Electric working machine

Abstract

Provided is an electric working machine comprising a battery, an electric motor that uses electric power from the battery as a drive source, a hydraulic pump that is driven by the electric motor to pump operating oil to a hydraulic actuator, an operating oil cooling circuit that includes an oil cooler for cooling the operating oil, and a space cooling refrigerant circuit that circulates a space cooling refrigerant, wherein: the electric working machine includes a battery temperature regulating circuit that circulates a heat medium for adjusting the temperature of the battery; and the battery temperature regulating circuit includes an electric heater for heating the heat medium, a battery cooling heat exchanger that causes the heating medium to exchange heat with the space cooling refrigerant that circulate through the space cooling refrigerant circuit to cool the heating medium, and a battery warming-up heat exchanger that causes the heating medium to exchange heat with the operating oil that flows through the operating oil cooling circuit to heat the heat medium.

Description

electric work machine

[0001] The present invention relates to an electric work machine that is powered by battery power.

[0002] Toward the realization of a carbon-free society, the construction machinery industry is also seeing increasing demand for electric drive systems to replace engines. However, unlike passenger cars, work machinery with high average loads requires a large amount of power to charge and discharge batteries. For this reason, the role of battery temperature regulation systems is particularly important in preventing battery degradation and maintaining stable output.

[0003] Furthermore, as electric vehicles (EVs) become increasingly powerful, it is becoming difficult to regulate the temperature of the battery using conventional air-cooling methods that use natural wind or air conditioning. For example, a battery cooling system that uses air conditioner refrigerant has been proposed (Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2019-26111

[0005] Batteries have an appropriate temperature range for proper operation. Work machines such as hydraulic excavators may operate in remote mountainous areas, areas with heavy snowfall, and various other cold environments, which can cause the battery to become extremely cold. If the battery temperature is extremely low, it is desirable to warm up the battery using, for example, an electric heater and raise the battery temperature to the appropriate temperature range as quickly as possible.

[0006] However, a configuration that solely uses an electric heater to warm up the battery consumes a lot of power to warm up a large battery, and if the battery temperature is extremely low, it takes a long time to warm up the large battery to the appropriate temperature using only the electric heater.

[0007] An object of the present invention is to provide an electric work machine that can achieve both cooling and heating performance for a battery and can suppress a decrease in energy efficiency due to warming up of the battery.

[0008] In order to achieve the above object, the present invention provides an electric work machine including a battery, an electric motor powered by the battery as a drive source, a hydraulic pump driven by the electric motor and pumping hydraulic oil to a hydraulic actuator, a hydraulic oil cooling circuit having an oil cooler for cooling the hydraulic oil, and an air conditioning refrigerant circuit for circulating an air conditioning refrigerant, the electric work machine including a battery temperature regulation circuit for circulating a heat medium for regulating the temperature of the battery, the battery temperature regulation circuit having an electric heater for heating the heat medium, a battery cooling heat exchanger for cooling the heat medium by heat exchange with the air conditioning refrigerant circulating through the air conditioning refrigerant circuit, and a battery warming heat exchanger for heating the heat medium by heat exchange with the hydraulic oil flowing through the hydraulic oil cooling circuit.

[0009] According to the present invention, it is possible to achieve both cooling and heating performance of the battery, and to suppress a decrease in energy efficiency due to warming up of the battery.

[0010] Fig. 1 is a side view showing the appearance of a hydraulic excavator, which is an example of an electric working machine according to an embodiment of the present invention. Fig. 2 is a schematic diagram showing an example of the configuration of a drive system mounted on the hydraulic excavator shown in Fig. 1. Fig. 3 is a schematic diagram showing an example of the configuration of a cooling circuit provided in the hydraulic excavator shown in Fig. 1. Fig. 4 is a flowchart showing an example of a control procedure for a first hydraulic oil control valve by a controller provided in the hydraulic excavator shown in Fig. 1. Fig. 5 is a flowchart showing an example of a control procedure for a second hydraulic oil control valve by a controller provided in the hydraulic excavator shown in Fig. 1.

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

[0012] (Electric Work Machine) Figure 1 is a side view showing the appearance of a hydraulic excavator 1, which is an example of an electric work machine according to an embodiment of the present invention. In Figure 1, the right side is the front of an upper rotating body 13. The overall configuration and operation of the hydraulic excavator 1 will be described with reference to this figure.

[0013] The hydraulic excavator 1 shown in Figure 1 comprises a lower traveling body 11 for traveling on a road surface, an upper rotating body 13 rotatably attached above the lower traveling body 11 via a rotating device 12, and a front working implement 14 connected to the front of the upper rotating body 13 so as to be able to move up and down and to perform work such as excavation. The lower traveling body 11 and the upper rotating body 13 form the vehicle body of the hydraulic excavator 1, and the front working implement 14 is attached to this vehicle body.

[0014] The undercarriage 11 is of a crawler type having crawlers 111 on the left and right sides (both ends in the vehicle width direction), but may also be of a wheel type. The left and right crawlers 111 are driven independently by respective travel motors 112. This allows the hydraulic excavator 1 to travel in the forward and backward directions, etc., with the left and right crawlers 111 in contact with the ground. In Fig. 1, only the right crawler 111 and travel motor 112 are shown.

[0015] The upper rotating body 13 includes a cab 13A in which an operator sits, a counterweight 13B for maintaining a weight balance with the front work implement 14, and a machinery room 13C for accommodating devices such as a battery, an electric motor, an electric motor control device, and a hydraulic pump, which will be described later. In the upper rotating body 13, the cab 13A is located in the front, the counterweight 13B in the rear, and the machinery room 13C between the cab 13A and the counterweight 13B. The upper rotating body 13 is driven by a swing motor 120 (see FIG. 2 ) provided on the swing device 12 to swing relative to the undercarriage 11.

[0016] The front work machine 14 comprises a boom 41 whose base end is rotatably attached to the upper rotating body 13 and which rotates (elevates) in the vertical direction relative to the upper rotating body 13, an arm 42 rotatably attached to the tip of the boom 41 and which rotates in the longitudinal direction relative to the boom 41, and a bucket 43 rotatably attached to the tip of the arm 42 and which rotates in the longitudinal direction relative to the arm 42.

[0017] The bucket 43 is an attachment used to excavate earth and sand, level the ground, and compact the ground, for example. The bucket 43 can be changed to other attachments, such as a grapple for grabbing wood, rocks, waste, etc., or a breaker for excavating rock. This allows the hydraulic excavator 1 to perform a variety of tasks, including excavation and crushing, using an attachment suited to the task.

[0018] The front work implement 14 also has a boom cylinder 410 that connects the upper rotating body 13 and the boom 41, an arm cylinder 420 that connects the boom 41 and the arm 42, a bucket cylinder 430 that connects the arm 42 and the bucket 43, and multiple pipes (not shown) that guide hydraulic oil to these hydraulic cylinders 410, 420, and 430, respectively.

[0019] The boom cylinder 410 rotates the boom 41 relative to the upper rotating body 13 by extending and retracting a rod 410C in and out of a tube. The arm cylinder 420 rotates the arm 42 relative to the boom 41 by extending and retracting a rod 420C in and out of a tube. The bucket cylinder 430 rotates the bucket 43 relative to the arm 42 by extending and retracting a rod 430C in and out of a tube.

[0020] The boom cylinder 410, arm cylinder 420, bucket cylinder 430, travel motor 112, and swing motor 120 are hydraulic actuators that are driven by hydraulic oil from the main pump 51 (FIG. 2). In the following description, the boom cylinder 410, arm cylinder 420, bucket cylinder 430, travel motor 112, and swing motor 120 may be collectively referred to as hydraulic actuators.

[0021] (Drive System) FIG. 2 is a schematic diagram showing an example of the configuration of a drive system mounted on the hydraulic excavator 1. The drive system of the hydraulic excavator 1 will be described with reference to FIG. 2. In FIG. 2, elements that have already been described are assigned the same reference numerals as in FIG. 1, and descriptions thereof will be omitted. Furthermore, since the boom cylinder 410, arm cylinder 420, and bucket cylinder 430 all have the same configuration as hydraulic cylinders, FIG. 2 illustrates only the boom cylinder 410 as a representative of the hydraulic cylinders, and descriptions of the arm cylinder 420 and the bucket cylinder 430 will be omitted. Similarly, since the travel motor 112 and the swing motor 120 all have the same configuration as hydraulic motors, FIG. 2 illustrates only the swing motor 120 as a representative of the hydraulic motors, and descriptions of the travel motor 112 will be omitted. Therefore, FIG. 2 does not illustrate directional control valves, operating devices, and the like corresponding to hydraulic actuators other than the boom cylinder 410 and the swing motor 120.

