Crane

Abstract

To improve cooling efficiency of a crane.SOLUTION: The electrically driven crane (100) includes a cooling pump (60, 61, 62) driven by an electric driving force and supplying a cooling liquid to a cooling object (25, 20, 10), and an adjustment means (50, 51, 52, 80) adjusting a flow rate of the cooling liquid supplied to the cooling object.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] As background art in this technical field, for example, Patent Document 1 describes a configuration in which a switching valve is provided in a cooling pipe in a hybrid working machine to switch the flow direction of a coolant supplied from a cooling pump. According to Patent Document 1, the switching valve can be switched depending on the output of the electric motor, thereby enabling efficient cooling of the inverter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6112667 Summary of the Invention [Problem to be solved by the invention]

[0004] However, Patent Document 1 does not specifically mention controlling the flow rate of the cooling pump, and there is still room for improvement in terms of increasing cooling efficiency.

[0005] An object of the present invention is to improve the cooling efficiency of a crane. [Means for solving the problem]

[0006] In order to achieve the above object, one aspect of the present invention is an electrically driven crane, comprising: a cooling pump driven by an electric driving force and supplying a cooling liquid to a cooling object; and an adjusting means for adjusting the flow rate of the cooling liquid supplied to the cooling object. Preferably, the adjusting means varies the flow rate of the cooling pump based on predetermined conditions.

[0007] In this invention, an electrically driven crane refers to a crane in the broad sense that drives a winch with an electric motor, and includes all types of cranes, such as a type in which the electric motor for driving the winch is driven by power supplied from an external power source, a type in which an engine drives a generator and the electric motor for driving the winch is driven by power supplied from the generator, etc. Also included in the crane of this invention is a type in which power supplied from an external power source or a generator is charged into a battery and the electric motor is driven by power supplied from the battery.

[0008] Furthermore, in the present invention, the cooling pump includes any configuration as long as it is driven by an electric driving force. For example, a configuration in which the driving force of the electric motor for driving the above-mentioned winch is introduced to the cooling pump via some kind of driving force transmission means, and the cooling pump is driven by this driving force, is included in the cooling pump of the present invention. Of course, a cooling pump driven by an electric motor dedicated to the cooling pump also falls under the category of the cooling pump of the present invention.

[0009] According to the present invention, the cooling efficiency of a crane can be improved. In addition, by increasing or decreasing the flow rate of the cooling liquid (or increasing or decreasing the flow rate) according to predetermined conditions, the trade-off between energy saving and cooling performance can be optimized. Note that other issues, configurations, and effects will become clear from the description of the following embodiments. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a side view of a crane. [Figure 2] FIG. 1 is a diagram showing the configuration of the main equipment of a crane. [Figure 3] 1 is a configuration diagram of a cooling system for a crane according to a first embodiment. FIG. [Figure 4] 4 is a flowchart of a control process of the cooling system according to the first embodiment. [Figure 5] FIG. 10 is a configuration diagram of a cooling system for a crane according to a second embodiment. [Figure 6]10 is a flowchart of a control process of a cooling system according to a second embodiment. [Figure 7] FIG. 10 is a configuration diagram of a cooling system for a crane according to a third embodiment. [Figure 8] 10 is a flowchart of a control process of a cooling system according to a third embodiment. [Figure 9] FIG. 10 is a configuration diagram of a cooling system according to a first modified example. [Figure 10] FIG. 10 is a configuration diagram of a cooling system according to a second modification. [Figure 11] FIG. 10 is a configuration diagram of a cooling system according to a third modification. [Figure 12] FIG. 10 is a configuration diagram of a cooling system according to a fourth modification. [Figure 13] FIG. 10 is a configuration diagram of a cooling system according to a fifth modified example. [Figure 14] 13 is a flowchart of a control process of a cooling system according to a sixth modification. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a crane according to the present invention will be described with reference to the drawings.

[0012] First Embodiment 1 is a side view of a crane 100. The crane 100 is a crawler crane and includes a running body 101, a rotating body 103 that is rotatably mounted on the running body 101 via a slewing ring 102, and a boom 104 that is rotatably supported on the rotating body 103. The running body 101 includes a track frame 101a and a crawler 101b attached to the track frame 101a.

