JP7797776B2 - Excavator - Google Patents

Description

The present invention relates to a shovel.

Conventionally, cooling circuits that cool multiple devices (e.g., electric motors, inverters, converters, etc.) are known (see Patent Documents 1 and 2).

Japanese Patent Application Laid-Open No. 2010-222815 JP 2012-154092 A

However, when multiple devices are cooled with a single cooling circuit, the specifications of the cooling circuit may be determined to match the device that requires the highest cooling performance. As a result, for example, if a higher flow rate than necessary is supplied to a device that requires relatively lower cooling performance, this may increase pressure loss in the cooling system, resulting in the need for a high-output water pump and other costs.

In view of the above issues, the objective is to provide an excavator that can cool multiple pieces of equipment more efficiently.

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 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,
In a state where 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 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.
Shovels are provided.

The above-described embodiment provides a shovel that can cool multiple pieces of equipment more efficiently.

FIG. 1 is a side view of a shovel according to one embodiment. FIG. 1 is a block diagram illustrating an example of a configuration of a shovel according to an embodiment. FIG. 2 is a diagram illustrating an example of a cooling circuit. FIG. 10 is a diagram showing another example of a cooling circuit. FIG. 2 is a diagram illustrating a specific example of the layout of a cooling circuit. FIG. 2 is a diagram illustrating a specific example of the layout of a cooling circuit.

The following describes the embodiments of the invention with reference to the drawings.

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

Figure 1 is a side view showing an example of a shovel according to this embodiment.

The excavator according to this embodiment comprises a lower traveling body 1, an upper rotating body 3 mounted on the lower traveling 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.

The lower traveling body 1 includes, for example, a pair of left and right crawlers, each of which is hydraulically driven by traveling hydraulic motors 1A, 1B (see Figure 2), thereby allowing it to self-propel.

The upper rotating body 3 rotates relative to the lower traveling body 1 by being electrically driven by a rotating electric motor 21 (see Figure 2), which will be described later.

The boom 4 is pivotally attached to the front center of the upper rotating body 3 so that it can be raised or lowered. An arm 5 is pivotally attached to the tip of the boom 4 so that it can rotate up and down, and a bucket 6 is pivotally attached to the tip of the arm 5 so that it can rotate up and down. The boom 4, arm 5, and bucket 6 are hydraulically driven by hydraulic actuators: a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9, respectively.

The cabin 10 is mounted on the front left side of the upper rotating body 3, and inside it is provided a cockpit where the operator sits, as well as the operating device 26 described below.

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

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

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

<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, 1B, the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, and the like, which hydraulically drive the lower traveling structure 1, the boom 4, the arm 5, and the bucket 6, respectively.

The motor-generator 12 will be described in detail in the section explaining the excavator's electric drive system.

The engine 11 is the main power source in the hydraulic drive system and is mounted at the rear of the upper rotating body 3. The engine 11 rotates at a predetermined 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 the main pump 14 and pilot pump 15 via a reduction gear 13. The engine 11 also drives the motor-generator 12 via the reduction gear 13, causing the motor-generator 12 to generate electricity.

The reducer 13 is mounted, for example, at the rear of the upper rotating body 3, and has two input shafts to which the engine 11 and the motor-generator 12 (described later) are connected, and one output shaft to which the main pump 14 and 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.

The main pump 14 is mounted at the rear of the upper rotating body 3 and supplies hydraulic oil to a control valve 17 via 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 (tilt angle) of the swash plate under the control of the excavator controller 30A (described below). This allows the main pump 14 to adjust the stroke length of the piston and control the discharge flow rate (discharge pressure).

The control valve 17 is mounted in the center of the upper rotating body 3 and is a hydraulic control device that controls the hydraulic drive system in response to the 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 supply hydraulic oil supplied from the main pump 14 to the hydraulic actuators: traveling hydraulic motors 1A (right) and 1B (left), boom cylinder 7, arm cylinder 8, and bucket cylinder 9. Specifically, the control valve 17 is a valve unit including multiple hydraulic control valves (directional control valves) that control the flow rate and direction of hydraulic oil supplied from the main pump 14 to each of the hydraulic actuators.

<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.