[0022] The hydraulic circuit 5 of the drive system shown in Figure 2 is configured to include a main pump 51 and a pilot pump 52, which are hydraulic pumps, a hydraulic oil tank 53 that stores hydraulic oil, a control valve 100, etc. The control valve 100 includes directional control valves 54, 55 that control the flow of hydraulic oil discharged from the main pump 51. The directional control valve 54 controls the flow (supply direction and supply flow rate) of hydraulic oil from the main pump 51 to the swing motor 120, thereby controlling the operation of the swing motor 120. The directional control valve 55 controls the flow (supply direction and supply flow rate) of hydraulic oil from the main pump 51 to the boom cylinder 410, thereby controlling the operation of the boom cylinder 410. The operator's cab 13A is provided with an operation mode selection switch 132, a motor control dial 133 that sets the rotation speed of the electric motor 50, operating lever devices 131A, 131B, a controller 90, etc.

[0023] The main pump 51 is a variable displacement hydraulic pump driven by the electric motor 50. The main pump 51 pumps out hydraulic oil drawn from a hydraulic oil tank 53 and supplies the hydraulic oil to the swing motor 120 and the boom cylinder 410 via directional control valves 54, 55. In this embodiment, a variable displacement hydraulic pump is used as the main pump 51, but this is not limiting, and a fixed displacement hydraulic pump can also be used as the main pump 51.

[0024] The pilot pump 52 is a fixed displacement hydraulic pump driven by the electric motor 50. The pilot pump 52 discharges hydraulic oil drawn from a hydraulic oil tank 53 and supplies the hydraulic oil to a pair of pressure-receiving chambers 54A, 54B of the directional control valve 54 and a pair of pressure-receiving chambers 55A, 55B of the directional control valve 55, respectively.

[0025] The hydraulic circuit 5 further includes a main relief valve 57 that defines the upper limit of the pressure in the discharge line of the main pump 51, a pilot relief valve 56 that defines the upper limit of the pressure in the discharge line of the pilot pump 52, and an on-off valve 58 that opens and closes the line between the directional control valve 55 and the hydraulic oil tank 53.

[0026] The control lever devices 131A, 131B correspond to the swing motor 120 and the boom cylinder 410, respectively, and may be, for example, electric levers that output an electric lever signal Lv (operation signal) corresponding to the amount of operation. The controller 90 controls the switching direction and stroke amount of the directional control valves 54, 55 by outputting command signals corresponding to the lever signals Lv input from the control lever devices 131A, 131B to the solenoid proportional valves 54a, 54b and the solenoid proportional valves 55a, 55b. At the same time, the controller 90 controls the pump capacity (discharge flow rate) of the main pump 51 by outputting command signals corresponding to the pump discharge pressure sensor 61, the electric motor rotation speed sensor (not shown), the lever signal Lv, etc. to the regulator 51a of the main pump 51. With this configuration, the control lever devices 131A, 131B allow each hydraulic actuator to perform a desired operation.

[0027] The directional control valve 54 is a center bypass type directional control valve and has a first switching position 54L for rotating the swing motor 120 forward, a neutral position 54N for communicating between the main pump 51 and the hydraulic oil tank 53 and returning the hydraulic oil directly to the hydraulic oil tank 53, and a second switching position 54R for rotating the swing motor 120 reversely. The directional control valve 54 is configured to be switched to any one of the first switching position 54L, the neutral position 54N, and the second switching position 54R by the stroke of an internal spool in response to the pilot pressures acting on the pair of pressure receiving chambers 54A, 54B, respectively. This controls the flow rate and direction (flow) of the hydraulic oil supplied from the main pump 51 to the swing motor 120.

[0028] Like directional control valve 54, directional control valve 55 is a center bypass type directional control valve and has a first switching position 55L for extending boom cylinder 410, a neutral position 55N for connecting main pump 51 and hydraulic oil tank 53 and returning hydraulic oil directly to hydraulic oil tank 53, and a second switching position 55R for retracting boom cylinder 410. Like directional control valve 54, directional control valve 55 is configured to be switched to any one of first switching position 55L, neutral position 55N, and second switching position 55R by an internal spool stroking in response to pilot pressures acting on a pair of pressure receiving chambers 55A, 55B, respectively. This controls the flow rate and direction (flow) of hydraulic oil supplied from main pump 51 to boom cylinder 410.

[0029] The on-off valve 58 is an electromagnetic proportional valve whose opening is adjusted in proportion to the magnitude of a command current, and the opening area is adjusted in proportion to the magnitude of the command current from the controller 90. Even when the on-off valve 58 is not in operation or when the load on the hydraulic actuator is small, the pressure of the main pump 51 can be freely adjusted by adjusting the opening of the on-off valve 58.

[0030] In the hydraulic excavator 1, the main pump 51 is driven by an electric motor 50. The electric motor 50 is driven by the power of the battery 30.

[0031] In addition to the battery 30 and the electric motor 50, an electric motor control device that controls the electric motor 50 and various electric accessories (e.g., the electric compressor 45) are connected to the power circuit 200 of the drive system. The electric motor control device includes an inverter 59, an on-board charger 35, a DCDC converter 60, etc.

[0032] The battery 30 is a drive source for the hydraulic excavator 1 and is formed, for example, from a lithium-ion battery or a nickel-metal hydride battery. The battery 30 is provided with a battery sensor (not shown) for detecting the operating state of the battery 30, such as the voltage, current, and remaining capacity (SOC). The state of the battery 30 is monitored by a battery controller 32 based on the output of the battery sensor.

[0033] The on-board charger 35 can charge the battery 30 using an external power supply 40. The on-board charger 35 is controlled by a controller 90 in accordance with the state of the battery 30 monitored by a battery controller 32, and controls charging of the battery 30.

[0034] The DC-DC converter 60 reduces the voltage (e.g., 650 V) of the battery 30 to generate a voltage (e.g., 24 V) for vehicle control, and supplies power to the controller 90, the radiator electric fan 220, the condenser electric fan 230, the oil cooler electric fan 240, etc.

[0035] The inverter 59 converts the DC voltage (battery voltage) of the battery 30 into AC voltage and supplies it to the electric motor 50 , thereby controlling the rotation speed of the electric motor 50 .

[0036] The controller 90 is a higher-level control device that controls the drive system of the hydraulic excavator 1, and controls the solenoid valves and lower-level control devices (inverter 59, battery controller 32, on-board charger 35) included in the hydraulic circuit.

[0037] (Cooling Circuit) Figure 3 is a schematic diagram showing an example of the configuration of a cooling circuit provided in the hydraulic excavator 1. The cooling circuit installed in the hydraulic excavator 1 will be described with reference to Figure 3. In Figure 3, elements that have already been described are given the same reference numerals as in Figures 1 and 2, and descriptions thereof will be omitted as appropriate. Furthermore, arrows shown on the heat exchangers in the figure, specifically, the battery cooling heat exchanger 351, the battery warming heat exchanger 352, the water-cooled condenser 368, and the electrical equipment warming heat exchanger 387, indicate the direction of heat transfer from the high-temperature side to the low-temperature side.

[0038] The cooling circuit 300 shown in FIG. 3 includes a battery temperature adjustment circuit 350 , an air-conditioning refrigerant circuit 360 , an electric equipment cooling circuit 370 , and a hydraulic oil cooling circuit 380 .

[0039] - Battery Temperature Regulation Circuit - The battery temperature regulation circuit 350 is a circuit that circulates a heat medium (e.g., water) that regulates the temperature of the battery 30. Connected to this battery temperature regulation circuit 350 are the battery 30, a battery cooling heat exchanger 351 that cools the heat medium flowing through the battery temperature regulation circuit 350 by heat exchange with a low-pressure cooling refrigerant circulating through an air-conditioning refrigerant circuit 360, a battery warming heat exchanger 352 that heats the heat medium by heat exchange with hydraulic oil flowing through a hydraulic oil cooling circuit 380, an electric heater 353 that heats the heat medium, a water pump 354 that circulates the heat medium through the battery temperature regulation circuit 350, and a heat medium temperature sensor 355 that measures the temperature of the heat medium. In other words, the battery temperature regulation circuit 350 has the battery 30, the battery warming heat exchanger 352, the battery cooling heat exchanger 351, the heat medium temperature sensor 355, the water pump 354, and the electric heater 353 on its path.

