WORK MACHINE

Abstract

A working machine contains: a fuel cell, a lithium-ion capacitor connected in parallel to the fuel cell; an electric motor to which power is supplied by at least one of the fuel cell and the lithium-ion capacitor, and a target object driven by the electric motor.

Description

Area

[0001] The present disclosure relates to a work machine. background

[0002] One of the most pressing concerns on the path to carbon neutrality is achieving zero emissions from off-highway machinery. A fuel cell-powered off-highway machine has been proposed as a means to achieve zero emissions.

[0003] A drive method of a fuel cell system is roughly divided into a drive method using a fuel cell as the main power source and a drive method using an energy storage device as the main power source. The drive method using a fuel cell as the main power source is a method that combines a high-performance fuel cell as the main power source and a low-power storage device that supports the fuel cell. The drive method using an energy storage device as the main power source is a method that combines a large-capacity energy storage device as the main power source and a small-capacity fuel cell that supplies power to the energy storage device.

[0004] Patent Literature 1 discloses a crane with a fuel cell unit of a propulsion method that uses an energy storage device as the main power source. The crane disclosed in Patent Literature 1 includes an electric double-layer capacitor (EDLC), also called a supercapacitor, as a storage battery. Citation listPatent literature

[0005] Patent Literature 1: US Patent Application No. 2013 / 0038249 Short summaryTechnical problem

[0006] The powertrain that uses an energy storage device as the main power source requires a large-capacity energy storage device. This increases the volume of the fuel cell system, which affects its mountability on a work machine. Furthermore, the use of a large-capacity energy storage device as the main power source increases the fluctuation of the state of charge (SOC). In general, a large fluctuation in SOC accelerates the deterioration of the energy storage device and shortens the service life of the device. To counteract the shortened service life of the energy storage device, the fluctuation in SOC must be reduced in relation to the storage capacity. Reducing the fluctuation in SOC requires a further increase in the capacity of the energy storage device.

[0007] An object of the present disclosure is to provide a work machine with a fuel cell system that has a long service life and is capable of counteracting enlargement. Solution to the problem

[0008] According to one aspect of the present invention, a work machine includes: a fuel cell; a lithium-ion capacitor connected in parallel to the fuel cell; an electric motor to which power is supplied by at least one of the fuel cell and the lithium-ion capacitor; and a target driven by the electric motor. Advantageous effects of the invention

[0009] According to the present disclosure, a work machine with a fuel cell system is provided that has a long service life and is capable of counteracting size growth. Brief Description of the Drawings Fig. 1 is a perspective view illustrating a work machine according to a first embodiment. Fig. 2 is a diagram illustrating a drive system of the working machine according to the first embodiment. Fig. 3 is a diagram illustrating a cooling system of the working machine according to the first embodiment. Fig. Figure 4 is a diagram illustrating the response of an internal combustion engine. Fig. Figure 5 is a diagram illustrating the response of a fuel cell. Fig. 6 is a diagram illustrating a drive system of a work machine according to a second embodiment. Fig. 7 is a diagram illustrating a drive system of a work machine according to a third embodiment. Fig. 8 is a diagram illustrating a drive system of a work machine according to a fourth embodiment. Fig. 9 is a diagram illustrating a drive system of a work machine according to a fifth embodiment. Description of the embodiments

[0010] Embodiments according to the present disclosure will be described below with reference to the drawings, but the present disclosure is not limited to the embodiments. The components described in the following embodiments can be combined with each other as appropriate. In some cases, some of the components are not used. [First embodiment]

[0011] A first embodiment is described. <arbeitsmaschine>

[0012] Fig. 1 is a perspective view illustrating a work machine 1 according to the present embodiment. In the present embodiment, the work machine 1 is an excavator, which is a type of construction machine.

[0013] As in Fig. 1, the working machine 1 includes: a chassis 2; a swing body 3 supported by the chassis 2; a working implement 4 supported by the swing body 3; and a working implement cylinder 5 that actuates the working implement 4.

[0014] The carriage 2 includes a drive wheel 2A and a crawler belt 2B, which is rotated by the drive wheel 2A. When the crawler belt 2B rotates, the work machine 1 can travel at the work site.

[0015] The swivel body 3 swivels in a state in which it is supported by the chassis 2.

[0016] The working equipment 4 (may also be referred to as working equipment) includes: a boom 4A connected to the swing body 3; an arm 4B connected to the boom 4A; and a bucket 4C connected to the arm 4B.

[0017] The work implement cylinder 5 is a hydraulic cylinder that generates power to operate the work implement 4. The work implement cylinder 5 includes: a boom cylinder 5A that operates the boom 4A; an arm cylinder 5B that operates the arm 4B; and a bucket cylinder 5C that operates the bucket 4C. <brennstoffzellensystem>

[0018] Fig. 2 is a diagram illustrating a drive system 6A of the work machine 1 according to the present embodiment. In the present embodiment, the drive system 6A includes a fuel cell system 7 that employs a drive method using a fuel cell 8 as the main power source. The drive method using the fuel cell 8 as the main power source is a method in which the high-performance fuel cell 8 is combined as the main power source with a small-sized energy storage device that supports the fuel cell 8. In the present embodiment, the energy storage device is a lithium-ion capacitor (LiC) 9.