The motor-generator 12 is an assist power source for the hydraulic drive system and is mounted on the rear of the upper rotating 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 motor 21 via an inverter 18A. The motor-generator 12 runs on three-phase AC power supplied from the capacitor 19 and the swing motor 21 via the inverter 18A, and drives the main pump 14 and pilot pump 15 via a reducer 13 in a manner that assists the engine 11. The motor-generator 12 also runs in a generating mode when driven by the engine 11, and can supply the generated power to the capacitor 19 and the swing motor 21. The inverter 18A may switch between power running and generating mode under the control of a hybrid controller (hereinafter referred to as "HB controller") 30B, which will be described later.

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

The voltage sensor 12s2 detects the applied voltage of each of the three phases of the motor-generator 12. The voltage sensor 12s2 is provided, for example, in the power path between the motor-generator 12 and the inverter 18A. The detection signals corresponding to the applied voltage of each 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 on-board 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 on-board network and input to the inverter 18A via the HB controller 30B.

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

The control circuit of the inverter 18A controls the drive of the motor-generator 12 while monitoring the operating state of the motor-generator 12. For example, the control circuit of the inverter 18A monitors the operating state of the motor-generator 12 based on detection signals from sensors (e.g., encoders, resolvers, etc.) that detect the rotational state of the motor-generator 12. The control circuit of the inverter 18A may also monitor the operating state of the motor-generator 12 by sequentially 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. The control circuit may then monitor the operating state of the motor-generator 12 based on the sequentially derived estimated values of the rotation angle and rotation speed, and perform drive control of the motor-generator 12 (hereinafter referred to as "sensorless control"). As a result, the motor generator 12 does not need to be equipped with a specific sensor (such as a rotary encoder) that detects the rotation angle or rotation position. This makes it possible to reduce the number of mechanical sensors, which not only reduces the cost of the shovel but also prevents detection errors due to sensor contamination, etc.

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 using a voltage command value for the motor-generator 12 input from the HB controller 30B or generated by the inverter itself during the control process, instead of the detected 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. Furthermore, at least one of the drive circuit and control circuit of the inverter 18A may be provided external to the inverter 18A (e.g., the HB controller 30B).

The slewing drive unit 40 includes a slewing motor 21, a resolver 22, a mechanical brake 23, and a slewing reducer 24. The slewing drive unit 40 is mounted on the upper slewing body 3 and drives the upper slewing body 3 via the slewing mechanism 2 using the power of the slewing motor 21.

Under the control of the HB controller 30B and the inverter 18B, the swing electric motor 21 performs power running, which drives the upper swing body 3 to swing, and regenerative running, which generates regenerative power to brake the upper swing body 3 to swing. 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 allows the regenerative power to charge the capacitor 19 and drive the motor-generator 12. Switching between power running and regenerative running of the swing electric motor 21 may be controlled 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 the rotating shaft 21A of the swing electric motor 21.

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

Under the control of the HB controller 30B, the mechanical brake 23 mechanically generates a braking force on the rotating shaft 21A of the rotation motor 21. This allows the mechanical brake 23 to brake the rotation of the upper rotating body 3 or to maintain the upper rotating body 3 in a stopped state.

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

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

The inverter 18B drives and controls the swing motor 21 under the control of the HB controller 30B. The inverter 18B includes, for example, a conversion circuit that converts DC power to three-phase AC power and 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 (e.g., a PWM signal) that determines the operation of the drive circuit.

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

In addition, at least one of the drive circuit and control circuit of inverter 18B may be provided external to inverter 18B.

<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, for example, inverters 18A, 18B of the electric drive system.

Capacitor 19 is an example of an energy storage device that supplies power to the motor-generator 12 and the swing motor 21 and charges the generated power of the motor-generator 12 and the swing motor 21. A relay (hereinafter referred to as "shutoff relay") is provided to disconnect capacitor 19 from the load-side main circuit, which includes the step-up/step-down converter 100. This disconnects capacitor 19 from the main circuit under the control of HB controller 30B when the shovel is stopped or an abnormality occurs with the shovel (for example, an accident such as tipping). This prevents an extremely large short-circuit current from flowing through capacitor 19 due to an abnormality while the operator is absent or present. A shutoff relay is provided, for example, on both the positive and negative sides of the power path between capacitor 19 and step-up/step-down converter 100.

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 and buck operation depending on the operating states of the motor generator 12 and the swing motor 21 so that the voltage value of the DC bus 110 remains within a certain range. The switching control between the boost and 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.

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 between the capacitor 19, the motor generator 12, and the swing motor 21.

<Excavator operation system>
The operating system of the excavator according to this embodiment includes a pilot pump 15, an operating device 26, a pressure sensor 29, and the like.