[0040] In the battery temperature adjustment circuit 350 illustrated in this embodiment, a heat medium is circulated by a water pump 354. This heat medium is cooled by a battery cooling heat exchanger 351, or heated by an electric heater 353 or a battery warming heat exchanger 352 as needed. The battery 30 is cooled or warmed by the heat medium cooled or heated in this manner. However, the arrangement of the battery 30, battery warming heat exchanger 352, battery cooling heat exchanger 351, water pump 354, and electric heater 353 on the path of the battery temperature adjustment circuit 350 is not necessarily limited to this order, and the design can be modified as needed.

[0041] In the battery cooling heat exchanger 351, heat is exchanged between the heat medium flowing through the battery temperature regulation circuit 350 and the cooling refrigerant flowing through the cooling refrigerant circuit 360. The cooling refrigerant circuit 360 will be described later. The battery cooling heat exchanger 351 brings into contact a flow path in the battery temperature regulation circuit 350 through which the heat medium flows from the battery 30 to the water pump 354 with a bypass refrigerant path 360a in the cooling refrigerant circuit 360 through which the cooling refrigerant flows from the receiver 362 to the electric compressor 45, thereby mutually exchanging heat between the fluids flowing through the respective flow paths. More specifically, within the battery cooling heat exchanger 351, the respective flow paths of the battery temperature regulation circuit 350 and the air-conditioning refrigerant circuit 360 are formed with heat transfer pipes made of a material (e.g., metal) with high heat transfer efficiency, and these flow paths are arranged in a serpentine pattern while maintaining contact with each other, thereby ensuring a sufficient surface area for the fluids flowing through the battery temperature regulation circuit 350 and the air-conditioning refrigerant circuit 360 to exchange heat with each other. As a result, in the battery cooling heat exchanger 351, heat is transferred efficiently from the higher-temperature fluid to the lower-temperature fluid passing through each flow path. The air-conditioning refrigerant in the bypass refrigerant path 360a passes through the expansion valve 367 and is in a low-pressure, low-temperature state (e.g., approximately 0°C) and is maintained at a temperature lower than that of the heat medium in the battery temperature regulation circuit 350. Therefore, the heat medium in the battery temperature regulation circuit 350 is cooled in the battery cooling heat exchanger 351.

[0042] Furthermore, in the battery warm-up heat exchanger 352, heat exchange occurs between the heat medium flowing through the battery temperature regulation circuit 350 and the hydraulic oil flowing through the hydraulic oil cooling circuit 380. The hydraulic oil cooling circuit 380 will be described later. The battery warm-up heat exchanger 352 brings into contact a flow path of the battery temperature regulation circuit 350 through which the heat medium flows from the battery 30 to the water pump 354 (in this embodiment, the flow path from the battery 30 to the battery cooling heat exchanger 351) with a first bypass oil path 380a of the hydraulic oil cooling circuit 380 through which hydraulic oil flows from the first hydraulic oil control valve 385 to the hydraulic oil tank 53, thereby mutually exchanging heat between the fluids passing through these flow paths. As with the battery cooling heat exchanger 351, the interior of the battery warm-up heat exchanger 352 has meandering flow paths, for example made of metal, in contact with each other, allowing for efficient heat transfer from the high-temperature side to the low-temperature side of the fluid flowing through each flow path. The temperature of the hydraulic oil flowing through the hydraulic oil cooling circuit 380 increases as it passes through the hydraulic pump and various hydraulic devices, and is higher than the temperature of the heat medium in the battery temperature regulation circuit 350. Therefore, the battery warm-up heat exchanger 352 heats the heat medium in the battery temperature regulation circuit 350.

[0043] The temperature of the heat medium measured by the heat medium temperature sensor 355 is input to the controller 90 ( FIG. 2 ). In this embodiment, the heat medium temperature sensor 355 is located between the battery cooling heat exchanger 351 and the water pump 354, and measures the temperature of the heat medium that has been cooled by the battery cooling heat exchanger 351 and before being heated by the electric heater 353. The temperature of the heat medium flowing through the battery temperature regulation circuit 350 is controlled within a predetermined appropriate temperature range by the battery cooling heat exchanger 351, the battery warming heat exchanger 352, and the electric heater 353, thereby suppressing deterioration of the battery 30 and maintaining a stable output of the battery 30. The battery warming heat exchanger 352 and the electric heater 353 are provided as means for heating the heat medium flowing through the battery temperature regulation circuit 350. The electric devices (such as the water pump 354) of the battery temperature regulation circuit 350, including the electric heater 353, are driven by the power of the battery 30, for example.

[0044] -Hydraulic Oil Cooling Circuit- The hydraulic oil cooling circuit 380 is a circuit that cools the hydraulic oil returning to the hydraulic oil tank 53 via the control valve 100, and includes the oil cooler 381 and the oil cooler electric fan 240 described above as a hydraulic oil cooling device on its path. The oil cooler electric fan 240 is controlled by the controller 90 (FIG. 2) in accordance with the temperature of the hydraulic oil. The temperature of the hydraulic oil is measured by a hydraulic oil temperature sensor 382 and input to the controller 90 (FIG. 2). In this embodiment, the hydraulic oil temperature sensor 382 is provided in the hydraulic oil tank 53. The electrical devices of the hydraulic oil cooling circuit 380, such as the oil cooler electric fan 240, are driven by power from the battery 30, for example.

[0045] The hydraulic oil cooling circuit 380 has a main oil passage 380c through which hydraulic oil flows via an oil cooler 381, and a first bypass oil passage 380a that is connected to the main oil passage 380c and through which hydraulic oil bypasses the oil cooler 381 and flows to the hydraulic oil tank 53. The first bypass oil passage 380a is connected to the battery warm-up heat exchanger 352. The battery warm-up heat exchanger 352 and the oil cooler 381 are in a parallel relationship. By connecting the first bypass oil passage 380a to the battery warm-up heat exchanger 352, heat exchange occurs in the battery warm-up heat exchanger 352 between the heat medium flowing through the battery temperature adjustment circuit 350 and the hydraulic oil flowing through the first bypass oil passage 380a.

[0046] The hydraulic oil cooling circuit 380 is provided with a first hydraulic oil control valve 385 that controls the flow rate of hydraulic oil flowing through the first bypass oil passage 380a. In this embodiment, a solenoid valve provided in the first bypass oil passage 380a is exemplified as the first hydraulic oil control valve 385, but any configuration that can control the flow rate of hydraulic oil guided to the battery warm-up heat exchanger 352 may be used, and the design of the first hydraulic oil control valve 385 can be modified as appropriate. In this embodiment, the flow rate of hydraulic oil guided to the battery warm-up heat exchanger 352 is adjusted by adjusting the opening degree (in this example, opening and closing) of the flow path of the first bypass oil passage 380a with the first hydraulic oil control valve 385. This first hydraulic oil control valve 385 is switched and controlled by the controller 90 in accordance with the hydraulic oil temperature measured by the hydraulic oil temperature sensor 382 and the temperature of the heat medium in the battery temperature adjustment circuit 350 measured by the heat medium temperature sensor 355, and controls the amount of heat input from the hydraulic oil to the heat medium in the battery temperature adjustment circuit 350.

[0047] The hydraulic oil cooling circuit 380 also has a second bypass oil passage 380b that allows hydraulic oil to bypass the oil cooler 381 and flow to the hydraulic oil tank 53. The second bypass oil passage 380b is connected to an electric equipment warm-up heat exchanger 387, which will be described later. The electric equipment warm-up heat exchanger 387 and the oil cooler 381 are in a parallel relationship. By connecting the second bypass oil passage 380b to the electric equipment warm-up heat exchanger 387, heat exchange occurs in the electric equipment warm-up heat exchanger 387 between the electric equipment refrigerant (e.g., water) flowing through the electric equipment cooling circuit 370 and the hydraulic oil flowing through the second bypass oil passage 380b.

[0048] The hydraulic oil cooling circuit 380 is provided with a second hydraulic oil control valve 386 that controls the flow rate of hydraulic oil flowing through the second bypass oil passage 380b. In this embodiment, a solenoid valve provided in the second bypass oil passage 380b is exemplified as the second hydraulic oil control valve 386, but any configuration that can control the flow rate of hydraulic oil guided to the electric equipment warm-up heat exchanger 387 may be used, and the design of the second hydraulic oil control valve 386 can be modified as appropriate. In this embodiment, the flow rate of hydraulic oil guided to the electric equipment warm-up heat exchanger 387 is adjusted by adjusting the opening degree (in this example, opening and closing) of the flow path of the second bypass oil passage 380b with the second hydraulic oil control valve 386. This second hydraulic oil control valve 386 is switched and controlled by the controller 90 in accordance with the hydraulic oil temperature measured by the hydraulic oil temperature sensor 382 and the temperature of the electrical equipment refrigerant in the electrical equipment cooling circuit 370 measured by the electrical equipment refrigerant temperature sensor 377 described later, thereby controlling the amount of heat input from the hydraulic oil to the electrical equipment refrigerant.