[0013] The rotating body 103 is provided with an operator's cab 109 and is equipped with a winch device consisting of a hoist drum 105 and a hoisting drum 106. A hoisting rope 105a is wound around the hoisting drum 105, and as the hoisting drum 105 is driven, the hoisting rope 105a is wound in or unwound, thereby raising or lowering the hook 110. A hoisting rope 106a is wound around the hoisting drum 106, and as the hoisting drum 106 is driven, the hoisting rope 106a is wound in or unwound, thereby raising or lowering the boom 104.

[0014] FIG. 2 is a configuration diagram of the main equipment of the crane 100. As shown in FIG. 2, the crane 100 is driven by power supplied from an external power source 5 or power charged from the external power source 5 to a battery 10. Specifically, the power supplied from the external power source 5 or the battery 10 is converted into alternating current of a different frequency via an inverter 20 and supplied to an electric motor 25. In this way, the electric motor 25 rotates. The electric motor 25 is connected to a hydraulic pump 30, and the rotation of the electric motor 25 drives the hydraulic pump 30. When the hydraulic pump 30 is driven, hydraulic oil stored in a hydraulic oil tank (not shown) is supplied to actuators 40-43 via control valves 35-38.

[0015] The actuators 40 to 43 are driven by hydraulic oil supplied from the hydraulic pump 30. The actuators 40 to 43 can be configured as follows, for example: Actuator 40 is a traveling hydraulic motor for driving the traveling body 101; actuator 41 is a swing hydraulic motor for driving the swing body 103 to swing; actuator 42 is a hoisting hydraulic motor for driving the hoist drum 105; and actuator 43 is a hoisting hydraulic motor for driving the hoisting drum 106.

[0016] The control valve 35 is used to control the flow direction of the hydraulic oil, and is also called a directional control valve. The control valve 35 is provided corresponding to the actuator 40, and the operation of the actuator 40 is switched by switching the position of the control valve 35. The same applies to the control valves 36 to 38. And, for example, by switching the position of the control valve corresponding to the hoist drum 105, the hoist drum 105 is hoisted up or down.

[0017] Similarly, power supplied from the external power supply 5 or the battery 10 is supplied via the inverter 20 to the cooling pump motors 50-52 and the fan motor 27, causing the cooling pump motors 50-52 and the fan motor 27 to rotate. The rotation of the cooling pump motors 50, 51, and 52 drives the cooling pumps 60, 61, and 62, respectively. The rotation of the fan motor 27 drives the cooling fan 32.

[0018] Next, the cooling system of this embodiment will be described. FIG. 3 is a configuration diagram of a cooling system C1 for a crane according to the first embodiment. As shown in FIG. 3, the cooling system C1 is formed by annularly connecting the electric motor 25, inverter 20, and battery 10, which are objects to be cooled, with a radiator 39 via cooling pipes L1 and L2. Three branch pipes L3 to L5 are provided in parallel between the cooling pipes L1 and L2. The electric motor 25 and a cooling pump 60 are provided in the branch pipe L3, the inverter 20 and a cooling pump 61 are provided in the branch pipe L4, and the battery 10 and a cooling pump 62 are provided in the branch pipe L5. Water as a coolant circulates through the pipes L1 to L5. The arrows in FIG. 3 indicate the direction of water flow.

[0019] A cooling fan 32 is provided opposite the radiator 39. A fan motor 27 is connected to the cooling fan 32, and the rotation of the fan motor 27 drives the cooling fan 32. When the cooling fan 32 rotates, cooling air is generated. The generated cooling air is introduced into the radiator 39 and exchanges heat with the water flowing inside the radiator 39. In this way, the water is cooled via the radiator 39.

[0020] Water cooled by the radiator 39 (hereinafter referred to as cooling water) flows through the branch pipe L3 and is introduced into the electric motor 25 by a cooling pump 60. The cooling water removes heat from the electric motor 25, thereby cooling the electric motor 25. Similarly, the cooling water flows through the branch pipes L4 and L5 and is introduced into the inverter 20 by a cooling pump 61 to cool the inverter 20, and is also introduced into the battery 10 by a cooling pump 62 to cool the battery 10.

