Excavator

Abstract

To provide a shovel that can cool multiple devices further efficiently.SOLUTION: A shovel according to one embodiment of the present invention comprises a cooling circuit 90 for circulating a refrigerant through a plurality of devices to be cooled related to an electric drive system. The cooling circuit 90 is provided with a detour circuit (cooling water channel 93A2) in which the refrigerant can bypass a revolving drive device 40 among the plurality of devices. For example, the detour circuit (cooling water channel 93A2) adjusts the pressure so that the flow rate of the revolving drive device 40 satisfies a predetermined required flow rate while allowing the inflow of the refrigerant from the main path (cooling water channel 93A).SELECTED DRAWING: Figure 3A

Description

[Technical Field]

[0001] The present invention relates to a shovel. [Background technology]

[0002] BACKGROUND ART Conventionally, cooling circuits that cool a plurality of devices (for example, an electric motor, an inverter, a converter, etc.) have been known (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-222815 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-154092 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when multiple devices are cooled by a single cooling circuit, the specifications of the cooling circuit may be determined to suit the device that requires the highest cooling performance, for example. Therefore, for example, if a flow rate higher than necessary is supplied to a device that requires relatively low cooling performance, this may increase pressure loss in the cooling system, resulting in a need for a high-power water pump, which may lead to increased costs.

[0005] In view of the above problems, an object of the present invention is to provide a shovel that can cool multiple pieces of equipment more efficiently. [Means for solving the problem]

[0006] In order to achieve the above object, in one embodiment of the present invention, A plurality of devices to be cooled; a cooling circuit that circulates a refrigerant through the plurality of devices; The plurality of devices include: DeaiRelatively small flow rate required specified This includes equipment such as: the cooling circuit includes a bypass path that bypasses the refrigerant to the equipment; The aforementioned specified a bypass path for bypassing the refrigerant to the equipment; the predetermined device has a required flow rate smaller than that of the device to which the detour route is not provided, When a refrigerant flows through a main path of the cooling circuit, the refrigerant constantly flows from the main path into both the detour path and the device that is a detour target of the detour path among the plurality of devices, the bypass path adjusts the flow rate of the refrigerant passing through the bypass target device among the plurality of devices so as to satisfy a predetermined required flow rate while allowing the refrigerant to flow in from the main path. Shovels are provided. In another embodiment of the present invention, A plurality of devices to be cooled; a cooling circuit that circulates a refrigerant through the plurality of devices; The plurality of devices include: Deai Relatively small flow rate required specified This includes equipment such as: the cooling circuit includes a bypass path that bypasses the refrigerant to the equipment; The aforementioned specified a bypass path for bypassing the refrigerant to the equipment; the predetermined device has a required flow rate smaller than that of the device to which the detour route is not provided, the bypass passage has a pressure adjustment mechanism; The pressure adjustment mechanism has a fixed degree of pressure adjustment. Shovels are provided. [Effects of the Invention]

[0007] According to the above-described embodiment, it is possible to provide a shovel that can cool a plurality of devices more efficiently. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a side view of a shovel according to one embodiment. [Figure 2] FIG. 1 is a block diagram illustrating an example of a configuration of a shovel according to an embodiment. [Figure 3A] FIG. 2 is a diagram illustrating an example of a cooling circuit. [Figure 3B] FIG. 10 is a diagram showing another example of a cooling circuit. [Figure 4A] FIG. 2 is a diagram illustrating a specific example of the layout of a cooling circuit. [Figure 4B] FIG. 2 is a diagram illustrating a specific example of the layout of a cooling circuit. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the invention will be described with reference to the drawings.

[0010] [Outline of the Excavator] First, with reference to FIG. 1, an outline of a shovel will be described as an example of a work machine.

[0011] FIG. 1 is a side view showing an example of a shovel according to this embodiment.

[0012] The excavator of this embodiment comprises a lower running body 1, an upper rotating body 3 mounted on the lower running body 1 so as to be rotatable via a rotating mechanism 2, a boom 4, an arm 5, and a bucket 6 as working devices, and a cabin 10 in which the operator rides.

[0013] The lower traveling body 1 includes, for example, a pair of left and right crawlers, and is self-propelled by the crawlers being hydraulically driven by traveling hydraulic motors 1A, 1B (see FIG. 2).

[0014] The upper rotating body 3 rotates relative to the lower traveling body 1 by being electrically driven by a rotating electric motor 21 (see FIG. 2) described later.

[0015] A boom 4 is pivotally attached to the front center of the upper rotating body 3 so as to be able to tilt up and down, an arm 5 is pivotally attached to the tip of the boom 4 so as to be able to rotate up and down, and a bucket 6 is pivotally attached to the tip of the arm 5 so as to be able to rotate up and down. The boom 4, arm 5, and bucket 6 are hydraulically driven by a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9, which serve as hydraulic actuators, respectively.

[0016] The cabin 10 is mounted on the front left side of the upper rotating body 3, and inside the cabin 10, a cockpit where an operator sits, an operating device 26 (described later), and the like are provided.

[0017] [Excavator configuration] Next, the configuration of the shovel according to this embodiment will be described with reference to FIG. 2 in addition to FIG.

[0018] FIG. 2 is a block diagram showing an example of the configuration of the excavator according to this embodiment, focusing on the drive system.

[0019] In the diagram, mechanical power lines are indicated by double lines, high-pressure hydraulic lines by thick solid lines, pilot lines by dashed lines, and electric drive and control lines by thin solid lines.