[0049] Furthermore, in the electric equipment warm-up heat exchanger 387, heat exchange occurs between the electric equipment refrigerant flowing through the electric equipment cooling circuit 370 and the hydraulic oil flowing through the hydraulic oil cooling circuit 380. The electric equipment warm-up heat exchanger 387 brings into contact a flow path (in this embodiment, a flow path from the electric equipment warm-up heat exchanger 387 to the electric heater 373) (in this embodiment, a flow path from the electric motor 50 to the water-cooled condenser 368) through which the electric equipment refrigerant flows from the objects to be cooled (electric motor 50, inverter 59, DCDC converter 60, on-board charger 35) in the electric equipment cooling circuit 370 toward the heater core 372, with a second bypass oil passage 380b through which hydraulic oil flows from the second hydraulic oil control valve 386 toward the hydraulic oil tank 53 in the hydraulic oil cooling circuit 380, thereby mutually exchanging heat between the fluids passing through the respective flow paths. Similar to the battery cooling heat exchanger 351, inside the electric equipment warm-up heat exchanger 387, the electric equipment cooling circuit 370 and the hydraulic oil cooling circuit 380 have serpentine flow paths, made of, for example, metal, that are in contact with each other, allowing for highly efficient heat transfer from the higher temperature side to the lower temperature side of the fluid flowing through each path. The temperature of the hydraulic oil flowing through the hydraulic oil cooling circuit 380 has increased as it has passed through the hydraulic pump and various hydraulic equipment, and is therefore higher than the temperature of the electric equipment refrigerant that flows into the electric equipment warm-up heat exchanger 387. Therefore, in the electric equipment warm-up heat exchanger 387, heat is transferred from the hydraulic oil in the hydraulic oil cooling circuit 380 to the electric equipment refrigerant in the electric equipment cooling circuit 370.

[0050] The oil cooler 381 exchanges heat between the cooling air from the oil cooler electric fan 240 and the hydraulic oil passing through the main oil passage 380c, through which hydraulic oil flows from the control valve 100 to the hydraulic oil tank 53 in the hydraulic oil cooling circuit 380. More specifically, the portion of the main oil passage 380c that passes through the oil cooler 381 is configured with heat transfer tubes equipped with fins and made of a material (e.g., metal) with high heat transfer efficiency. The oil cooler electric fan 240 is also positioned so that the cooling air hits the fins that make up the oil cooler 381. As a result, in the oil cooler 381, the heat of the hydraulic oil flowing through the heat transfer tubes is transferred to the cooling air, cooling the hydraulic oil.

[0051] - Cooling refrigerant circuit - The cooling refrigerant circuit 360 is a circuit that circulates a cooling refrigerant (for example, R-1234yf), and has a cooling function that cools the air inside the driver's cab 13A (FIG. 1) using a refrigeration cycle, and a function that cools the heat medium of the battery temperature adjustment circuit 350 using the battery cooling heat exchanger 351.

[0052] The cooling refrigerant circuit 360 is connected to the electric compressor 45, the condenser 361, the receiver 362, the variable throttle 363, the expansion valve 364, the HVAC evaporator 365, the variable throttle 366, the expansion valve 367, the water-cooled condenser (heat exchanger) 368, and the battery cooling heat exchanger 351. That is, the cooling refrigerant circuit 360 has, on its path, the electric compressor 45, the water-cooled condenser (heat exchanger) 368, the condenser 361, the receiver 362, the variable throttle 363, the expansion valve 364, the HVAC evaporator 365, the variable throttle 366, the expansion valve 367, and the battery cooling heat exchanger 351. The electric devices of the cooling refrigerant circuit 360, including the electric compressor 45 (such as the condenser electric fan 230), are driven by power from the battery 30, for example.

[0053] The electric compressor 45 compresses the cooling refrigerant. The high-temperature, high-pressure cooling refrigerant discharged from the electric compressor 45 is sequentially cooled by the water-cooled condenser 368 and the condenser 361, and liquefied at high pressure. Specifically, the water-cooled condenser 368 is connected to the cooling refrigerant circuit 360 and the electrical equipment cooling circuit 370, and the high-temperature, high-pressure cooling refrigerant discharged from the electric compressor 45 is cooled in the water-cooled condenser 368 by heat exchange with the electrical equipment refrigerant in the electrical equipment cooling circuit 370. The condenser 361 is located downstream of the water-cooled condenser 368, and the high-pressure cooling refrigerant cooled by the water-cooled condenser 368 is further cooled and condensed in the condenser 361 by cooling air from the condenser electric fan 230. The rotation speed of the condenser electric fan 230 may be constant, but it is preferably variable depending on the rotation speed of the electric compressor 45. The target rotation speed of the condenser electric fan 230 corresponds to the required value of the battery cooling heat exchanger 351 (for example, a value corresponding to the measurement value of the heat medium temperature sensor 355) and the required value of the HVAC evaporator 365 (a value corresponding to the room temperature of the driver's cab 13A and the temperature of the air-conditioning refrigerant).

[0054] The high-pressure cooling refrigerant that has passed through the condenser 361 passes through the receiver 362. In the receiver 362, a portion of the cooling refrigerant that was not liquefied in the condenser 361 is separated from the liquefied cooling refrigerant, and moisture and impurities are removed from the separated cooling refrigerant using a desiccant and a strainer.

[0055] The high-pressure cooling refrigerant that has passed through the receiver 362 passes through an electronically controlled expansion valve 364. The expansion valve 364 reduces the pressure of the high-pressure cooling refrigerant to low-pressure cooling refrigerant. The cooling refrigerant that has been reduced in pressure after passing through the expansion valve 364 flows into the HVAC evaporator 365 in a gas-liquid two-phase state.

[0056] The HVAC evaporator 365 is a heat exchanger that exchanges heat between the cooling refrigerant decompressed by the expansion valve 364 and outside air, and the low-pressure cooling refrigerant evaporates by absorbing heat from the air inside the cab 13A. Air inside the cab 13A is drawn into a flow path in which the HVAC evaporator 365 is disposed by a blower fan (not shown), cooled as it passes through the HVAC evaporator 365, and then blown into the cab 13A. The HVAC evaporator 365 functions as an air-conditioning heat exchanger for the cab 13A. The low-pressure cooling refrigerant evaporated in the HVAC evaporator 365 is drawn back into the electric compressor 45.

[0057] The cooling refrigerant circuit 360 includes a main refrigerant path 360b through which the cooling refrigerant flows via the HVAC evaporator 365, and a bypass refrigerant path 360a connected to the main refrigerant path 360b and through which the cooling refrigerant flows, bypassing the HVAC evaporator 365. The bypass refrigerant path 360a is connected to a battery cooling heat exchanger 351. The battery cooling heat exchanger 351 is connected in parallel to the HVAC evaporator 365 in the cooling refrigerant circuit 360. The cooling refrigerant in a gas-liquid two-phase state decompressed by the expansion valve 367 absorbs heat from the heat medium in the battery temperature regulation circuit 350 as it passes through the battery cooling heat exchanger 351. As a result, the heat medium in the battery temperature regulation circuit 350 is cooled by the battery cooling heat exchanger 351.

