Construction machine

Abstract

To improve durability of a shaft body of a fan device by suppressing a gyro moment generated when an upper rotating body performs a rotating operation.SOLUTION: A hydraulic excavator 1 includes: an angular velocity measuring device 15 for measuring a revolving angular velocity ω when an upper revolving body 4 revolves by operating an operating device 11L; a rotation speed measuring device 16 for measuring rotation speeds of electric motors 13C, 14C; a fluid temperature measuring device 17 for measuring a temperature of a fluid to be cooled; and an outside air temperature measuring device 18 for measuring an outside air temperature. When the revolving angular velocity ω becomes a predetermined value or more in a state in which temperatures of cooling water and hydraulic oil are lower than a predetermined value, the outside air temperature is lower than a predetermined value, and a motor rotation speed N is a predetermined value or more, a control device 19 performs control to suppress gyro moment acting on shaft bodies 13B, 14B by setting the motor rotation speed N to a motor rotation speed N2 lower than the predetermined value.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a construction machine, such as a hydraulic excavator, that is provided with a fan device that supplies cooling air to a heat exchanger on a rotatable upper rotating body. [Background technology]

[0002] A hydraulic excavator as a construction machine comprises a self-propelled lower running body, an upper rotating body rotatably mounted on the lower running body, and a working device rotatably provided on the front side of the upper rotating body.

[0003] The upper rotating body comprises a rotating frame, a cab provided at the front of the rotating frame in which the operator sits, an operating device provided within the cab and operated to rotate the work equipment and rotate the upper rotating body, a heat exchanger provided on the rotating frame to cool fluids such as the engine cooling water and hydraulic oil, and a cooling fan that supplies cooling air to the heat exchanger.

[0004] The cooling fan is driven by a prime mover such as an engine by connecting it to the output shaft of the prime mover via a belt or a viscous clutch. The cooling fan is also driven by a hydraulic motor. However, a structure in which the cooling fan is driven by the prime mover increases the load on the prime mover. Even when the cooling fan is driven by a hydraulic motor, the load on the prime mover increases because hydraulic oil from a hydraulic pump driven by the prime mover is used.

[0005] Therefore, some hydraulic excavators are equipped with an electric fan device to prevent the load on the prime mover from increasing. The fan device is composed of a cooling fan facing the heat exchanger, a shaft connected to the center of rotation of the cooling fan, and an electric motor that rotates and drives the shaft (Patent Document 1). Electric fan devices are provided exclusively for each of the cooling water heat exchangers, hydraulic oil heat exchangers, etc. In addition, hydraulic excavators equipped with a fan device are equipped with a control device that controls the electric motor of the fan device. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-198135 A Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, in a configuration such as that disclosed in Patent Document 1 in which a dedicated fan device is provided for each of the cooling water heat exchangers, the hydraulic oil heat exchangers, etc., it is necessary to supply cooling air to only one heat exchanger, so the fan device can be made compact.

[0008] Here, the upper rotating body rotates on the lower traveling body, and the fan device rotates the cooling fan at high speed by the electric motor. Therefore, when the upper rotating body rotates while the cooling fan is rotated at high speed by the electric motor, a gyro moment may be generated. The gyro moment is a force (moment) that acts in an axial direction perpendicular to both the moment axis and the rotation axis when a moment is applied from the outside to a rotating object so as to rotate the rotation axis.

[0009] In Patent Document 1, by miniaturizing the fan device, the shaft connecting the electric motor and the cooling fan also has a small diameter, which causes a problem in that the shaft is subjected to a gyroscopic moment, which may reduce its durability.

[0010] The present invention has been made in consideration of the above-mentioned problems with the conventional technology, and an object of the present invention is to provide a construction machine capable of improving the durability of a fan device. [Means for solving the problem]

[0011] The present invention relates to a construction machine having a rotatable upper rotating body, the upper rotating body being provided with a cooling fan for blowing cooling air to a heat exchanger, an electric motor for rotating the cooling fan, and a control device for controlling the electric motor, the control device being characterized in that, when the electric motor is driven at a predetermined rotation speed or higher and the rotation angular velocity of the upper rotating body becomes equal to or higher than the predetermined rotation angular velocity, the control device drives the electric motor at a rotation speed lower than the predetermined rotation speed. Effect of the Invention