[0019] The drive system 6A includes: the fuel cell 8, the lithium-ion capacitor 9 connected in parallel to the fuel cell 8; and a pump drive motor 10 and a swing motor 11, both of which receive power from at least one of the fuel cell 8 and the lithium-ion capacitor 9. The pump drive motor 10 and the swing motor 11 are individual electric motors.

[0020] The drive system 6A includes: a power line 13 individually connected to the pump drive motor 10 and the swing motor 11; a first connection line 14 connecting the fuel cell 8 and a first portion 13A of the power line 13; a second connection line 15 connecting the lithium-ion capacitor 9 and a second portion 13B of the power line 13; and a DC / DC converter 16 (first DC / DC converter) disposed in the first connection line 14 between the fuel cell 8 and the first portion 13A.

[0021] The fuel cell 8 generates electrical power through an electrochemical reaction between hydrogen and oxygen. The fuel cell 8 is arranged on the pivoting body 3. The fuel cell 8 is connected to a hydrogen tank 12. The hydrogen tank 12 is arranged in the pivoting body 3. An outside air inlet is provided at least on a part of the pivoting body 3. The fuel cell 8 generates electrical power through an electrochemical reaction between the hydrogen supplied from the hydrogen tank 12 and the oxygen contained in the air coming from the outside air inlet.

[0022] The lithium-ion capacitor 9 stores regenerative energy. In the present embodiment, the lithium-ion capacitor 9 stores regenerative energy of the swing motor 11. The lithium-ion capacitor 9 is charged by both or one of the regenerative voltage of the swing motor 11 and the voltage of the fuel cell 8. The lithium-ion capacitor 9 is charged by the regenerative power supplied from the swing motor 11 via the second connection line 15. The lithium-ion capacitor 9 is charged by the power supplied from the fuel cell 8 via the DC / DC converter 16 and the second connection line 15. The lithium-ion capacitor 9 is arranged in the swing body 3. The lithium-ion capacitor 9 has a positive electrode and a negative electrode. The positive electrode and the negative electrode of the lithium-ion capacitor 9 are made of different materials.The positive electrode of the lithium-ion capacitor 9 is often made of the same material as the positive electrode of an electric double-layer capacitor (EDLC). The negative electrode of the lithium-ion capacitor 9 is often made of the same material as the negative electrode of a lithium-ion secondary battery. For example, the positive electrode of the lithium-ion capacitor 9 is made of activated carbon, and the negative electrode of the lithium-ion capacitor 9 is made of carbon. During charging and discharging of the lithium-ion capacitor 9, a chemical reaction occurs at the negative electrode, while essentially no chemical reaction occurs at the positive electrode.

[0023] The lithium-ion capacitor 9 has a higher energy density [Wh / L] than the electric double-layer capacitor. Energy density refers to the amount of energy that can be extracted per unit volume. The lithium-ion capacitor 9 is superior to the electric double-layer capacitor in terms of service life and heat resistance.

[0024] The lithium-ion capacitor 9 is superior to the lithium-ion secondary battery in terms of responsiveness. This means that the lithium-ion capacitor 9 can be charged and discharged at a higher rate than the lithium-ion secondary battery.

[0025] The pump drive motor 10 is driven by power supplied from the fuel cell 8 or the lithium-ion capacitor 9, or both. The work machine 1 includes a hydraulic pump 19. The pump drive motor 10 generates power to enable the operation of the hydraulic pump 19. The hydraulic pump 19 is driven by a pump drive motor 10, which is an electric motor. The hydraulic pump 19 is an example of a target object of the work machine 1 driven by the electric motor.

[0026] The hydraulic oil discharged from the hydraulic pump 19 is supplied individually to the implement cylinder 5 and a travel motor 2C of the chassis 2 via a control valve 20. Supplying the hydraulic oil to the implement cylinder 5 actuates the implement cylinder 5. Supplying the hydraulic oil to the travel motor 2C enables the operation of the travel motor 2C. The travel motor 2C is a hydraulic motor that drives the drive wheels 2A of the chassis 2.

[0027] The swing motor 11 is powered by power supplied from the fuel cell 8 or the lithium-ion capacitor 9, or both. The swing motor 11 generates power that enables the swing of the swing body 3. The swing body 3 is swung by an electric motor 11, which is a swing motor. The swing body 3 is an example of a target object section of the work machine 1 driven by the electric motor.

[0028] The power line 13 is individually connected to the pump drive motor 10 and the swing motor 11. Part of the power line 13 is connected to the pump drive motor 10 via an inverter 17. Another part of the power line 13 is connected to the swing motor 11 via an inverter 18.