[0020] <Excavator hydraulic drive system> The hydraulic drive system of the excavator according to this embodiment includes the engine 11, the motor generator 12, the reducer 13, the main pump 14, and the control valve 17. As described above, the hydraulic drive system according to this embodiment also includes the traveling hydraulic motors 1A and 1B, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 that hydraulically drive the lower traveling structure 1, the boom 4, the arm 5, and the bucket 6, respectively.

[0021] The motor generator 12 will be described in detail in the explanation of the electric drive system of the excavator.

[0022] The engine 11 is the main power source in the hydraulic drive system and is mounted on the rear of the upper rotating body 3. The engine 11 rotates at a predetermined constant target speed under the control of an engine controller (ECM: Engine Control Module) 30C, which will be described later. The engine 11 is, for example, a diesel engine that uses diesel as fuel, and drives a main pump 14 and a pilot pump 15 via a reduction gear 13. The engine 11 also drives a motor generator 12 via the reduction gear 13, causing the motor generator 12 to generate electricity.

[0023] The reducer 13 is mounted, for example, on the rear of the upper rotating body 3, and has two input shafts to which the engine 11 and a motor-generator 12 (described later) are connected, and one output shaft to which the main pump 14 and the pilot pump 15 are coaxially connected in series. The reducer 13 can transmit the power of the engine 11 and the motor-generator 12 to the main pump 14 and the pilot pump 15 at a predetermined reduction ratio. The reducer 13 can also distribute and transmit the power of the engine 11 to the motor-generator 12, the main pump 14, and the pilot pump 15 at a predetermined reduction ratio.

[0024] The main pump 14 is mounted on the rear of the upper rotating body 3 and supplies hydraulic oil to a control valve 17 through a high-pressure hydraulic line 16. The main pump 14 is driven by the engine 11, or by the engine 11 and a motor generator 12. The main pump 14 is, for example, a variable displacement hydraulic pump, and a regulator (not shown) controls the angle (tilting angle) of the swash plate under the control of an excavator controller 30A (described later). This allows the main pump 14 to adjust the stroke length of the piston and control the discharge flow rate (discharge pressure).

[0025] The control valve 17 is a hydraulic control device that is mounted in the center of the upper rotating body 3 and controls the hydraulic drive system in response to an operator's operation of the control device 26. As described above, the control valve 17 is connected to the main pump 14 via the high-pressure hydraulic line 16, and is configured to be able to supply hydraulic oil supplied from the main pump 14 to the traveling hydraulic motors 1A (for the right) and 1B (for the left), which serve as hydraulic actuators, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9. Specifically, the control valve 17 is a valve unit that includes a plurality of hydraulic control valves (directional control valves) that control the flow rate and direction of the hydraulic oil supplied from the main pump 14 to each of the hydraulic actuators.

[0026] <Excavator electric drive system> The electric drive system of the excavator according to this embodiment includes, as components that assist the hydraulic drive system, a motor generator 12, a current sensor 12s1, a voltage sensor 12s2, a reducer 13, and an inverter 18A. The electric drive system of the excavator according to this embodiment also includes, as components related to the electric drive of the driven element (specifically, the upper rotating body 3), a swing drive device 40, a current sensor 21s, and an inverter 18B.

[0027] The motor generator 12 is an assist power source for the hydraulic drive system and is mounted on the rear of the upper swing body 3. The motor generator 12 is, for example, an interior permanent magnet (IPM) motor. The motor generator 12 is connected to a power storage system 120 including a capacitor 19 and a swing electric motor 21 via an inverter 18A. The motor generator 12 performs power running operation using three-phase AC power supplied from the capacitor 19 and the swing electric motor 21 via the inverter 18A, and drives the main pump 14 and the pilot pump 15 via a reducer 13 in a manner assisting the engine 11. The motor generator 12 also performs power generation operation by being driven by the engine 11, and can supply the generated power to the capacitor 19 and the swing electric motor 21. Switching control between power running operation and power generation operation of the motor generator 12 may be achieved by the inverter 18A under control of a hybrid controller (hereinafter referred to as "HB controller") 30B, which will be described later.

[0028] The current sensor 12s1 detects the current of each of the three phases (U phase, V phase, and W phase) of the motor generator 12. The current sensor 12s1 is provided, for example, on a power path between the motor generator 12 and the inverter 18A. Detection signals corresponding to the current of each of the three phases of the turning electric motor 21 detected by the current sensor 12s1 are directly input to the inverter 18A via an in-vehicle network such as a one-to-one communication line or a CAN (Controller Area Network). The detection signals may also be input to the HB controller 30B via the in-vehicle network such as a one-to-one communication line or a CAN, and input to the inverter 18A via the HB controller 30B.

[0029] The voltage sensor 12s2 detects the applied voltages of the three phases of the motor generator 12. The voltage sensor 12s2 is provided, for example, on a power path between the motor generator 12 and the inverter 18A. Detection signals corresponding to the applied voltages of the three phases of the turning electric motor 21 detected by the voltage sensor 12s2 are directly input to the inverter 18A via a one-to-one communication line or an in-vehicle network such as a CAN. The detection signals may also be input to the HB controller 30B via the one-to-one communication line or the in-vehicle network and input to the inverter 18A via the HB controller 30B.

[0030] The inverter 18A, under the control of the HB controller 30B, drives and controls the motor generator 12. The inverter 18A includes, for example, a conversion circuit that converts DC power into three-phase AC power and converts three-phase AC power into DC power, a drive circuit that switches and drives the conversion circuit, and a control circuit that outputs a control signal (for example, a PWM (Pulse Width Modulation) signal) that defines the operation of the drive circuit.