[0021] In this embodiment, cooling pumps 60, 61, and 62 are provided independently for each object to be cooled (electric motor 25, inverter 20, and battery 10), so that the temperature of each object to be cooled can be individually controlled by controlling the capacity of the desired cooling pump 60, 61, or 62. In this embodiment, the flow rate of the cooling pumps 60, 61, and 62 is adjusted by controlling the rotation speed of the cooling pump motors 50, 51, and 52. Therefore, the cooling pump motors 50, 51, and 52 correspond to the "adjustment means" of the present invention.

[0022] In this embodiment, water is used as the coolant, but other cooling media, such as antifreeze (brine), may also be used.

[0023] The electric motor 25, the inverter 20, and the battery 10 are provided with temperature sensors T1, T2, and T3, respectively, and these temperature sensors T1, T2, and T3 are connected to the control device 80 via electrical wiring (dotted lines in Figure 3).

[0024] The control device 80 is a controller for controlling the operation of the cooling system C1 and constitutes a part of the "adjustment means" of the present invention. The control device 80 controls the operation of the cooling pumps 60, 61, 62 and the fan motor 27 based on the temperature data output from the temperature sensors T1, T2, T3.

[0025] The control device 80 includes a CPU (Central Processing Unit) 81 and a memory 82. The memory 82 is configured, for example, with a ROM (Read Only Memory), a RAM (Random Access Memory), an HDD (Hard Disk Drive), or a combination of these. The control device 80 realizes the processing described below by having the CPU 81 read and execute program code stored in the ROM or HDD. The RAM is used as a work area when the CPU 81 executes the program.

[0026] However, the specific configuration of the control device 80 is not limited to this, and may be realized by hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0027] Next, the processing of the control device 80 will be described. Fig. 4 is a flowchart of the control processing of the cooling system C1 according to the first embodiment. As shown in Fig. 4, in the first embodiment, in order to control the flow rates of the cooling pumps 60, 61, and 62, the temperature t A ,t B ,t C The control device 80 then repeatedly executes the process shown in Fig. 4 at predetermined time intervals (for example, every second).

[0028] 4 will be described in detail. First, the control device 80 receives the measured temperature t of the electric motor 25 input from the temperature sensor T1. A is the threshold T ASimilarly, the control device 80 determines whether the measured temperature t of the inverter 20 input from the temperature sensor T2 has exceeded the B is the threshold T B The measured temperature t of the battery 10 input from the temperature sensor T3 is checked to see if it exceeds the C is the threshold T C Then, it is judged individually whether or not the measured temperature t A is the threshold T A If it exceeds this value, the temperature of the electric motor 25 is high, and therefore the control device 80 controls the flow rate of the cooling pump 60 corresponding to the electric motor 25 to increase (step S12).

[0029] Similarly, the measured temperature t B is the threshold T B If the measured temperature t exceeds t, the controller 80 controls the cooling pump 61 corresponding to the inverter 20 to increase the flow rate because the temperature of the inverter 20 is high. C is the threshold T C If it exceeds this value, the control device 80 controls the flow rate of the cooling pump 62 corresponding to the battery 10 to increase, since the temperature of the battery 10 is high.

[0030] On the other hand, the measured temperature t A is the threshold T A In the following cases, the temperature of the electric motor 25 has not risen significantly, and therefore the control device 80 controls the flow rate of the cooling pump 60 corresponding to the electric motor 25 to be reduced (step S13).

[0031] Similarly, the measured temperature t B is the threshold T B In the following cases, the controller 80 controls the flow rate of the cooling pump 61 corresponding to the inverter 20 to be reduced because the temperature of the inverter 20 has not risen significantly. C is the threshold T C In the following cases, the control device 80 controls the flow rate of the cooling pump 62 corresponding to the battery 10 to be reduced because the temperature of the battery 10 has not risen significantly.

[0032] In this way, the control device 80 individually increases or decreases the flow rate of the cooling pumps 60, 61, 62 corresponding to each of the cooling targets 25, 20, 10 in accordance with the relationship between the measured temperature of each of the cooling targets 25, 20, 10 and the threshold value. The threshold value is determined arbitrarily taking into consideration the life span and operating efficiency of each of the cooling targets 25, 20, 10.

