Work machine

Abstract

To provide a work machine which can enhance a degree of freedom of arrangement of heat exchangers of a plurality of cooling systems, and can make the plurality of cooling systems compact.SOLUTION: A work machine includes: a work device; an actuator; a hydraulic system including a hydraulic pump for supplying hydraulic oil to the actuator; an electric apparatus; a power generator for generating power supplied directly or indirectly to the electric apparatus; a first cooling system for circulating a first cooling medium and cooling the electric apparatus; and a second cooling system for circulating a second cooling medium and cooling the power generator, wherein the first cooling system includes: a first heat exchanger for exchanging heat between the hydraulic oil and the first cooling medium and cooling hydraulic oil; a second heat exchanger for exchanging heat between the first cooling medium and the second cooling medium, and cooling the second cooling medium; and a third heat exchanger for changing heat between the first cooling medium and outdoor air, and cooling the first cooling medium so that a temperature of the first cooling medium is lower than a temperature of the hydraulic oil and the second cooling medium before heat exchange.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a working machine having a hydraulic system for operating a working device and a cooling system for cooling an electric device. [Background technology]

[0002] 2. Description of the Related Art Some working machines, such as construction machines and agricultural machines, use electric motors to drive hydraulic pumps and traveling devices in hydraulic systems that operate the working devices (see, for example, Patent Document 1).

[0003] Such working machines are equipped with heat exchangers that cool the hydraulic oil flowing through the hydraulic system and heat exchangers that cool the cooling medium for cooling electric devices such as electric motors. That is, since this type of working machine has multiple components that generate heat when driven (operating), it has multiple cooling systems for cooling these to appropriate temperatures, and each cooling system is provided with a heat exchanger. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-20294 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the multiple heat exchangers equipped in the above-mentioned working machine are gas-liquid heat exchangers (so-called radiators) that exchange heat between a medium to be cooled (e.g., cooling water, hydraulic oil, etc.) and outside air. Therefore, each of the multiple heat exchangers is disposed in a position where outside air can be taken in. Also, this type of heat exchanger requires a cooling fan that forcibly sends outside air toward the heat exchanger to exchange heat between the medium to be cooled and the outside air.

[0006] As a result, the arrangement of multiple heat exchangers places restrictions on the layout of other equipment. In addition, in order to increase the heat exchange efficiency of this type of heat exchanger, the heat exchanger needs to be large and a cooling fan is required, which increases the occupancy rate of each heat exchanger.

[0007] SUMMARY OF THE PRESENT EMBODIMENTS In view of the above, an object of the present invention is to provide a work machine that allows for greater freedom in the arrangement of heat exchangers of a plurality of cooling systems and allows for the plurality of cooling systems to be made compact. [Means for solving the problem]

[0008] A working machine according to the present invention includes a working device, a hydraulic system including an actuator for operating the working device and a hydraulic pump for supplying hydraulic oil to the actuator, at least one electric device, a generator for generating electricity to be supplied directly or indirectly to the electric device, a first cooling system for circulating a first cooling medium to cool the electric device, and a second cooling system for circulating a second cooling medium to cool the generator, wherein the first cooling system includes a first heat exchanger for cooling the hydraulic oil by heat exchange between the hydraulic oil and the first cooling medium, a second heat exchanger for cooling the second cooling medium by heat exchange between the first cooling medium and the second cooling medium, and a third heat exchanger for exchanging heat between the first cooling medium and outside air, and cooling the first cooling medium such that the temperature of the first cooling medium is lower than the temperatures of the hydraulic oil and the second cooling medium before the heat exchange. Effect of the Invention

[0009] According to the present invention, the degree of freedom in arranging the heat exchangers of the multiple cooling systems can be increased, and the multiple cooling systems can be made compact. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a side view of a working machine according to one embodiment of the present invention. [Diagram 2]FIG. 2 is a schematic system diagram including a hydraulic system, a first cooling system, a second cooling system, and a third cooling system of the work machine according to the embodiment. [Diagram 3] FIG. 3 is a schematic block diagram of an electrical system of the work machine according to the embodiment. [Figure 4] FIG. 4 is a perspective view of a plate heat exchanger employed in the first heat exchanger and the second heat exchanger of the first cooling system of the work machine according to the embodiment. [Diagram 5] FIG. 5 is a schematic exploded perspective view of the plate heat exchanger shown in FIG. [Figure 6] FIG. 6 is a schematic perspective view for explaining the arrangement of the third heat exchanger, the fourth heat exchanger, and the cooling fan of the work machine according to the embodiment. [Figure 7] FIG. 7 is a schematic perspective view for explaining the arrangement of the third heat exchanger, the fourth heat exchanger, and the cooling fan of a work machine according to another embodiment of the present invention. [Figure 8] FIG. 8 is a schematic perspective view for explaining the arrangement of the third heat exchanger, the fourth heat exchanger, and the cooling fan of a work machine according to another embodiment of the present invention. [Figure 9] FIG. 9 is a schematic perspective view for explaining the arrangement of a third heat exchanger, a fourth heat exchanger, and a cooling fan in a work machine according to still another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] As shown in Fig. 1, the work machine 1 includes a traveling device 2 and a machine body 3 supported by the traveling device 2. The work machine 1 also includes a working device 4 for performing a predetermined task, and a hydraulic system 5 (see Fig. 2) including actuators 50a, 50b for operating the working device 4 and a hydraulic pump 51 for supplying hydraulic oil to the actuators 50a, 50b. The work machine 1 also includes at least one electric device 6a, 6b, 6c (see Figs. 1 to 3), and a generator 7 for generating electricity to be directly or indirectly supplied to the electric devices 6a, 6b, 6c. Accordingly, the work machine 1 according to this embodiment includes an internal combustion engine 8 for driving the generator 7.

[0013] As shown in FIG. 2, the work machine 1 of this embodiment is equipped with electric equipment 6a, 6b, 6c and a generator 7, and is also equipped with a first cooling system 10 that circulates a first cooling medium A to cool the electric equipment 6a, 6b, 6c, and a second cooling system 11 that circulates a second cooling medium B to cool the generator 7.

[0014] Returning to Fig. 1, the traveling devices 2 are arranged on both sides (left and right sides) in a direction (hereinafter referred to as width direction) perpendicular to the linear direction (direction moving forward and backward in a straight line: hereinafter referred to as front-rear direction) of the machine body 3. That is, the work machine 1 is equipped with a pair of traveling devices 2, 2 connected to the machine body 3, and the pair of traveling devices 2, 2 are arranged on both the left and right sides (symmetrically) of the machine body 3.

[0015] In this embodiment, a crawler type traveling device is adopted for each of the pair of traveling devices 2, 2. Accordingly, each of the pair of traveling devices 2, 2 includes an idler 20, a driving wheel 21, a plurality of rollers 22..., an endless annular crawler belt 23, and a driving motor 24.

[0016] Each of the pair of traveling devices 2 includes a pair of idlers 20, 20. The pair of idlers 20, 20 are arranged at an interval in the front-rear direction. Each of the pair of idlers 20, 20 is rotatable about an axis extending in the width direction. Like the idler 20, each of the multiple rollers 22... is rotatable about an axis extending in the width direction. The multiple rollers 22... are arranged at an interval in the front-rear direction between the pair of idlers 20, 20.

[0017] The drive wheel 21 is disposed between the pair of idlers 20, 20. In this embodiment, the drive wheel 21 is disposed above the multiple rollers 22 between the pair of idlers 20, 20. The drive wheel 21 is rotatable about an axis extending in the width direction. The drive wheel 21 has a plurality of engagement teeth on its outer periphery that engage with the crawler belt 23. The drive wheel 21 receives drive from a drive motor 24, which is a drive source, and is driven to rotate about the axis.

[0018] The drive motor 24 is an electric motor serving as the electric device 6a. In this embodiment, the drive motor 24 is a three-phase AC synchronous motor with embedded permanent magnets. The drive motor 24 (6a) may be another type of synchronous motor, and may be an AC motor or a DC motor.

[0019] The drive motor 24 (6a) has a housing and a motor body accommodated in the housing. In this embodiment, the drive motor 24 (6a) is liquid-cooled, and has a flow path for circulating a first cooling medium A, as shown in FIG. 2. This flow path includes a start end (IN) that serves as an inlet for the first cooling medium A and a finish end (OUT) that serves as an outlet for the first cooling medium A. The inlet (IN) and the outlet (OUT) are configured so as to be connectable to a pipe that constitutes the flow path for circulating the first cooling medium A. The flow path of the drive motor 24 is configured by a cavity formed in the peripheral wall of the housing or a cavity formed in a water jacket disposed inside or outside the housing.

[0020] The motor body has a rotatable rotor including an output shaft journaled in a housing, and a stator that generates a force for rotating the rotor. The output shaft of the drive motor 24 (6a) directly or indirectly transmits a rotational force to the drive wheels 21. That is, the output shaft of the drive motor 24 (6a) is connected to the drive wheels 21 or operatively connected to the drive wheels 21 via a drive transmission mechanism such as a reducer. As a result, the drive wheels 21 rotate when driven by the drive motor 24 (6a).

[0021] Returning to Fig. 1, the crawler belt 23 is wound around the idler 20, the drive wheel 21, and the rollers 22.... The inner circumference of the crawler belt 23 engages with the outer circumference (engagement teeth) of the drive wheel 21. As a result, as the drive wheel 21 rotates by being driven by the drive motor 24 (6a), the rotational torque is transmitted to the crawler belt 23 via the engagement teeth. In other words, the crawler belt 23 revolves around the pair of idlers 20, 20, the multiple rollers 22..., and the drive wheel 21.

[0022] As described above, the drive motor 24 is an electric motor which is an electric device 6a. Accordingly, the work machine 1 includes an inverter 25 (6b) for a motor which is an electric device 6b (hereinafter, referred to as a motor inverter) and controls the rotation of the drive motor 24, as shown in Figs. 2 and 3.