[0031] The control circuit of the inverter 18A controls the drive of the motor-generator 12 while grasping the operating state of the motor-generator 12. For example, the control circuit of the inverter 18A grasps the operating state of the motor-generator 12 based on detection signals from sensors (e.g., an encoder, a resolver, etc.) that detect the rotation state of the motor-generator 12. Alternatively, the control circuit of the inverter 18A may grasp the operating state of the motor-generator 12 by successively estimating the rotation angle, etc. of the rotating shaft of the motor-generator 12 based on detection signals from the current sensor 12s1 and the voltage sensor 12s2. For example, the control circuit may estimate the rotation angle, rotation speed, etc. of the rotating shaft of the motor-generator 12 based on a known extended electromotive force (EEFM) model. Then, the control circuit may perform drive control of the motor-generator 12 (hereinafter referred to as "sensorless control") while grasping the operating state of the motor-generator 12 based on the estimated values ​​of the rotation angle and rotation speed that are successively derived. This eliminates the need for the motor-generator 12 to be provided with a predetermined sensor (e.g., a rotary encoder, etc.) that detects the rotation angle or rotation position. This allows for a reduction in the number of mechanical sensors, which reduces the cost of the shovel and also reduces detection failures due to sensor contamination, etc.

[0032] When sensorless control is applied, the control circuit of the inverter 18A may estimate the rotation angle of the rotating shaft of the motor generator 12, etc., using a voltage command value for the motor generator 12 input from the HB controller 30B or generated by the control circuit itself during the control process, instead of the detection value of the voltage applied to the motor generator 12 by the voltage sensor 12s2. In this case, the voltage sensor 12s2 may be omitted. At least one of the drive circuit and control circuit of the inverter 18A may be provided outside the inverter 18A (for example, in the HB controller 30B).

[0033] The swing drive device 40 includes a swing electric motor 21, a resolver 22, a mechanical brake 23, and a swing reducer 24. The swing drive device 40 is mounted on the upper swing body 3, and drives the upper swing body 3 via the swing mechanism 2 with the power of the swing electric motor 21.

[0034] The swing electric motor 21 performs a power running operation to drive the upper swing body 3 to swing, and a regenerative operation to generate regenerative power to brake the upper swing body 3 to swing, under the control of the HB controller 30B and the inverter 18B. The swing electric motor 21 is connected to the power storage system 120 via the inverter 18B, and is driven by three-phase AC power supplied from the capacitor 19 and the motor generator 12 via the inverter 18B. The swing electric motor 21 also supplies regenerative power to the capacitor 19 and the motor generator 12 via the inverter 18B. This makes it possible to charge the capacitor 19 and drive the motor generator 12 with the regenerative power. Switching control between the power running operation and the regenerative operation of the swing electric motor 21 may be realized by the inverter 18B under the control of the HB controller 30B. A resolver 22, a mechanical brake 23, and a swing reducer 24 are connected to a rotating shaft 21A of the swing electric motor 21.

[0035] The resolver 22 detects the rotation position (rotation angle), rotation speed, etc. of the turning electric motor 21. A detection signal corresponding to the rotation angle, etc. detected by the resolver 22 may be directly input to the inverter 18B via a one-to-one communication line, an in-vehicle network such as a CAN, etc. Alternatively, the detection signal may be input to the HB controller 30B via a one-to-one communication line, an in-vehicle network such as a CAN, etc., and input to the inverter 18B via the HB controller 30B.

[0036] The mechanical brake 23, under the control of the HB controller 30B, mechanically generates a braking force on the rotating shaft 21A of the swing electric motor 21. This allows the mechanical brake 23 to brake the swing of the upper swing body 3 or to maintain the upper swing body 3 in a stopped state.

[0037] The swing reducer 24 is connected to the rotating shaft 21A of the swing electric motor 21, and reduces the output (torque) of the swing electric motor 21 at a predetermined reduction ratio, thereby increasing the torque and driving the upper swing body 3 to swing. That is, during power running, the swing electric motor 21 drives the upper swing body 3 (swing mechanism 2) to swing via the swing reducer 24. The swing reducer 24 also increases the inertial rotational force of the upper swing body 3 and transmits it to the swing electric motor 21 to generate regenerative power. That is, during regenerative operation, the swing electric motor 21 generates regenerative power using the inertial rotational force of the upper swing body 3 transmitted via the swing reducer 24, thereby braking the upper swing body 3 in swing.

[0038] The current sensor 21s detects the current of each of the three phases (U phase, V phase, and W phase) of the turning electric motor 21. The current sensor 21s is provided, for example, on a power path between the turning electric motor 21 and the inverter 18B. Detection signals corresponding to the current of each of the three phases of the turning electric motor 21 detected by the current sensor 21s may be directly input to the inverter 18B via a one-to-one communication line or an in-vehicle network such as a CAN. Alternatively, the detection signals may be input to the HB controller 30B via a one-to-one communication line or an in-vehicle network such as a CAN, and input to the inverter 18B via the HB controller 30B.

[0039] The inverter 18B, under the control of the HB controller 30B, drives and controls the turning electric motor 21. The inverter 18B includes, for example, a conversion circuit that converts DC power to three-phase AC power and converts three-phase AC power to DC power, a drive circuit that switches and drives the conversion circuit, and a control circuit that outputs a control signal (for example, a PWM signal) that defines the operation of the drive circuit.

[0040] Specifically, the control circuit of the inverter 18B performs speed feedback control and torque feedback control for the turning electric motor 21 based on detection signals from the current sensor 21s and the resolver 22.

[0041] At least one of the drive circuit and control circuit of the inverter 18B may be provided outside the inverter 18B.