[0012] According to the present invention, the durability of the fan device in a construction machine can be improved. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a left side view of a hydraulic excavator according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a simplified plan view showing an upper rotating body. [Diagram 3] FIG. 4 is an explanatory diagram showing a state in which a gyro moment is generated. [Figure 4] FIG. 2 is a configuration diagram showing a control system for a cooling fan. [Diagram 5] 4 is a flowchart showing a process performed by a control device of a cooling fan. [Figure 6] FIG. 4 is a characteristic diagram showing the relationship between the rotation angular velocity and the motor rotation speed. [Figure 7] FIG. 11 is a configuration diagram showing a cooling fan control system according to a second embodiment of the present invention. [Figure 8] 10 is a flowchart showing a process of a cooling fan control device according to a second embodiment. [Figure 9] FIG. 11 is a characteristic diagram showing the relationship between the rotation angular velocity and the motor rotation speed according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a crawler type hydraulic excavator will be taken as an example of a construction machine according to an embodiment of the present invention and will be described in detail with reference to the accompanying drawings.

[0015] Figures 1 to 6 show a first embodiment. In Figure 1, a hydraulic excavator 1 as a construction machine is composed of a self-propelled lower traveling body 2, an upper rotating body 4 rotatably provided on the lower traveling body 2 via a rotating device 3, and a working device 5 rotatably provided on the front side of the upper rotating body 4. The working device 5 performs work such as excavating earth and sand by rotating.

[0016] The lower traveling body 2 is equipped with traveling devices 2B (only the left side is shown) consisting of drive wheels, idler wheels, and tracks on both the left and right sides of the truck frame 2A. The traveling devices 2B run forward and backward by rotating the drive wheels with a traveling hydraulic motor to make the tracks go around. In addition, by giving the left and right traveling devices 2B a speed difference or reversing the direction of the tracks, the vehicle can turn left and right and rotate on the spot.

[0017] The slewing device 3 rotates the upper rotating body 4 on the lower running body 2 in the direction of arrow A or arrow B (see FIG. 2) around a central point O1 (rotation axis O1-O1). The slewing device 3 is provided between the track frame 2A of the lower running body 2 and the rotating frame 6 of the upper rotating body 4, and includes a slewing ring 3A made of an annular bearing centered on the central point O1 (rotation axis O1-O1), and a slewing hydraulic motor (not shown) that meshes with the inner ring of the slewing ring 3A to rotate the upper rotating body 4.

[0018] The upper rotating body 4 is configured to include a rotating frame 6, a cab 7 mounted on the left front side of the rotating frame 6 and forming a driver's cab inside, a counterweight 8 attached to the rear of the rotating frame 6 and balancing the weight with the work implement 5, an engine located between the cab 7 and the counterweight 8 and mounted on the rotating frame 6, a hydraulic pump (none of which are shown) driven by the engine and supplying pressure oil (working oil) to the hydraulic actuator, a heat exchanger 9 that cools the fluid, fan devices 13 and 14, and a control device 19, which will be described later. Note that instead of the engine, an electric motor or a hybrid engine that combines an engine and an electric motor can also be used.

[0019] A driver's seat 10 where an operator sits is provided inside the cab 7. A travel operation device (not shown) for traveling the lower traveling body 2 is provided in front of the driver's seat 10. On the left and right of the driver's seat 10, operation devices 11L, 11R for rotating the working device 5 and rotating the upper rotating body 4 by tilting a lever back and forth and left and right are provided.

[0020] The heat exchanger 9 may be a radiator that cools the cooling water as a fluid for cooling a prime mover such as an engine or an electric motor, an oil cooler that cools the hydraulic oil as a fluid, an intercooler that cools the air (intake air) as a fluid compressed by a turbocharger (not shown) provided in the engine, a condenser that cools the refrigerant as a fluid used in an air conditioner, a fuel cooler that cools the fuel as a fluid supplied to the engine, etc. For example, in this embodiment, a case where a radiator 9A and an oil cooler 9B are arranged side by side in the front-rear direction is illustrated. A fan device 13 is arranged in the front radiator 9A, and a fan device 14 is arranged in the rear oil cooler 9B.

[0021] The center joint 12 is provided between the track frame 2A of the lower traveling body 2 and the slewing frame 6 of the upper rotating body 4. The center joint 12 is disposed at the center point O1 (slewing axis O1-O1) of the slewing ring 3A of the slewing device 3. The center joint 12 circulates hydraulic oil and electricity between the lower traveling body 2 and the upper rotating body 4 while allowing the upper rotating body 4 to rotate.