[0033] In this embodiment, the flow rates of the cooling pumps 60, 61, and 62 are increased or decreased by controlling the rotation speeds of the cooling pump motors 50, 51, and 52 as described above. However, instead of this configuration, the cooling pumps 60, 61, and 62 may be variable displacement pumps, and the increase or decrease may be achieved by adjusting the strokes of these cooling pumps. In this case, the mechanism for adjusting the strokes of the cooling pumps corresponds to the "adjusting means" of the present invention. Note that, when the flow rates of the cooling pumps 60, 61, and 62 are changed by adjusting the strokes, the cooling pump motors 50, 51, and 52 that drive the cooling pumps 60, 61, and 62 do not necessarily have to be variable speed motors.

[0034] As described above, according to the first embodiment, the flow rates of the cooling pumps 60, 61, and 62 can be individually controlled according to the temperatures of the objects to be cooled, namely, the electric motor 25, the inverter 20, and the battery 10, thereby improving cooling efficiency. Furthermore, because an appropriate amount of cooling water can be supplied to each of the objects to be cooled, excessive rotation of the cooling fan 32 is suppressed. As a result, the cooling system C1 according to the first embodiment also contributes to noise reduction. Specifically, in the case of an electrically driven crane 100, since no engine is installed, the sound of the cooling fan 32 is the dominant noise source. However, as described above, the cooling efficiency of the cooling system C1 is improved, and the rotation speed of the cooling fan 32 is suppressed, thereby significantly contributing to noise reduction. Furthermore, the improved cooling efficiency can extend the life of the objects to be cooled, namely, the electric motor 25, the inverter 20, and the battery 10.

[0035] In this embodiment, a configuration has been exemplified in which dedicated cooling pump motors 50, 51, and 52 are provided for each of the cooling pumps 60, 61, and 62, but the cooling pumps 60, 61, and 62 may also be driven, for example, from the electric motor 25 via some kind of power transmission means (e.g., gears, belts, etc.).

[0036] Furthermore, although the configuration in which cooling pumps 60, 61, and 62 are provided for cooling targets 25, 20, and 10, respectively, may be used, a configuration in which cooling water is supplied from one cooling pump 60 to all cooling targets 25, 20, and 10. In this case, it goes without saying that the size of cooling pump 60 is selected so that a sufficient amount of cooling water can be supplied simultaneously to all cooling targets 25, 20, and 10. Furthermore, the rotation speed of cooling fan 32 may be constant or variable. If it is variable, control device 80 may control the rotation speed of fan motor 27 based on temperature data from temperature sensors T1 to T3.

[0037] Second Embodiment 5 is a configuration diagram of a cooling system C2 for a crane according to the second embodiment. The second embodiment is characterized in that it is configured to increase or decrease the flow rate of cooling pumps 60, 61, and 62 according to the workload of the crane 100. Therefore, the following description will focus on the characteristics of the second embodiment, and will omit a description of what is common to the first embodiment.

[0038] 5, in a cooling system C2 according to the second embodiment, a control device 80 calculates the flow rate of the hydraulic pump 30 based on the discharge pressure of the hydraulic pump 30 detected by a pressure sensor P1 provided in the hydraulic pump 30, the tilt (displacement) control pressure of the hydraulic pump 30 detected by a pressure sensor P2 also provided in the hydraulic pump 30, a pump displacement control current (pump tilt control signal) output to the hydraulic pump 30, and the rotation speed of the electric motor 25 detected by a rotation sensor R1 provided in the electric motor 25. The control device 80 then estimates the workload (operating status) of the crane 100 from the flow rate of the hydraulic pump 30, and controls the flow rates of the cooling pumps 60, 61, 62 based on the estimation result.

[0039] Fig. 6 is a flowchart of the control process of the cooling system C2 according to the second embodiment. As shown in Fig. 6, in the second embodiment, the workload of the crane 100 is used as a predetermined condition to control the flow rates of the cooling pumps 60, 61, and 62. The control device 80 then repeatedly executes the process shown in Fig. 6 at predetermined time intervals (for example, every second).

[0040] As shown in FIG. 6, the control device 80 calculates the load torque of the hydraulic pump 30 based on the discharge pressure of the hydraulic pump 30 detected by the pressure sensors P1 and P2, the pump displacement control current output to the hydraulic pump 30, and the rotation speed of the electric motor 25 detected by the rotation sensor R1, and calculates the motor output of the electric motor 25 from the load torque (step S21).