[0023] In this embodiment, the motor inverter 25 (6b) is a liquid-cooled type. Specifically, the motor inverter 25 (6b) includes electric components such as a power module (IGBT, IPM, MOSFET), an electrolytic capacitor, and a reactor, as well as a heat sink for cooling these electric components. The heat sink is a liquid-cooled type and has an internal flow path for circulating a first cooling medium A, as shown in FIG. 2. The internal flow path includes a start end (IN) that serves as an inlet for the first cooling medium A, and a finish end (OUT) that serves as an outlet for the first cooling medium A. The inlet (IN) and the outlet (OUT) are configured to be connectable to piping that constitutes the flow path for circulating the first cooling medium A.

[0024] Returning to Fig. 1, the work machine 1 according to this embodiment is a riding machine. Accordingly, a cabin 30 is mounted on the machine body 3. Inside the cabin 30, in addition to a driver's seat DS where the driver sits, a steering wheel for driving, an operating section for performing various operations, etc. are equipped.

[0025] The work device 4 has a boom 40 connected to the machine body 3, and a work tool (attachment) 41 connected to the boom 40, the work tool 41 having a predetermined function.

[0026] In this embodiment, the work machine 1 is a track loader (compact track loader). That is, the work device 4 is a loader device that performs loading work as a predetermined work.

[0027] The booms 40 are provided as a pair with a gap in the width direction. That is, the pair of booms 40, 40 are connected to the machine body 3 with a gap in the width direction. Specifically, one boom 40 of the pair of booms 40, 40 is disposed on the left side of the machine body 3. In contrast, the other boom 40 of the pair of booms 40, 40 is disposed on the right side of the machine body 3. Each of the pair of booms 40, 40 has a base end and a tip end opposite to the base end. The base end of each of the pair of booms 40, 40 is connected to the machine body 3 via a shaft extending in the width direction. This allows the pair of booms 40, 40 to swing (rotate) around the shaft (base end). The base end and the tip of the pair of booms 40, 40 are connected to each other by a connector.

[0028] The working implement 41 is a bucket. The working implement (bucket) 41 is connected to the tip of each of the pair of booms 40, 40 so as to be rotatable about an axis extending in the width direction.

[0029] As described above, the work machine 1 is equipped with the actuators 50a, 50b that operate the work device (loader device) 4. The work machine 1 according to this embodiment is equipped, as actuators, with a lifting cylinder 50a that lifts and lowers the pair of booms 40, 40, and a tilting cylinder 50b that tilts the work tool (bucket) 4.

[0030] Each of the lifting cylinder 50a and the tilting cylinder 50b is a hydraulic cylinder that expands and contracts by supplying and recovering hydraulic oil. The hydraulic cylinders 50a and 50b extend in one direction and have one end in that direction and the other end opposite to the one end. Specifically, the hydraulic cylinders 50a and 50b are cylindrical cylinder bodies extending in one direction, and have a cylinder body having a base end and a tip end in one direction, and a piston rod having a piston at one end, the piston being mounted inside the cylinder body so as to be movable in one direction, and the other end side of the piston rod protruding from the tip of the cylinder body. As a result, in the hydraulic cylinders 50a and 50b, the base end of the cylinder body becomes one end of the hydraulic cylinder, and the other end of the piston rod becomes the other end of the hydraulic cylinder.

[0031] In the lifting cylinder (hydraulic cylinder) 50a, one end (the base end of the cylinder body) is rotatably connected to the machine body 3 about an axis extending in the width direction, and the other end (the other end of the piston rod) is rotatably connected to the booms 40, 40 about an axis extending in the width direction. As a result, when the lifting cylinder 50a expands and contracts in one direction, the pair of booms 40, 40 rotate about the base end, and the tip sides of the pair of booms 40, 40 rise and fall.

[0032] One end (the base end of the cylinder body) of the tilting cylinder (hydraulic cylinder) 50b is rotatably connected to the booms 40, 40 about an axis extending in the width direction, and the other end (the other end of the piston rod) is rotatably connected to the working tool (bucket) 41 about an axis extending in the width direction. As a result, when the tilting cylinder 50b expands and contracts in one direction, the bucket 41 rotates around the tip of the booms 40, 40 to change its position. That is, the bucket 41 performs scooping and dumping operations by swinging.

[0033] The working machine 1 of this embodiment is configured such that the working tool 41 can be replaced from the bucket to another tool, and various tasks other than excavation and loading tasks (or other excavation tasks) can be performed. That is, the bucket 41 can be attached and detached to the tip of the booms 40, 40, and a working tool 41 other than the bucket 41 can also be attached and detached. In this embodiment, the working machine 1 can also attach a hydraulic attachment as another working tool 41 to the tip of the booms 40, 40 by removing the bucket 41. The hydraulic attachment means a hydraulically driven working tool (attachment) 41 having a hydraulic actuator 50c (see FIG. 2) such as a hydraulic motor or a hydraulic cylinder, and examples of hydraulic attachments include a hydraulic crusher, a hydraulic breaker, an angle broom, an earth auger, a pallet fork, a sweeper, a mower, a snow blower, and the like.

[0034] In this embodiment, a diesel engine is used as the internal combustion engine 8. The internal combustion engine 8 is water-cooled, and has an internal flow path for circulating the third cooling medium C, as shown in FIG. 2. Accordingly, the flow path of the internal combustion engine 8 has an inlet (IN) for allowing the third cooling medium C to flow in and an outlet (OUT) for allowing the third cooling medium C to flow out. The internal combustion engine 8 is supported on the aircraft body 3 via a vibration isolation mechanism. In this embodiment, the internal combustion engine 8 is disposed at the rear of the aircraft body 3 (see FIG. 1).

[0035] The generator 7 generates electricity when driven by the internal combustion engine 8. Accordingly, the work machine 1 includes a battery 70 that stores the electricity generated by the generator 7 and supplies the stored electricity to the electric devices 6a, 6b, 6c, etc., as shown in Fig. 3. The battery 70 is connected to a plurality of electric devices mounted on the work machine 1 (including the drive motor 24 (6a), the motor inverter 25 (6b), and the generator inverter 71 (6b), as well as a first pump 103, a second pump 110, a third pump 121, a throttle valve 506, a cooling fan 104, a control valve 53, etc., which will be described later), and supplies electricity to these devices as well.

[0036] In this embodiment, the generator 7 also functions as an electric motor that drives the hydraulic pump 51. That is, the generator 7 according to this embodiment is a motor-generator that has a function as an electric motor that receives power from the battery 70 to drive the hydraulic pump 51, and a function as the generator 7 (generator).

[0037] In this embodiment, the generator (motor generator) 6 is a three-phase AC synchronous motor with embedded permanent magnets. The generator (motor generator) 6 has a housing fixed to the internal combustion engine 8 and a motor body accommodated in the housing. The motor body has a rotatable rotor and a stator that generates a force to rotate the rotor.

[0038] The generator (motor-generator) 6 is supported on the vehicle body 3 via a vibration isolation mechanism. In this embodiment, the generator (motor-generator) 6 is fixed to the front of the internal combustion engine 8 (see FIG. 1). The generator (motor-generator) 6 is liquid-cooled, and has a flow path for circulating the second cooling medium B, as shown in FIG. 2. This flow path includes a start end (IN) serving as an inlet for the second cooling medium B and a finish end (OUT) serving as an outlet for the second cooling medium B. The inlet (IN) and the outlet (OUT) are configured so as to be connectable to a pipe constituting the flow path for circulating the second cooling medium B. Note that, like the drive motor 24 (6a), the flow path of the generator (motor-generator) 6 is configured by a cavity formed in the peripheral wall of the housing or a cavity formed in a water jacket arranged inside or outside the housing.

[0039] In this embodiment, since the generator 7 is a motor-generator, the work machine 1 includes a generator inverter 71, which is an electric device 6c, as shown in Figs.

[0040] In this embodiment, the generator inverter 71 (6c) is a liquid-cooled type. Specifically, like the motor inverter 25 (6b), the generator inverter 71 (6c) includes electric components such as power modules (IGBT, IPM, MOSFET), electrolytic capacitors, and reactors, as well as a heat sink for cooling these electric components. The heat sink is a liquid-cooled type and has an internal flow path for circulating the first cooling medium A, as shown in FIG. 2. The internal flow path includes a start end (IN) that serves as an inlet for the first cooling medium A and a finish end (OUT) that serves as an outlet for the first cooling medium A. The inlet (IN) and the outlet (OUT) are configured to be connectable to piping that constitutes the flow path for circulating the first cooling medium A.

[0041] As described above, in this embodiment, the work machine 1 includes the drive motor 24 (6a), the motor inverter 25 (6b), and the generator inverter 71 (6c) as electric devices, each of which is liquid-cooled. As shown in FIG. 3, the work machine 1 includes a control unit 9 that controls the entire work machine 1, and these electric devices 6a, 6b, and 6c operate based on instructions from the control unit 9. The control unit 9 is also connected to electric devices other than the drive motor 24 (6a), the motor inverter 25 (6b), and the generator inverter 71 (6c) (electric devices such as the first pump 103, the second pump 110, the third pump 121, the throttle valve 506, the cooling fan 104, and the control valve 53) and controls these devices as well.

[0042] As described above, the hydraulic system 5 includes the hydraulic pump 51. Moreover, as shown in Fig. 2, the hydraulic system 5 includes a hydraulic oil tank 52 that stores hydraulic oil S, a primary system 5A that connects the actuators 50a, 50b and the hydraulic oil tank 52 via the hydraulic pump 51 and supplies the hydraulic oil S stored in the hydraulic oil tank 52 to the actuators 50a, 50b by driving the hydraulic pump 51, and a secondary system 5B that connects the actuators 50a, 50b and the hydraulic oil tank 52 and returns the hydraulic oil S from the actuators 50a, 50b to the hydraulic oil tank 52. Moreover, the hydraulic system 5 includes a control valve 53 that controls the flow of the hydraulic oil S.

[0043] The power of the internal combustion engine 8 and the power of the generator (motor-generator) 6 are transmitted to the hydraulic pump 51 either alternatively or in combination. That is, the hydraulic pump 51 is driven by at least one of the internal combustion engine 8 and the generator (motor-generator) 6.

[0044] In this embodiment, the hydraulic pump 51 is a multiple hydraulic pump. Specifically, the hydraulic pump 51 is a multiple hydraulic pump that includes a main pump, a sub pump, and a pilot pump, which are connected in series. Note that FIG. 2 shows a system connected to the main pump as the hydraulic system 5.