[0058] The variable throttles 363 and 366 in the cooling refrigerant circuit 360 are refrigerant control valves that adjust the flow rate ratio between the cooling refrigerant that passes through the receiver 362 and flows to the expansion valve 364 and the cooling refrigerant that flows to the expansion valve 367, and control the flow rate of the cooling refrigerant that flows through the bypass refrigerant path 360a. The variable throttles 363 and 366 are provided downstream of the branching point of the bypass refrigerant path 360a in the cooling refrigerant circuit 360, with the variable throttle 363 located between the branching point and the expansion valve 364 and the variable throttle 366 located between the branching point and the expansion valve 367. The opening areas of the variable throttles 363 and 366 are adjusted by the controller 90 in accordance with the temperature of the heat medium in the battery temperature regulation circuit 350 measured by the heat medium temperature sensor 355, and the amount of heat removed by the battery cooling heat exchanger 351 is controlled. For example, if the temperature of the heat medium in the battery temperature regulation circuit 350 is below the lower limit of a predetermined appropriate range, the opening area of ​​the variable throttle 366 is narrowed, and the flow rate of the air-conditioning refrigerant flowing through the battery cooling heat exchanger 351 is reduced. At this time, the opening degree of the variable throttle 363 may be maintained at a predetermined value, but if the room temperature of the driver's cab 13A is higher than the set temperature of the air conditioning, the opening of the variable throttle 363 may be widened to prioritize air-conditioning performance. Conversely, if the temperature of the heat medium in the battery temperature regulation circuit 350 exceeds the upper limit of the appropriate range, the opening area of ​​the variable throttle 366 is widened, the opening of the variable throttle 363 is narrowed, and the flow rate of the air-conditioning refrigerant flowing through the battery cooling heat exchanger 351 is increased. If the temperature of the heat medium in the battery temperature regulation circuit 350 is within the appropriate range, the opening degrees of the variable throttles 363 and 366 are maintained.

[0059] In the water-cooled condenser 368, heat is exchanged between the cooling refrigerant flowing through the cooling refrigerant circuit 360 and the electrical equipment refrigerant flowing through the electrical equipment cooling circuit 370. The electrical equipment cooling circuit 370 will be described later. The water-cooled condenser 368 brings into contact a flow path of the cooling refrigerant circuit 360 through which the cooling refrigerant flows from the electric compressor 45 to the receiver 362 (in this embodiment, the flow path from the electric compressor 45 to the condenser 361) with a flow path of the electrical equipment cooling circuit 370 through which the electrical equipment refrigerant flows from the electric motor 50 to the heater core 372 (in this embodiment, the flow path from the electrical equipment warm-up heat exchanger 387 to the electric heater 373), thereby allowing the fluids passing through these flow paths to exchange heat with each other. Similar to the battery cooling heat exchanger 351, inside the water-cooled condenser 368, the air-conditioning refrigerant circuit 360 and the electric equipment cooling circuit 370 have serpentine flow paths, made of, for example, metal, in contact with each other, allowing heat to be transferred efficiently from the high-temperature side to the low-temperature side of the fluid flowing through each flow path. The air-conditioning refrigerant compressed by the electric compressor 45 in the air-conditioning refrigerant circuit 360 has a higher temperature and is therefore hotter than the electric equipment refrigerant flowing into the water-cooled condenser 368. Therefore, in the water-cooled condenser 368, heat is transferred from the air-conditioning refrigerant in the air-conditioning refrigerant circuit 360 to the electric equipment refrigerant in the electric equipment cooling circuit 370.

[0060] Condenser 361 is a flow path through which cooling refrigerant flows from water-cooled condenser (heat exchanger) 368 of cooling refrigerant circuit 360 toward receiver 362, and exchanges heat between the cooling air from condenser electric fan 230 and the cooling refrigerant passing through the flow path. More specifically, the flow path through which the cooling refrigerant flows in condenser 361 is composed of heat transfer tubes, for example made of metal, equipped with fins. Furthermore, condenser electric fan 230 is positioned so that the cooling air hits the fins that make up condenser 361. As a result, heat from the cooling refrigerant flowing through the heat transfer tubes in condenser 361 is transferred to the cooling air, and the cooling refrigerant is cooled.

[0061] -Electric Equipment Cooling Circuit- The electric equipment cooling circuit 370 is a circuit that circulates an electric equipment refrigerant (for example, water) that cools the electric motor 50 and the electric motor control device (the inverter 59, the DCDC converter 60, the on-board charger 35, etc.). The electric motor 50, the inverter 59, the on-board charger 35, the DCDC converter 60, the water pump 371, the heat exchanger 387 for warming up the electric equipment, the water-cooled condenser 368, the electric heater 373 for the electric equipment cooling circuit, the heater core 372 for heating, the radiator 375, and the electric equipment refrigerant temperature sensor 377 are connected to the electric equipment cooling circuit 370. That is, the electric equipment cooling circuit 370 has, on its path, the electric motor 50, the electric equipment refrigerant temperature sensor 377, the electric equipment warm-up heat exchanger 387, the water-cooled condenser 368, the electric heater 373, the heater core 372, the radiator 375, the water pump 371, the on-board charger 35, the DCDC converter 60, and the inverter 59. The electric equipment of the electric equipment cooling circuit 370, including the electric heater 373 (such as the water pump 371 and the electric radiator fan 220), is driven by power from the battery 30, for example.

[0062] The electric equipment refrigerant flows through the electric equipment cooling circuit 370, absorbs heat from the objects to be cooled, such as the electric motor 50, inverter 59, DCDC converter 60, on-board charger 35, and water-cooled condenser 368, and is heated therein. The electric equipment refrigerant is then heated, as necessary, by the electric equipment warm-up heat exchanger 387 or the electric heater 373. The electric equipment refrigerant circulating through the electric equipment cooling circuit 370 dissipates heat in the heater core 372 for heating, and is then cooled by the radiator 375 located downstream. In this embodiment, the electric equipment refrigerant temperature sensor 377 is located between the objects to be cooled (the electric motor 50, inverter 59, DCDC converter 60, and on-board charger 35) and the electric equipment warm-up heat exchanger 387, and measures the temperature of the electric equipment refrigerant after cooling the objects to be cooled and raising its temperature, and before being further heated by other heating devices such as the electric equipment warm-up heat exchanger 387.

[0063] Because the hydraulic excavator 1 operates by driving the main pump 51 with the electric motor 50, the temperatures of the electric motor 50, inverter 59, and DCDC converter 60 rise while the hydraulic actuator is being driven to perform work, and the temperature of the on-board charger 35 rises while the battery 30 is being charged. Therefore, to prevent the electric motor 50, inverter 59, DCDC converter 60, and on-board charger 35 from overheating (for example, 70°C or higher) during work or charging, the electric equipment cooling circuit 370 is activated and the electric equipment refrigerant flows through the electric equipment cooling circuit 370. The electric equipment refrigerant is circulated through the electric equipment cooling circuit 370 by the water pump 371, absorbs heat from objects to be cooled such as the electric motor 50, and increases in temperature. As it passes through the radiator 375, it is cooled by cooling air from the radiator electric fan 220.

[0064] The electric motor 50, the inverter 59, the DCDC converter 60, and the on-board charger 35 are each equipped with a temperature sensor that measures the temperature of each, and the radiator electric fan 220 is feedback-controlled by the controller 90 in accordance with the outputs of these temperature sensors. For example, when the temperature of at least one of the electric motor 50, the inverter 59, the DCDC converter 60, and the on-board charger 35 is equal to or higher than a first set temperature (e.g., 70°C or a value set lower than that), the rotation speed of the radiator electric fan 220 is increased, and when the temperatures of all of the electric motor 50, the inverter 59, the DCDC converter 60, and the on-board charger 35 are lower than a second set temperature (e.g., the first set temperature or a value set lower than that), the rotation speed of the radiator electric fan 220 is decreased. However, for example, when the outside air temperature is extremely low and the refrigerant for the electrical equipment falls below a preset temperature (for example, the lower limit of the appropriate operating temperature for the electrical equipment or a value set higher than that), the radiator electric fan 220 may be configured to stop even during work or charging.

[0065] On the other hand, in this embodiment, a heater core 372 for heating is connected to the electric equipment cooling circuit 370. The heater core 372 is provided inside the cab 13A and heats the air blown into the cab 13A by a blower fan (not shown). Because the heater core 372 functions as a heat exchanger for heating the cab 13A, it is desirable that the electric equipment refrigerant passing through the heater core 372 be at a high temperature (e.g., 80°C).

[0066] Therefore, in the electric equipment cooling circuit 370, an electric heater 373 for heating the electric equipment refrigerant is provided in a path where the electric equipment refrigerant passes through the electrically driven equipment (electric motor 50, inverter 59, DCDC converter 60, on-board charger 35, etc.) and reaches the heater core 372, and is configured to adjust the temperature of the electric equipment refrigerant to a temperature that can be used by the heater core 372. Using the heat of the electric equipment refrigerant for heating is desirable from the perspective of energy efficiency. The temperature of the heater core 372 is detected by a temperature sensor (not shown), and the electric heater 373 is feedback-controlled by the controller 90 in accordance with the output of this temperature sensor. For example, if the temperature of the heater core 372 is equal to or higher than a set temperature (e.g., 80°C), the electric heater 373 is turned OFF, and if the temperature of the heater core 372 is lower than the set temperature, the electric heater 373 is turned ON.