[0022] The front fan device 13 is composed of an axial flow type cooling fan 13A facing the radiator 9A, a shaft 13B connected to the rotation center of the cooling fan 13A, and an electric motor 13C that rotates and drives the shaft 13B. The fan device 13 supplies cooling air generated by the cooling fan 13A to the radiator 9A by rotating the cooling fan 13A together with the shaft 13B around an axis O2-O2 passing through the center of the shaft 13B by the electric motor 13C. The rotation speed of the electric motor 13C (cooling fan 13A) of the fan device 13 is controlled by the control device 19.

[0023] The rear fan device 14 is composed of an axial flow type cooling fan 14A facing the oil cooler 9B, a shaft 14B connected to the rotation center of the cooling fan 14A, and an electric motor 14C that rotates and drives the shaft 14B. The fan device 14 supplies cooling air generated by the cooling fan 14A to the oil cooler 9B by rotating the cooling fan 14A together with the shaft 14B about an axis O3-O3 passing through the center of the shaft 14B by the electric motor 14C. The rotation speed of the electric motor 14C (cooling fan 14A) of the fan device 14 is controlled by a control device 19.

[0024] The angular velocity measuring device 15 is provided on the rotating device 3 or in the vicinity of the rotating device 3 (see FIG. 2). The angular velocity measuring device 15 measures a rotation angular velocity when the upper rotating body 4 rotates in the direction of arrow A or the direction of arrow B by operating the lever of the operation device 11L or the lever of the operation device 11R. As shown in FIG. 4, the angular velocity measuring device 15 is electrically connected to the control device 19. The data measured by the angular velocity measuring device 15 is output to the control device 19.

[0025] The rotation speed measuring device 16 is provided in each of the fan devices 13 and 14. The rotation speed measuring device 16 measures the rotation speeds of the electric motors 13C and 14C (the rotation speeds of the cooling fans 13A and 14A). Data measured by the rotation speed measuring device 16 is output to the control device 19 and used for feedback control.

[0026] The fluid temperature measuring device 17 is a temperature sensor that measures the temperature of the fluid to be cooled by the heat exchanger 9. Specifically, the fluid temperature measuring device 17 measures the temperature of the cooling water flowing in the radiator 9A and the temperature of the hydraulic oil flowing in the oil cooler 9B. The temperature data measured by the fluid temperature measuring device 17 is output to the control device 19. The temperature of the fluid measured by the fluid temperature measuring device 17 is used to determine the target rotation speeds of the electric motors 13C, 14C of the fan devices 13, 14, as well as to determine whether or not overheating will occur.

[0027] The outside air temperature measuring device 18 measures the temperature of the outside air. The temperature data measured by the outside air temperature measuring device 18 is output to the control device 19. The outside air temperature measured by the outside air temperature measuring device 18 is used to determine the target rotation speeds of the electric motors 13C, 14C of the fan devices 13, 14, and is also used to determine whether or not overheating will occur. The outside air temperature measuring device 18 may be omitted.

[0028] The control device 19 is provided on the upper rotating body 4. The control device 19 controls the electric motors 13C, 14C of the fan devices 13, 14. The input side of the control device 19 is connected to the angular velocity measuring device 15, the rotation speed measuring device 16, the fluid temperature measuring device 17, and the outside air temperature measuring device 18. The output side of the control device 19 is connected to the electric motors 13C, 14C of the fan devices 13, 14.

[0029] When the temperature of the fluid to be cooled, for example, engine cooling water, is lower than a predetermined value and the motor rotation speed N1 of the electric motor 13C is higher than the predetermined motor rotation speed, the control device 19 reduces the motor rotation speed N1 of the electric motor 13C to the motor rotation speed N2 when the rotation angular velocity ω of the upper rotating body 4 becomes higher than the predetermined rotation angular velocity ω1. By performing this control, the gyro moment acting on the shaft body 13B during the rotation operation of the upper rotating body 4 can be suppressed.