[0045] The main pump is composed of a fixed displacement gear pump or a variable displacement hydraulic pump 51. The hydraulic oil S discharged from the main pump is supplied to the actuators 50a, 50b to operate the actuators 50a, 50b. Specifically, the hydraulic actuators operated by the main pump are the lift cylinder 50a, the tilt cylinder 50b, and the actuator 50c of the hydraulic attachment that is attached in place of the bucket 41.

[0046] The sub-pump is a hydraulic pump for increasing the amount of hydraulic oil S supplied to the actuators 50a, 50b operated by the main pump. The pilot pump is a hydraulic pump for supplying hydraulic oil S for pilot signals to a control valve that controls the actuators 50a, 50b operated by the main pump. The sub-pump and the pilot pump are each composed of, for example, a fixed displacement gear pump.

[0047] The hydraulic oil tank 52 is equipped with a level gauge for measuring the liquid level (liquid volume) of the stored hydraulic oil S, as well as a temperature sensor 507 for measuring the temperature of the stored hydraulic oil S, as shown in Fig. 3. The temperature sensor 507 transmits a signal relating to the actual temperature of the hydraulic oil S stored in the hydraulic oil tank 52 (the hydraulic oil S returned from the actuators 50a, 50b, 50c) to the control unit 9.

[0048] Returning to FIG. 2, the primary system 5A is a system that connects the hydraulic oil tank 52 and the actuators 50a and 50b, and supplies the hydraulic oil in the hydraulic oil tank 52 to the actuators 50a and 50b. Specifically, the primary system 5A includes a first supply oil passage 500 that connects a suction port (a port that draws in the hydraulic oil S) of the hydraulic pump 51 (main pump) and the hydraulic oil tank 52, a second supply oil passage 501 that connects a discharge port (a port that discharges the hydraulic oil S) of the hydraulic pump 51 (main pump) and the control valve 53, and a third supply oil passage 502 that connects the control valve 53 and the actuators 50a and 50b. As a result, the hydraulic pump 51 (main pump) sucks in the hydraulic oil S in the hydraulic oil tank 52 and discharges it toward the control valve 53 and the actuators 50a and 50b.

[0049] The secondary system 5B is a system that connects the actuators 50a, 50b and the hydraulic oil tank 52, and returns the hydraulic oil S supplied to the actuators 50a, 50b to the hydraulic oil tank 52. Specifically, the secondary system 5B includes a first return oil passage 503 that connects the actuators 50a, 50b and the control valve 53, and returns the hydraulic oil S of the actuators 50a, 50b to the control valve 53, and a second return oil passage 504 that connects the control valve 53 and the hydraulic oil tank 52, and returns the hydraulic oil S that has returned from the actuators 50a, 50b to the control valve 53 to the hydraulic oil tank 52.

[0050] The first supply oil passage 500, the second supply oil passage 501, the third supply oil passage 502, the first return oil passage 503, and the second return oil passage 504 are configured by piping. A first heat exchanger 100a of the first cooling system 10, which will be described later, is interposed in the secondary system 5B. In this embodiment, the first heat exchanger 100a is interposed in the second return oil passage 504 of the secondary system 5B. Although details will be described later, the first heat exchanger 100a is formed with a flow passage that is a flow passage for circulating the hydraulic oil S and that constitutes a part of the second return oil passage 504.

[0051] In this embodiment, the hydraulic system 5 (secondary system 5B) has a bypass 505 that connects a first position P1 on the upstream side of the first heat exchanger 100a and a second position P2 on the downstream side on the second return oil passage 504. The bypass 505 has a throttle valve 506 that adjusts the flow rate of the hydraulic oil S.

[0052] The control valve 53 has a plurality of control valves 53a, 53b, and 53c. The control valve 53 shown in Fig. 2 has three control valves 53a, 53b, and 53c. In the following description, the three control valves 53a, 53b, and 53c will be referred to as a first control valve 53a, a second control valve 53b, and a third control valve 53c.

[0053] The first control valve 53a is a valve that controls the lifting cylinder (hydraulic actuator) 50a. The second control valve 53b is a valve that controls the tilting cylinder (hydraulic actuator) 50b. The third control valve 53c is a valve that controls an actuator 50c provided on a hydraulic attachment. The hydraulic attachment is a hydraulically driven work tool 41. The actuator 50c of the hydraulic attachment is connected to the third control valve 53c via a connecting member 54.

[0054] The control valve 53 has two paths, a third supply oil passage 502 and a first return oil passage 503, which are paths connected to the actuators 50a, 50b, and 50c, but the supply path and the return path are switched by the operation of the actuators 50a and 50b (control of the control valves 53a, 53b, and 53c (the first control valve 53a, the second control valve 53b, and the third control valve 53c)). That is, the third supply oil passage 502, which is the supply path, becomes the first return oil passage 503, and the first return oil passage 503, which is the return path, becomes the third supply oil passage 502.

[0055] The work machine 1 includes a drive motor (electric motor) 24 (6a), a generator 7, an internal combustion engine 8, and a hydraulic system 5 as components (heat sources) that generate heat as a result of driving (load), and is therefore equipped with a cooling system for cooling these.

[0056] The working machine 1 (cooling system) includes a circulation path for circulating a medium for exchanging heat with a heat source and for removing heat from the heat source by heat exchange. Specifically, as described above, the working machine 1 (cooling system) includes a first cooling system 10 that circulates a first cooling medium A to cool the electric devices 6a, 6b, and 6c, and a second cooling system 11 that circulates a second cooling medium B to cool the generator 7. In addition, since the working machine 1 (cooling system) includes an internal combustion engine 8, it includes a third cooling system 12 that circulates a third cooling medium C to cool the internal combustion engine 8.

[0057] The first cooling system 10 includes a first heat exchanger 100a that cools the hydraulic oil S by heat exchange between the hydraulic oil S flowing through the hydraulic system 5 and a first cooling medium A, a second heat exchanger 100b that cools the second cooling medium B by heat exchange between the first cooling medium A and a second cooling medium B, and a third heat exchanger 100c that exchanges heat between the first cooling medium A and outside air and cools the first cooling medium A so that the temperature of the first cooling medium A is lower than the temperatures of the hydraulic oil S and the second cooling medium B before the heat exchange. Furthermore, in this embodiment, the first cooling system 10 includes a refrigerant tank 102 that stores the first cooling medium A, and a pump (hereinafter referred to as a first pump) 103 that sucks up and discharges the first cooling medium A in the refrigerant tank 102.

[0058] The first heat exchanger 100a and the second heat exchanger 100b are liquid-cooled heat exchangers. In this embodiment, a plate-type heat exchanger is used as the liquid-cooled heat exchanger, as shown in Fig. 4 and Fig. 5. The plate-type heat exchangers 100a, 100b include a plurality of heat transfer plates 101.... As shown in Fig. 5, the plurality of heat transfer plates 101... are stacked in a face-to-face state, and a first flow path R1 through which the heat exchange medium A flows and a second flow path R2 through which the heat exchange media B, S flow are alternately formed at the boundaries of the heat transfer plates 101....

[0059] Specifically, each of the heat transfer plates 101 is formed by pressing a metal plate, and has a plurality of concave and convex stripes formed on the front and back surfaces. On each of the front and back surfaces, the concave and convex stripes are alternately arranged in a direction perpendicular to the extending direction of the concave stripes (convex stripes). As described above, since the heat transfer plate 101 is formed by pressing a metal plate, the concave stripes on the front surface form convex stripes on the back surface, and the convex stripes on the front surface form concave stripes on the back surface. The convex stripes of each of the stacked heat transfer plates 101 cross and collide with the convex stripes of the adjacent heat transfer plates 101. As a result, the concave stripes of the adjacent heat transfer plates 101 form a first flow path R1 or a second flow path R2.

[0060] Each of the heat transfer plates 101 has openings at four corners. When the heat transfer plates 101 are stacked, the four openings of each of the heat transfer plates 101 are aligned in the stacking direction of the heat transfer plates 101 to form a flow path that communicates with the first flow path R1 or the second flow path R2.

[0061] Specifically, of the four openings, two openings constitute two flow paths Ra1, Ra2 connected to the first flow path R1, and the remaining two openings constitute two flow paths Rb1, Rb2 connected to the second flow path R2. Of the two flow paths Ra1, Ra2 connected to the first flow path R1, one flow path Ra1 is an inflow path through which the heat exchange medium A flows in, and the other flow path Ra2 is an outflow path through which the heat exchange medium A that has passed through the first flow path R1 flows out.

[0062] Accordingly, one end opening of the inlet passage Ra1 (the opening of the outermost heat transfer plate 101...) forms an inlet (IN) through which the heat exchange medium A flows, and one end opening of the outlet passage Ra2 (the opening of the outermost heat transfer plate 101...) forms an outlet (OUT) through which the heat exchange medium A flows out.

[0063] Of the two flow paths Rb1, Rb2 connected to the second flow path R2, the flow path Rb1 is an inflow path for the heat exchange media S, B to flow in, and the other flow path Rb2 is an outflow path for the heat exchange media S, B that have passed through the second flow path R2 to flow out. Accordingly, one end opening of the inflow path Rb1 (the opening of the outermost heat transfer plate 101...) forms an inlet (IN) for the heat exchange media S, B to flow in, and one end opening of the outflow path Rb2 (the opening of the outermost heat transfer plate 101...) forms an outlet (OUT) for the heat exchange media S, B to flow out.

[0064] Returning to FIG. 2, in the first heat exchanger 100a, a first cooling medium A is caused to flow through a first flow path R1 as a heat exchange medium, and hydraulic oil S is caused to flow through a second flow path R2 as a medium to be heat exchanged.

[0065] On the other hand, in the second heat exchanger 100b, the first cooling medium A flows through the first flow path R1 as a heat exchange medium, and the second cooling medium B flows through the second flow path R2 as a medium to be heat exchanged.

