Electric handling device, drive control method for servo motor

Abstract

To provide an electric cargo handling device capable of shortening transportation time of cargo by favorably setting rotation speed of a servo motor according to the weight of the cargo or favorably setting transport speed of the cargo, and a drive control method for the servo motor.SOLUTION: An electric cargo handling device 1 provided with a servo motor 6 for supplying power to transport cargo 2 and a control unit 15 for controlling driving of the servo motor 6, the device comprising an input unit 20 for allowing a user to input information to the control unit 15, and the control unit 15 calculating maximum rotation speed at which the servo motor 6 can operate or maximum elevating speed of the cargo 2 at which the electric cargo handling device 1 can operate on the basis of the weight of the cargo 2 input from the input unit 20 by the user or a torque input from the input unit 20 by the user and required to lift the cargo 2 by using the servo motor 6, and torque properties with respect to the rotation speed of the servo motor 6, and driving the servo motor 6 with the maximum rotation speed or the maximum elevating speed as an upper limit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to electric load handling devices such as winch type elevators and articulated arm type elevators. In particular, the present invention relates to an electric load handling device that raises and lowers a load in the vertical direction based on an operation by an operation means such as an operation grip or an operation pendant switch.

Background Art

[0002] As a conventional control method for a crane, there is a method as shown in Patent Document 1. In this method, the weight of the lifted load is detected, and the torque that can be output, the operable acceleration / deceleration, and the operating speed are calculated from the weight, and acceleration / deceleration control is performed to shorten the lifting / lowering operation time and improve workability.

[0003] Although Patent Document 1 does not describe torque, since the setting of the operable acceleration / deceleration and speed is determined by torque, it is considered that the description is omitted. For example, when the weight of the actually lifted load is smaller than the rated weight of the crane, it is possible to move the load with a smaller torque compared to the case of lifting the rated weight. Therefore, the acceleration and deceleration can be increased to increase the lifting / lowering speed, and as a result, the time required for the lifting / lowering operation can be made shorter and the transportation work can be completed. By controlling the acceleration / deceleration and speed of the crane according to the weight of the load in this way, it is considered that the time required for the lifting / lowering operation can be optimized according to the weight of the load and the output capacity of the motor.

[0004] The above-described control method is considered to function particularly effectively when the hoisting height (lifting / lowering operation distance) of the crane is long, exceeding 10 m. However, it is not considered suitable for work such as in a factory assembly line where the hoisting height is relatively short, about 1 to 2 m, and where delicate speed adjustment and position setting operations are required by an operation grip or an operation lever. This is because, in the above-described control method, the lifting / lowering speed is not known until the load is lifted and the lifting / lowering operation is performed, so it is considered that fine speed adjustment and position setting operations are not easy.

[0005] Next, the electric motor mounted on the electric handling device will be described. There are various types of motors such as torque motors, DC motors, induction motors, and servo motors mounted on the current electric handling devices. In particular, there are AC (Alternating Current) servo motors and DC (Direct Current) servo motors for servo motors, and further, AC servo motors include synchronous AC servo motors and induction-type AC servo motors. When attempting to mount a servo motor on an electric handling device, considering maintainability, energy efficiency, motor output capacity, etc., the synchronous AC servo motor is considered to be the most suitable. Therefore, in the following description of the servo motor, the case of mounting a synchronous AC servo motor on an electric handling device will be assumed and described.

[0006] FIG. 5 is a diagram showing the configuration of a conventional electric handling device that mounts a DC motor as an electric motor and performs open-loop control without detecting the rotation information (information such as rotation speed and rotation position) of the electric motor.