[0041] Then, the control device 80 determines whether the motor output is greater than a target value (threshold value) (step S22). If the motor output is greater than the target value, it can be estimated that the workload of the crane 100 is high and the amount of heat generated by the electric motor 25, inverter 20, and battery 10, which are to be cooled, is large. Therefore, the control device 80 controls the flow rates of the cooling pumps 60, 61, and 62 to increase (step S23).

[0042] On the other hand, if the motor output is below the target value, it can be estimated that the workload of the crane 100 is not particularly high and the heat generation of the electric motor 25, inverter 20, and battery 10, which are the objects to be cooled, is small, so the control device 80 controls the flow rate of the cooling pumps 60, 61, and 62 to be reduced (step S24).

[0043] As described above, according to the second embodiment, it is possible to expect improved cooling efficiency and reduced noise, similar to the first embodiment. Furthermore, in the second embodiment, the workload of the crane 100 can be estimated and the flow rate of the cooling pumps 60, 61, and 62 can be increased or decreased, which is advantageous in that sensors or the like for measuring the temperature of each of the cooling targets 25, 20, and 10 are not required.

[0044] <Third embodiment> 7 is a configuration diagram of a cooling system C3 for a crane according to the third embodiment. The third embodiment is characterized in that the flow rates of cooling pumps 60, 61, and 62 are increased or decreased depending on the pressure loss in the cooling circuit of the cooling system C3. Therefore, the following description will focus on the features of the third embodiment, and descriptions common to the first and second embodiments will be omitted.

[0045] 7, a cooling system C3 according to the third embodiment includes pressure sensors P11, P13, and P15 that detect the discharge pressures of cooling pumps 60, 61, and 62, pressure sensors P12, P14, and P16 that detect the pressures at the coolant outlets of the objects to be cooled 25, 20, and 10, and a pressure sensor P17 that detects the pressure at the coolant inlet of a radiator 39. For example, the pressure difference between the coolant pressures before and after the electric motor 25, i.e., the pressure loss, can be determined from the pressure sensors P11 and P12. Similarly, the pressure loss in the coolant system between the two pressure sensors can be determined from the difference between the values ​​of the two pressure sensors.

[0046] The control device 80 controls the flow rates of the cooling pumps 60, 61, and 62 based on the pressure difference (pressure loss) of the cooling water as a predetermined condition. Fig. 8 is a flowchart of the control process of the cooling system C3 according to the third embodiment. The control device 80 repeatedly executes the process shown in Fig. 8 at predetermined time intervals (for example, every second).

[0047] As shown in FIG. 8, the control device 80 calculates the pressure loss before and after (between the inlet and outlet) each of the objects to be cooled 25, 20, 10 from the pressure data input from the pressure sensors P11 to P17 (step S31).

[0048] Then, the control device 80 determines whether the pressure loss is greater than a target value (threshold value) (step S32). If the pressure loss is greater than the target value, it can be assumed that the cooling flow paths in the branch pipes L3 to L5 or the cooling targets 25, 20, and 10 are not supplying a sufficient flow rate due to contamination or the like. In this case, the control device 80 controls the cooling pumps 60, 61, and 62 to increase the flow rate (step S33).

[0049] On the other hand, if the pressure loss is equal to or less than the target value, the supply of cooling water to the objects to be cooled 25, 20, 10 is good, and therefore the control device 80 controls the cooling pumps 60, 61, 62 to reduce the flow rates (step S34).

[0050] As described above, according to the third embodiment, it is possible to expect improved cooling efficiency and reduced noise, similar to the first and second embodiments. Furthermore, in the third embodiment, the pressure loss in the cooling water system is detected to control the flow rate of the cooling pumps 60, 61, and 62, so that the state of adhesion of dirt in the cooling water system can be confirmed, which has the advantage of making it possible to predict the optimal timing for cleaning and improving maintenance efficiency.

[0051] Next, various modified examples of the cooling system described above will be explained. Figures 9 to 12 are configuration diagrams of the cooling system according to each modified example.

[0052] <Variation 1> 9 is characterized in that variable displacement cooling pumps 60a to 62a are used as the "adjustment means" according to the present invention. By using variable displacement cooling pumps in this way, the pump flow rate can be controlled with high precision, further improving cooling efficiency.