[0066] The third cooling system 12 includes a fourth heat exchanger 120 that exchanges heat between the third cooling medium C and outside air and is arranged in parallel with the third heat exchanger 100c. Accordingly, at least one of the first cooling system 10 and the third cooling system 12 has a cooling fan 104 arranged next to the third heat exchanger 100c and the fourth heat exchanger 120. In other words, at least one of the first cooling system 10 and the third cooling system 12 has the cooling fan 104 that sends outside air toward the third heat exchanger 100c and the fourth heat exchanger 120.

[0067] As shown in FIG. 6, each of the third heat exchanger 100c and the fourth heat exchanger 120 is a so-called radiator, and includes a tube that forms a flow path for circulating a cooling medium (first cooling medium A, third cooling medium C) and a plurality of fins arranged around the tube.

[0068] In each of the third heat exchanger 100c and the fourth heat exchanger 120, the tube body forms a flow path as a pipe line. The tube body (flow path) has a starting end and an ending end, and the starting end forms an inlet through which the cooling medium (first cooling medium A, third cooling medium C) flows in, and the ending end forms an outlet through which the cooling medium (first cooling medium A, third cooling medium C) flows out. The inlet and the outlet are connected to pipes that form the flow path. In the radiators 100c and 120, the length of the flow path (tube body) is set according to the heat exchange capacity.

[0069] Generally, in the radiators 100c and 120, the flow paths (pipes) are arranged in a curved manner so that a flow path (pipe) of a required length is arranged in a specified space. That is, the flow paths (pipes) of the radiators 100c and 120 have a plurality of straight sections formed in a straight line and U-shaped turn sections connecting adjacent straight sections, and the straight sections and turn sections are alternately connected to form a flow path of the required length.

[0070] The tube (straight portion) is disposed so as to penetrate through a number of fins arranged in the direction in which the straight portion extends. The fins are disposed at intervals in a predetermined direction (the direction in which the straight portion extends). As a result, gaps (air passages) are formed between adjacent fins to allow outside air to pass in a direction perpendicular to the predetermined direction. Note that only the fins that appear on the outer surface (appearance) are shown in FIG. 6.

[0071] In this embodiment, based on the above configuration, the third heat exchanger 100c and the fourth heat exchanger 120 are arranged to overlap each other so that their air passages (gaps between the fins) are continuous in the same direction.

[0072] The cooling fan 104 is an electric fan driven by an electric motor M, and in this embodiment, is provided in the first cooling system 10 (see FIG. 2). The cooling fan 104 includes a push fan that pushes in outside air, and a suction fan that draws in outside air.

[0073] In this embodiment, a suction fan is used for the cooling fan 104, and is disposed inside the body 3 relative to the third heat exchanger 100c and the fourth heat exchanger 120, with the direction in which the outside air is suctioned coinciding with the ventilation direction of the third heat exchanger 100c and the fourth heat exchanger 120. In this way, the cooling fan 104 suctions in the outside air and sends the outside air toward the third heat exchanger 100c and the fourth heat exchanger 120 arranged side by side (sends the outside air outside the body 3 toward the third heat exchanger 100c and the fourth heat exchanger 120).

[0074] As a result, the sent outside air passes through the third heat exchanger 100c and the fourth heat exchanger 120 (between the fins), and the first cooling medium A and the third cooling medium C exchange heat with the outside air and are cooled.

[0075] 2, the first pump 103 is an electric pump and has a suction port for sucking in the first cooling medium A and a discharge port for discharging the first cooling medium A sucked in from the suction port. Accordingly, the first cooling system 10 has a suction side pipe 105 that connects the refrigerant tank 102 and the suction port of the first pump 103, and circulates the first cooling medium A from the refrigerant tank 102 to the first pump 103 (sucks up the first cooling medium A), and a discharge side pipe 106 that connects the discharge port of the first pump 103 and the refrigerant tank 102, and circulates the first cooling medium A discharged by the first pump 103 and returns the first cooling medium A to the refrigerant tank 102.

[0076] As described above, the first cooling system 10 includes the first heat exchanger 100a, the second heat exchanger 100b, and the third heat exchanger 100c. Specifically, the first heat exchanger 100a, the second heat exchanger 100b, and the third heat exchanger 100c are arranged on the discharge side piping 106 of the first cooling system 10. In this embodiment, the third heat exchanger 100c, the second heat exchanger 100b, and the first heat exchanger 100a are arranged in this order from upstream to downstream on the discharge side piping 106. That is, the third heat exchanger 100c is arranged at the most upstream position in the flow direction of the first cooling medium A, the first heat exchanger 100a is arranged at the most downstream position in the flow direction of the first cooling medium A, and the second heat exchanger 100b is arranged between the first heat exchanger 100a and the third heat exchanger 100c.

[0077] Accordingly, the discharge side piping 106 includes a first discharge side piping 106a connecting the discharge port of the first pump 103 and the inlet (IN) of the first cooling medium (heat exchange medium) A of the third heat exchanger 100c, a second discharge side piping 106b connecting the outlet (OUT) of the first cooling medium (heat exchange medium) A of the third heat exchanger 100c and the inlet (IN) of the first cooling medium (heat exchange medium) A of the second heat exchanger 100b, a third discharge side piping 106c connecting the outlet (OUT) of the first cooling medium (heat exchange medium) A of the second heat exchanger 100b and the inlet (IN) of the first cooling medium (heat exchange medium) A of the first heat exchanger 100a, and a fourth discharge side piping 106d connecting the outlet (OUT) of the first cooling medium (heat exchange medium) A of the first heat exchanger 100a and the refrigerant tank 102.

[0078] An inlet (IN) for the heat exchange medium (hydraulic oil S) of the first heat exchanger 100a is connected to the control valve 53 (upstream) side of the second return oil passage 504, and an outlet (OUT) for the heat exchange medium (hydraulic oil S) of the first heat exchanger 100a is connected to the hydraulic oil tank 52 (downstream) side of the second return oil passage 504. As a result, the flow paths (inlet path Rb1, second flow path R2, outlet path Rb2: see FIG. 5) through which the hydraulic oil (heat exchange medium) S of the first heat exchanger 100a flows constitute a part of the second return oil passage 504.

[0079] Furthermore, a plurality of electric devices 6a, 6b, 6c (liquid-cooled electric devices 6a, 6b, 6c) are arranged in the first cooling system 10. In this embodiment, the plurality of electric devices 6a, 6b, 6c are arranged on the discharge side piping 106 of the first cooling system 10. More specifically, the plurality of electric devices 6a, 6b, 6c are arranged on the second discharge side piping 106b of the discharge side piping 106.

[0080] The multiple electric devices 6a, 6b, 6c are arranged in ascending order of heat resistance and heat generation temperature during operation from the upstream side to the downstream side in the flow direction of the first cooling medium A. In this embodiment, the generator inverter 71 (6c), the motor inverter 25 (6b), and the drive motor 24 (6a) are arranged in this order from the upstream side to the downstream side of the first cooling system 10.

[0081] That is, in the first cooling system 10, the inverters 71(6c), 25(6b) have lower heat resistance than the other electric equipment 6a (the drive motor 24(6a) in this embodiment), so the inverters 71(6c), 25(6b) are arranged upstream of the other electric equipment 6a. In this embodiment, the generator inverter 71(6c) has specifications that are lower in heat resistance than the motor inverter 25(6b), so the generator inverter 71(6c) is arranged upstream of the motor inverter 25(6b).

[0082] Accordingly, the second discharge side piping 106b has a first connection piping 107a connecting the outlet (OUT) of the first cooling medium (heat exchange medium) A of the third heat exchanger 100c to the inlet (IN) of the generator inverter 71 (6c), a second connection piping 107b connecting the outlet (OUT) of the generator inverter 71 (6c) to the inlet (IN) of the motor inverter 25 (6b), a third connection piping 107c connecting the outlet (OUT) of the motor inverter 25 (6b) to the inlet (IN) of the drive motor 24 (6a), and a fourth connection piping 107d connecting the outlet (OUT) of the drive motor 24 (6a) to the inlet (IN) of the first cooling medium (heat exchange medium) A of the second heat exchanger 100b.

[0083] The second cooling system 11 has an annular flow path (circulation flow path) through which the second cooling medium B circulates. A pump (hereinafter referred to as the second pump) 110 for discharging (pumping) the second cooling medium B, a second heat exchanger 100b, and a generator 7 are arranged on the circulation flow path of the second cooling system 11. The second pump 110 is an electric pump, and has an inlet port for sucking in the second cooling medium B and a discharge port for discharging the second cooling medium B.

[0084] In order to form a circulation flow path, the second cooling system 11 has a first pipe 111a connecting the discharge port of the second pump 110 and the inlet (IN) of the second cooling medium (medium to be heat exchanged) B of the second heat exchanger 100b, a second pipe 111b connecting the outlet (OUT) of the second cooling medium (medium to be heat exchanged) B of the second heat exchanger 100b and the inlet (IN) of the generator 7, and a third pipe 111c connecting the outlet (OUT) of the generator 7 and the suction port of the second pump 110. As a result, the second cooling system 11 uses the second flow path R2 of the second heat exchanger 100b and the internal flow path of the generator 7 as part of the circulation flow path, and circulates the second cooling medium B while passing through the second heat exchanger 100b and the generator 7 by driving the second pump 110.

[0085] In this embodiment, the second cooling medium B is a liquid whose specific heat is smaller than that of the first cooling medium A and whose boiling point is higher than that of the first cooling medium A. Specifically, the first cooling medium (heat exchange medium) A flowing through the first cooling system 10 is water. In contrast, the second cooling medium (medium to be heat exchanged) B flowing through the second cooling system 11 is oil. Accordingly, the hydraulic oil S flowing through the hydraulic system 5 is a medium to be heat exchanged that flows through the second flow path R2 of the first heat exchanger 100a. Therefore, the first heat exchanger 100a exchanges heat between the water, which is the first cooling medium (heat exchange medium) A, and the oil (hydraulic oil) S, which is the medium to be heat exchanged, and the second heat exchanger 100b exchanges heat between the water, which is the first cooling medium (heat exchange medium) A, and the oil, which is the second cooling medium (medium to be heat exchanged) B. Accordingly, for the second pump 110 of the second cooling system 11, an oil pump capable of pumping oil having a higher viscosity than water is adopted.

