing contains the fuel battery and is electrically connected to the vehicle body. The refrigerant pipe penetrates through the housing and allows a refrigerant to flow from the outside of the housing to the fuel battery. The refrigerant pipe is electrically insulated from the housing. The refrigerant and the vehicle body are electrically connected at the outside of the housing.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to earthmoving machinery.

Background Art

[0002] In recent years, in order to use clean energy as the power source of earthmoving machinery instead of fossil fuels, it has been considered to equip earthmoving machinery with fuel cells. Patent Document 1 discloses a technique for grounding means of a vehicle equipped with a fuel cell.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, while a fuel cell has a low insulation resistance, a high insulation resistance is required for earthmoving machinery such as dump trucks. For example, in ISO14990-1, ISO14990-2, and ISO14990-3, an insulation resistance of 1 MΩ or more is required between the power circuit provided in earthmoving machinery and the equipotential bonding circuit. An object of the present disclosure is to provide an earthmoving machinery that can achieve a high insulation resistance while mounting a fuel cell.

Means for Solving the Problems

[0005] According to one aspect of the present disclosure, an earthmoving machinery includes a vehicle body, a fuel cell, a housing that stores the fuel cell and is electrically connected to the vehicle body, and a refrigerant pipe that penetrates the housing and allows refrigerant to flow from the outside of the housing to the fuel cell, the refrigerant pipe being electrically insulated from the housing and configured such that the refrigerant and the vehicle body are electrically connected outside the housing.

Effects of the Invention

[0006] According to the above embodiment, high insulation resistance can be achieved while incorporating a fuel cell. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic perspective view showing a transport vehicle according to the first embodiment. [Figure 2] This is a schematic diagram showing the configuration of a fuel cell unit according to the first embodiment. [Figure 3] This is a schematic block diagram showing the configuration of the electrical system of a transport vehicle according to the first embodiment. [Modes for carrying out the invention]

[0008] <First Embodiment> 《Configuration of transport vehicle 10》 The embodiments will be described in detail below with reference to the drawings. The transport vehicle 10 according to the first embodiment is a rigid-frame dump truck used to transport crushed stone and other materials excavated in mines, etc. The transport vehicle 10 is driven by a fuel cell that uses hydrogen gas as fuel. The transport vehicle 10 is an example of earthmoving machinery. Figure 1 is a schematic perspective view showing a transport vehicle 10 according to the first embodiment. The transport vehicle 10 comprises a dump body 11, a vehicle body 12, and a running gear 13.

[0009] The dump body 11 is the component on which the cargo is loaded. At least a portion of the dump body 11 is positioned above the vehicle body 12. The dump body 11 performs dumping and lowering operations. Through the dumping and lowering operations, the dump body 11 is adjusted to a dumping position and a loading position. The dumping position refers to the position in which the dump body 11 is raised. The loading position refers to the position in which the dump body 11 is lowered.

[0010] The dumping operation refers to the movement of separating the dump body 11 from the vehicle body 12 and tilting it in the dumping direction. The dumping direction is towards the rear of the vehicle body 12. In this embodiment, the dumping operation includes raising the front end of the dump body 11 and tilting the dump body 11 backward. Due to the dumping operation, the loading surface of the dump body 11 is tilted downward toward the rear.

[0011] The lowering operation refers to the operation of bringing the dump body 11 closer to the vehicle body 12. In this embodiment, the lowering operation includes lowering the front end of the dump body 11.

[0012] When performing soil removal operations, the dump body 11 performs a dumping operation to change from a loading position to a dumping position. If there is cargo loaded on the dump body 11, the cargo is discharged backward from the rear end of the dump body 11 by the dumping operation. When performing loading operations, the dump body 11 is adjusted to a loading position.