[0042] <Excavator power storage system> The power storage system 120 of the excavator according to this embodiment includes a capacitor 19, a step-up / step-down converter 100, and a DC bus 110. The power storage system 120 is mounted on the right front part of the upper rotating body 3 together with inverters 18A, 18B of the electric drive system, for example.

[0043] The capacitor 19 is an example of an electricity storage device that supplies power to the motor generator 12 and the swing electric motor 21 and charges the generated power of the motor generator 12 and the swing electric motor 21. In addition, a relay (hereinafter referred to as "shutoff relay") is provided to disconnect the capacitor 19 from a main circuit on the load side including the step-up / step-down converter 100. As a result, the capacitor 19 is disconnected from the main circuit under the control of the HB controller 30B when the shovel is stopped or when an abnormality occurs in the shovel (for example, when an accident such as tipping occurs). This makes it possible to prevent a situation in which an extremely large short-circuit current flows through the capacitor 19 due to an abnormality when the operator is absent or present. The shutoff relay is provided, for example, on both the positive and negative sides of the power paths between the capacitor 19 and the step-up / step-down converter 100.

[0044] The buck-boost converter 100 boosts the power of the capacitor 19 and outputs it to the DC bus 110, or reduces the power supplied to the DC bus 110 and stores it in the capacitor 19. The buck-boost converter 100 switches between boost operation and buck operation depending on the operating states of the motor generator 12 and the swing electric motor 21 so that the voltage value of the DC bus 110 falls within a certain range. The switching control between the boost operation and the buck operation of the buck-boost converter 100 may be realized by the HB controller 30B based on the detected voltage value of the DC bus 110, the detected voltage value of the capacitor 19, and the detected current value of the capacitor 19.

[0045] The DC bus 110 is provided between the inverters 18A, 18B and the step-up / step-down converter 100, and controls the exchange of power among the capacitor 19, the motor generator 12, and the swing electric motor 21.

[0046] <Excavator operation system> Moreover, the operating system of the excavator according to this embodiment includes the pilot pump 15, the operating device 26, the pressure sensor 29, and the like.

[0047] The pilot pump 15 is mounted on the rear of the upper rotating body 3 and supplies pilot pressure to the operating device 26 via a pilot line 25. The pilot pump 15 is, for example, a fixed displacement hydraulic pump, and is driven by the engine 11 or by the engine 11 and the motor-generator 12.

[0048] The operation device 26 includes, for example, levers 26A and 26B and a pedal 26C. The operation device 26 is provided near the cockpit of the cabin 10 and is an operation input means through which the operator operates each driven element (e.g., the undercarriage 1, the upper revolving body 3, the boom 4, the arm 5, the bucket 6, etc.). In other words, the operation device 26 is an operation input means through which the operator operates hydraulic actuators (e.g., the traveling hydraulic motors 1A and 1B, the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, etc.) and electric actuators (e.g., the revolving electric motor 21) that drive each driven element. The operation device 26 (levers 26A and 26B and pedal 26C) is connected to the control valve 17 via a secondary hydraulic line 27. As a result, a pilot signal (pilot pressure) corresponding to the operating state of the undercarriage 1, the boom 4, the arm 5, the bucket 6, etc., through the operation device 26 is input to the control valve 17. Therefore, the control valve 17 can drive each hydraulic actuator according to the operating state of the operating device 26. In addition, the operating device 26 is connected to a pressure sensor 29 via a hydraulic line 28 on the secondary side thereof.

[0049] The operating device 26 may be of an electrical type. In this case, an electrical signal representing the operation content of the operating device 26 (for example, the operation direction, the operation amount, etc.) is input to the control device 30 (for example, the shovel controller 30A). The control device 30 (the shovel controller 30A) then controls a proportional valve connected to the control valve 17 via a pilot line in accordance with the content of the electrical signal, i.e., the operation content of the operating device 26. As a result, a pilot pressure corresponding to the operation content of the operating device 26 is input from the proportional valve, and the control valve 17 can drive each hydraulic actuator in accordance with the operating state of the operating device 26.

[0050] As described above, the pressure sensor 29 is connected to the operating device 26 via the hydraulic line 28, and detects the secondary pilot pressure of the operating device 26, i.e., the pilot pressure corresponding to the operating state of each operating element in the operating device 26. The pressure sensor 29 is connected to the shovel controller 30A, and pressure signals (pressure detection values) corresponding to the operating states of the lower traveling structure 1, upper rotating structure 3, boom 4, arm 5, bucket 6, etc. in the operating device 26 are taken into the shovel controller 30A.

[0051] If the operating device 26 is an electrical type, the pressure sensor 29 is omitted because the operating state of the operating device 26 is input directly to the control device 30 (shovel controller 30A) as an electrical signal from the operating device 26.

[0052] <Excavator control system> The control system of the excavator according to this embodiment includes a control device 30.

[0053] The control device 30 includes a shovel controller 30A, an HB controller 30B, and an engine controller 30C.

[0054] The functions of the shovel controller 30A, the HB controller 30B, the engine controller 30C, etc. may be realized by any hardware or a combination of hardware and software. For example, the shovel controller 30A, the HB controller 30B, the engine controller 30C, etc. may be configured mainly by a microcomputer including a processor such as a CPU (Central Processing Unit), a memory device (main storage device) such as a RAM (Random Access Memory), a non-volatile auxiliary storage device such as a ROM (Read Only Memory), an interface device, etc.