[0067] The electric equipment warm-up heat exchanger 387 has a configuration similar to that of the battery warm-up heat exchanger 352. As described above, the hydraulic oil cooling circuit 380 has a second bypass oil passage 380b that bypasses the oil cooler 381 and allows hydraulic oil to flow to the hydraulic oil tank 53, and this second bypass oil passage 380b is connected to the electric equipment warm-up heat exchanger 387. As a result, in the electric equipment warm-up heat exchanger 387, heat exchange occurs between the electric equipment refrigerant flowing in the electric equipment cooling circuit 370 and the hydraulic oil flowing in the second bypass oil passage 380b. As described above, the second bypass oil passage 380b is provided with the second hydraulic oil control valve 386, and the flow rate of the hydraulic oil guided to the electric equipment warm-up heat exchanger 387 is adjusted by opening and closing the flow path of the second bypass oil passage 380b with the second hydraulic oil control valve 386. The second hydraulic oil control valve 386 is switched by the controller 90 in response to the hydraulic oil temperature measured by the hydraulic oil temperature sensor 382 and the temperature of the electrical equipment refrigerant in the electrical equipment warm-up heat exchanger 387 measured by the electrical equipment refrigerant temperature sensor 377, thereby controlling the amount of heat input from the hydraulic oil to the electrical equipment refrigerant in the electrical equipment cooling circuit 370. This reduces the amount of heat required from the electric heater 373 to adjust the temperature of the heater core 372 to a set temperature during heating, thereby reducing the power consumption of the hydraulic excavator 1 (e.g., the power consumption of the battery 30). Furthermore, by utilizing the waste heat of the hydraulic oil, the amount of heat dissipated by the oil cooler 381 can be reduced, thereby reducing the power consumption of the oil cooler electric fan 240. Furthermore, heater performance at low temperatures is improved, improving the operating environment for the operator.

[0068] The water-cooled condenser 368 is connected to the electric equipment cooling circuit 370 and is a heat exchanger that exchanges heat between the air conditioning refrigerant compressed by the compressor 45 in the air conditioning refrigerant circuit 360 and the electric equipment refrigerant flowing downstream of the electric motor 50 and upstream of the heater core 372. In the air conditioning refrigerant circuit 360, the air conditioning refrigerant discharged from the electric compressor 45 is high-temperature and high-pressure. In the water-cooled condenser 368, heat is transferred from the high-temperature, high-pressure air conditioning refrigerant discharged from the electric compressor 45 to the electric equipment refrigerant flowing in the electric equipment cooling circuit 370. The water-cooled condenser 368 serves the same function as the electric equipment warm-up heat exchanger 387. In other words, the amount of heat required by the electric heater 373 during heating is reduced, thereby reducing the power consumption of the hydraulic excavator 1 (e.g., power consumption of the battery 30). Furthermore, heater performance at low temperatures is improved, improving the operating environment for the operator. In addition, since the temperature of the air-conditioning refrigerant is lowered in the water-cooled condenser 368, the amount of heat dissipation of the air-conditioning refrigerant required from the condenser 361 in the air-conditioning refrigerant circuit 360 can be reduced, which also leads to a reduction in the power consumption of the condenser electric fan 230.

[0069] The radiator 375 is a flow path through which the electrical equipment refrigerant flows from the heater core 372 to the water pump 371 in the electrical equipment cooling circuit 370, and exchanges heat between the cooling air from the radiator electric fan 220 and the electrical equipment refrigerant passing through the flow path. More specifically, the flow path through the electrical equipment refrigerant in the radiator 375 is formed of heat transfer tubes, for example made of metal, equipped with fins. The radiator electric fan 220 is positioned so that the cooling air hits the fins that make up the radiator 375. As a result, heat from the electrical equipment refrigerant flowing through the heat transfer tubes in the radiator 375 is transferred to the cooling air, cooling the electrical equipment refrigerant.

[0070] (Control) —First Hydraulic Oil Control Valve— Fig. 4 is a flowchart showing an example of a control procedure for the first hydraulic oil control valve 385 by the controller 90. The controller 90 periodically and repeatedly executes the flow in Fig. 4 while energized, and when the power is turned off, executes appropriate delay processing or the like and ends the flow in Fig. 4.

[0071] 4 starts, the controller 90 determines whether the current heat medium temperature Tb of the battery temperature regulation circuit 350 measured by the heat medium temperature sensor 355 is lower than a preset temperature Tb1 (e.g., the lower limit of a preset appropriate range for the heat medium temperature Tb) (Tb<Tb1) (step S11). If the heat medium temperature Tb is equal to or higher than the preset temperature Tb1 (Tb≧Tb1) and there is no need to heat the heat medium to maintain the battery 30 at an appropriate temperature (No), the controller 90 closes the first hydraulic oil control valve 385 and stops the supply of hydraulic oil to the battery warm-up heat exchanger 352 (step S14). If the heat medium temperature Tb is lower than the preset temperature Tb1 (Tb<Tb1) and there is no need to heat the heat medium to maintain the battery 30 at an appropriate temperature (Yes), the controller 90 determines whether the heat medium temperature Tb is lower than the current hydraulic oil temperature To measured by the hydraulic oil temperature sensor 382 (Tb<To) (step S12). If the heat medium temperature Tb is equal to or higher than the hydraulic oil temperature To (Tb≧To) and the heat medium cannot be heated by the hydraulic oil (No), the controller 90 closes the first hydraulic oil control valve 385 and stops the supply of hydraulic oil to the battery warm-up heat exchanger 352 (step S14). If the heat medium temperature Tb is lower than the hydraulic oil temperature To (Tb<To) and the heat medium can be heated by the hydraulic oil (Yes), the controller 90 opens the first hydraulic oil control valve 385 and supplies hydraulic oil to the battery warm-up heat exchanger 352 (step S13). After executing the process of step S13 or step S14 and controlling the first hydraulic oil control valve 385, the controller 90 returns to step S11. The order of determinations in steps S11 and S12 can be changed as appropriate.

[0072] As in the above example, the controller 90 controls the first hydraulic oil control valve 385 based on the outputs of the hydraulic oil temperature sensor 382 and the heat medium temperature sensor 355. This keeps the heat medium temperature Tb of the battery temperature adjustment circuit 350 above the lower limit value for keeping the battery 30 at an appropriate temperature.

[0073] 4 , the controller 90 also controls the cooling of the heat medium in the battery temperature regulation circuit 350 by the battery cooling heat exchanger 351. The amount of heat transfer in the battery cooling heat exchanger 351 is adjusted by the variable throttles 363, 366, etc. of the air-conditioning refrigerant circuit 360. For example, if the temperature of the heat medium in the battery temperature regulation circuit 350 is below the lower limit of a preset appropriate range, the opening area of ​​the variable throttle 366 is narrowed, and the flow rate of the air-conditioning refrigerant flowing through the battery cooling heat exchanger 351 is reduced. In this case, the opening degree of the variable throttle 363 may be maintained at a predetermined value. However, if the room temperature of the driver's cab 13A is higher than the set temperature of the air conditioning, the opening of the variable throttle 363 may be widened to prioritize air-conditioning performance. Conversely, if the temperature of the heat medium in the battery temperature regulation circuit 350 exceeds the upper limit of the appropriate range, the opening of the variable throttle 366 is widened and the opening of the variable throttle 363 is narrowed, increasing the flow rate of the air-conditioning refrigerant flowing through the battery cooling heat exchanger 351. If the temperature of the heat medium in the battery temperature regulation circuit 350 is within the appropriate range, it is maintained, and the openings of the variable throttles 363 and 366 are maintained.

[0074] Furthermore, a target rotation speed of the condenser electric fan 230 is set in accordance with a required value of the battery cooling heat exchanger 351 corresponding to the measurement value of the heat medium temperature sensor 355, for example, and a required value of the HVAC evaporator 365 corresponding to the room temperature of the driver's cab 13A and the temperature of the cooling refrigerant, and the controller 90 controls the rotation speed of the condenser electric fan 230 to the target rotation speed.

[0075] - Second hydraulic oil control valve - Figure 5 is a flowchart showing an example of a control procedure for the second hydraulic oil control valve 386 by the controller 90. While energized, the controller 90 periodically and repeatedly executes the flow in Figure 5 in parallel with the flow in Figure 4, and when the power is turned off, executes a delay process or the like as appropriate and ends the flow in Figure 5.