[0029] The fuel cell 8 and the lithium-ion capacitor 9 are connected in parallel to the power line 13. The fuel cell 8 and the first section 13A of the power line 13 are connected to each other via the first connecting line 14. The lithium-ion capacitor 9 and the second section 13B of the power line 13 are connected to each other via the second connecting line 15. The fuel cell 8 individually supplies power to the pump drive motor 10 and the swing motor 11 via the first connecting line 14 and the power line 13. The lithium-ion capacitor 9 can individually supply power to the pump drive motor 10 and the swing motor 11 via the second connecting line 15 and the power line 13.

[0030] The DC / DC converter 16 (also referred to as a DC / DC converter) is arranged on the first connecting line 14 between the fuel cell 8 and the power line 13. The DC / DC converter 16 converts a voltage of the fuel cell 8. The power of the fuel cell 8 is individually supplied to the pump drive motor 10 and the swing motor 11 via the DC / DC converter 16. The DC / DC converter 16 amplifies the voltage of the fuel cell 8 with a predetermined amplification ratio. The voltage of the fuel cell 8 amplified by the DC / DC converter 16 is individually applied to the inverter 17 connected to the pump drive motor 10 and to the inverter 18 connected to the swing motor 11.

[0031] The DC / DC converter 16 is a unidirectional DC / DC converter that can only deliver power from the primary side to the secondary side. The primary side of the DC / DC converter 16 is a low-voltage side (the fuel cell 8 side). The secondary side of the DC / DC converter 16 is a high-voltage side (the power line 13 side).

[0032] The converter 17 is connected to a portion of the power line 13. The converter 17 converts a direct current from the power line 13 into a three-phase alternating current and supplies the resulting current to the pump drive motor 10. The pump drive motor 10 is driven based on the three-phase alternating current supplied by the converter 17.

[0033] The converter 18 is connected to a portion of the power line 13. The converter 18 converts a direct current from the power line 13 into a three-phase alternating current and supplies the resulting current to the swing motor 11. The swing motor 11 is driven based on the three-phase alternating current supplied by the converter 18.

[0034] The fuel cell 8 is a main power source of the drive system 6A. The fuel cell 8 supplies power to the pump drive motor 10 and the swing motor 11 individually. The pump drive motor 10 and the swing motor 11 are individually driven only by the power supplied by the fuel cell 8. That is, most of the power for individually driving the pump drive motor 10 and the swing motor 11 is covered by the power output from the fuel cell 8. The power output from the lithium-ion capacitor 9 is used for the pump drive motor 10 and the swing motor 11 individually when immediate response is required. <Kühlsystem>

[0035] Fig. 3 is a diagram illustrating a cooling system 21 of the working machine 1 according to the present embodiment. As shown in Fig. 3, the cooling system 21 includes: a first cooling system 23 that cools a hydraulic system 22 of the work machine 1; a second cooling system 25 that cools the lithium-ion capacitor 9, the DC / DC converter 16, and a component 24 of the fuel cell system 7; and a third cooling system 27 that cools the fuel cell 8 of the fuel cell system 7. An example of the component 24 of the fuel cell system 7 is an air compressor driven to supply the fuel cell 8 with air from the outside air intake port described above.

[0036] The first cooling system 23 includes: a radiator 23A that cools the refrigerant; a circulation channel 23B that includes the radiator 23A and the hydraulic system 22; and a circulation pump 23C that circulates the refrigerant in the circulation channel 23B.

[0037] The second cooling system 25 includes: a radiator 25A that cools the refrigerant; a circulation channel 25B that includes the radiator 25A, the lithium-ion capacitor 9, the DC / DC converter 16, and the component 24; and a circulation pump 25C that circulates the refrigerant in the circulation channel 25B.

[0038] The third cooling system 27 includes: a radiator 27A that cools the refrigerant; a circulation channel 27B that encloses the radiator 27A and the fuel cell 8; and a circulation pump 27C that circulates the refrigerant in the circulation channel 27B.

[0039] The lithium-ion capacitor 9 is highly heat-resistant compared to a lithium-ion secondary battery and an electric double-layer capacitor, for example. If the upper limit of the operating temperature range of the lithium-ion secondary battery and the electric double-layer capacitor is defined as temperature T1, the upper limit of the operating temperature range of the lithium-ion capacitor 9 is temperature T2, which is higher than temperature T1. For example, temperature T1 is approximately 65°C, and temperature T2 is approximately 80°C. This eliminates the need to provide a dedicated cooling system for the lithium-ion capacitor 9. As shown in Fig. As illustrated in Figure 3, in the present embodiment, the lithium-ion capacitor 9 is cooled by the second cooling system 25 for cooling the DC / DC converter 16 and the components 24 of the fuel cell system 7. That is, the lithium-ion capacitor 9, the DC / DC converter 16, and the component 24 of the fuel cell system 7 share the second cooling system 25. This counteracts an increase in the size of the cooling system 21. <wirkungen>

[0040] As described above, according to the present embodiment, the work machine 1 is provided with the fuel cell system 7, which has a long service life and can suppress enlargement. In the present embodiment, the fuel cell system 7 adopts a drive method that uses the fuel cell 8 as the main power source. Unlike the drive method that uses the energy storage device as the main power source, the fuel cell system 7 that adopts the drive method using the fuel cell 8 as the main power source does not require a large-capacity energy storage device. This suppresses enlargement of the fuel cell system 7. Furthermore, the lithium-ion capacitor 9 is superior to the lithium-ion secondary battery and the electric double-layer capacitor in terms of service life and heat resistance.In addition, the energy density [Wh / L] of the lithium-ion capacitor 9 is higher than that of the electric double-layer capacitor. The power density [W / L] of the lithium-ion capacitor 9 is higher than that of the lithium-ion secondary battery and the electric double-layer capacitor. Therefore, the lithium-ion capacitor 9 can ensure high storage capacity while maintaining a constant size.