[0030] As shown in Figure 3, when the cooling fan 13A of the fan unit 13 rotates in the direction of the arrow C and the upper rotating body 4 rotates in the direction of the arrow A around the axis line O1-O1, if the motor rotation speed N of the electric motor 13C is higher than a predetermined motor rotation speed and the rotation angular velocity ω is higher than a predetermined rotation angular velocity ω1, a gyro moment acts on the shaft body 13B of the rotating fan unit 13 in the direction of the arrow D.

[0031] In this embodiment, the predetermined motor rotation speed used for controlling the motor rotation speed N of the electric motor 13C has a certain range.

[0032] Next, the process of the control device 19 for suppressing the gyro moment acting on the shaft body 13B when the upper rotating body 4 is rotated while rotating the cooling fan 13A of the fan device 13 will be described with reference to the flowchart of Fig. 5. In the flowchart of Fig. 5, steps showing the flow of the process are indicated by "S". The process related to the control of the fan device 14 is omitted because it is similar to that of the fan device 13.

[0033] 5, in step 1, the coolant temperature T1 measured by the fluid temperature measuring device 17 is acquired, and the outside air temperature T2 measured by the outside air temperature measuring device 18 is acquired. Then, in step 2, the motor rotation speed N1 of the cooling fan 13A (electric motor 13C) is calculated based on the coolant temperature T1 and the outside air temperature T2 acquired in step 1. In this embodiment, the control device 19 calculates the motor rotation speed N1 by using, for example, a predetermined data table (MAP).

[0034] In step 3, the rotation angular velocity ω measured by the angular velocity measuring device 15 when the upper rotating body 4 rotates is obtained. In the following step 4, it is determined whether the rotation angular velocity ω when the upper rotating body 4 rotates is equal to or greater than a predetermined rotation angular velocity ω1 shown in FIG. 6. If the rotation angular velocity ω of the upper rotating body 4 is less than the rotation angular velocity ω1, i.e., if the result is NO in step 4, there is no risk of a gyro moment being generated when the upper rotating body 4 is rotated. Therefore, the process proceeds to step 5, and the electric motor 13C (cooling fan 13A) is controlled at the motor rotation speed N1.

[0035] On the other hand, if the swing angular velocity ω of the upper swing body 4 is equal to or greater than the swing angular velocity ω1 in step 4, that is, if the result is YES, then the process proceeds to step 6 since there is a risk that a gyro moment will be generated when the upper swing body 4 is caused to swing.

[0036] In step 6, it is determined whether the cooling water temperature T1 is less than a predetermined fluid temperature Ta. This predetermined fluid temperature Ta is a temperature at which overheating will not occur (even if it does occur, it will be only minor) even if the electric motor 13C is controlled at a motor speed lower than the motor speed N1 in the following steps. If it is determined in step 6 that the cooling water temperature T1 is not less than the predetermined fluid temperature Ta, that is, NO, there is a risk of overheating occurring if the electric motor 13C is controlled at a motor speed lower than the motor speed N1. Therefore, the process proceeds to step 5, and the electric motor 13C (cooling fan 13A) is controlled at the motor speed N1.

[0037] On the other hand, if it is determined in step 6 that the cooling water temperature T1 is lower than the predetermined fluid temperature Ta, i.e., the result is YES, then control of the electric motor 13C at a motor speed lower than the motor speed N1 will not cause overheating, or even if it does occur, it will only be severe, so the flow proceeds to step 7.

[0038] In step 7, a motor rotation speed N2 lower than the motor rotation speed N1 of the electric motor 13C is calculated according to the swing angular velocity ω. Then, the process proceeds to step 8, and the electric motor 13C (cooling fan 13A) is controlled at the motor rotation speed N2. In this embodiment, the control device 19 calculates the motor rotation speed N2 by using, for example, a predetermined data table (MAP).

[0039] The hydraulic excavator 1 applied to this embodiment has the above-mentioned configuration, and its operation will now be described.

[0040] The operator gets into the cab 7 and sits in the driver's seat 10, and can operate the levers of the operating device for traveling to drive the lower traveling body 2. In addition, by operating the levers of the operating devices 11L, 11R for work, the operator can rotate the upper rotating body 4 with the rotating device 3 and rotate the working device 5 to perform work such as excavating soil and sand.

[0041] Thus, according to this embodiment, when the electric motors 13C, 14C are driven at a predetermined rotation speed or higher and the rotation angular velocity ω of the upper rotating body 4 becomes equal to or higher than a predetermined rotation angular velocity ω1, the control device 19 that controls the electric motors 13C, 14C controls the electric motors 13C, 14C to be driven at a rotation speed N1 that is lower than the predetermined rotation speed.