[0055] The shovel controller 30A controls the driving of the shovel in cooperation with various controllers including the HB controller 30B and the engine controller 30C. For example, the shovel controller 30A may comprehensively control the operation of the entire shovel (specifically, various devices mounted on the shovel) based on two-way communication with various controllers such as the HB controller 30B and the engine controller 30C.

[0056] The HB controller 30B performs drive control of the electric drive system based on various information input from the shovel controller 30A (for example, control commands including a detection value of the pressure sensor 29 corresponding to the operation state of the operation device 26). For example, the HB controller 30B drives the inverter 18A and controls switching between the operation states (powering operation and power generation operation) of the motor generator 12 based on a detection value detected by the pressure sensor 29 corresponding to the operation state of the operation device 26. Also, for example, the HB controller 30B drives the inverter 18B and controls switching between the operation states (powering operation and regenerative operation) of the swing electric motor 21 based on a detection value detected by the pressure sensor 29 corresponding to the operation state of the operation device 26. Also, for example, the HB controller 30B drives the buck-boost converter 100 and controls switching between the step-up operation and the step-down operation of the buck-boost converter 100, in other words, between the discharge state and the charge state of the capacitor 19, based on a detection value detected by the pressure sensor 29 corresponding to the operation state of the operation device 26.

[0057] The engine controller 30C controls the drive of the engine 11 based on various information input from the shovel controller 30A (for example, control commands including the set rotation speed of the engine 11 and the operation mode of the shovel corresponding to the set rotation speed of the engine 11). Specifically, the engine controller 30C realizes the drive control of the engine 11 by outputting control commands to actuators such as a fuel injection device of the engine 11 to be controlled and a starter motor for starting the engine 11.

[0058] [Cooling circuit for electric drivetrain equipment] Next, a cooling circuit 90 for equipment relating to the electric drive system of the excavator will be described with reference to FIG. 3 (FIGS. 3A and 3B).

[0059] In addition to the cooling circuit 90, the excavator is also equipped with a cooling circuit for the engine 11, but a description thereof will be omitted.

[0060] 3A and 3B are diagrams showing an example and another example of a cooling circuit 90 for an electric drive train of a shovel, respectively.

[0061] 3A and 3B, the cooling circuit 90 cools a plurality of devices related to the electric drive system, and circulates coolant (an example of a refrigerant) cooled by a radiator 91 using a water pump 92. Specifically, the cooling circuit 90 cools the swing drive device 40, the capacitor 19, the inverters 18A and 18B, the step-up / step-down converter 100, the motor generator 12, and the reducer 13.

[0062] In this example, the inverters 18A and 18B are housed in a single housing to form the inverter 18.

[0063] The cooling circuit 90 includes a radiator 91, a water pump 92, and cooling water passages 93A, 93A1, 93A2, 93B1, 93B, 93C, 93C1, 93C2, 93D, 93D1, 93D2, 93E, and 93F. Hereinafter, the cooling water passages 93A, 93A1, 93A2, 93B1, 93B, 93C, 93C1, 93C2, 93D, 93D1, 93D2, 93E, and 93F may be collectively referred to as the cooling water passage 93.

[0064] The radiator 91 is a heat exchanger that cools the refrigerant and is mounted, for example, on the left rear side of the upper rotating body 3 (see FIG. 4A).

[0065] Water pump 92 is powered by a battery (e.g., a lead battery) mounted on upper rotating body 3, and circulates refrigerant within cooling circuit 90. Specifically, water pump 92 is connected to radiator 91 through cooling water passage 93, draws in refrigerant cooled by radiator 91, and discharges it into cooling water passage 93A on the downstream side. Water pump 92 is mounted, for example, on the left rear side of upper rotating body 3, adjacent to radiator 91 (see FIG. 4A).

[0066] The cooling water passage 93A branches into cooling water passages 93A1 and 93A2.

[0067] The cooling water passage 93A1 is connected to a rotation drive device 40 (an example of equipment to be cooled) including a rotation electric motor 21.

[0068] The cooling water supplied to the slewing drive unit 40 through the cooling water passage 93A1 passes through a cooling water passage arranged within the slewing drive unit 40, cools the slewing drive unit 40, and then flows out into the cooling water passage 93B1 connected downstream of the slewing drive unit 40.

[0069] The cooling water passage 93A2 (an example of a bypass) branches off from the cooling water passage 93A and is connected to the cooling water passage 93B downstream of the swing drive unit 40 so that the cooling water can bypass the swing drive unit 40. This allows a portion of the cooling water to pass through the cooling water passage 93A2, thereby reducing the pressure loss of the cooling water passing through the portion of the cooling circuit 90 surrounding the swing drive unit 40 (the portion indicated by the dotted line in the figure). Furthermore, because a portion of the cooling water can pass through the cooling water passage 93A2, the temperature rise of the cooling water as a whole can be suppressed. This allows the water pump 92 to be made smaller (lower output) and the radiator 91 to be made smaller, thereby reducing the cost of the excavator. In this case, "bypassing" means that the cooling water flows downstream of the cooling circuit 90 without passing through the equipment to be bypassed (in this example, the swing drive unit 40). Furthermore, "detouring" means that the cooling water flows through a path (in this example, cooling water path 93A2) that branches off from the main path (in this example, cooling water path 93A) that connects to the equipment to be detouring (slewing drive device 40) and that does not contain any cooling target. Furthermore, "detouring" does not mean the length of the travel distance of the cooling water compared to when passing through the equipment to be detouring (slewing drive device 40).