[0007] In the conventional electric load handling device 100 shown in Fig. 5, when a user operates the operation grip 102 of the operation box 101, for example, in the upward direction, the operation amount detection unit 103 detects the grip operation amount in the upward direction. The grip operation amount detected by the operation amount detection unit 103 is converted into a speed command by the speed command conversion unit 104, and a grip speed command in the upward direction is issued. The grip upward speed command issued by the speed command conversion unit 104 is amplified by the amplifier 105 and converted into a motor drive command by the motor drive unit 106, and then input to the electric motor 107. The electric motor 107 rotates based on the motor drive command, and this rotation is transmitted to the sheave (load sheave) 109 via the speed reducer 108. As a result, the sheave 109 rotates and the chain (load chain) 110 is wound up, and the load 112 suspended from the hook 111 at the tip of the chain 110 rises. In this way, the lifting mechanism (107 - 111) of the electric load handling device 100 operates in the upward direction, and when the user stops operating the operation grip 102, the lifting mechanism stops on the spot. Then, when the user operates the operation grip 102 in the downward direction, the lifting mechanism starts to operate in the downward direction and continues to operate in the downward direction until the operation of the operation grip 102 in the downward direction is stopped.

[0008] The DC motor mounted as the electric motor 107 in the electric load handling device 100 has a torque droop characteristic with respect to the rotational speed as shown in Fig. 6 when the DC voltage applied to the DC motor is kept constant. For this reason, when the torque changes due to the weight of the load 112, the lifting speed also changes. The operation at this time will be described with reference to Fig. 6. In Fig. 6, when the weight of the load 112 increases and the torque required for the lifting operation of the DC motor increases, the operating point P (the operating point on the straight line (torque droop characteristic straight line) showing the torque droop characteristic) moves upward to the left, and as a result, the rotational speed of the DC motor decreases and the lifting speed also decreases. On the other hand, when the weight of the load 112 is small, since the torque required to lift the load 112 is small, the operating point P moves downward to the right in Fig. 6, and the rotational speed increases and the lifting speed also increases.

[0009] When lifting and moving a load 112 of unknown weight using such an electric handling device 100, unless the operation grip 102 is actually operated to lift and move the load 112, it is impossible to know at what speed the lifting and lowering operation will be performed. For this reason, the user of the electric handling device 100 needs to operate the operation grip 102 while visually recognizing the actual lifting and lowering speed of the load 112. Although the lifting and lowering speed of the load 112 can be changed by changing the speed command value with the operation grip 102, in the case of open-loop control, the lifting and lowering speed will change depending on the weight of the lifted load 112. For this reason, like the crane described in Patent Document 1, the electric handling device 100 is not suitable for work that requires fine speed adjustment and position setting operations.

[0010] FIG. 7 is a diagram showing the configuration of a conventional electric handling device equipped with a servo motor as an electric motor.

[0011] In the electric handling device 113 shown in FIG. 7, closed-loop control by speed feedback is performed, in which information on the rotational speed of the servo motor 115 detected by the rotational speed detection unit 114 is read and the servo motor 115 is controlled. In this control, in the main control circuit (speed command difference calculation unit) 116, difference calculation processing is performed between the speed command value from the speed command conversion unit 104 and the current speed of the servo motor 115 detected and fed back by the rotational speed detection unit 114. The resulting differential speed is amplified by the amplifier 105 and converted into a motor drive command by the motor drive unit 106, and based on this, the servo motor 115 is driven.

[0012] In the closed-loop control by such speed feedback, feedback control is performed until the differential speed becomes substantially zero, that is, until the speed command value issued from the speed command conversion unit 104 based on the grip operation matches the current speed of the servo motor 115 detected by the rotational speed detection unit 114. Therefore, if the output capacity of the servo motor 115 mounted on the electric handling device 113 is sufficiently large with respect to the weight of the load 112, the servo motor 115 can be rotated at the rotational speed according to the speed command from the operation grip 102 regardless of the magnitude of the weight of the load 112.