[0042] This makes it possible to suppress the gyroscopic moment that occurs when the upper rotating body 4 rotates. As a result, even if the shaft bodies 13B, 14B have a small diameter due to the miniaturization of the fan devices 13, 14, it is possible to improve the durability of the shaft bodies 13B, 14B.

[0043] In the embodiment, the vehicle further includes a fluid temperature measuring device 17 as a temperature sensor for measuring the temperature of the cooling water flowing through the radiator 9A and the temperature of the hydraulic oil flowing through the oil cooler 9B. The control device 19 can set the rotation speed of the electric motors 13C, 14C based on the temperatures of the cooling water and the hydraulic oil detected by the fluid temperature measuring device 17 and drive them.

[0044] Next, Figures 7 and 8 show a second embodiment of the present invention. The second embodiment is characterized in that it is provided with an operation amount measuring device that measures the amount of operation when the operating device is operated, and thereby predicts and controls the rotation angular velocity of the upper rotating body from the amount of operation when the operating device is operated. Note that in the second embodiment, the same components as those in the first embodiment described above are given the same reference numerals, and their explanations will be omitted.

[0045] 7, an operation amount measuring device 21 provided in place of the angular velocity measuring device 15 of the first embodiment is provided in one of the operation devices 11L, 11R that performs the rotation operation of the upper rotating body 4, for example, the left operation device 11L. The operation amount measuring device 21 measures the operation amount when the lever of the operation device 11L is operated. The data measured by the operation amount measuring device 21 is output to the control device 22.

[0046] In this case, the greater the lever of the operation device 11L is tilted, the higher the rotation angular velocity ω of the upper rotating body 4 becomes, and therefore the operation amount of the operation device 11L measured by the operation amount measuring device 21 can be used for controlling the fan devices 13, 14. When the rotation operation is performed by the right-side operation device 11R, the operation amount measuring device 21 is provided on the operation device 11R.

[0047] The control device 22 according to the second embodiment is provided on the upper rotating body 4, similar to the control device 19 according to the first embodiment, and controls the electric motors 13C, 14C of the fan units 13, 14. An operation amount measuring device 21 is connected to the input side of the control device 22 instead of the angular velocity measuring device 15.

[0048] When the operation amount when the lever is operated is input from the operation amount measuring device 21, the control device 22 predicts the swing angular velocity ω of the upper rotating body 4 from this operation amount. Then, the predicted swing angular velocity ω is compared with a predetermined swing angular velocity ω1. This control also makes it possible to suppress the gyro moment acting on the shaft body 13B during the swing operation of the upper rotating body 4.

[0049] Next, the processing of the control device 22 will be described with reference to the flowchart of Fig. 8. The flowchart of Fig. 8 is made up of steps 11 to 18, but since steps 11, 12, and 15 to 18 are similar to steps 1, 2, and 5 to 8 in the flowchart of Fig. 5, their description will be omitted. Furthermore, steps indicating the flow of processing are indicated by "S". Processing relating to the control of the fan device 14 will be omitted because it is similar to that of the fan device 13.

[0050] 8, the rotation angular velocity ω when the upper rotating body 4 rotates is predicted from the operation amount of the lever of the operation device 11L measured by the operation amount measuring device 21 (for example, the tilt angle of the lever). In the following step 14, it is determined whether the rotation angular velocity ω predicted in step 13 is equal to or greater than a predetermined rotation angular velocity ω1. If the predicted rotation angular velocity ω of the upper rotating body 4 is equal to or greater than the predetermined rotation angular velocity ω1, that is, if the result of the determination in step 14 is YES, then the process proceeds to step 15 since there is a risk of a gyro moment being generated when the upper rotating body 4 is rotated.

[0051] On the other hand, if the predicted rotation angular velocity ω of the upper rotating body 4 is not equal to the predetermined rotation angular velocity ω1 in step 14, that is, if the result is NO, there is no risk of a gyro moment being generated when the upper rotating body 4 is rotated. Therefore, the process proceeds to step 16.

[0052] Thus, the second embodiment configured as above can also provide the same actions and effects as the first embodiment. In particular, in the second embodiment, the control device 22 predicts the rotation angular velocity ω of the upper rotating body 4 from the operation amount of the operation device 11L measured by the operation amount measuring device 21, and the predicted rotation angular velocity ω is used to control the electric motors 13C, 14C.