[0013] The vehicle body 12 includes a vehicle frame (not shown). The vehicle frame constitutes a protective equipotential bonding circuit for the transport vehicle 10. The vehicle body 12 rotatably supports the dump body 11 via hinge pins provided on the vehicle frame. The vehicle body 12 is supported by the running gear 13. A platform 121 is provided on the vehicle frame above the front wheels of the running gear 13. The platform 121 is a flat plate that forms the upper surface of the vehicle frame. A driver's cab 122, a control cabinet 123, and a retarder grid 69 are provided on the platform 121. A fuel cell system 40 is also provided on the vehicle frame. An opening with a grille 124 fitted into it is provided on the front of the vehicle body 12.

[0014] The control cabinet 123 performs power conversion. Specifically, the control cabinet 123 controls the power between the fuel cell system 40, various electrical equipment (battery 62, drive motor 65, hydraulic pump motor 67, etc.), and the retarder grid 69. The retarder grid 69 is a resistor that absorbs the regenerative power generated by the braking of the traction unit 13. The retarder grid 69 converts the regenerative power into thermal energy.

[0015] The running gear 13 supports the vehicle body 12. The running gear 13 moves the transport vehicle 10. The running gear 13 moves the transport vehicle 10 forward or backward. At least a portion of the running gear 13 is positioned below the vehicle body 12. The running gear 13 comprises a pair of front wheels and a pair of rear wheels. The front wheels are steering wheels, and the rear wheels are drive wheels.

[0016] Figure 2 is a schematic diagram showing the configuration of the fuel cell unit 41 according to the first embodiment. The fuel cell system 40 comprises a plurality of fuel cell units 41. Each fuel cell unit 41 comprises a housing 411 and a fuel cell 412, as shown in Figure 2. The fuel cell 412 is housed in the housing 411. The fuel cell 412 generates electricity by electrochemically reacting hydrogen supplied from a hydrogen tank (not shown) with oxygen contained in the outside air. The fuel cell 412 is provided with a cooling water channel 413, which is a passage through which cooling water flows, and is configured to allow temperature control of the fuel cell 412. The housing 411 is made of metal. The housing 411 and the fuel cell 412 are electrically insulated. For example, a spacer made of an insulator may be provided between the housing 411 and the fuel cell 412. The housing 411 is electrically connected to the vehicle frame. That is, the housing 411 is frame-grounded.

[0017] The fuel cell system 40 includes a plurality of radiators 42 corresponding to the fuel cell unit 41. Each radiator 42 is provided side by side at the rear stage of the grille 124. The radiator 42 cools the cooling water by the outside air flowing in through the grille and supplies it to the corresponding fuel cell unit 41. The radiator 42 is electrically connected to the vehicle body frame. That is, the radiator 42 is frame grounded. A cooling water pipe 43 (first cooling water pipe 43A and second cooling water pipe 43B) is connected to the radiator 42. One end of the first cooling water pipe 43A is connected to the discharge port of the radiator 42, and the other end is connected to the inlet of the cooling water channel 413 in the fuel cell 412. One end of the second cooling water pipe 43B is connected to the discharge port of the cooling water channel 413 of the fuel cell 412, and the other end is connected to the inlet of the radiator 42. The wall surface of the cooling water channel 413 in the fuel cell 412 is made of metal. Therefore, the cooling water passing through the cooling water channel 413 is electrically connected to the output voltage of the fuel cell 412. Note that the cooling water is an example of a refrigerant, and the cooling water pipe 43 is an example of a refrigerant pipe.