[0086] The third cooling system 12 has an annular flow path (circulation flow path) through which the third cooling medium C circulates. A pump (hereinafter referred to as the third pump) 121 for discharging (pumping) the third cooling medium C, and a fourth heat exchanger 120 are arranged on the circulation flow path of the third cooling system 12. The third pump 121 is an electric pump, and has an inlet port for sucking in the third cooling medium C and a discharge port for discharging the third cooling medium C.

[0087] In order to form a circulation flow path, the third cooling system 12 has a first flow path piping 122a connecting the discharge port of the third pump 121 and the inlet (IN) of the fourth heat exchanger 120, a second flow path piping 122b connecting the outlet (OUT) of the fourth heat exchanger 120 and the inlet (IN) of the internal combustion engine 8, and a third flow path piping 122c connecting the outlet (OUT) of the internal combustion engine 8 and the suction port of the third pump 121. As a result, the third cooling system 12 uses the flow path (pipe) of the fourth heat exchanger 120 and the flow path of the internal combustion engine 8 as part of the circulation flow path, and circulates the third cooling medium C while passing through the fourth heat exchanger 120 and the internal combustion engine 8 by driving the third pump 121. The third cooling medium C is water (antifreeze).

[0088] As described above, the fourth heat exchanger (radiator) 120 is disposed so as to overlap with the third heat exchanger (radiator) 100c in the direction in which the outside air flows. That is, since the third heat exchanger (radiator) 100c and the fourth heat exchanger (radiator) 120 are gas-liquid heat exchangers, they are disposed so that the outside air forcedly sent in by the cooling fan 104 can pass through them in the same direction.

[0089] The work machine 1 according to this embodiment is as described above. When the travelling device 2 travels, the drive motor 24 (6a) is driven, and the temperatures of the drive motor 24 (6a) and the motor inverter 25 (6b) rise according to the load on the drive motor 24 (6a). When the work device 4 is used to perform work, the internal combustion engine 8 is driven to drive the generator 7, and the hydraulic pump 51 is driven via the generator 7. As a result, the temperature of the internal combustion engine 8 rises according to the load, and the temperatures of the generator 7 and the generator inverter 71 (6c) rise according to the amount of power generated. In the hydraulic system 5, the temperature of the hydraulic oil S rises according to the load on the hydraulic pump 51 (the operation (load) of the actuators 50a, 50b).

[0090] In response to this, the work machine 1 (controller 9) drives the first pump 103 of the first cooling system 10, the second pump 110 of the second cooling system 11, and the third pump 121 of the third cooling system 12.

[0091] In the first cooling system 10, when the first pump 103 is driven, the first cooling medium A (water) in the refrigerant tank 102 is sucked up by the first pump 103 and sent out to the downstream side. When the first cooling medium A discharged from the first pump 103 passes through the third heat exchanger 100c, it is subjected to heat exchange with outside air by forced airflow by the cooling fan 104, and is cooled to a set temperature. Then, the first cooling medium A cooled to the set temperature by heat exchange with the outside air is sent to the downstream side, and passes (circulates) through the generator inverter 71 (6c), the motor inverter 25 (6b), and the drive motor 24 (6a) in this order.

[0092] Accordingly, the first cooling medium A exchanges heat with the generator inverter 71 (6c), the motor inverter 25 (6b), and the drive motor 24 (6a), which are in a heat generating state, and cools them. Since the temperature rise rate (rising temperature) during operation increases in the order of the generator inverter 71 (6c), the motor inverter 25 (6b), and the drive motor 24 (6a), the first cooling medium A cools the electric devices 6a, 6b, and 6c in order of the lowest cooling temperature, thereby minimizing the temperature rise of the first cooling medium A caused by cooling the multiple electric devices 6a, 6b, and 6c. In other words, the first cooling medium A flows downstream (toward the second heat exchanger 100b) without reaching the boiling point, while maintaining a temperature at which cooling is possible even on the downstream side (a temperature at which the temperature width necessary for cooling on the downstream side remains).

[0093] In the second cooling system 11, the second pump 110 circulates (distributes) the second cooling medium (oil) B through the circulation flow path, and when the second cooling medium (oil) B passes through the generator 7, it exchanges heat with the generator 7 in a heat generating state, thereby cooling the generator 7. The second cooling medium B that has exchanged heat with the generator 7 passes through the second pump 110 and the second heat exchanger 100b. At this time, the second cooling medium B passing through the second heat exchanger 100b exchanges heat with the first cooling medium A of the first cooling system 10 and is cooled. The temperature of the second cooling medium B increases due to the heat exchange with the generator 7, but since the second cooling medium B is a liquid having a lower specific heat than the first cooling medium A and a higher boiling point than the first cooling medium A, it is prevented from becoming lower than the temperature of the first cooling medium A. That is, when heat is exchanged in the second heat exchanger 100b, the temperature of the first cooling medium A is prevented from becoming higher than the temperature of the second cooling medium B, and within the second heat exchanger 100b, the first cooling medium A absorbs heat from the second cooling medium B to cool the second cooling medium B.

[0094] Thus, by circulating (distributing) the second cooling medium B through the circulation path of the second cooling system 11, the generator 7 is cooled stably.

[0095] Then, the first cooling medium A having passed through the second heat exchanger 100b flows downstream (towards the first heat exchanger 100a).

[0096] When passing through the first heat exchanger 100a, the first cooling medium A exchanges heat with the hydraulic oil S that is flowing through the hydraulic system 5 and passes through the first heat exchanger 100a, thereby cooling the hydraulic oil S. The temperature of the hydraulic oil S rises according to the amount of work (amount of heat) done by the actuators 50a, 50b, and 50c, but like the second cooling medium B, the hydraulic oil S is a liquid with a lower specific heat than the first cooling medium A and a higher boiling point than the first cooling medium A, so that the temperature of the hydraulic oil S is prevented from becoming lower than the temperature of the first cooling medium A. That is, in a state where heat is exchanged in the first heat exchanger 100a, the temperature of the first cooling medium A is prevented from becoming higher than the temperature of the hydraulic oil S, and the first cooling medium A takes the heat of the hydraulic oil S in the first heat exchanger 100a to cool the hydraulic oil S.

[0097] In the hydraulic system 5, the temperature of the hydraulic oil S has an appropriate temperature for operating the actuators 50a, 50b, and 50c, and excessive cooling can affect the operation of the actuators 50a, 50b, and 50c. In this embodiment, the work machine 1 (hydraulic system 5) is equipped with a temperature sensor 507 that measures the temperature of the hydraulic oil S in the hydraulic oil tank 52, and the control unit 9 adjusts the opening of the throttle valve 506 based on the measurement result of the temperature sensor 507 so as to maintain the temperature of the hydraulic oil S at an appropriate temperature.

[0098] Specifically, the hydraulic system 5 includes a bypass 505 that connects a first position P1 on the upstream side of the first heat exchanger 100a to a second position P2 on the downstream side, and a throttle valve 506 is provided in the bypass 505. Accordingly, by opening and closing the throttle valve 506, the hydraulic oil S flowing from the upstream side (the control valve 53 side) flows either through the second heat exchanger 100b only or through the second heat exchanger 100b and the bypass 505. In addition, by adjusting the opening degree of the throttle valve 506, the ratio between the flow rate of the hydraulic oil S flowing through the second heat exchanger 100b and the flow rate of the hydraulic oil S flowing through the bypass 505 can be changed.

[0099] Therefore, when the entire amount of the hydraulic oil S is circulated through the second heat exchanger 100b and the temperature of the hydraulic oil S becomes lower than the appropriate temperature due to heat exchange with the first cooling medium A, opening the throttle valve 506 causes the hydraulic oil S circulating through the bypass 505 (uncooled hydraulic oil S) and the hydraulic oil S circulating through the second heat exchanger 100b (cooled hydraulic oil S with a lowered temperature) to merge in the hydraulic oil tank 52. As a result, by adjusting the opening of the throttle valve 506, the ratio of the hydraulic oil S from the two systems is changed, so that the temperature of the hydraulic oil S in the hydraulic oil tank 52 can be made to be the appropriate temperature, and the hydraulic system 5 (actuators 50a, 50b) can be operated appropriately.

[0100] Then, the first cooling medium A that has exchanged heat with the hydraulic oil S returns to the refrigerant tank 102 at the highest temperature corresponding to the amount of heat that has been cooled (heat removed) in sequence. Then, the first cooling medium A is pumped up by the first pump 103 again, passes through the third heat exchanger 100c, and is cooled down to the initial temperature.

[0101] In the third cooling system 12, the third pump 121 circulates (distributes) the third cooling medium C (antifreeze) through the circulation flow path, and when the third cooling medium C (antifreeze) passes through the internal combustion engine 8, it exchanges heat with the internal combustion engine 8 in a heat generating state, thereby cooling the internal combustion engine 8. The third cooling medium C that has exchanged heat with the internal combustion engine 8 passes through the third pump 121 and the fourth heat exchanger 120. Since the fourth heat exchanger 120 is arranged alongside the third heat exchanger 100c, the third cooling medium C passing through the fourth heat exchanger 120 is cooled by the forced blowing of the cooling fan 104 of the first cooling system 10, by exchanging heat with the outside air, similar to the first cooling medium A of the first cooling system 10. As a result, the third cooling medium C is circulated (distributed) through the circulation path of the third cooling system 12, and the internal combustion engine 8 is stably cooled.

[0102] In the work machine 1 according to this embodiment, the work device 4 (hydraulic system 5) is switched between a state in which the internal combustion engine 8 drives the hydraulic pump 51 via the generator 7, and a state in which the generator 7 receives power supply from a battery 70 and functions as a motor to drive the hydraulic pump 51. In this case, the temperature of the generator 7 rises due to driving (load), but, similar to the case in which the generator 7 is driven by the internal combustion engine 8, it is appropriately cooled by the second cooling medium B of the second cooling system 11, and the second cooling medium B is cooled by the first cooling medium A circulating in the first cooling system 10 (second heat exchanger 100b).