[0053] <Variation 2> In Modification 2 shown in Fig. 10, a single cooling pump 60 is used to supply cooling water to the electric motor 25, inverter 20, and battery 10, which are the objects to be cooled, and variable throttles 70, 71, and 72 are provided between the cooling pump 60 and the electric motor 25, between the cooling pump 60 and the inverter 20, and between the cooling pump 60 and the battery 10, respectively. That is, in Modification 2, the variable throttles 70, 71, and 72 are used as the "adjustment means" according to the present invention. According to Modification 2, the flow rates of cooling water to the electric motor 25, the inverter 20, and the battery 10 are adjusted by the variable throttles 70 to 72. This makes it possible to reduce the number of cooling pumps.

[0054] <Variation 3> 11 shows a third modification in which three cooling pumps 60-62 are fixed, and the flow rate of cooling water to each of the cooling targets 25, 20, and 10 is adjusted by variable throttles 70-72 as adjustment means. Using fixed cooling pumps 60-62 as in this modification has the advantage of reducing costs compared to variable displacement cooling pumps.

[0055] <Variation 4> 12 is characterized in that switching valves 73, 74 are provided as adjustment means between the objects to be cooled 25, 20, 10 and the cooling pump 60. When the switching valve 73 is in position A, cooling water is supplied from the cooling pump 60 to the electric motor 25. On the other hand, since the inverter 20 is connected to a water tank 75, cooling water from the cooling pump 60 is not supplied to the inverter 20. On the other hand, when the switching valve 73 is in position B, cooling water is supplied to the inverter 20 but is not supplied to the electric motor 25.

[0056] When the switching valve 74 is in position A, the cooling water from the cooling pump 60 is supplied to the inverter 20 but is not supplied to the battery 10. When the switching valve 74 is in position B, the cooling water from the cooling pump 60 is supplied to the battery 10 but is not supplied to the inverter 20.

[0057] In other words, when the selector valve 73 is at position A and the selector valve 74 is at position A, the cooling water is supplied to the electric motor 25 and the inverter 20. When the selector valve 73 is at position A and the selector valve 74 is at position B, the cooling water is supplied to the electric motor 25 and the battery 10. When the selector valve 73 is at position B and the selector valve 74 is at position A, the cooling water is supplied only to the inverter 20. When the selector valve 73 is at position B and the selector valve 74 is at position B, the cooling water is supplied to the inverter 20 and the battery 10.

[0058] According to this variant 4, the cooling water flow rate of the electric motor 25, inverter 20, and battery 10 can be selectively controlled simply by switching the switching valves 73 and 74, making control simpler than when controlling the discharge flow rate of the cooling pump.

[0059] <Variation 5> FIG. 13 is a configuration diagram of a cooling system according to Modification 5. Modification 5 shown in FIG. 13 is characterized in that three sets of cooling fans 32 and fan motors 27 are provided. In Modification 5, the control device 80 selects the number of cooling fans 32 to drive based on the input coolant temperature. For example, when the coolant inlet temperature of the radiator 39 detected by the temperature sensor T4 exceeds an upper threshold, the control device 80 drives three cooling fans 32 to increase the amount of cooling air introduced into the radiator 39. When the coolant inlet temperature of the radiator 39 is below a lower threshold, the control device 80 drives one cooling fan 32 to decrease the amount of cooling air introduced into the radiator 39. When the coolant inlet temperature of the radiator 39 is equal to or higher than the lower threshold and equal to or lower than the upper threshold, the control device 80 drives two cooling fans 32.

[0060] In this way, by selecting the number of cooling fans 32 to be driven based on the temperature of the cooling water, it is possible to improve the cooling efficiency.

[0061] <Variation 6> Next, a modified example of the flow rate control of the cooling pump will be described. Fig. 14 is a flowchart of the control process of the cooling system according to Modification 6. The flowchart shown in Fig. 14 is particularly effective when it is desired to control both the increase / decrease in the flow rate of the cooling pump and the increase / decrease in the rotation speed of the cooling fan. The specific procedure will be described below.

[0062] The control device 80 determines whether or not a cooling capacity increase condition is met (step S41), and if the condition is met, in step S42, executes control to increase the flow rates of the cooling pumps 60, 61, and 62. Next, in step S43, executes control to increase the rotation speed of the cooling fan 32. In other words, when increasing the cooling capacity, the control device 80 prioritizes control to increase the flow rates of the cooling pumps 60, 61, and 62 over control to increase the rotation speed of the cooling fan 32.