[0018] The cooling water pipe 43 has an inner pipe 431 made of an insulator and a shield part 432 made of metal covering the inner pipe 431. Therefore, the cooling water passing through the cooling water pipe 43 is electrically insulated from the housing 411. On the other hand, the shield part 432 of the cooling water pipe 43 is electrically connected to the housing 411. A circulation pump 44 for circulating the cooling water is provided in the first cooling water pipe 43A. The circulation pump 44 is driven by a circulation pump motor 64. The circulation pump motor 64 is electrically connected to the vehicle body frame. That is, the circulation pump motor 64 is frame grounded. The circulation pump 44 is provided outside the housing 411 and is an example of a refrigerant pump that pumps the cooling water in the cooling water pipe 43. The length of the first cooling water pipe 43A from the fuel cell 412 to the pump 44 and the length of the second cooling water pipe 43B from the radiator 42 are not less than the lengths at which the resistance of the cooling water in each cooling pipe becomes a predetermined insulation resistance (for example, 1 MΩ). Here, if the length of the pipe is L, the resistivity of the cooling water is ρ, and the cross-sectional area of the pipe is S, the resistance of the cooling water can be expressed as R = ρ·L / S.

[0019] With the above configuration, the fuel cell 412 is connected to the frame-earthed circulation pump motor 64 and the radiator 42 via the cooling water flowing through the cooling water pipe 43. Since the inner pipe 431 of the cooling water pipe 43 is made of an insulator and is configured to have a length such that the resistance of the cooling water is equal to or greater than the insulation resistance, the fuel cell 412 can ensure the insulation resistance required for the construction machinery. Since the cooling water is installed on the frame earth via the insulation resistance, it will have a potential between the output voltage of the fuel cell and the frame earth. However, by providing a metal shield part 432 outside the cooling water pipe 43, even if water leakage occurs in the cooling water pipe 43, the leaked cooling water touches the shield part 432 and is frame-earthed via the circulation pump motor 64 or the radiator 42.

[0020] 《Configuration of Electrical System 60》 FIG. 3 is a schematic block diagram showing the configuration of the electrical system 60 of the transport vehicle 10 according to the first embodiment. The electrical system 60 includes a fuel cell unit 41, a first DCDC converter 61, a battery 62, a second DCDC converter 63, a circulation pump motor 64, a traveling motor 65, a first inverter 66, a hydraulic pump motor 67, a second inverter 68, a retard grid 69, and a control device 80. The first DCDC converter 61, the second DCDC converter 63, the first inverter 66, the second inverter 68, and the control device 80 are provided in the control cabinet 123.

[0021] The electrical system 60 is equipped with the same number of first DC-DC converters 61 as the number of fuel cell units 41. Each first DC-DC converter 61 is connected to the corresponding fuel cell unit 41. The first DC-DC converter 61 supplies DC power generated by the fuel cell system 40 to busbar B. The first DC-DC converter 61 is an isolated DC-DC converter. That is, the first DC-DC converter 61 has a transformer, and the primary side (fuel cell unit 41 side) and the secondary side (busbar B side) are isolated. As a result, even if multiple fuel cell units 41 are installed in parallel, if each fuel cell unit 41 can secure the necessary insulation resistance, the entire electrical system 60 can also secure the necessary insulation resistance.

[0022] Battery 62 stores the electricity generated in the fuel cell system 40. Battery 62 may also store regenerative power generated in the drive motor 65. Battery 62 outputs the stored electricity. The second DC-DC converter 63 supplies the electricity charged in battery 62 to bus B. The second DC-DC converter 63 also charges battery 62 by adjusting the voltage of the DC power flowing to bus B and supplying it to battery 62. In other words, the second DC-DC converter 63 is an example of a DC-DC converter that can convert power in both directions. Battery 62 is equipped with a Battery Management System (BMS) (not shown) that monitors the state of battery 62. The BMS measures the charge rate of battery 62 and outputs the measurement data to the control device 80.

[0023] The circulation pump motor 64 drives the circulation pump 44 shown in Figure 2 using the DC power flowing through busbar B. The traction motor 65 is a three-phase AC electric motor that drives the traction device 13. The first inverter 66 converts the DC power flowing through busbar B into three-phase AC power and supplies it to the traction motor 65. The first inverter 66 also converts the regenerative power generated by the traction motor 65 into DC current and supplies it to the retarder grid 69.