[0103] In this way, the work machine 1 of this embodiment can cool the hydraulic oil S circulating through the hydraulic system 5 and the second cooling medium (oil) B circulating through the second cooling system 11 to an appropriate temperature by the first cooling medium A circulating through the first cooling system 10.

[0104] The work machine 1 according to this embodiment is as described above, and the present invention (preferable embodiments) provides the work machine 1 described in the following items.

[0105] (Item 1) The hydraulic system 5 includes a working device 4, actuators 50a, 50b, 50c for operating the working device 4, and a hydraulic pump 51 for supplying hydraulic oil S to the actuators 50a, 50b, 50c, at least one electric device 6a, 6b, 6c, a generator 7 for generating electricity to be directly or indirectly supplied to the electric device 6a, 6b, 6c, a first cooling system 10 for circulating a first cooling medium A to cool the electric device 6a, 6b, 6c, and a second cooling system 11 for circulating a second cooling medium B to cool the generator 7. the first cooling system 10 includes a first heat exchanger 100a that cools the hydraulic oil S by heat exchange between the hydraulic oil S and the first cooling medium A, a second heat exchanger 100b that cools the second cooling medium B by heat exchange between the first cooling medium A and the second cooling medium B, and a third heat exchanger 100c that exchanges heat between the first cooling medium A and outside air and cools the first cooling medium A such that the temperature of the first cooling medium A is lower than the temperatures of the hydraulic oil S and the second cooling medium B before the heat exchange.

[0106] According to the work machine 1 of item 1, the first cooling medium A circulating (distributing) through the first cooling system 10 is cooled to an appropriate temperature (a temperature that can cool each component to an appropriate temperature) by exchanging heat with the outside air in the third heat exchanger 100c. Accordingly, even if the temperature of the electric devices 6a, 6b, 6c rises (or tries to rise) due to driving (operation), it is cooled by the first cooling medium A that has been heat exchanged (cooled) through the third heat exchanger 100c, and operates at an appropriate temperature (does not overload). In addition, the temperature of the hydraulic oil S circulating (distributing) through the hydraulic system 5 rises due to the work of the hydraulic pump 51 and the actuators 50a, 50b, 50c, and the temperature of the second cooling medium B circulating (distributing) through the second cooling system 11 rises due to heat exchange (cooling) with the generator 7. However, the first cooling medium A circulating through the first cooling system 10 exchanges heat with the hydraulic oil S in the first heat exchanger 100a, and exchanges heat with the second cooling medium B in the second heat exchanger, thereby cooling the hydraulic oil S and the second cooling medium B to an appropriate temperature.

[0107] In this way, the heat exchangers (first heat exchanger 100a, second heat exchanger 100b) that cool (exchange heat) the hydraulic oil S of the hydraulic system 5 and the second cooling medium B of the second cooling system 11 do not need to exchange heat with outside air. In other words, the heat exchangers do not need to be located in a position where outside air can be taken in. This increases the freedom in arranging the heat exchangers (first heat exchanger 100a, second heat exchanger 100b) by adjusting the piping arrangement of each system, and multiple cooling systems including the hydraulic system 5 can be made compact.

[0108] (Item 2) The hydraulic system 5 includes a hydraulic oil tank 52 that stores the hydraulic oil S, a primary system 5A that connects the actuators 50a, 50b, 50c and the hydraulic oil tank 52 via the hydraulic pump 51 and supplies the hydraulic oil S stored in the hydraulic oil tank 52 to the actuators 50a, 50b, 50c by driving the hydraulic pump 51, and a secondary system 5B that connects the actuators 50a, 50b, 50c and the hydraulic oil tank 52 and returns the hydraulic oil S from the actuators 50a, 50b, 50c to the hydraulic oil tank 52, and the first heat exchanger 100a is disposed on the secondary system 5B and exchanges heat between the hydraulic oil S circulating through the secondary system 5B and the first cooling medium A.

[0109] According to the work machine 1 of item 2, the first heat exchanger 100a is disposed on the secondary system 5B through which the hydraulic oil S, whose temperature has increased due to the work (operation) of the hydraulic pump 51 and the actuators 50a, 50b, and 50c, flows, and therefore the hydraulic oil S can be cooled before returning to the hydraulic oil tank 52 by exchanging heat between the hydraulic oil S and the first cooling medium A in the first heat exchanger 100a. Therefore, the hydraulic oil S stored in the hydraulic oil tank 52 can be prevented from becoming overheated, and the hydraulic pump 51 draws up the hydraulic oil S at an appropriate temperature from the hydraulic oil tank 52 and supplies it to the actuators 50a, 50b, and 50c.

[0110] (Item 3) The hydraulic system 5 includes a temperature sensor 507 that measures the temperature of the hydraulic oil S in the hydraulic oil tank 52, and a bypass 505 that connects a first position P1 upstream of the first heat exchanger 100a on the secondary system 5B to a second position P2 downstream of the first heat exchanger 100a, and the bypass 505 has a throttle valve 506 that adjusts the flow rate of the hydraulic oil S so that the measurement result of the temperature sensor 507 becomes an appropriate temperature of the hydraulic oil S.

[0111] According to the work machine 1 of item 3, by opening and closing the throttle valve 506, it is possible to set a state in which the hydraulic oil S flows only through the first heat exchanger 100a, and a state in which the hydraulic oil S flows through both the first heat exchanger 100a and the bypass 505. In addition, by adjusting the opening degree of the throttle valve 506, it is possible to change the ratio between the flow rate of the hydraulic oil S flowing through the first heat exchanger 100a and the flow rate of the hydraulic oil S flowing through the bypass 505. In other words, the ratio between the hydraulic oil S cooled (heat exchanged) in the first heat exchanger 100a and the hydraulic oil S flowing through the bypass 505 can be changed.

[0112] The hydraulic oil S flowing through the first heat exchanger 100a and the hydraulic oil S passing through the bypass 505 join (mix) in the hydraulic oil tank 52, so that the temperature sensor 507 measures the temperature of the hydraulic oil S in the hydraulic oil tank 52, and by adjusting the opening (flow rate) of the throttle valve 506 so that the temperature becomes an appropriate temperature for the hydraulic oil S, it is possible to prevent the hydraulic oil S from being cooled too much (below an appropriate temperature for operating the hydraulic system 5). This allows the hydraulic system 5 (actuators 50a, 50b, 50c, hydraulic pump 51) to perform at a specified capacity.

[0113] (Item 4) The work machine 1 is described in any one of items 1 to 3, and is provided with a plurality of the electric devices 6a, 6b, 6c, and the plurality of electric devices 6a, 6b, 6c are arranged in a first cooling system 10 and cooled in order of decreasing heat resistance and decreasing heat generation temperature during operation from the upstream side to the downstream side in the flow direction of the first cooling medium A.

[0114] According to the work machine 1 of item 4, the electric devices 6a, 6b, 6c are arranged on the first cooling system 10 in the order of the lowest heat resistance and the lowest heat generation temperature during operation from the upstream side to the downstream side in the flow direction of the first cooling medium A, so that the electric devices 6a, 6b, 6c with low heat resistance can be cooled preferentially, and the occurrence of failures of the electric devices 6a, 6b, 6c with low heat resistance can be suppressed. In addition, since the electric devices 6a, 6b, 6c located on the upstream side of the first cooling system 10 have a lower heat generation temperature during operation, the first cooling medium A flows downstream with a margin for removing heat from the electric devices 6a, 6b, 6c on the downstream side. Therefore, when the electric devices 6a, 6b, 6c are cooled by the first cooling medium A, it is possible to prevent a situation in which the electric devices 6a, 6b, 6c arranged on the downstream side cannot be cooled.

[0115] (Item 5) The working machine 1 described in item 4 includes an electric motor 24 and an inverter 25 that drives the electric motor 24 as the multiple electrical devices 6a, 6b, the electric motor 24 and the inverter 25 are arranged on the first cooling system 10, and the inverter 25 is arranged upstream of the electric motor 24 in the flow direction of the first cooling medium A.

[0116] According to the work machine 1 of item 5, since the inverter 25 has a lower heat resistance than the electric motor 24, by disposing the inverter 25 upstream of the electric motor 24 as described above, the inverter 25, which has a lower heat resistance, can be preferentially heat exchanged (cooled). Therefore, it is possible to prevent the inverter 25 from breaking down due to overheating.

[0117] (Item 6) The work machine 1 according to any one of items 1 to 5, further comprising a generator inverter 71 for driving the generator 7 as the electric equipment 6c, the generator inverter 71 being disposed on the first cooling system 10.

[0118] According to the work machine 1 of item 6, the generator inverter 71 has low heat resistance like the motor inverter 25. Therefore, by placing the generator inverter 71 in the first cooling system 10, it is possible to prevent the occurrence of breakdowns due to overheating of the generator inverter 71.

[0119] (Item 7) 2. The work machine 1 according to item 1, wherein the second cooling medium B is a liquid having a specific heat smaller than that of the first cooling medium A and a boiling point higher than that of the first cooling medium A.

[0120] According to the work machine 1 of item 7, even if the temperature of the first cooling medium A rises due to the cooling of the electric devices 6a, 6b, and 6c circulating through the first cooling system 10, it is possible to prevent the temperature of the first cooling medium A from exceeding the temperature of the second cooling medium B. In other words, it is possible to prevent a situation in which the temperature of the first cooling medium A becomes higher than the temperature of the second cooling medium B before the first cooling medium A reaches the second heat exchanger 100b, making it impossible to cool the second cooling medium B (unable to remove the heat from the second cooling medium B).

[0121] (Item 8) 8. The work machine 1 according to item 7, wherein the first cooling medium A is water and the second cooling medium B is oil.

[0122] According to the work machine 1 of item 8, the first cooling medium A and the second cooling medium B have no special characteristics and are easy to handle.

[0123] (Item 9) The work machine 1 described in item 1, wherein the first heat exchanger 100a is arranged downstream of the second heat exchanger 100b and upstream of the third heat exchanger 100c, and the second heat exchanger 100b is arranged downstream of the electrical equipment 6a, 6b, and 6c.