[0076] 5 starts, the controller 90 determines whether the heater is ON based on an operation signal from an air conditioning operating device (not shown) installed in the cab 13A (step S21). If the heater is not ON (heating OFF) and there is no need to heat the electrical equipment refrigerant (No), the controller 90 closes the second hydraulic oil control valve 386 and stops the supply of hydraulic oil to the electrical equipment warm-up heat exchanger 387 (step S25). If the heater is ON (heating ON) and there is a need to heat the electrical equipment refrigerant (Yes), the controller 90 determines whether the current electrical equipment refrigerant temperature Te of the battery temperature regulation circuit 350, measured by the electrical equipment refrigerant temperature sensor 377, is lower than a preset temperature Te1 (e.g., the lower limit of a preset appropriate range for the electrical equipment refrigerant temperature Te) (Te<Te1) (step S22). If the electrical equipment refrigerant temperature Te is equal to or higher than the set temperature Te1 (Te≧Te1) and there is no need to heat the electrical equipment refrigerant to maintain the electrical equipment at the appropriate temperatures (No), the controller 90 closes the second hydraulic oil control valve 386 and stops the supply of hydraulic oil to the electrical equipment warm-up heat exchanger 387 (step S25). If the electrical equipment refrigerant temperature Te is lower than the set temperature Te1 (Te<Te1) and there is a need to heat the electrical equipment refrigerant to maintain the electrical equipment at the appropriate temperatures (Yes), the controller 90 determines whether the electrical equipment refrigerant temperature Te is lower than the current hydraulic oil temperature To measured by the hydraulic oil temperature sensor 382 (Te<To) (step S23). If the electrical equipment refrigerant temperature Te is equal to or higher than the hydraulic oil temperature To (Te≧To) and the electrical equipment refrigerant cannot be heated by hydraulic oil (No), the controller 90 closes the second hydraulic oil control valve 386 and stops the supply of hydraulic oil to the electrical equipment warm-up heat exchanger 387 (step S25). If the electrical equipment refrigerant temperature Te is lower than the hydraulic oil temperature To (Te<To) and the electrical equipment refrigerant can be heated by hydraulic oil (Yes), the controller 90 opens the second hydraulic oil control valve 386 and supplies hydraulic oil to the electrical equipment warm-up heat exchanger 387 (step S24). After executing the process of step S24 or step S25 and controlling the second hydraulic oil control valve 386, the controller 90 returns to step S22. The order of determinations in steps S21-S23 can be changed as appropriate.

[0077] As in the above example, the controller 90 controls the second hydraulic oil control valve 386 based on the outputs of the hydraulic oil temperature sensor 382 and the electrical equipment refrigerant temperature sensor 377. This keeps the electrical equipment refrigerant temperature Te in the electrical equipment cooling circuit 370 above the lower limit value required to maintain the electrical equipment, such as the electric motor 50, at an appropriate temperature.

[0078] In parallel with the control shown in FIG. 5, the controller 90 also controls the radiator electric fan 220 and the electric heater 373 as described above in order to control the temperature of the refrigerant for the electrical equipment.

[0079] For example, the controller 90 increases the rotation speed of the electric radiator fan 220 when the temperature of at least one of the electric motor 50, the inverter 59, the DCDC converter 60, and the on-board charger 35 is equal to or higher than a first set temperature (e.g., 70°C or a value set lower than that), and decreases the rotation speed of the electric radiator fan 220 when the temperatures of all of the electric motor 50, the inverter 59, the DCDC converter 60, and the on-board charger 35 are below a second set temperature (e.g., the first set temperature or a value set lower than that). The controller 90 may be configured to stop the electric radiator fan 220 even during work or charging when the outside air temperature is significantly low and the electrical equipment refrigerant falls below a preset set temperature (e.g., the lower limit of the appropriate operating temperature of the electrical equipment or a value set higher than that).

[0080] Furthermore, when the heating is ON, the controller 90 performs feedback control of the electric heater 373 in accordance with the temperature of the heater core 372. For example, if the temperature of the heater core 372 is equal to or higher than a set temperature (e.g., 80°C), the electric heater 373 is turned OFF, and if the temperature of the heater core 372 is lower than the set temperature, the electric heater 373 is turned ON. When the heating is OFF, the controller 90 turns the electric heater 373 OFF.

[0081] (Effects) (1) In this embodiment, a battery temperature regulation circuit 350 is provided that circulates a heat medium for regulating the temperature of the battery 30. The battery temperature regulation circuit 350 is connected to an electric heater 353 that heats the heat medium, a battery cooling heat exchanger 351 that cools the heat medium by heat exchange with an air-conditioning refrigerant, and a battery warming heat exchanger 352 that heats the heat medium by heat exchange with hydraulic oil. Therefore, the heat medium for regulating the battery temperature is cooled by heat exchange with the air-conditioning refrigerant, thereby preventing overheating of the battery 30. Furthermore, the heat medium for regulating the battery temperature is heated by the exhaust heat of the hydraulic oil or the electric heater 353, thereby warming up the battery 30. In this way, the battery 30 can be maintained at an appropriate temperature, deterioration of the battery 30 can be suppressed, and an appropriate output state can be maintained. Furthermore, by using the exhaust heat of the hydraulic oil as a heating source for the heat medium for regulating the battery temperature, the power consumption of the electric heater 353 can be reduced, and when the electric heater 353 is driven by power from the battery 30, the power consumption of the battery 30 can also be reduced. Furthermore, because the exhaust heat of the hydraulic oil can be added to the heat of the electric heater 353 as a heating source for the heat medium, even when the outside air temperature is low and the temperature of the heat medium is significantly low, the heat medium can be raised to a predetermined temperature more quickly than when the heat medium is heated only by the electric heater 353. As such, according to this embodiment, it is possible to achieve both the cooling performance and heating performance of the battery 30 of the hydraulic excavator 1, and to suppress a decrease in energy efficiency due to warming up of the battery 30.

[0082] Furthermore, heat is dissipated from the hydraulic oil to the heat medium used to adjust the battery temperature, and the amount of heat dissipated by the oil cooler 381 can be reduced, resulting in energy savings in the hydraulic oil cooling circuit 380. For example, the power consumption of the oil cooler electric fan 240 can be reduced, and when the oil cooler electric fan 240 is driven by power from the battery 30, this can also contribute to further reducing the power consumption of the battery 30. Furthermore, because many of the cooling circuit 300 are constructed using existing parts, it is possible to reduce costs that would otherwise be incurred by increasing the number of parts.

[0083] (2) By controlling the first hydraulic oil control valve 385 with the controller 90 based on the outputs of the heat medium temperature sensor 355 and the hydraulic oil temperature sensor 382, ​​it is possible to prevent the temperature of the heat medium flowing through the battery temperature regulation circuit 350 from falling below the temperature necessary to maintain the battery 30 at an appropriate temperature. Furthermore, when there is no need to heat the heat medium in the battery temperature regulation circuit 350, the first hydraulic oil control valve 385 can be closed to stop the supply of hydraulic oil to the battery warm-up heat exchanger 352.

[0084] (3) The cooling refrigerant circuit 360 is provided with a bypass refrigerant passage 360a that bypasses the HVAC evaporator 365 and connects to the battery cooling heat exchanger 351, and a refrigerant control valve (variable throttles 363, 366) that controls the flow rate of the cooling refrigerant flowing through this bypass refrigerant passage 360a is provided, making it possible to adjust the flow rate ratio between the cooling refrigerant flowing through the HVAC evaporator 365 and the cooling refrigerant flowing through the battery cooling heat exchanger 351. This allows the cooling circuit 300 to be operated flexibly, giving priority to cooling the battery 30 or to cooling performance.

[0085] (4) In configuring the electric equipment cooling circuit 370 that circulates the electric equipment refrigerant that cools the electric motor control devices such as the inverter 59 and the electric motor 50, the electric equipment cooling circuit 370 is configured to connect a heater core 372 for heating, an electric heater 373 that heats the electric equipment refrigerant, and an electric equipment warm-up heat exchanger 387 that heats the electric equipment refrigerant by heat exchange with the hydraulic oil. The electric equipment warm-up heat exchanger 387 is provided with a second bypass oil passage 380b that allows the hydraulic oil to flow bypassing the oil cooler 381 in the hydraulic oil cooling circuit 380, and is connected to this second bypass oil passage 380b so that heat exchange occurs between the hydraulic oil flowing in the hydraulic oil cooling circuit 380 and the electric equipment refrigerant flowing in the electric equipment cooling circuit 370.