[0041] In general, the response of the fuel cell 8 is lower than that of the internal combustion engine. In the present embodiment, the lithium-ion capacitor 9 is used as an energy storage device, so that the fuel cell 8 can be adequately supported by the lithium-ion capacitor 9.

[0042] Fig. Figure 4 is a diagram illustrating the response of an internal combustion engine. Fig. Figure 5 is a diagram illustrating the response of a fuel cell. Fig. 4 and Fig. 5, the horizontal axis represents time and the vertical axis represents power. The combustion engine or fuel cell begins to deliver energy when an operating lever located in the cab of the working machine 1 is operated by an operator. In the Fig. 4 and Fig. In the example illustrated in Figure 5, the actuating lever is actuated at time ta. As in Fig. 4, in the case of an internal combustion engine, at time tb, an energy is released that corresponds to the amount of actuation of the operating lever. As shown in Fig. As illustrated in Figure 5, in the case of a fuel cell, at time tc, the energy corresponding to the amount of operation of the operating lever is released. The time from time ta to time tc is longer than the time from time ta to time tb. Thus, the response of the fuel cell is lower than the response of the internal combustion engine.

[0043] In a drive method using a fuel cell as the main energy source, the energy storage device outputs energy (power) to assist the fuel cell 8 until energy (power) corresponding to an operation amount of an operation lever is output from the fuel cell 8. That is, the energy storage device outputs energy to compensate for a shortage of energy output from the fuel cell 8 depending on the operation amount of the operation lever. As shown in the Fig. 4 and Fig. 5, the amount of energy of the energy storage device required to support the fuel cell 8 is greater than the amount of energy of the energy storage device required to support the internal combustion engine.

[0044] When the electric double-layer capacitor is used as an energy storage device, the energy density of the electric double-layer capacitor is lower than that of the lithium-ion capacitor 9. Therefore, assuming that the electric double-layer capacitor has a volume equivalent to that used to assist the internal combustion engine, it would be difficult for the electric double-layer capacitor to sufficiently assist the fuel cell 8. That is, it would be difficult for the electric double-layer capacitor to sufficiently compensate for the lack of energy output from the fuel cell 8.

[0045] In the present embodiment, the lithium-ion capacitor 9 is used as the energy storage device. The energy density of the lithium-ion capacitor 9 is higher than that of the electric double-layer capacitor. Therefore, the lithium-ion capacitor 9 can sufficiently support the fuel cell 8. That is, the lithium-ion capacitor 9 can output enough energy to sufficiently compensate for the energy deficiency of the fuel cell 8. [Second embodiment]

[0046] A second embodiment will be described. In the following description, the same or equivalent components as in the above-described embodiment are denoted by the same reference numerals, and the description of the components will be simplified or omitted.

[0047] Fig. 6 is a diagram illustrating a drive system 6B of a work machine 1 according to the present embodiment. The drive system 6B according to the present embodiment differs from the drive system 6A according to the above-described first embodiment in that the drive system 6B includes a DC / DC converter 28 (second DC / DC converter) arranged in the second connection line 15 between the lithium-ion capacitor 9 and the second portion 13B of the power line 13. The DC / DC converter 16 and the DC / DC converter 28 are connected in parallel to each other.

[0048] In the present embodiment, when the lithium-ion capacitor 9 compensates for the shortage of power output from the fuel cell 8, the power of the lithium-ion capacitor 9 is individually supplied to the pump drive motor 10 and the swing motor 11 via the DC / DC converter 28. The voltage of the lithium-ion capacitor 9 boosted by the DC / DC converter 28 is individually applied to the inverter 17 connected to the pump drive motor 10 and the inverter 18 connected to the swing motor 11. The DC / DC converter 28 boosts the voltage of the lithium-ion capacitor 9 at a predetermined boost ratio. The voltage of the lithium-ion capacitor 9 boosted by the DC / DC converter 28 is individually applied to the inverter 17 connected to the pump drive motor 10 and the inverter 18 connected to the swing motor 11.

[0049] The DC / DC converter 28 is a bidirectional DC / DC converter capable of supplying power from the primary side to the secondary side and from the secondary side to the primary side. The primary side of the DC / DC converter 28 is a low-voltage side (the lithium-ion capacitor 9 side). The secondary side of the DC / DC converter 28 is a high-voltage side (the power line 13 side). The DC / DC converter 28 reduces the regenerative voltage of the swing motor 11 at a predetermined reduction ratio. When the regenerative voltage of the swing motor 11 reduced by the DC / DC converter 28 is applied to the lithium-ion capacitor 9, the lithium-ion capacitor 9 is charged.