[0124] According to the work machine 1 of item 9, the amount of work (amount of heat generated) of the generator 7 is greater than the amount of work (amount of heat generated) of the electric equipment 6a, 6b, 6c, and the amount of work (amount of heat generated) of the hydraulic system 5 (the hydraulic pump 51 and the actuators 50a, 50b, 50c) is greater than the amount of work (amount of heat generated) of the generator 7. Therefore, the temperature rise of the second cooling medium B is greater than the temperature rise of the electric equipment 6a, 6b, 6c, and the temperature rise of the hydraulic oil S is greater than the temperature rise of the second cooling medium B.

[0125] Therefore, the first heat exchanger 100a is disposed downstream of the second heat exchanger 100b, and the second heat exchanger 100b is disposed downstream of the electric devices 6a, 6b, and 6c, so that the electric devices 6a, 6b, and 6c, the second cooling medium B, and the hydraulic oil S can be appropriately cooled while suppressing the temperature rise of the first cooling medium caused by cooling the objects. In addition, the first heat exchanger 100a is disposed upstream of the third heat exchanger 100c, so that the first cooling medium A, which has risen in temperature the most in the first cooling system 10, can be heat exchanged (cooled) by the third heat exchanger 100c. This allows the electric devices 6a, 6b, and 6c, the second cooling medium B, and the hydraulic oil S in the first cooling system 10 to be appropriately cooled.

[0126] (Item 10) The work machine 1 described in item 1 includes an internal combustion engine 8 that drives the generator 7, and a third cooling system 12 that circulates the third cooling medium C to cool the internal combustion engine 8, the third cooling system 12 exchanging heat between the third cooling medium C and outside air and including a fourth heat exchanger 120 arranged in parallel to the third heat exchanger 100c, and at least one of the first cooling system 10 and the third cooling system 12 has a cooling fan 104 that sends the outside air toward the third heat exchanger 100c and the fourth heat exchanger 120.

[0127] According to the work machine 1 of item 10, the temperature of the third cooling medium C flowing (circulating) through the third cooling system 12 rises due to the drive (work) of the internal combustion engine 8, but the third cooling medium C is cooled by heat exchange with outside air when passing through the fourth heat exchanger 120, and circulates through the third cooling system 12 while continuously cooling the internal combustion engine 8. In addition, at least one of the first cooling system 10 and the third cooling system 12 has a cooling fan 104 that sends outside air toward the third heat exchanger 100c and the fourth heat exchanger 120, and therefore the heat exchange efficiency (cooling efficiency) of the third cooling medium C is increased by the forced air blown by the cooling fan 104.

[0128] Furthermore, since the third heat exchanger 100c is provided in parallel with the fourth heat exchanger, the heat exchange efficiency (cooling efficiency) of not only the third cooling medium C circulating through the third cooling system 12 but also the first cooling medium A circulating through the first cooling system 10 can be increased by forced airflow from a single cooling fan 104. Also, the cooling fan 104 possessed by at least one of the first cooling system 10 and the third cooling system 12 is a shared cooling fan 104 that cools heat exchangers in systems other than the system to which it belongs, so the occupancy rate of the cooling fan 104 can be reduced. In other words, the cooling system can be made compact.

[0129] (Item 11) The generator 7 is a motor-generator that has an output shaft that transmits driving force to the hydraulic pump 51 and is switchable between a power generating state in which it receives driving force from the internal combustion engine 8 to generate electricity and a drive state in which it receives electric power supply to rotate and drive the hydraulic pump 51. The work machine 1 described in item 10 drives the hydraulic pump 51 via the output shaft in the power generating state and the drive state.

[0130] According to the work machine 1 of item 11, the generator 7 is a motor-generator that can be switched between a power generating state in which it generates electricity by being driven by the internal combustion engine 8 and a drive state in which it receives electric power supply and drives it to rotate, so that the work machine does not depend only on the drive of the internal combustion engine 8. In other words, the work machine is a hybrid work machine that can be driven by either the internal combustion engine 8 or the generator 7, or by a combination of the two.

[0131] (Item 12) The work machine 1 described in item 1, wherein each of the first cooling medium A and the second cooling medium B is a liquid, the first heat exchanger 100a and the second heat exchanger 100b are liquid-cooled heat exchangers that exchange heat between liquids, and the third heat exchanger 100c is an air-cooled heat exchanger that exchanges heat between a gas and a liquid.

[0132] According to the work machine 1 of item 12, the third heat exchanger 100c is an air-cooled heat exchanger that exchanges heat between gas and liquid, but the first heat exchanger 100a and the second heat exchanger 100b are liquid-cooled heat exchangers that exchange heat between liquids, and therefore the work machine 1 can be made compact.

[0133] (Item 13) The liquid-cooled heat exchangers 100a, 100b are plate-type heat exchangers in which a plurality of heat transfer plates 101... are stacked, and a first flow path R1 for circulating a heat exchange medium A and a second flow path R2 for circulating heat exchange media S, B are alternately formed on each of the heat transfer plates 101.... In the first heat exchanger 100a, the first cooling medium A is circulated through the first flow path R1 as the heat exchange medium, and the hydraulic oil S is circulated through the second flow path R2 as the heat exchange medium. In the second heat exchanger 100b, the first cooling medium A is circulated through the first flow path R1 as the heat exchange medium, and the second cooling medium B is circulated through the second flow path R2 as the heat exchange medium.

[0134] According to the work machine 1 of item 13, the first heat exchanger 100a and the second heat exchanger 100b are plate-type heat exchangers having a plurality of stacked heat transfer plates 101..., in which a first flow path R1 through which the heat exchange medium A flows and a second flow path R2 through which the heat exchange media S, B flow are alternately formed on the boundary between each heat transfer plate 101..., so that the first heat exchanger 100a and the second heat exchanger 100b can be made compact.

[0135] In addition, in the first heat exchanger 100a, the heat exchange efficiency between the first cooling medium A and the hydraulic oil S is high, and in the second heat exchanger 100b, the heat exchange efficiency between the first cooling medium A and the second heat exchange medium A can be increased. That is, in the plate type heat exchangers 100a and 100b, the opposing surfaces of the adjacent heat transfer plates 101 serve as heat transfer surfaces, so that the heat exchange efficiency is high and efficient cooling is possible.

[0136] It should be noted that the present invention is not limited to the above-described embodiment, and modifications can be made as appropriate without departing from the spirit and scope of the present invention.

[0137] For example, in the above embodiment, a track loader (compact track loader) has been described as an example of the work machine 1, but the work machine 1 is not limited to a track loader (compact track loader). The work machine 1 may be an agricultural machine, a construction machine, a UV (utility vehicle), etc. More specifically, the work machine 1 may be a tractor, a skid steer loader, a wheel loader, a backhoe, etc.

[0138] In the above embodiment, the riding work machine 1 has been described, but the present invention is not limited to this. For example, the work machine 1 may be remotely operated by a driver outside the work machine 1. Furthermore, the work machine 1 may be operated autonomously by a control unit 9 provided in the work machine 1.

[0139] In the above embodiment, a crawler-type traveling device is adopted as the traveling device 2, but this is not limited thereto. For example, the traveling device 2 may be a tire-type traveling device or a combined tire-type and crawler-type traveling device. The tire-type traveling device includes a pair of front wheels arranged on both the left and right sides at the front side in the traveling direction, and a pair of rear wheels arranged on both the left and right sides at the rear side in the traveling direction, with at least one of the front wheels and the rear wheels being a steering wheel that determines the traveling direction, and at least the other of the front wheels and the rear wheels being a driving wheel that receives drive from a drive source and is driven to rotate.

[0140] In the composite traveling device, either the front or rear side in the traveling direction is configured as a tire-type traveling device, and either the front or rear side in the traveling direction is configured as a crawler-type traveling device. In this case, the tire-type traveling device is a pair of left and right wheels (tires), including a pair of wheels (tires) that are steered wheels, and the crawler-type traveling device is configured similarly to the traveling device 2 in the above embodiment and is disposed on both the left and right sides of the machine body 3. The driving source of the traveling device 2 may be an electric motor or an internal combustion engine (engine) as in the above embodiment. However, it is assumed that the working machine 1 is equipped with the electric motor of the traveling device 2 or other electric devices 6a, 6b, 6c as the electric devices 6a, 6b, 6c, and the electric devices 6a, 6b, 6c are cooled by the first cooling system 10. In addition, when the work machine 1 is equipped with multiple electrical devices 6a, 6b, and 6c, the multiple electrical devices 6a, 6b, and 6c are arranged and cooled in the first cooling system 10 in order of decreasing heat resistance and decreasing heat generation temperature during operation, from the upstream side to the downstream side in the flow direction of the first cooling medium A.

[0141] In the above embodiment, the drive motor (electric motor) 24, the motor inverter (inverter) 25, and the generator inverter 71 are arranged on the first cooling system 10 as the electric devices 6a, 6b, and 6c, but the present invention is not limited thereto. For example, in addition to the drive motor (electric motor) 24, the motor inverter (inverter) 25, and the generator inverter 71, other electric devices may be arranged on the first cooling system 10, and other electric devices may be arranged on the first cooling system 10 instead of the drive motor (electric motor) 24, the motor inverter (inverter) 25, and the generator inverter 71. That is, it is sufficient that at least one electric device is arranged on the first cooling system 10, taking into account the need for cooling.

[0142] In the above embodiment, the generator (motor generator) 6 drives the hydraulic pump 51, but this is not limiting. The generator (motor generator) 6 may drive a device other than the hydraulic pump 51. In other words, the second cooling system 11 may cool the generator (motor generator) 6 that drives a device other than the hydraulic pump 51.

[0143] In the above embodiment, the generator 7 has a function as a motor for driving the hydraulic pump 51, but is not limited thereto. For example, the generator 7 may have only a function as a generator for generating electric power to be supplied to the electric devices 6a, 6b, and 6c. Therefore, the second cooling system 11 may cool the generator 7 having only a function as a generator 7.

[0144] In the above embodiment, a diesel engine is used as the internal combustion engine 8, but the present invention is not limited to this. For example, the internal combustion engine 8 may be a gasoline engine, an LPG engine, or the like.