[0053] In this case, the cooling fans 13A, 14A cannot suddenly increase or decrease the rotation speed. In response to this, the control device 22 can match the control timing of the motor rotation speeds N of the electric motors 13C, 14C to the rotation operation of the upper rotating body 4 by predicting the rotation operation of the upper rotating body 4.

[0054] In the first embodiment, as shown in FIG. 6, the control device 19 performs control to reduce the motor rotation speed N1 of the electric motors 13C, 14C to the motor rotation speed N2 when the rotation angular velocity ω of the upper rotating body 4 becomes equal to or greater than a predetermined rotation angular velocity ω1. However, the present invention is not limited to this, and may be controlled as shown in the characteristic diagram of FIG. 9. Specifically, the control device may control the motor rotation speed N of the electric motors 13C, 14C to change in response to a change in the rotation angular velocity ω of the upper rotating body 4. In other words, the control device may control the motor rotation speed N of the electric motors 13C, 14C to gradually decrease as the rotation angular velocity ω of the upper rotating body 4 increases. This control method can also suppress the generation of a gyro moment. This control method can be similarly applied to the second embodiment.

[0055] In the first embodiment, the swing angular velocity ω of the upper swing body 4 measured by the angular velocity measuring device 15 is used for control, and in the second embodiment, the swing angular velocity ω of the upper swing body 4 is predicted from the operation amount of the operation device 11L measured by the operation amount measuring device 21, and the predicted swing angular velocity ω is used for control. However, the present invention is not limited to this, and the swing angular velocity ω measured by the angular velocity measuring device 15 and the predicted swing angular velocity ω may be combined for control.

[0056] In each embodiment, a crawler-type hydraulic excavator 1 has been described as an example of a construction machine. However, the present invention is not limited to this, and may be applied to, for example, a hydraulic excavator equipped with a wheel-type lower traveling body as a construction machine. Furthermore, the present invention may be widely applied to construction machines equipped with a swing mechanism such as a hydraulic crane. [Explanation of symbols]

[0057] 1. Hydraulic excavator (construction machinery) 3 Swivel device 4. Upper rotating body 6 Swivel Frame 7 Cab 9 Heat exchanger 9A Radiator 9B Oil cooler 11L,11R operating device 13,14 Fan unit 13A, 14A Cooling Fan 13B,14B Shaft 13C, 14C Electric motor 15 Angular velocity measuring device 16 Rotational speed measuring device 17 Fluid temperature measuring device (temperature sensor) 18. Outside air temperature measuring device 19,22 Control device 21 Manipulated variable measuring device N(N1,N2) Motor rotation speed ω Turning angular velocity ω1 given turning angular velocity T1 Fluid temperature T2 Outside air temperature

Claims

1. A rotatable upper rotating body is provided. In a construction machine in which the upper rotating body is provided with a cooling fan that blows cooling air to a heat exchanger, an electric motor that rotates the cooling fan, and a control device that controls the electric motor, The construction machine is characterized in that, when the electric motor is being driven at a predetermined rotation speed or higher and the rotation angular velocity of the upper rotating body becomes equal to or higher than the predetermined rotation angular velocity, the control device drives the electric motor at a rotation speed lower than the predetermined rotation speed.

2. The construction machine according to claim 1, a temperature sensor for measuring the temperature of the fluid to be cooled by the heat exchanger; The control device sets the rotation speed of the electric motor based on the temperature of the fluid detected by the temperature sensor, and drives the electric motor.

3. The construction machine according to claim 2, Further provided is an operating device that instructs the rotation operation of the upper rotating body, The control device estimates the rotation angular velocity of the upper rotating body from the amount of operation of the operating device.

4. The construction machine according to claim 2, The construction machine is characterized in that the control device changes the rotation speed of the electric motor in accordance with a change in the rotation angular velocity of the upper rotating body.

5. The construction machine according to claim 2, The control device controls the rotation speed of the electric motor at the predetermined rotation speed when the temperature of the fluid detected by the temperature sensor is higher than the predetermined temperature, even if the rotation angular velocity of the upper rotating body becomes higher than the predetermined rotation angular velocity while the electric motor is being driven at a predetermined rotation speed or higher.

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