[0024] The hydraulic pump motor 67 is a three-phase AC electric motor that drives a hydraulic pump (not shown) for driving the dump body 11. The second inverter 68 converts the DC power flowing through busbar B into three-phase AC power and supplies it to the hydraulic pump motor 67.

[0025] The control device 80 controls the first DC-DC converter 61, the second DC-DC converter 63, the first inverter 66, and the second inverter 68.

[0026] Action / Effect As described above, the transport vehicle 10 according to the first embodiment has the following configuration. The transport vehicle 10 includes a housing 411 that is electrically connected to the vehicle body 12 and houses the fuel cell 412, and a cooling water pipe 43 that penetrates the housing 411 and carries refrigerant to the fuel cell 412 from outside the housing 411. In the first embodiment, the cooling water pipe 43 is electrically insulated from the housing 411, and the cooling water passing through the cooling water pipe 43 is electrically connected to the vehicle body 12 outside the housing 411. By electrically insulating the fuel cell 412 according to the first embodiment from the housing 411, it is possible to prevent it from being electrically connected to the vehicle body 12 with low resistance through the housing 411. In addition, although electricity flows through the cooling water passing through the cooling water pipe 43, since it is insulated from the housing 411 and electrically connected to the vehicle body 12 outside the housing 411, it is possible to obtain resistance corresponding to the distance from the fuel cell 412 to the point where it is grounded to the frame. As a result, the transport vehicle 10 can achieve high insulation resistance while being equipped with a fuel cell 412.

[0027] Furthermore, in the first embodiment, the circulation pump motor 64 is frame-grounded, so that the electricity flowing through the cooling water in the cooling water piping 43 is frame-grounded via the circulation pump motor 64. In other embodiments of the transport vehicle 10, frame grounding may not be achieved via the circulation pump motor 64, but for example, via the circulation pump 44, or by other configurations such as contacting the shaft of the motor 64 with a frame-grounded brush (not shown). In addition, since the radiator 42 in the first embodiment is frame-grounded, the electricity flowing through the cooling water is frame-grounded not only via the circulation pump motor 64 but also via the radiator 42. On the other hand, the radiator 42 can be left at a floating potential without being frame-grounded. In this case, since the radiator 42 has a potential, it is covered with the grille 124 and housing to prevent easy access by people. The circulation pump motor 64 and the circulation pump 44 can also be left at a floating potential. In this case, since the circulation pump motor 64 and circulation pump 44 have an electrical potential, they are covered with a housing (not shown) to prevent easy access by people.

[0028] Furthermore, in the transport vehicle 10 according to the first embodiment, the length of the first cooling water pipe 43A from the fuel cell 412 to the pump 44 and the length of the second cooling water pipe 43B from the radiator 42 are greater than or equal to the length at which the resistance of the cooling water passing through the cooling water pipe 43 becomes a predetermined insulation resistance. As a result, the transport vehicle 10 can obtain the desired insulation resistance. In addition, by ensuring the insulation resistance with the length of the portion that is outside the housing 411, the length of the piping inside the housing 411 can be shortened, and the size of the housing 411 itself can be reduced. Furthermore, although the distances between the multiple fuel cell units 41 and the corresponding radiators 42 in the transport vehicle 10 according to the first embodiment are all different, the insulation resistance of each fuel cell unit 41 can be made uniform by making the length of the portion of the cooling water pipe 43 that is outside the housing 411 the same.

[0029] Furthermore, the cooling water piping 43 according to the first embodiment has an inner pipe 431 made of an insulator and a shield portion 432 made of metal that covers the inner pipe 431. As a result, even if water leaks from the cooling water piping 43, the cooling water can be grounded to the frame by coming into contact with the shield portion 432.