[0013] FIG. 10 shows the relationship between the grip operation amount of the electric handling device 113 equipped with the servo motor 115 and the rotational speed of the servo motor 115. The rotational speed of the servo motor 115 faithfully goes up and down according to the speed command by the grip operation regardless of the magnitude of the weight of the load 112. In FIG. 10, the diagonal line drawn obliquely upward from the origin (the diagonal line indicating the characteristics of the rotational speed of the servo motor 115) indicates that the servo motor 115 rotates in proportion to the grip operation amount. Depending on the work content by the electric handling device 113, it may be easier to work by issuing a speed command having a curved characteristic like a quadratic curve with respect to the grip operation amount as shown by the broken line in FIG. 10. When the servo motor 115 is used as the electric motor, the servo motor 115 can be faithfully rotated without causing an operation delay in response to various speed command requirements from the operation grip 102, so that an easy-to-use electric handling device 113 suitable for the work content can be realized.

[0014] Here, in a conventional electric handling device, for example, the weight of the load is detected by a weight sensor, and further, while the user directly grips the load and applies force, a slight weight change at this time is detected to move the load up and down for positioning work (hereinafter referred to as "floating operation"). There is a device equipped with such a function. In an electric handling device equipped with this floating operation function, since a lifting operation for accurate and delicate speed adjustment and positioning is required, it is necessary to mount a servo motor and perform advanced motor control. When attempting to realize the floating operation function with a conventional electric handling device 100 by open-loop control as shown in FIG. 5, it is difficult to perform delicate and stable speed adjustment and positioning operations in this control, so it is considered difficult to realize a floating operation function that can withstand practical use.

[0015] While an electric handling device can perform high-performance and high-quality motor control by mounting a servo motor, in terms of manufacturing cost, compared to the case of mounting a low-cost torque motor or DC motor, a detection sensor for detecting the rotational position, rotational speed, torque (motor current) information, etc. of the motor is required and advanced motor control is required, so the manufacturing cost increases. However, an electric handling device equipped with a servo motor has advantages such as being able to perform delicate speed adjustment and positioning operations as described above and being able to realize a floating operation function that can withstand practical use, so there are many scenarios required according to the work content.

[0016] Next, as shown in FIG. 7, the torque, rotational speed, duty ratio, etc. of the servo motor 115 when the servo motor 115 is mounted on the electric handling device 113 will be described. Generally, since the load handling work by an electric handling device is performed continuously for a long time, the servo motor mounted on the electric handling device is basically used within the rated torque that enables continuous operation.

[0017] FIG. 8 is a diagram showing the basic structure of the electric handling device 113 equipped with the servo motor 115. In FIG. 8, the torque of the servo motor 115 is T m[N·m], the rotational speed of the servo motor 115 is N [rpm], and the duty ratio of the servo motor 115 is P m [W]. Then, the duty ratio P m is expressed by the following formula (1). (1) P m =2πT m ·N / 60

[0018] From the above formula (1), the duty ratio P m is proportional to the product of the torque T m and the rotational speed N. Therefore, the maximum duty ratio P m(MAX) that can be output in the continuous operation of the servo motor 115 is near the intersection of the constant torque characteristic line A within the rated rotational speed and the torque droop characteristic line B when exceeding the rated rotational speed in the torque - rotational speed characteristic diagram of the conventional electric handling device 113 equipped with the servo motor 115 shown in FIG. 9. Here, the "vicinity" where the straight line A and the straight line B intersect means that the position of the maximum duty ratio P m(MAX) changes somewhat according to the slope of the torque droop characteristic line B when the servo motor 115 operates at a high rotational speed exceeding the rated rotational speed. When the slope of the torque droop characteristic line B is large, the point where the straight line A and the straight line B intersect, that is, the duty ratio P m of the servo motor 115 is maximum near the rated rotational speed. Conversely, when the slope is small, the duty ratio P m is maximum in the high - rotational - speed region slightly exceeding the rated rotational speed.