[0086] In construction machines that have an engine (internal combustion engine), engine coolant heated by the engine can be used as a heating medium, but the hydraulic excavator 1 of this embodiment is an electric work machine that is powered by electricity from the battery 30, and therefore cannot use engine coolant. Therefore, in this embodiment, in the electric equipment cooling circuit 370, the temperature of the electric equipment refrigerant that has been heated by cooling the electric equipment (electric motor 50, inverter 59, DCDC converter 60, on-board charger 35, etc.) is adjusted by the electric heater 373 so that it can be used as a heating medium for heating, and the electric equipment refrigerant can be used in the heater core 372. By using the heat of the electric equipment refrigerant required for electric work machines in this way for heating, there is no need to install a new circuit for heating, which is advantageous in terms of energy efficiency.

[0087] Furthermore, an electric equipment warm-up heat exchanger 387 can be connected to the electric equipment cooling circuit 370, allowing the electric equipment refrigerant to be heated by heat exchange with the hydraulic oil when necessary. This reduces the amount of heat required from the electric heater 373 to adjust the temperature of the heater core 372 to a set temperature during heating, thereby reducing the power consumption of the hydraulic excavator 1 (for example, the power consumption of the battery 30). At the same time, by dissipating the waste heat from the hydraulic oil to the electric equipment refrigerant, the amount of heat dissipation required by the oil cooler 381 can be reduced, and the power consumption of the oil cooler electric fan 240 can also be reduced. Furthermore, improving the heating capacity of the electric equipment refrigerant also improves heating performance, leading to an improved operating environment for the operator in environments with low outside temperatures.

[0088] (5) By controlling the second hydraulic oil control valve 386 with the controller 90 based on the outputs of the hydraulic oil temperature sensor 382 and the electrical equipment refrigerant temperature sensor 377, the second hydraulic oil control valve 386 is opened when necessary (when the heating is ON) to supply hydraulic oil to the electrical equipment warm-up heat exchanger 387 and heat the electrical equipment refrigerant, and when not necessary (when the heating is OFF), the second hydraulic oil control valve 386 is closed to stop the supply of hydraulic oil to the electrical equipment warm-up heat exchanger 387 and automatically stop heating the electrical equipment refrigerant.

[0089] (6) Furthermore, by connecting the water-cooled condenser 368, which heats the electrical equipment refrigerant by heat exchange with the air-conditioning refrigerant, to the electrical equipment cooling circuit 370, the amount of heating required by the electric heater 373 during heating is further reduced, thereby reducing the power consumption of the hydraulic excavator 1 (e.g., power consumption of the battery 30). Furthermore, the improved heating capacity of the electrical equipment refrigerant also improves heating performance, leading to an improved operating environment for the operator in low-ambient temperatures. Additionally, because the water-cooled condenser 368 lowers the temperature of the air-conditioning refrigerant, the amount of heat dissipation required of the condenser 361 in the air-conditioning refrigerant circuit 360 is reduced, contributing to a reduction in the power consumption of the condenser electric fan 230. If the condenser electric fan 230 is driven by the battery 30, the power consumption of the battery 30 is also reduced.

[0090] (Modifications) The present invention is not limited to the above-described embodiment, and may include various modifications. For example, the present invention is not necessarily limited to a configuration that includes all of the components described in the above embodiment. For example, it is possible to replace some of the components with other components. It is also possible to delete some of the components of the embodiment or add other components. Furthermore, although the hydraulic excavator 1 has been used as an example of an electrically powered construction machine to which the present invention is applied, the present invention is also applicable to other construction machines such as wheel loaders.

[0091] 1...hydraulic excavator (electric work machine), 30...battery, 50...electric motor, 51...main pump (hydraulic pump), 54, 55...directional control valve, 90...controller, 112...travel motor (hydraulic actuator), 120...swing motor (hydraulic actuator), 350...battery temperature adjustment circuit, 351...battery cooling heat exchanger, 352...battery warming heat exchanger, 353...electric heater, 355...heat medium temperature sensor, 360...cooling refrigerant circuit, 360a...bypass refrigerant path, 360b...main refrigerant path, 363...variable throttle (refrigerant control valve), 365...HVAC evaporator, 366...variable throttle (refrigerant control valve) control valve), 368...water-cooled condenser (heat exchanger), 370...electrical equipment cooling circuit, 372...heater core, 373...electric heater (heater), 377...electrical equipment refrigerant temperature sensor, 380...hydraulic oil cooling circuit, 380a...first bypass oil passage, 380b...second bypass oil passage, 380c...main oil passage, 381...oil cooler, 382...hydraulic oil temperature sensor, 385...first hydraulic oil control valve, 386...second hydraulic oil control valve, 387...electrical equipment warm-up heat exchanger, 410...boom cylinder (hydraulic actuator), 420...arm cylinder (hydraulic actuator), 430...bucket cylinder (hydraulic actuator)

Claims

1. An electrically-operated working machine comprising: a battery; an electric motor driven by electric power from the battery; a hydraulic pump driven by the electric motor and pumping hydraulic oil to a hydraulic actuator; a hydraulic oil cooling circuit having an oil cooler for cooling the hydraulic oil; and a cooling refrigerant circuit for circulating a cooling refrigerant, wherein the electrically-operated working machine further comprises a battery temperature regulation circuit for circulating a heat medium for regulating a temperature of the battery, the battery temperature regulation circuit having: an electric heater for heating the heat medium; a battery cooling heat exchanger for cooling the heat medium by heat exchange with the cooling refrigerant circulating through the cooling refrigerant circuit; and a battery warming heat exchanger for heating the heat medium by heat exchange with the hydraulic oil flowing through the hydraulic oil cooling circuit.

2. An electric working machine as described in claim 1, wherein the hydraulic oil cooling circuit has a main oil passage that causes the hydraulic oil to flow through the oil cooler, and a first bypass oil passage that is connected to the main oil passage and causes the hydraulic oil to flow bypassing the oil cooler, and the first bypass oil passage is connected to the battery warm-up heat exchanger.

3. An electric working machine as described in claim 2, comprising: a first hydraulic oil control valve that controls the flow rate of the hydraulic oil flowing through the first bypass oil passage; a controller that controls the first hydraulic oil control valve; a hydraulic oil temperature sensor that measures the temperature of the hydraulic oil; and a heat medium temperature sensor that measures the temperature of the heat medium flowing through the battery temperature adjustment circuit, wherein the controller controls the first hydraulic oil control valve based on outputs of the hydraulic oil temperature sensor and the heat medium temperature sensor.

4. An electric working machine as described in claim 1, wherein the cooling refrigerant circuit comprises: a main refrigerant path for causing the cooling refrigerant to flow through an HVAC evaporator; a bypass refrigerant path connected to the main refrigerant path and bypassing the HVAC evaporator to connect to the battery cooling heat exchanger; and a refrigerant control valve for controlling the flow rate of the cooling refrigerant flowing through the bypass refrigerant path.

5. An electric working machine as described in claim 1, comprising an electric equipment cooling circuit for circulating an electric equipment refrigerant for cooling the electric motor, the electric equipment cooling circuit having a heater for heating the electric equipment refrigerant, a heater core for heating, and an electric equipment warm-up heat exchanger for heating the electric equipment refrigerant by heat exchange between the electric equipment refrigerant and the hydraulic oil flowing through the hydraulic oil cooling circuit, the hydraulic oil cooling circuit having a main oil passage for flowing the hydraulic oil via the oil cooler, and a second bypass oil passage connected to the main oil passage for flowing the hydraulic oil bypassing the oil cooler, the second bypass oil passage being connected to the electric equipment warm-up heat exchanger.

6. An electric working machine as described in claim 5, comprising: a second hydraulic oil control valve that controls the flow rate of the hydraulic oil flowing through the second bypass oil passage; a controller that controls the second hydraulic oil control valve; a hydraulic oil temperature sensor that measures the temperature of the hydraulic oil; and an electrical equipment refrigerant temperature sensor that measures the temperature of the electrical equipment refrigerant, wherein the controller controls the second hydraulic oil control valve based on outputs of the hydraulic oil temperature sensor and the electrical equipment refrigerant temperature sensor.

7. An electric working machine as described in claim 5, characterized in that the electric equipment cooling circuit is provided with a heat exchanger that exchanges heat between the cooling refrigerant compressed by a compressor in the cooling refrigerant circuit and the electric equipment refrigerant flowing downstream of the electric motor and upstream of the heater core.

Images