[0063] Next, the control device 80 determines whether the cooling capacity reduction condition is met (step S44), and if the condition is met, in step S45, executes control to reduce the rotation speed of the cooling fan 32. Next, in step S46, executes control to reduce the flow rates of the cooling pumps 60, 61, and 62. In other words, when reducing the cooling capacity, the control device 80 prioritizes control to reduce the rotation speed of the cooling fan 32 over control to reduce the flow rates of the cooling pumps 60, 61, and 62.

[0064] In this sixth modification, the cooling capacity increase condition is, as described in the first to third embodiments, when the temperature of the electric motor 25, inverter 20, or battery 10, which are the objects to be cooled, exceeds a predetermined threshold value (step S11 / Yes), when the motor output exceeds a target value (step S22 / Yes), when the pressure loss exceeds a target value (step S32 / Yes), etc. Also, the cooling capacity decrease condition is, as described in the first to third embodiments, when the temperature of the electric motor 25, inverter 20, or battery 10, which are the objects to be cooled, falls below a predetermined threshold value (step S11 / No), when the motor output falls below a target value (step S22 / No), when the pressure loss falls below a target value (step S32 / No), etc.

[0065] In this variant 6, when it is desired to increase the cooling capacity, the flow rate of the cooling pumps 60, 61, and 62 is controlled to increase before the rotation speed of the cooling fan 32, thereby achieving the effect of reducing noise caused by the cooling fan 32.

[0066] <Variation 7> Alternatively, a configuration may be adopted in which a plurality of rotation speeds of the cooling fan 32 are set in advance in association with a plurality of operation modes (control modes), and the operator selects an operation mode in the operator cab 109, whereby the control device 80 controls the rotation of the cooling fan at the rotation speed corresponding to the selected operation mode. For example, three modes may be provided: a low-noise operation mode (first mode), a medium-noise operation mode (second mode), and a high-noise operation mode (third mode), and the rotation speed of the cooling fan 32 in the low-noise operation mode is set to a first rotation speed, the rotation speed of the cooling fan 32 in the medium-noise operation mode is set to a second rotation speed, and the rotation speed of the cooling fan 32 in the high-noise operation mode is set to a third rotation speed, and the rotation speed of the cooling fan 32 are preset to values ​​such that the first rotation speed < the second rotation speed < the third rotation speed.

[0067] The control device 80 then controls the rotation of the cooling fan 32 by referring to the rotation speed corresponding to the operation mode selected by the operator. According to this seventh modification, the rotation speed of the cooling fan 32 can be easily controlled, and when working in a noise-suppressed state, for example at night, the operator can simply set the low-noise operation mode, which suppresses the rotation speed of the cooling fan 32 and reduces the impact of noise on the surrounding area. Moreover, workability is improved because it is only necessary to set the operation mode.

[0068] In this seventh modification, as shown in Fig. 13, for example, a configuration may be adopted in which a plurality of cooling fans 32 are provided, and the number of cooling fans 32 to be used may be changed depending on the operation mode. For example, if it is preset that one cooling fan 32 is used in the low noise operation mode, two cooling fans are used in the medium noise operation mode, and three cooling fans 32 are used in the high noise operation mode, the control device 80 can easily reduce noise by rotating the number of cooling fans 32 according to the operation mode selected by the operator.

[0069] In the above-described embodiment and modified examples, the radiator 39 may be configured as a unit together with other heat exchangers, such as an oil cooler, etc. In this case, however, the cooling air generated by the cooling fan 32 must be supplied to heat exchangers other than the radiator 39, and therefore the cooling fan 32 must be designed to be able to provide the air volume required by all of these heat exchangers.

[0070] In addition, an example has been disclosed in which the objects to be cooled, that is, the electric motor 25, the inverter 20, and the battery 10, are arranged in parallel. However, in addition to this example, it is also possible to arrange each of the objects to be cooled 25, 20, and 10 in series and provide a line that bypasses each of the objects to be cooled 25, 20, and 10, thereby suitably controlling the flow rate of the cooling water supplied to each of the objects to be cooled 25, 20, and 10.