[0019] In FIG. 8, in order to stop the load 112 lifted by the electric handling device 113 in the air, the torque generated by the weight of the load 112 to rotate the sheave 109 in the downward direction and the torque for the servo motor 115 to drive the sheave 109 in the upward direction via the speed reducer 108 need to be equal. Let the torque to rotate the sheave 109 in the downward direction at this time be T L [N·m], the transmission efficiency of the speed reducer 108 be η, and the reduction ratio of the speed reducer 108 be R. Then, the following formula (2) holds. (2) T L =η·R·T m

[0020] Here, when the radius of the sheave 109 is r [m] and the rated weight of the load 112 is W [N], the torque T in the downward direction L is T L = r·W Therefore, substituting this torque T L into the above formula (2) gives r·W = η·R·T m and the reduction ratio R of the speed reducer 108 is expressed by the following formula (3). (3) R = r·W / (η·T m )

[0021] When the reduction ratio R is calculated by the above formula (3), the lifting speed V of the load 112 at this time can be expressed by the following formula (4). (4) V = 2πrN / R

[0022] The above formula (4) shows that as the reduction ratio R of the speed reducer 108 increases, the lifting speed V of the load 112 decreases in inverse proportion to the reduction ratio R. Also, from the above formula (3) T m = r·W / (η·R) Therefore, substituting this torque T m into the above formula (1) gives the following formula (5). (5) P m = 2πT m ·N / 60 = 2π·r·W·N / (η·R·60)

[0023] From the above formula (1), the power P m of the servo motor 115 m is proportional to the product of the torque T m and the rotational speed N. Furthermore, from Fig. 9, the torque characteristic of the servo motor 115 maintains a substantially constant value up to the rated rotational speed. Therefore, it is considered that the power P m becomes maximum near the rated rotational speed N0. Thus, near the rated rotational speed N0, since P m(MAX) = P (6) P m(MAX) = 2π·r·W·N0 / (η·R·60)

[0024] When obtaining the reduction ratio R of the speed reducer 108 from the above formula (6), (7) R = 2π·r·W·N0 / (η·P m(MAX) ·60) is obtained. In the above formula (7), the radius r and the rotational speed N0 (=rated rotational speed) of the sheave 109 are fixed values, and the maximum work rate P m(MAX) is the rated output (fixed value) of the servo motor 115. Therefore, it can be understood that it is necessary to determine the reduction ratio R of the speed reducer 108 to be proportional to the weight W of the load 112 from the above formula (7).

[0025] For example, when the weight W of the load 112 carried by the electric load handling device 113 increases, by increasing the reduction ratio R of the speed reducer 108 in proportion to the weight W, it becomes possible to lift the load 112 at the maximum work rate (rated output) of the servo motor 115. However, when the reduction ratio R of the speed reducer 108 is increased, as shown in the above formula (4), the rotational speed of the servo motor 115 decreases in inverse proportion to the reduction ratio R.

[0026] Comparing the product specifications of electric load handling devices equipped with servo motors commercialized by each manufacturer of electric load handling devices, it can be seen that when the rated output of the servo motor is the same, the weight (rated weight) that the electric load handling device can carry and the maximum lifting speed are substantially inversely proportional (rated weight × maximum lifting speed = approximately constant). From this, it is considered that for electric load handling devices equipped with servo motors marketed by each manufacturer, in order to output the maximum work rate (rated output) of the servo motor, the reduction ratio of the speed reducer is set according to the rated weight that can be transported, and based on this, the maximum lifting speed is determined.

Prior Art Documents

Patent Documents

[0027]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0028] In a conventional electric handling device equipped with a servo motor, it is natural to select the rated output based on the weight of the load to be transported. It is considered that a relatively low-cost servo motor with a relatively small rated output is adopted while considering the specifications of the power supply (single-phase power supply or three-phase power supply). In order to use a low-output servo motor at the maximum work rate (rated output), it is necessary to optimize the device by changing the reduction ratio of the speed reducer according to the weight of the load (rated weight).