[0050] In the present embodiment, the lithium-ion capacitor 9 is charged by one or both of the regenerative voltage of the swing motor 11 and the voltage of the fuel cell 8. The lithium-ion capacitor 9 is charged by the regenerative voltage applied by the swing motor 11 via the second connection line 15. The lithium-ion capacitor 9 is charged by the power supplied from the fuel cell 8 via the DC / DC converter 16, the second connection line 15, and the DC / DC converter 28.

[0051] As described above, according to the present embodiment, the voltage of the lithium-ion capacitor 9 is boosted by the DC / DC converter 28. The voltage of the lithium-ion capacitor 9 boosted by the DC / DC converter 28 is individually applied to the inverter 17 connected to the pump drive motor 10 and to the inverter 18 connected to the swing motor 11. With this configuration, it is possible to obtain an appropriate voltage for driving the pump drive motor 10 and the swing motor 11 even when the voltage of the lithium-ion capacitor 9 is low. [Third Embodiment]

[0052] A third embodiment will be described. In the following description, the same or equivalent components as in the above-described embodiment are denoted by the same reference numerals, and the description of the components will be simplified or omitted.

[0053] Fig. 7 is a diagram illustrating a drive system 6C of a work machine 1 according to the present embodiment. The drive system 6C includes: a power line 13 individually connected to the pump drive motor 10 and the swing motor 11; a first connection line 14 connecting the fuel cell 8 and a first portion 13A of the power line 13; a third connection line 29 connecting the lithium-ion capacitor 9 and a third portion 14A of the first connection line 14; a DC / DC converter 16A (primary-side DC / DC converter) arranged on the first connection line 14 between the fuel cell 8 and the third portion 14A; and a DC / DC converter 16B (secondary-side DC / DC converter) arranged on the first connection line 14 between the third portion 14A and the first portion 13A.

[0054] The DC / DC converter 16A is a unidirectional DC / DC converter that can only supply power from the primary side to the secondary side. The primary side of the DC / DC converter 16A is a low-voltage side (fuel cell 8 side). The secondary side of the DC / DC converter 16A is a high-voltage side (third section 14A side). The DC / DC converter 16A amplifies the voltage of the fuel cell 8 at a predetermined amplification ratio.

[0055] The DC / DC converter 16B is a bidirectional DC / DC converter capable of outputting power from the primary side to the secondary side and from the secondary side to the primary side. The primary side of the DC / DC converter 16B is a low-voltage side (the lithium-ion capacitor 9 side). The secondary side of the DC / DC converter 16B is a high-voltage side (the power line 13 side). The DC / DC converter 16B boosts the voltage of the fuel cell 8 and the voltage of the lithium-ion capacitor 9 by a predetermined boost ratio. The DC / DC converter 16B steps down the regenerative voltage of the swing motor 11 at a predetermined reduction ratio.

[0056] The power from the fuel cell 8 is individually supplied to the pump drive motor 10 and the swing motor 11 via the DC / DC converter 16A and the DC / DC converter 16B. The voltage of the fuel cell 8, boosted by the DC / DC converter 16A and the DC / DC converter 16B, is individually applied to the inverter 17 connected to the pump drive motor 10 and to the inverter 18 connected to the swing motor 11.

[0057] When the lithium-ion capacitor 9 compensates for the power shortage of the fuel cell 8, the power from the lithium-ion capacitor 9 is individually supplied to the pump drive motor 10 and the swing motor 11 via the DC / DC converter 16B. The voltage of the lithium-ion capacitor 9 boosted by the DC / DC converter 16B is individually applied to the inverter 17 connected to the pump drive motor 10 and the inverter 18 connected to the swing motor 11.

[0058] When the regenerative voltage of the swing motor 11 reduced by the DC / DC converter 16B is applied to the lithium-ion capacitor 9, the lithium-ion capacitor 9 is charged.

[0059] The lithium-ion capacitor 9 is charged by the power supplied from the fuel cell 8 via the DC / DC converter 16A and the third connecting line 29.

[0060] As described above, according to the present embodiment, a plurality of DC / DC converters (16A and 16B) are arranged in the first connection line 14, whereby it is possible to obtain a suitable voltage for driving the pump drive motor 10 and the swing motor 11 from the fuel cell 8 even when the boost ratio of one DC / DC converter is low. Moreover, the DC / DC converter 16B obtains a suitable voltage for driving the pump drive motor 10 and the swing motor 11 from the lithium-ion capacitor 9 even when the voltage of the lithium-ion capacitor 9 is low. In a case where the lithium-ion capacitor 9 is charged by the power of the fuel cell 8, the charging efficiency is high because the number of DC / DC converters arranged between the fuel cell 8 and the lithium-ion capacitor 9 is only one, namely the DC / DC converter 16A. [Fourth Embodiment]

[0061] A fourth embodiment will be described. In the following description, the same or equivalent components as in the above-described embodiment are denoted by the same reference numerals, and the description of the components will be simplified or omitted.