The pilot pump 15 is mounted at 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.

The operating device 26 includes, for example, levers 26A and 26B and a pedal 26C. The operating device 26 is located near the cockpit of the cabin 10 and serves as an operation input means for the operator to operate each driven element (e.g., the undercarriage 1, the upper rotating body 3, the boom 4, the arm 5, and the bucket 6, etc.). In other words, the operating device 26 serves as an operation input means for operating the hydraulic actuators (e.g., the traveling hydraulic motors 1A and 1B, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9, etc.) and the electric actuators (e.g., the swing electric motor 21) that drive each driven element. The operating 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, and the bucket 6, etc., in the operating device 26 is input to the control valve 17. Therefore, the control valve 17 can drive each hydraulic actuator depending on the operating state of the operating device 26. The operating device 26 is also connected to a pressure sensor 29 via a secondary hydraulic line 28.

The operating device 26 may be electrical. In this case, an electrical signal indicating the operation of the operating device 26 (e.g., the direction of operation, the amount of operation, etc.) is input to the control device 30 (e.g., shovel controller 30A). The control device 30 (shovel controller 30A) then controls the 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 of the operating device 26. As a result, a pilot pressure corresponding to the operation 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.

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 excavator controller 30A, and pressure signals (pressure detection values) corresponding to the operating states of the undercarriage 1, upper rotating body 3, boom 4, arm 5, bucket 6, etc. in the operating device 26 are input to the excavator controller 30A.

Note that if the operating device 26 is electrical, the pressure sensor 29 is omitted. This is because the operating state of the operating device 26 is input directly to the control device 30 (excavator controller 30A) as an electrical signal from the operating device 26.

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

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

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

The shovel controller 30A works in conjunction with various controllers, including the HB controller 30B and engine controller 30C, to control the operation of the shovel. For example, the shovel controller 30A may perform integrated control of the operation of the entire shovel (specifically, the various devices mounted on the shovel) based on bidirectional communication with various controllers, such as the HB controller 30B and engine controller 30C.

The HB controller 30B controls the drive of the electric drive system based on various information input from the shovel controller 30A (e.g., control commands including the 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 the switching of the operating state (powering operation and power generation operation) of the motor generator 12 based on the 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 the switching of the operating state (powering operation and regenerative operation) of the swing electric motor 21 based on the detection value detected by the pressure sensor 29 corresponding to the operation state of the operation device 26. Furthermore, for example, the HB controller 30B drives the buck-boost converter 100 based on a detection value detected by the pressure sensor 29 that corresponds to the operating state of the operating device 26, and controls the buck-boost converter 100 to switch between boost operation and buck operation, in other words, between the discharged state and the charged state of the capacitor 19.

The engine controller 30C controls the operation 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 operation control of the engine 11 by outputting control commands to actuators such as the fuel injection device of the engine 11 to be controlled and the starter motor for starting the engine 11.

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

In addition to the cooling circuit 90, the excavator is also equipped with a cooling circuit for the engine 11, but a description of this will be omitted.

Figures 3A and 3B show an example and another example of a cooling circuit 90 for an electric drive system of an excavator, respectively.

As shown in Figures 3A and 3B, the cooling circuit 90 cools multiple 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 unit 40, capacitor 19, inverters 18A and 18B, step-up/step-down converter 100, motor generator 12, and reducer 13.

In this example, inverters 18A and 18B are housed in a single housing and form inverter 18.

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, cooling water passages 93A, 93A1, 93A2, 93B1, 93B, 93C, 93C1, 93C2, 93D, 93D1, 93D2, 93E, and 93F may be collectively referred to as cooling water passage 93.

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

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

Cooling water passage 93A branches into cooling water passages 93A1 and 93A2.

The cooling water passage 93A1 is connected to a slewing drive unit 40 (an example of equipment to be cooled) that includes a slewing motor 21.

The cooling water supplied to the slewing drive unit 40 through the cooling water passage 93A1 passes through a cooling water passage disposed 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.