[0145] In the above embodiment, in each of the second cooling system 11 and the third cooling system 12, the cooling medium (second cooling medium B, third cooling medium C) sent out by the pump (second pump 110, third pump 121) flows through a circular flow path (circulation flow path) and returns directly to the pump (second pump 110, third pump 121), but this is not limited thereto. For example, in each of the second cooling system 11 and the third cooling system 12, a tank for storing the cooling medium (second cooling medium B, third cooling medium C) or a pocket for storing the cooling medium (second cooling medium B, third cooling medium C) may be arranged upstream of the pump (second pump 110, third pump 121), and the pump (second pump 110, third pump 121) may suck up the cooling medium (second cooling medium B, third cooling medium C) stored in the tank or pocket and discharge it toward the second heat exchanger 100b.

[0146] In the above embodiment, a permanent magnet embedded type three-phase AC synchronous motor is used as the generator (motor generator) 6. However, the present invention is not limited to this. For example, the generator (motor generator) 6 may be another type of synchronous motor, or may be an AC motor or a DC motor.

[0147] In the above embodiment, no particular mention was made of the plate type heat exchangers adopted for the first heat exchanger 100a and the second heat exchanger 100b. However, when a plate type heat exchanger is adopted, it may be of a brazing type in which adjacent heat transfer plates 101, 101 are sealed with brazing to form the first flow path R1, the second flow path R2, the inlet paths Ra1, Rb1, and the outlet paths Ra2, Rb2, or it may be of a gasket type in which a gasket is inserted between adjacent heat transfer plates 101, 101.

[0148] In the above embodiment, the first heat exchanger 100a and the second heat exchanger 100b are configured as plate-type heat exchangers as liquid-cooled heat exchangers, but are not limited thereto. For example, the first heat exchanger 100a and the second heat exchanger 100b may be configured as multi-tube heat exchangers on the premise that they are liquid-cooled heat exchangers.

[0149] In the above embodiment, the first cooling system 10 has the cooling fan 104 that sends outside air to the third heat exchanger 100c and the fourth heat exchanger 120, but is not limited thereto. For example, as shown in Fig. 7, the third cooling system 12 may have a cooling fan 123 that sends outside air to the third heat exchanger 100c and the fourth heat exchanger 120. In this case, similarly to the above embodiment, the cooling fan 123 may be a suction fan that draws in outside air from the third heat exchanger 100c and the fourth heat exchanger 120 side, or may be a push fan that pushes outside air toward the third heat exchanger 100c and the fourth heat exchanger 120 side, as shown in Fig. 7.

[0150] 8, the first cooling system 10 and the third cooling system 12 may each have cooling fans 104, 123 that send outside air to the third heat exchanger 100c and the fourth heat exchanger 120. In this case, the cooling fan 104 of the first cooling system 10 may be a suction fan that draws in outside air from the third heat exchanger 100c and the fourth heat exchanger 120 side, and the cooling fan 123 of the third cooling system 12 may be a push fan that pushes outside air to the third heat exchanger 100c and the fourth heat exchanger 120 side, so that the flow directions of the outside air are the same. Also, as shown in FIG. 8, the cooling fan 123 of the third cooling system 12 may be a suction fan that draws in outside air from the third heat exchanger 100c and the fourth heat exchanger 120 side, and the cooling fan 104 of the first cooling system 10 may be a push fan that pushes outside air to the third heat exchanger 100c and the fourth heat exchanger 120 side.

[0151] Even in this case, the cooling fans 104, 123 in the system of their own are also used for cooling the heat exchangers 100c, 120 in the other system.

[0152] In the above embodiment, the third heat exchanger 100c and the fourth heat exchanger 120 are arranged overlapping each other in the ventilation direction of the outside air so that their ventilation paths (gaps between the fins) are continuous in the same direction, but this is not limited thereto. For example, as shown in FIG. 9, the third heat exchanger 100c and the fourth heat exchanger 120 may be arranged side by side in a direction perpendicular to the ventilation direction of the outside air. That is, the third heat exchanger 100c and the fourth heat exchanger 120 may be arranged overlapping each other in the ventilation direction of the outside air, or may be arranged side by side in a direction perpendicular to the ventilation direction of the outside air, as long as the ventilation directions are in the same state. In this case, either one of the first cooling system 10 and the third cooling system 12 may be provided with a common cooling fan 104, 123, which is a push fan that pushes the outside air toward the third heat exchanger 100c and the fourth heat exchanger 120, or a suction fan that sucks the outside air from the third heat exchanger 100c and the fourth heat exchanger 120 side. The cooling fan 123 shown in FIG. 9 is a suction fan included in the third cooling system 12. [Explanation of symbols]

[0153] 1: Work equipment 4: Work equipment 5: Hydraulic system 5A: Primary system 5B: Secondary system 6a: Electrical equipment 6b: Electrical equipment 6c: Electrical equipment 7: Generator 8: Internal combustion engine 10:First cooling system 11:Second cooling system 12:Third cooling system 50a: Actuator (lifting cylinder) 50b: Actuator (tilting cylinder) 50c: Actuator (hydraulic actuator) 51: Hydraulic pump (multiple hydraulic pumps) 52: Hydraulic oil tank 71: Generator inverter 100a: First heat exchanger (plate heat exchanger) 100b: Second heat exchanger (plate heat exchanger) 100c: Third heat exchanger (radiator) 101: Heat transfer plate 104: Cooling fan 120: Fourth heat exchanger (radiator) 123: Cooling fan 505: Bypass 506:Throttling valve 507: Temperature sensor A: First cooling medium (heat exchange medium) B:Second cooling medium (heat exchange medium) C: Third cooling medium P1 :First position P2 :Second position R1: First flow path R2: Second flow path S: Hydraulic oil (heat exchange medium)

Claims

1. A working device; a hydraulic system including an actuator that operates the working device and a hydraulic pump that supplies hydraulic oil to the actuator; At least one electrical device; A generator that generates electric power to be directly or indirectly supplied to the electric device; a first cooling system that circulates a first cooling medium to cool the electric device; a second cooling system that circulates a second cooling medium to cool the generator, The first cooling system includes: a first heat exchanger that cools the hydraulic oil by exchanging heat between the hydraulic oil and the first cooling medium; a second heat exchanger that exchanges heat between the first cooling medium and the second cooling medium to cool the second cooling medium; and a third heat exchanger that exchanges heat between the first cooling medium and outside air and cools the first cooling medium so that a temperature of the first cooling medium is lower than temperatures of the hydraulic oil and the second cooling medium before the heat exchange.

2. The hydraulic system includes: A hydraulic oil tank that stores the hydraulic oil; a primary system that connects the actuator and the hydraulic oil tank via the hydraulic pump and supplies the hydraulic oil stored in the hydraulic oil tank to the actuator by driving the hydraulic pump; a secondary system that connects the actuator and the hydraulic oil tank and returns the hydraulic oil from the actuator to the hydraulic oil tank; The work machine according to claim 1 , wherein the first heat exchanger is disposed on the secondary system and exchanges heat between the hydraulic oil flowing through the secondary system and the first cooling medium.

3. The hydraulic system includes: a temperature sensor for measuring a temperature of the hydraulic oil in the hydraulic oil tank; a bypass connecting a first position upstream of the first heat exchanger and a second position downstream of the first heat exchanger in the secondary system, The bypass is 3. The work machine according to claim 2, further comprising a throttle valve that adjusts the flow rate of the hydraulic oil so that the measurement result of the temperature sensor becomes an appropriate temperature for the hydraulic oil.

4. A plurality of the electrical devices are provided, The work machine according to claim 1, wherein the plurality of electrical devices are arranged in a first cooling system in order of decreasing heat resistance and decreasing heat generation temperature during operation from the upstream side to the downstream side in the flow direction of the first cooling medium, and are cooled thereby.

5. The plurality of electrical devices include: An electric motor; an inverter that drives the electric motor, the electric motor and the inverter are disposed on the first cooling system, The work machine according to claim 4 , wherein the inverter is disposed upstream of the electric motor in a flow direction of the first cooling medium.

6. a generator inverter that drives the generator as the electric device, The work machine according to claim 1 , wherein the generator inverter is disposed on the first cooling system.

7. 2. The work machine according to claim 1, wherein the second cooling medium is a liquid having a specific heat smaller than that of the first cooling medium and a boiling point higher than that of the first cooling medium.

8. the first cooling medium is water; 8. The work machine according to claim 7, wherein the second cooling medium is oil.

9. The first heat exchanger is disposed downstream of the second heat exchanger and upstream of the third heat exchanger, The work machine according to claim 1 , wherein the second heat exchanger is disposed downstream of the electrical device.

10. an internal combustion engine that drives the generator; a third cooling system that circulates a third cooling medium to cool the internal combustion engine, the third cooling system includes a fourth heat exchanger that exchanges heat between the third cooling medium and outside air and is arranged in parallel with the third heat exchanger; 2 . The work machine according to claim 1 , wherein at least one of the first cooling system and the third cooling system has a cooling fan that sends the outside air toward the third heat exchanger and the fourth heat exchanger.

11. The generator has an output shaft that transmits driving force to the hydraulic pump, 11. The working machine according to claim 10, which is a motor-generator switchable between a power generating state in which it generates electricity by receiving drive from the internal combustion engine and a drive state in which it receives a supply of electric power and drives the hydraulic pump via the output shaft in the power generating state and the drive state.

12. each of the first cooling medium and the second cooling medium is a liquid; The first heat exchanger and the second heat exchanger are liquid-cooled heat exchangers that exchange heat between liquids, 2. The work machine according to claim 1, wherein the third heat exchanger is an air-cooled heat exchanger that exchanges heat between a gas and a liquid.

13. The work machine according to claim 12, wherein the liquid-cooled heat exchanger is a plate-type heat exchanger in which a plurality of heat transfer plates are stacked, and a first flow path for circulating a heat exchange medium and a second flow path for circulating a heat exchange medium are alternately formed on each heat transfer plate as a boundary, and in the first heat exchanger, the first cooling medium is circulated through the first flow path as the heat exchange medium, and the hydraulic oil is circulated through the second flow path as the heat exchange medium, and in the second heat exchanger, the first cooling medium is circulated through the first flow path as the heat exchange medium, and the second cooling medium is circulated through the second flow path as the heat exchange medium.

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