[0062] Fig. 8 is a diagram illustrating a drive system 6D of a work machine 1 according to the present embodiment. The drive system 6D includes: a power line 13 individually connected to the pump drive motor 10 and the swing motor 11; a first connection line 14 connecting the fuel cell 8 and a first portion 13A of the power line 13; a second connection line 15 connecting the lithium-ion capacitor 9 and a second portion 13B of the power line 13; and a DC / DC converter 16C (first DC / DC converter) disposed in the first connection line 14 between the fuel cell 8 and the first portion 13A.

[0063] In the present embodiment, the DC / DC converter 16C is a unidirectional DC / DC converter capable of outputting power only from the primary side to the secondary side. The primary side of the DC / DC converter 16C is a low-voltage side (fuel cell 8 side). The secondary side of the DC / DC converter 16C is a high-voltage side (power line 13 side).

[0064] In the present embodiment, the drive system 6D includes: a boosting lithium-ion capacitor 90; and a switching device 30 that changes a connection state between the fuel cell 8 and the boosting lithium-ion capacitor 90.

[0065] The switching device 30 switches states between a first state in which the fuel cell 8 and the DC / DC converter 16C are connected in series via the boosting lithium-ion capacitor 90 and a second state in which the fuel cell 8 and the DC / DC converter 16C are connected in series without passing through the boosting lithium-ion capacitor 90.

[0066] The switching device 30 switches to a third state in which the power from the fuel cell 8 is supplied to the boosting lithium-ion capacitor 90 to charge the boosting lithium-ion capacitor 90.

[0067] The switching device 30 includes: a first switching element 31 connected to the fuel cell 8, and a second switching element 32 connected to the DC / DC converter 16C.

[0068] The negative electrode of the boosting lithium-ion capacitor 90 is connected to a first terminal 41 and a third terminal 43. The first terminal 41 and the third terminal 43 are connected in parallel with each other with respect to the negative electrode of the boosting lithium-ion capacitor 90. The positive electrode of the boosting lithium-ion capacitor 90 is connected to a second terminal 42.

[0069] The first switching element 31 is connected to either the first terminal 41 or the second terminal 42. The second switching element 32 is connected to either the second terminal 42 or the third terminal 43. The fuel cell 8 is connected to either the first terminal 41 or the second terminal 42 via the first switching element 31. The DC / DC converter 16C is connected to either the second terminal 42 or the third terminal 43 via the second switching element 32.

[0070] The first state includes a state in which the first switching element 31 is connected to the first terminal 41 and the second switching element 32 is connected to the second terminal 42. In the first state, the fuel cell 8, the boosting lithium-ion capacitor 90, and the DC / DC converter 16C are connected in series.

[0071] The second state includes a state in which the first switching element 31 is connected to the first terminal 41 and the second switching element 32 is connected to the third terminal 43. The second state includes a state in which both the first switching element 31 and the second switching element 32 are connected to the second terminal 42. In the second state, the fuel cell 8 and the DC / DC converter 16C are connected in series without passing through the boosting lithium-ion capacitor 90.

[0072] The third state includes a state in which the first switching element 31 is connected to the second terminal 42 and the second switching element 32 is connected to the third terminal 43.

[0073] In the first state, the power from the fuel cell 8 is supplied to the boosting lithium-ion capacitor 90, and the power from the boosting lithium-ion capacitor 90 is supplied individually to the pump drive motor 10 and the swing motor 11 via the DC / DC converter 16C. The DC / DC converter 16C boosts the voltage of the fuel cell 8 at a predetermined boost ratio. In the first state, the voltage of the fuel cell 8 is boosted by the boosting lithium-ion capacitor 90, and the voltage of the fuel cell 8 boosted by the boosting lithium-ion capacitor 90 is further boosted by the DC / DC converter 16C. The voltage of the fuel cell 8 amplified by the lithium-ion capacitor 90 and the DC / DC converter 16C is applied individually to the inverter 17 connected to the pump drive motor 10 and to the inverter 18 connected to the swing motor 11.In the first state, power from the fuel cell 8 is fed into the negative electrode of the lithium-ion capacitor 90, and the power output from the positive electrode of the lithium-ion capacitor 90 is fed into the DC / DC converter 16C.

[0074] In the second state, the power from the fuel cell 8 is individually supplied to the pump drive motor 10 and the swing motor 11 via the DC / DC converter 16C. In the second state, the voltage of the fuel cell 8, boosted by the DC / DC converter 16C, is individually applied to the inverter 17 connected to the pump drive motor 10 and the inverter 18 connected to the swing motor 11.

[0075] In the third state, power from the fuel cell 8 is input to the positive electrode of the boosting lithium-ion capacitor 90, and the power output from the negative electrode of the boosting lithium-ion capacitor 90 is input to the DC / DC converter 16C. The boosting lithium-ion capacitor 90 is charged with power from the fuel cell 8. The voltage of the fuel cell 8, stepped down by the boosting lithium-ion capacitor 90, is input to the DC / DC converter 16C.