Cooling water passage 93A2 (an example of a bypass) branches off from cooling water passage 93A and connects to cooling water passage 93B downstream of the swing drive unit 40, allowing the cooling water to bypass the swing drive unit 40. This allows a portion of the cooling water to pass through cooling water passage 93A2, reducing the pressure loss of the cooling water passing through the portion of the cooling circuit 90 surrounding the swing drive unit 40 (the dotted line portion in the figure). Furthermore, because a portion of the cooling water can pass through cooling water passage 93A2, the temperature rise of the cooling water as a whole can be suppressed. This allows for a smaller water pump 92 (lower output) and a smaller radiator 91, thereby reducing the cost of the excavator. In this context, "bypass" refers to the cooling water flowing downstream of cooling circuit 90 without passing through the equipment being bypassed (in this case, the swing drive unit 40). Additionally, "detouring" refers to a path 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 in which the cooling water flows through a path (in this example, cooling water path 93A2) that does not contain any cooling objects. Additionally, "detouring" does not refer to the length of the distance the cooling water travels compared to when it passes through the equipment to be detouring (slewing drive device 40).

Specifically, cooling water passage 93A2 allows cooling water to flow in from cooling water passage 93A (an example of the main path) while adjusting the pressure so that the flow rate passing through the slewing drive unit 40 meets 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 piece of equipment to be cooled. This reduces the pressure loss of the cooling water passing through the portion of the cooling circuit 90 that is in contact with the slewing drive unit 40, while still meeting the required flow rate of the slewing drive unit 40.

For example, the cross-sectional area and length of cooling water passage 93A2 are appropriately set so that the flow rate of cooling water flowing from cooling water passage 93A through cooling water passage 93A1 into the slewing drive unit 40 satisfies the required flow rate, while some cooling water bypasses the slewing drive unit 40 through cooling water passage 93A2. Specifically, cooling water passage 93A2 may be set so that its cross-sectional area is relatively smaller than that of cooling water passage 93A. This makes it more difficult for cooling water to flow into cooling water passage 93A2, ensuring the required flow rate of cooling water flowing into cooling water passage 93A1.

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 bypass the slewing drive unit 40 through the cooling water passage 93A2 while satisfying the required flow rate of cooling water flowing from the cooling water passage 93A through the cooling water passage 93A1 to the slewing drive unit 40. The throttle valve 94 may have a fixed throttle opening or a variable throttle opening. In the latter case, the control device 30 (e.g., HB controller 30B) may control the throttle valve 94 opening while monitoring the flow rate of cooling water in the slewing drive unit 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 slewing drive unit 40, further reducing pressure loss in the slewing drive unit 40 portion of the cooling circuit 90.

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

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

Cooling water passage 93C branches into cooling water passages 93C1 and 93C2.

Cooling water passage 93C1 is connected to inverter 18 (an example of equipment to be cooled), and cooling water passage 93C2 is connected to boost/buck converter 100 (an example of equipment to be cooled). In other words, inverter 18 and boost/buck converter 100 are connected in parallel in cooling circuit 90.

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.

The cooling water supplied to the buck-boost converter 100 through the cooling water passage 93C2 passes through a cooling water passage disposed 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.

Cooling water passages 93D1 and 93D2 merge into cooling water passage 93D, which is connected to the motor-generator 12 (an example of equipment to be cooled).

The cooling water supplied to the motor-generator 12 through the cooling water passage 93D passes through a cooling water passage disposed 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.

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

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

The cooling water passage 93F is connected to the radiator 91. The cooling water, whose temperature has risen by cooling multiple cooling objects, is cooled by the radiator 91 and supplied to the water pump 92 via the cooling water passage 93G. This allows the cooling circuit 90 to continuously cool multiple cooling objects while circulating the cooling water.

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

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

The equipment for which a detour route is set up 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 some of the cooling water to bypass the equipment with a relatively high pressure loss, as described above, thereby efficiently reducing the pressure loss of the entire cooling circuit 90. 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 setting up an appropriate detour route.

Furthermore, the equipment for which a bypass route is set up 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, more efficiently suppressing the rise in cooling water temperature. 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 differ greatly, the size of the radiator 91 can be optimized by appropriately providing a bypass route.

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

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

For example, cooling water passage 93A2 may be configured to bypass not only the slewing drive device 40 but also the capacitor 19. In this case, cooling water passage 93A2 may be configured to merge with cooling water passage 93C instead of cooling water passage 93B.

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

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

[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).

Figures 4A and 4B are diagrams illustrating specific examples of the layout of the cooling circuit 90. Specifically, Figure 4A is a top view showing an example of the layout of the cooling circuit 90 in the upper rotating body 3. Figure 4B is a perspective view showing an example of the layout of a cooling water passage 93A2 (bypass path) that allows cooling water to bypass the rotating drive unit 40.