[0070] Specifically, the cooling water passage 93A2 allows the inflow of cooling water from the cooling water passage 93A (an example of a main passage) while adjusting the pressure so that the flow rate passing through the swing drive device 40 satisfies a predetermined required flow rate. The required flow rate is the minimum flow rate necessary to adequately cool the equipment to be cooled, and is specified in advance for each equipment to be cooled. This makes it possible to reduce the pressure loss of the cooling water passing through the portion of the cooling circuit 90 that is in contact with the swing drive device 40 while still satisfying the required flow rate of the swing drive device 40.

[0071] For example, the flow path cross-sectional area and length of the cooling water path 93A2 are appropriately set so that the flow rate of the cooling water flowing from the cooling water path 93A through the cooling water path 93A1 into the swing drive device 40 satisfies the required flow rate, while some of the cooling water bypasses the swing drive device 40 through the cooling water path 93A2. Specifically, the flow path cross-sectional area of ​​the cooling water path 93A2 may be set to be relatively smaller than that of the cooling water path 93A. This makes it difficult for the cooling water to flow into the cooling water path 93A2, so that the required flow rate of the cooling water flowing into the cooling water path 93A1 can be ensured.

[0072] 3B, a throttle valve 94 (an example of a pressure adjustment mechanism) may be installed in the cooling water passage 93A2. This allows the throttle valve 94 to operate to satisfy the required flow rate of cooling water flowing from the cooling water passage 93A through the cooling water passage 93A1 into the swing drive device 40 while allowing some of the cooling water to bypass the swing drive device 40 through the cooling water passage 93A2. The throttle valve 94 may have a fixed throttle opening or may have a variable throttle opening. In the latter case, the control device 30 (for example, the HB controller 30B) may control the throttle opening of the throttle valve 94 while monitoring the flow rate of the cooling water in the swing drive device 40. This allows more cooling water to flow into the cooling water passage 93A2 while satisfying the required flow rate of cooling water flowing into the swing drive device 40, thereby further reducing pressure loss in the portion of the cooling circuit 90 that serves the swing drive device 40.

[0073] Cooling water passage 93A2 and cooling water passage 93B1 merge into cooling water passage 93B, and cooling water passage 93B is connected to capacitor 19 (an example of equipment to be cooled).

[0074] The cooling water supplied to capacitor 19 through cooling water passage 93B passes through a cooling water passage disposed within capacitor 19, cools capacitor 19, and then flows out into cooling water passage 93C connected to the downstream side of capacitor 19.

[0075] The cooling water passage 93C branches into cooling water passages 93C1 and 93C2.

[0076] The cooling water passage 93C1 is connected to the inverter 18 (an example of equipment to be cooled), and the cooling water passage 93C2 is connected to the step-up / step-down converter 100 (an example of equipment to be cooled). That is, the inverter 18 and the step-up / step-down converter 100 are connected in parallel in the cooling circuit 90.

[0077] The cooling water supplied to the inverter 18 through the cooling water passage 93C1 passes through a cooling water passage disposed within the inverter 18, cools the inverters 18A and 18B, and then flows out into the cooling water passage 93D1 connected downstream of the inverter 18.

[0078] The cooling water supplied to the buck-boost converter 100 through the cooling water passage 93C2 passes through a cooling water passage arranged within the buck-boost converter 100, cools the buck-boost converter 100, and then flows out into the cooling water passage 93D2 connected downstream of the buck-boost converter 100.

[0079] The cooling water passages 93D1 and 93D2 merge into a cooling water passage 93D, and the cooling water passage 93D is connected to the motor generator 12 (an example of equipment to be cooled).

[0080] The cooling water supplied to the motor-generator 12 through the cooling water passage 93D passes through a cooling water passage arranged within the motor-generator 12, cools the motor-generator 12, and then flows out into the cooling water passage 93E connected downstream of the motor-generator 12.

[0081] The cooling water passage 93E is connected to the reducer 13 (an example of equipment to be cooled).

[0082] The cooling water supplied from the cooling water passage 93E to the reducer 13 passes through a cooling water passage arranged within the reducer 13, cools the reducer 13, and then flows out into the cooling water passage 93F connected downstream of the reducer 13.

[0083] Cooling water passage 93F is connected to radiator 91. The cooling water whose temperature has risen by cooling multiple cooling objects is cooled by radiator 91 and supplied to water pump 92 through cooling water passage 93G. In this way, cooling circuit 90 can continuously cool multiple cooling objects while circulating the cooling water.

[0084] In addition, in this example, instead of or in addition to the cooling water passage 93A2, a cooling water passage (hereinafter collectively referred to as a "bypass passage" together with the cooling water passage 93A2) may be provided that allows the cooling water to bypass other equipment to be cooled in the cooling circuit 90.

[0085] For example, the detour may be provided so as to be able to bypass the inverter 18. In this case, the detour is provided in such a manner that the cooling water branches off from the cooling water passage 93C1 and merges with the cooling water passage 93D1.

[0086] The equipment for which the bypass route is set is, for example, an equipment with a relatively high pressure loss among the multiple equipment to be cooled by the cooling circuit 90. This allows a portion of the cooling water to bypass the equipment with a relatively high pressure loss, as described above, and therefore the pressure loss of the entire cooling circuit 90 can be efficiently reduced. This allows the output of the water pump 92 to be further reduced, further reducing the cost of the excavator. In other words, even if there is an equipment with a relatively high pressure loss that could become a bottleneck among the multiple equipment to be cooled by the cooling circuit 90, the output and size of the water pump 92 can be optimized by providing an appropriate bypass route.