[0076] In the present embodiment, the lithium-ion capacitor 9 is charged by one or both of the regenerative voltage of the swing motor 11 and the voltage of the fuel cell 8. The lithium-ion capacitor 9 is charged by the regenerative voltage applied by the swing motor 11 via the second connection line 15. The lithium-ion capacitor 9 is charged by the power applied by the fuel cell 8 via the DC / DC converter 16C and the second connection line 15.

[0077] Typically, the voltage of the fuel cell 8 is high when the current output from the fuel cell 8 is low, and low when the current output from the fuel cell 8 is high and the voltage of the fuel cell 8 is low. That is, the voltage of the fuel cell 8 fluctuates. In the present embodiment, the switching device 30 operates when the voltage of the fuel cell 8 is low to establish the first state. In the first state, the fuel cell 8 and the boosting lithium-ion capacitor 90 are connected in series. By the boosting lithium-ion capacitor 90, a suitable voltage for driving the pump drive motor 10 and the swing motor 11 can be obtained without excessively increasing the boost ratio of the DC / DC converter 16C. When the voltage of the fuel cell 8 is high, the switching device 30 operates to establish the third state.In the third state, the fuel cell 8 and the boosting lithium-ion capacitor 90 are connected in series in the reverse direction of the first state. The voltage of the fuel cell 8 is lowered by the boosting lithium-ion capacitor 90, resulting in a suppression of the power of the voltage applied to the DC / DC converter 16C. When the voltage of the fuel cell 8 is in the middle range, the switching device 30 switches to the second state. [Fifth Embodiment]

[0078] A fifth embodiment will be described. In the following description, the same or equivalent components as in the above-described embodiment are denoted by the same reference numerals, and the description of the components will be simplified or omitted.

[0079] Fig. 9 is a diagram illustrating a drive system 6E of a work machine 1 according to the present embodiment. The drive system 6E according to the present embodiment is a modification of the drive system 6A according to the first embodiment described above. In the above-described embodiment, the electric motor to which power is supplied from at least one of the fuel cell 8 or the lithium-ion capacitor 9 includes both the pump drive motor 10 and the swing motor 11. It is also possible to set only the pump drive motor 10 as the electric motor to which power is supplied from the fuel cell 8 or the lithium-ion capacitor 9.

[0080] In the present embodiment, the swing motor 110 that swings the swing body 3 is a hydraulic motor driven by hydraulic oil discharged from the hydraulic pump 19. The hydraulic pump 19 discharges hydraulic oil, which is supplied to the swing motor 110. The hydraulic oil discharged from the hydraulic pump 19 is supplied to the swing motor 110 via the control valve 20.

[0081] Furthermore, in other single drive systems, namely the drive system 6B according to the second embodiment, the drive system 6C according to the third embodiment, or the drive system 6D according to the fourth embodiment, it is permissible to specify the pump drive motor 10 alone as an electric motor to which power is supplied from at least one of the fuel cell 8 and the lithium-ion capacitor 9. [Other embodiments]

[0082] In the above embodiment, the work machine 1 is an excavator. The work machine 1 can also be a bulldozer or a wheel loader. List of reference symbols 1 WORKING MACHINE 2 CHASSIS 2A DRIVE WHEEL 2B CATERPILLAR 2C DRIVE MOTOR 3 SWIVEL BODY 4 WORKING EQUIPMENT 4A BOOM 4B ARM 4C SHOVEL 5 WORKING EQUIPMENT CYLINDERS 5A BOOM CYLINDER 5B ARM CYLINDER 5C BUCKET CYLINDER 6A DRIVE SYSTEM 6B DRIVE SYSTEM 6C DRIVE SYSTEM 6D DRIVE SYSTEM 6E DRIVE SYSTEM 7 FUEL CELL SYSTEM 8 FUEL CELL 9 LITHIUM-ION CAPACITOR 10 PUMP DRIVE MOTOR (ELECTRIC MOTOR) 11 SWIVEL MOTOR (ELECTRIC MOTOR) 12 HYDROGEN TANK 13 POWER LINE 13A FIRST SECTION 13B SECTION TWO 14 FIRST CONNECTING LINE 14A THIRD SECTION 15 SECOND CONNECTION LINE 16 DC / DC CONVERTERS (FIRST DC / DC CONVERTER) 16A DC / DC CONVERTER (PRIMARY SIDE DC / DC CONVERTER) 16B DC / DC CONVERTER (SECONDARY SIDE DC / DC CONVERTER) 16C DC / DC CONVERTER (FIRST DC / DC CONVERTER) 17 INVERTERS 18 INVERTERS 19 HYDRAULIC PUMP 20 CONTROL VALVE 21 COOLING SYSTEM 22 HYDRAULIC SYSTEM 23 FIRST COOLING SYSTEM 23A RADIATOR 23B CIRCULATION DUCT 23C CIRCULATION PUMP 24 COMPONENTS 25 SECOND COOLING SYSTEM 25A RADIATOR 25B CIRCULATION DUCT 25C CIRCULATION PUMP 27 THIRD COOLING SYSTEM 27A RADIATOR 27B CIRCULATION DUCT 27C CIRCULATION PUMP 28 DC / DC CONVERTER (SECOND DC / DC CONVERTER) 29 THIRD CONNECTION LINE 30 SWITCHING DEVICE 31 FIRST SWITCHING ELEMENT 32 SECOND SWITCHING ELEMENT 41 FIRST CONNECTION 42 SECOND CONNECTION 43 THIRD CONNECTION 90 BOOSTING LITHIUM-ION CAPACITOR 110 SWIVEL MOTOR QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 2013 / 0038249