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

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

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

The cooling water passage 93A is, for example, a hose connecting a pipe provided at the cooling water outlet of the water pump 92 and a pipe provided at the cooling water inlet of the slewing drive unit 40. The cooling water passage 93A extends between the rear left portion of the upper rotating body 3 on which the water pump 92 is mounted and the vicinity of the rotation axis of the upper rotating body 3 on which the slewing drive unit 40 is mounted, i.e., the center of the upper rotating body 3 in the front-to-rear and left-to-right directions.

The cooling water passage 93B is, for example, a hose that connects a pipe provided at the cooling water outlet of the slewing 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 center of the upper rotating body 3, on which the slewing drive unit 40 is mounted, in the front-to-back and left-to-right directions, and the front right part of the upper rotating body 3, on which the capacitor 19 is mounted.

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

The cooling water passage 93C1 is, for example, a hose that connects the branch corresponding to the cooling water passage 93C to 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.

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

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

The cooling water passage 93D2 is, for example, a hose connecting the cooling water outlet pipe of the buck-boost converter 100 to 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 buck-boost converter 100.

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, to a pipe provided at the cooling water inlet of the motor-generator 12. The hose corresponding to the cooling water passage 93D extends between the front right portion 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 portion of the upper rotating body 3 on which the motor-generator 12 is mounted.

The cooling water passage 93E is, for example, a hose connecting a pipe provided at the cooling water outlet of the motor-generator 12 to a pipe provided at the cooling water inlet of the reducer 13 adjacent to the motor-generator 12.

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 portion of the upper rotating body 3 on which the reducer 13 is mounted and the rear left portion of the upper rotating body 3 on which the radiator 91 is mounted.

As shown in Figure 4B, a metal L-shaped pipe (an example of a branching part) corresponding to cooling water channel 93A1 is connected to the cooling water inlet of the slewing drive unit 40, and a hose corresponding to cooling water channel 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 channel 93A2 (a bypass path) is connected to it.

An L-shaped pipe (an example of a confluence) corresponding to cooling water channel 93B1 is connected to the cooling water outlet of the slewing drive unit 40, and a hose corresponding to cooling water channel 93B is connected to it. A confluence pipe is also installed in the L-shaped pipe, and the other end of the hose corresponding to cooling water channel 93A2 is connected to it.

For example, if the cooling water passage 93A2 (bypass path) branches off from the hose connecting the water pump 92 and the slewing drive unit 40, a branch section will need to be provided in the hose, resulting 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, if the cooling water passage 93A2 (bypass path) merges into the hose connecting the slewing drive unit 40 and the capacitor 19, a merge section will need to be provided in the hose, resulting 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.

In contrast, in this example, components equivalent to a branch and a junction are set at the inlet and outlet of the equipment (slewing drive unit 40) to be bypassed in cooling water channel 93A2. This allows the components used to connect the hose equivalent to cooling water channel 93 to the equipment to be bypassed to also serve as the branch and junction of the detour. This prevents the need to add additional components equivalent to branch and junction, or to split the hose equivalent to cooling water channel 93 into two. This prevents an increase in the number of components and reduces the cost of the excavator.

In addition, 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 point may be provided at the inlet of the most upstream device of the two or more devices to be bypassed, and the merging point may be provided at the outlet of the most downstream device of the two or more devices to be bypassed.

The above describes in detail the embodiments for implementing the present invention, but 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.

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 (e.g., oil).

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.

In addition, while the above-described embodiment and modified examples have been described with respect to the cooling circuit 90 of a shovel, a similar configuration (bypass path) may be applied to other work machines (e.g., hybrid crawler cranes, wheel loaders, etc.) that have a cooling circuit for cooling multiple pieces of equipment to be cooled. Furthermore, a similar configuration may be installed in any machine (e.g., hybrid automobiles, electric automobiles, etc.) that has a cooling circuit for cooling multiple pieces of equipment to be cooled.

12 Motor generator (equipment)
13 Reducer (equipment)
18 Inverter (equipment)
19 Capacitor (device)
21 Swing motor 40 Swing drive device (equipment)
90 Cooling circuit 91 Radiator 92 Water pump 93 Cooling water passage 93A Cooling water passage (main path)
93A2 Cooling waterway (detour)
94 Throttle valve (pressure adjustment mechanism)
100 Boost/Buck Converter (Device)

Claims (6)

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,
In a state where 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. 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. 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. 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. 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. 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 .