[0071] <Other embodiments> In the above-described embodiment, a crawler crane is used as an example of a crane, but the present invention is not limited to this and can be applied to any type of cranes, including other mobile cranes such as wheel cranes, truck cranes, rough terrain cranes, and all-terrain cranes, as well as tower cranes, overhead cranes, jib cranes, retractable cranes, stacker cranes, gantry cranes, unloaders, earth drills, and other foundation machines.

[0072] Furthermore, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention, and all technical matters included in the technical ideas described in the claims are subject to the present invention. The above-described embodiments are preferred examples, but a person skilled in the art can realize various alternatives, modifications, variations, or improvements from the contents disclosed in this specification, and these are included in the technical scope described in the appended claims. [Explanation of symbols]

[0073] 5 External power supply 10 Battery (cooling target) 20 Inverter (cooling target) 25 Electric motor (to be cooled) 27 Fan motor 30 Hydraulic pump 32 Cooling fan 39 Radiator 40~42 Actuator 50-52 Cooling pump motor (adjustment means) 60~62 Cooling pump (adjustment means) 70~72 Variable aperture (adjustment means) 73, 74 Switching valve (adjusting means) 80 Control device (adjustment means) 100 Crane 103 Rotating body 104 Boom 105 Hoisting drum 105a Hoisting Rope 106 Elevating Drum 106a Descending Rope 109 Driver's Cab 110 Hook L1~L5 pipeline P1~P2, P11~P17 pressure sensors R1 rotation sensor T1~T4 temperature sensors

Claims

1. An electrically driven crane, a cooling pump that is driven by an electric driving force and supplies a cooling liquid to an object to be cooled; an adjusting means for adjusting the flow rate of the cooling liquid supplied to the object to be cooled. A crane characterized by:

2. The crane of claim 1, The adjusting means varies the flow rate of the cooling pump based on predetermined conditions. A crane characterized by:

3. The crane according to claim 2, the temperature of the object to be cooled is used as the predetermined condition, The adjusting means is increasing the flow rate of the cooling pump when the temperature of the object to be cooled exceeds a predetermined threshold; reducing the flow rate of the cooling pump when the temperature of the object to be cooled is equal to or lower than the predetermined threshold value; A crane characterized by:

4. The crane according to claim 2, The work load of the crane is used as the predetermined condition, The adjusting means is increasing the flow rate of the cooling pump when the workload of the crane exceeds a predetermined threshold; reducing the flow rate of the cooling pump when the workload of the crane is below the predetermined threshold; A crane characterized by:

5. The crane according to claim 4, an electric motor driven by power supplied from an external power source; a variable displacement hydraulic pump driven by the electric motor; an actuator driven by hydraulic oil supplied from the hydraulic pump, The adjusting means is The workload of the crane is estimated based on the discharge pressure of the hydraulic pump, a control signal related to the pump tilt of the hydraulic pump, and the rotation speed of the electric motor. A crane characterized by:

6. The crane according to claim 2, a pressure difference between the upstream and downstream sides of the cooling target of the cooling liquid is used as the predetermined condition; The adjusting means is increasing the flow rate of the cooling pump when the pressure difference exceeds a predetermined threshold; reducing the flow rate of the cooling pump when the pressure difference is equal to or less than the predetermined threshold; A crane characterized by:

7. The crane of claim 1, A plurality of cooling targets are provided, the plurality of cooling targets and the cooling pump are connected via respective flow paths; The adjusting means switches the flow path through which the cooling liquid flows based on a predetermined condition. A crane characterized by:

8. The crane of claim 1, A cooling fan and a fan motor that rotates and drives the cooling fan; a radiator that cools the coolant by heat exchange with cooling air generated by rotation of the cooling fan, the cooling pump is a variable displacement pump; The adjusting means prioritizes control of the flow rate of the cooling pump over control of the rotation speed of the cooling fan. A crane characterized by:

9. 9. The crane of claim 8, The control modes of the cooling fan include a first mode in which the rotation speed of the cooling fan is set to a first rotation speed, and a second mode in which the rotation speed of the cooling fan is set to a second rotation speed that is greater than the first rotation speed. A crane characterized by:

10. 10. The crane of claim 9, A plurality of the cooling fans are provided, The number of the cooling fans driven in the first mode is smaller than that in the second mode. A crane characterized by:

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