[0005] < / wirkungen> < / brennstoffzellensystem> < / arbeitsmaschine>

Claims

[1] Work machine, comprising: a fuel cell; a lithium-ion capacitor connected in parallel to the fuel cell; an electric motor supplied with power by at least one of the fuel cell or the lithium-ion capacitor; and a target object driven by the electric motor. [2] Work machine according to claim 1, further comprising: a power line connected to the electric motor; a first connecting line connecting the fuel cell and a first portion of the power line; a second connecting line connecting the lithium-ion capacitor and a second portion of the power line; and a first DC / DC converter arranged in the first connecting line between the fuel cell and the first section, whereby the power from the fuel cell is supplied to the electric motor via the first DC / DC converter. [3] Working machine according to claim 2, further comprising a second DC / DC converter arranged in the second connecting line between the lithium-ion capacitor and the second section, The power from the lithium-ion capacitor is supplied to the electric motor via the second DC / DC converter. [4] A working machine according to claim 2 or 3, wherein the lithium-ion capacitor is charged by the power supplied from the fuel cell via the first DC / DC converter and the second connecting line. [5] Work machine according to claim 1, further comprising: a power line connected to the electric motor; a first connecting line connecting the fuel cell and a first portion of the power line; a third connecting line connecting the lithium-ion capacitor and a third portion of the first connecting line; a primary-side DC / DC converter arranged in the first connecting line between the fuel cell and the third section; and a secondary-side DC / DC converter arranged in the first connecting line between the third section and the first section, The power from the fuel cell is supplied to the electric motor via the primary-side DC / DC converter and the secondary-side DC / DC converter. [6] A work machine according to claim 5, wherein the power from the lithium-ion capacitor is supplied to the electric motor via the secondary-side DC / DC converter. [7] A working machine according to claim 5 or 6, wherein the lithium-ion capacitor is charged by the power supplied from the fuel cell via the primary-side DC / DC converter and the third connecting line. [8] Work machine according to claim 2, further comprising: a boosting lithium-ion capacitor; and a switching device that switches between two states, namely a first state in which the fuel cell and a first DC / DC converter are connected in series via the boosting lithium-ion capacitor, and a second state in which the fuel cell and the first DC / DC converter are connected in series without passing through the boosting lithium-ion capacitor. [9] Working machine according to claim 8, wherein in the first state, the power from the fuel cell is supplied to the boosting lithium-ion capacitor and the power from the boosting lithium-ion capacitor is supplied to the electric motor via the first DC / DC converter, and in the second state, the power from the fuel cell is supplied to the electric motor via the first DC / DC converter. [10] The work machine according to claim 8 or 9, wherein the switching device switches to a third state, the third state being a state in which the power from the fuel cell is supplied to the boosting lithium-ion capacitor to charge the boosting lithium-ion capacitor. [11] Working machine according to claim 10, wherein, in the first state, the power from the fuel cell is fed into a negative electrode of the boosting lithium-ion capacitor and the power output from a positive electrode of the boosting lithium-ion capacitor is fed into the first DC / DC converter, and in the third state, the power from the fuel cell is fed into a positive electrode of the boosting lithium-ion capacitor, and the power output from the negative electrode of the boosting lithium-ion capacitor is fed into the first DC / DC converter. [12] Working machine according to claim 1, further comprising a cooling system that cools a DC / DC converter that converts a voltage of the fuel cell, The lithium-ion capacitor is cooled by the cooling system. [13] A working machine according to any one of claims 1 to 12, further comprising a hydraulic pump, wherein the target object includes the hydraulic pump driven by the electric motor. [14] Work machine according to claim 13, further comprising: a work tool; and an implement cylinder that operates the implement, The hydraulic pump discharges hydraulic oil which is supplied to the implement cylinder. [15] Work machine according to claim 13 or 14, further comprising: a chassis with a drive wheel; and a traction motor that rotates the drive wheel, The hydraulic pump discharges hydraulic oil which is supplied to the traction motor. [16] Work machine according to claim 15, further comprising: a swivel body supported by the chassis; and a swivel motor that swivels the swivel body, The hydraulic pump discharges hydraulic oil which is supplied to the swing motor. [17] Work machine according to one of claims 1 to 12, further comprising: a chassis; and a swivel body supported by the chassis, wherein the target object contains the swivel body which is swiveled by the electric motor. [18] The working machine according to claim 17, wherein the lithium-ion capacitor is charged by a regenerative voltage of the electric motor that pivots the pivoting body.

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