[0030] Furthermore, in the first embodiment, the transport vehicle 10 is connected to a first DC-DC converter 61, which is an insulated DC-DC converter, corresponding to each of the multiple fuel cell units 41. As a result, if the necessary insulation resistance is secured for each fuel cell unit 41, the necessary insulation resistance can be secured for the entire electrical system 60. For example, in the comparative example, if the first DC-DC converter 61 is a non-insulated DC-DC converter, the fuel cell units 41 are connected in parallel, so the insulation resistance that each fuel cell unit 41 must secure is several times the parallel insulation resistance required for earthmoving machinery. Therefore, in the transport vehicle 10 according to the first embodiment, the insulation resistance that each fuel cell unit 41 must secure can be reduced. Note that if a non-insulated DC-DC converter is used as the first DC-DC converter 61, the length of the cooling water piping 43 may be set to a length that can obtain a resistance value several times the parallel insulation resistance required for one fuel cell unit 41, thereby ensuring the necessary insulation resistance for the entire electrical system 60.

[0031] <Other Embodiments> Although one embodiment has been described in detail with reference to the drawings above, the specific configuration is not limited to that described above, and various design changes are possible. The fuel cell system 40 according to the above embodiment includes, but is not limited to, a plurality of radiators 42 corresponding to a plurality of fuel cell units 41. For example, the fuel cell system 40 may include a single radiator 42. In this case, the cooling water cooled by the radiator 42 may be branched to each fuel cell unit 41, for example, via a manifold. A circulation pump 44 is provided downstream of the manifold for each fuel cell unit 41. In another embodiment, the cooling water cooled by the radiator 42 may be supplied to a plurality of fuel cell units 41 by a single circulation pump 44. In this case, the cooling water piping 43 branches downstream of the circulation pump 44 and is connected in parallel to each fuel cell unit 41. [Explanation of Symbols]

[0032] 10…Transport vehicle 11…Dump body 12…Vehicle body 121…Platform 122…Driver's cab 123…Control cabinet 124…Grille 13…Running gear 40…Fuel cell system 41…Fuel cell unit 411…Housing 412…Fuel cell 413…Cooling water channel 42…Radiator 43…Cooling water piping 431…Internal piping 432…Shield section 43A…First cooling water piping 43B…Second cooling water piping 44…Circulation pump 60…Electrical system 61…First DC-DC converter 62…Battery 63…Second DC-DC converter 64…Circulation pump motor 65…Running motor 66…First inverter 67…Hydraulic pump motor 68…Second inverter 69…Retarder grid 80…Control device B…Busline

Claims

1. The car body and, Fuel cells and A housing that houses the fuel cell and is electrically connected to the vehicle body, A refrigerant pipe that penetrates the housing and allows refrigerant to flow from outside the housing to the fuel cell, the refrigerant pipe being electrically insulated from the housing and configured such that the refrigerant and the vehicle body are electrically connected outside the housing. Equipped with, Of the refrigerant piping, the length from the fuel cell to the point where the refrigerant and the vehicle body are electrically connected is greater than or equal to the length at which the resistance of the refrigerant flowing through the refrigerant piping becomes a predetermined insulation resistance. Earthmoving machinery.

2. A refrigerant pump is provided outside the housing and pumps the refrigerant through the refrigerant piping. A pump motor that drives the refrigerant pump and Equipped with, The pump motor is electrically connected to the vehicle body. Earthmoving machinery according to claim 1.

3. The refrigerant piping comprises an inner pipe made of an insulator and a shield portion made of metal that covers the inner pipe. Earthmoving machinery according to claim 1 or claim 2.

4. The shield portion is electrically connected to the housing, The fuel cell is connected to the internal piping, but the shielding section is not connected. Earthmoving machinery according to claim 3.

5. Multiple fuel cells, including the aforementioned fuel cell, Multiple isolated DC-DC converters, each having a primary side connected to each of the multiple fuel cells and a secondary side connected to each other in parallel. Earthmoving machinery according to any one of claims 1 to 4, comprising:

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