[0087] Furthermore, the equipment for which the bypass route is set is, for example, an equipment that requires a relatively small (low) flow rate among the multiple equipment to be cooled by the cooling circuit 90. This allows more cooling water to bypass the equipment without cooling it, thereby more efficiently suppressing the rise in the temperature of the cooling water. This allows the radiator 91 to be further miniaturized, further reducing the cost of the excavator. In other words, even if the required flow rates of the multiple equipment to be cooled by the cooling circuit 90 are significantly different, the size of the radiator 91 can be optimized by appropriately providing a bypass route.

[0088] That is, the equipment for which a detour route is set may be at least one of the equipment with a relatively high pressure loss among the multiple equipment to be cooled by the cooling circuit 90 and the equipment with a relatively small (low) required flow rate.

[0089] The bypass route may be set in a manner that allows bypassing not only one device to be cooled by the cooling circuit 90, but also two or more devices.

[0090] For example, the cooling water passage 93A2 may be provided so as to be able to bypass not only the swing drive device 40 but also the capacitor 19. In this case, the cooling water passage 93A2 may be set in a manner such that it merges with the cooling water passage 93C instead of the cooling water passage 93B.

[0091] The detour may be provided so as to bypass both the inverter 18 and the step-up / step-down converter, which are connected in parallel. In this case, the detour may be set so that the cooling water branches off from the cooling water passage 93C and merges with the cooling water passage 93D.

[0092] In this example, in the cooling circuit 90, some of the equipment to be cooled (the inverter 18 and the boost / buck converter 100) are connected in parallel, but all of the equipment may be connected in series, or all of the equipment may be connected in parallel.

[0093] [Example of cooling circuit layout] Next, the layout of the cooling circuit 90 will be specifically described with reference to FIG. 4 (FIGS. 4A and 4B).

[0094] 4A and 4B are diagrams illustrating a specific example of the layout of the cooling circuit 90. Specifically, Fig. 4A is a top view showing an example of the layout of the cooling circuit 90 in the upper revolving body 3. Fig. 4B is a perspective view showing an example of the layout of a cooling water passage 93A2 (bypass path) for cooling water to bypass the revolving drive device 40.

[0095] As shown in FIG. 4A, the radiator 91, the water pump 92, and multiple devices to be cooled are attached to the rotating frame 3F that forms the bottom of the upper rotating body 3, either directly or via predetermined parts (e.g., brackets, other devices, etc.).

[0096] The radiator 91 and the water pump 92 are mounted on the rear left side of the upper rotating body 3. Cooling water cooled by the radiator 91 is sucked into the water pump 92 through a cooling water passage 93G and discharged from the water pump 92 to a cooling water passage 93A.

[0097] The cooling water passage 93G is, for example, a hose that connects a pipe provided at the outlet of the cooling water of the radiator 91 and a pipe provided at the inlet of the cooling water of the water pump 92.

[0098] The cooling water passage 93A is, for example, a hose that connects a pipe provided at the cooling water outlet of the water pump 92 and a pipe provided at the cooling water inlet of the swing drive unit 40. The cooling water passage 93A extends between the left rear portion of the upper swing body 3 on which the water pump 92 is mounted and the vicinity of the swing axis of the upper swing body 3 on which the swing drive unit 40 is mounted, that is, the center portion of the upper swing body 3 in the front-rear and left-right directions.

[0099] The cooling water passage 93B is, for example, a hose that connects a pipe provided at the cooling water outlet of the swing drive unit 40 and a pipe provided at the cooling water inlet of the capacitor 19. The hose corresponding to the cooling water passage 93B extends between the central part in the front-rear and left-right directions of the upper swing body 3 on which the swing drive unit 40 is mounted and the front right part of the upper swing body 3 on which the capacitor 19 is mounted.

[0100] Cooling water passage 93C is, for example, a branched portion provided at the outlet of the cooling water at the rear end of capacitor 19. Two hoses corresponding to cooling water passages 93C1 and 93C2 are connected to the branched portion.

[0101] The cooling water passage 93C1 is, for example, a hose that connects a branch corresponding to the cooling water passage 93C and a pipe provided at the cooling water inlet at the rear end of the inverter 18, which is installed above the capacitor 19 and at the left end.

[0102] The cooling water passage 93C2 is, for example, a hose that connects a branch corresponding to the cooling water passage 93C and a pipe provided at the cooling water inlet at the rear end of the boost / buck converter 100, which is installed above the capacitor 19 and in the center on the left and right.

[0103] The cooling water passage 93D1 is, for example, a confluence provided at the outlet of the cooling water of the inverter 18.

[0104] The cooling water passage 93D2 is, for example, a hose connecting the cooling water outlet pipe of the boost-buck converter 100 and a confluence corresponding to the cooling water passage 93D1 located at the rear end of the inverter 18 adjacent to the left side of the boost-buck converter 100.

[0105] The cooling water passage 93D is, for example, a hose that connects a confluence located at the rear end of the inverter 18, which corresponds to the cooling water passage 93D1, and a pipe provided at the cooling water inlet of the motor generator 12. The hose that corresponds to the cooling water passage 93D extends between the front right part of the upper rotating body 3 on which the inverter 18 and the step-up / step-down converter 100 are mounted, and the rear right part of the upper rotating body 3 on which the motor generator 12 is mounted.

[0106] The cooling water passage 93E is, for example, a hose that connects a pipe provided at the cooling water outlet of the motor generator 12 and a pipe provided at the cooling water inlet of the reducer 13 adjacent to the motor generator 12.

[0107] The cooling water passage 93E is, for example, a hose that connects a pipe provided at the cooling water outlet of the reducer 13 and a pipe provided at the cooling water inlet of the radiator 91. The hose corresponding to the cooling water passage 93E extends between the rear right part of the upper rotating body 3 on which the reducer 13 is mounted and the rear left part of the upper rotating body 3 on which the radiator 91 is mounted.

[0108] 4B, a metal L-shaped pipe (an example of a branching portion) corresponding to cooling water passage 93A1 is connected to the cooling water inlet of the slewing drive device 40, and a hose corresponding to cooling water passage 93A is connected to it. In addition, a branching pipe is installed in the L-shaped pipe, and one end of a hose corresponding to cooling water passage 93A2 (a detour) is connected to it.

[0109] An L-shaped pipe (an example of a junction) corresponding to cooling water passage 93B1 is connected to the cooling water outlet of the slewing drive device 40, and a hose corresponding to cooling water passage 93B is connected to it. A junction pipe is installed in the L-shaped pipe, and the other end of the hose corresponding to cooling water passage 93A2 is connected to it.

[0110] For example, in a configuration in which the cooling water passage 93A2 (detour) branches off from the middle of the hose connecting the water pump 92 and the swing drive unit 40, a branch section needs to be provided in the middle of the hose, which results in the need for a part equivalent to the branch section and two hoses connected to both the upstream and downstream sides of the branch section. Similarly, in a configuration in which the cooling water passage 93A2 (detour) merges into the middle of the hose connecting the swing drive unit 40 and the capacitor 19, it results in the need for a part equivalent to the merge section and two hoses connected to both the upstream and downstream sides of the branch section.

[0111] In contrast to this, in this example, components corresponding to a branching section and a junction section are set at the inlet and outlet of the equipment (slewing drive device 40) to be detoured of the cooling water passage 93A2, respectively. This allows the components for connecting the hose corresponding to the cooling water passage 93 to the equipment to be detoured to also serve as the branching section and junction section of the detour. This prevents the need to add additional components corresponding to the branching section and the hose corresponding to the cooling water passage 93, or to split the hose into two. This prevents an increase in the number of components, and reduces the cost of the excavator.

[0112] In the cooling circuit 90, the detour path may be provided so as to be able to bypass two or more devices connected in series as described above. In this case, the branching section may be provided at the inlet of the most upstream device of the two or more devices to be bypassed, and the merging section may be provided at the outlet of the most downstream device of the two or more devices to be bypassed.

[0113] Although the embodiments for carrying out the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as set forth in the claims.

[0114] For example, in the above-described embodiment, the cooling circuit 90 circulates cooling water (coolant) as a refrigerant, but it may also circulate other liquids (for example, oil).

[0115] Furthermore, in the above-described embodiment and modified examples, the cooling circuit 90 circulates a liquid as a refrigerant, but it may also circulate a gas.

[0116] Furthermore, in the above-described embodiment and modified examples, the cooling circuit 90 of a shovel has been described, but a similar configuration (bypass path) may be applied to other work machines (for example, hybrid crawler cranes, wheel loaders, etc.) that have a cooling circuit for cooling multiple pieces of equipment to be cooled. Also, a similar configuration may be installed in any object (for example, a hybrid automobile, an electric automobile, etc.) that has a cooling circuit for cooling multiple pieces of equipment to be cooled. [Explanation of symbols]

[0117] 12 Motor generator (equipment) 13 Reducer (equipment) 18 Inverter (device) 19 Capacitor (device) 21 Electric motor for turning 40 Swing drive device (equipment) 90 Cooling circuit 91 Radiator 92 Water pump 93 Cooling Channel 93A Cooling water channel (main route) 93A2 Cooling waterway (detour) 94 Throttle valve (pressure adjustment mechanism) 100 Buck-boost converter (device)

Claims

1. A plurality of devices to be cooled; a cooling circuit that circulates a refrigerant through the plurality of devices; The plurality of devices includes a predetermined device that requires a relatively small flow rate among the devices, the cooling circuit includes a bypass path that bypasses the refrigerant to the equipment; The detour path is provided to detour the refrigerant to the predetermined device, the predetermined device has a required flow rate smaller than that of the device to which the detour route is not provided, When a refrigerant flows through a main path of the cooling circuit, the refrigerant constantly flows from the main path into both the detour path and the device that is a detour target of the detour path among the plurality of devices, the bypass path adjusts the flow rate of the refrigerant passing through the bypass target device among the plurality of devices so as to satisfy a predetermined required flow rate while allowing the refrigerant to flow in from the main path. Shovel.

2. A plurality of devices to be cooled; a cooling circuit that circulates a refrigerant through the plurality of devices; The plurality of devices includes a predetermined device that requires a relatively small flow rate among the devices, the cooling circuit includes a bypass path that bypasses the refrigerant to the equipment; The detour path is provided to detour the refrigerant to the predetermined device, the predetermined device has a required flow rate smaller than that of the device to which the detour route is not provided, the bypass passage has a pressure adjustment mechanism; The pressure adjustment mechanism has a fixed degree of pressure adjustment. Shovel.

3. the bypass path adjusts a pressure so that a flow rate passing through a bypass target device among the plurality of devices satisfies a predetermined required flow rate while allowing an inflow of refrigerant from the main path. The shovel according to claim 2.

4. The bypass path has a smaller flow path cross-sectional area than the main path. The shovel according to any one of claims 1 to 3.

5. the detour route detours around two or more devices among the plurality of devices; A shovel according to any one of claims 1 to 4.

6. the detour route is set to connect a branching section attached to an inlet of an upstream device among the devices to be detoured and a merging section attached to an outlet of a downstream device among the devices to be detoured. A shovel according to any one of claims 1 to 5.

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