[0029] For example, when transporting loads of up to 100 kg, up to 150 kg, and up to 200 kg respectively, if we try to maximize the work rate of three electric handling devices equipped with servo motors with the same rated output, it is necessary to install speed reducers with different reduction ratios for each device. As a result, since each electric handling device needs to be designed, manufactured, and managed as a different model, both the manufacturing cost and the management cost will increase significantly.

[0030] To avoid these costs, it is conceivable to design an electric handling device with a rated weight of 200 kg and use this device as a device with a rated weight of 100 kg or 150 kg. However, in this case, since a device with a large reduction ratio, that is, a device designed for a low lifting speed, will be used to transport a light load of 100 kg or 150 kg in order to transport a load of 200 kg, compared with an optimized electric handling device with the speed reducer itself changed as described above, the lifting speed will be low and the workability will deteriorate.

[0031] Generally, since users of electric handling devices generally want to avoid continuously performing operations such as transporting a load with a weight far below the rated weight at a low lifting and lowering speed, they select and purchase an electric handling device with an optimized lifting and lowering speed according to the weight of the load. Therefore, each manufacturer of electric handling devices has to design electric handling devices according to the weight of the load and enrich the product lineup. This is also evident from the specifications of many currently marketed electric handling devices equipped with servo motors.

[0032] In addition, the crane control method in Patent Document 1 described above attempts to shorten the time until a predetermined lifting and lowering speed is reached by changing the acceleration of the electric motor according to the weight of the load, thereby shortening the lifting and lowering time of the load. That is, since the predetermined lifting and lowering speed itself is not changed according to the weight of the load, the lifting and lowering time of the load cannot be sufficiently shortened.

[0033] Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an electric handling device and a drive control method for a servo motor that can shorten the transport time of a load by suitably setting the rotation speed of the servo motor or the lifting and lowering speed of the load according to the weight of the load.

Means for Solving the Problems

[0034] To solve the above problems, the present invention provides a servo motor that supplies power for transporting a load, and a control unit that controls the drive of the servo motor, in an electric handling device, the control unit has an input unit for the user to input information, The control unit calculates the maximum rotational speed at which the servo motor can operate or the maximum lifting and lowering speed of the load that the electric load handling device can operate, based on the weight of the load handled input from the input unit by the user or the torque required to lift the load by the servo motor input from the input unit by the user, and the torque characteristics with respect to the rotational speed of the servo motor, and drives the servo motor with the maximum rotational speed or the maximum lifting and lowering speed as an upper limit. An electric load handling device is provided.

[0035] Furthermore, the present invention is a drive control method for a servo motor provided in an electric load handling device, including a step of calculating the maximum rotational speed at which the servo motor can operate or the maximum lifting and lowering speed of the load that the electric load handling device can operate, based on the weight of the load handled input by the user or the torque required to lift the load by the servo motor input by the user, and the rotational speed and torque characteristics of the servo motor, and a step of driving the servo motor with the desired maximum rotational speed of the servo motor or the desired maximum lifting and lowering speed of the load input by the user within the range of the maximum rotational speed or the maximum lifting and lowering speed as an upper limit. A drive control method for a servo motor is provided.

Advantages of the Invention

[0036] According to the present invention, an electric load handling device and a drive control method for a servo motor can be provided, which can suitably set the rotational speed of the servo motor according to the weight of the load or suitably set the lifting and lowering speed of the load to shorten the load handling time.

Brief Description of the Drawings

[0037]

Figure 1

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Mode for Carrying Out the Invention

[0038] (First Embodiment) FIG. 1 is a diagram showing the configuration of an electric cargo handling device according to the first embodiment of the present invention. As shown in FIG. 1, the electric cargo handling device 1 according to the present embodiment is a hoisting type elevator, and includes a cargo handling device main body 3 for suspending and transporting a cargo 2, an operation box 4 for operating the cargo handling device main body 3, and a control device 5 for controlling the cargo handling device main body 3.

[0039] In the cargo handling device main body 3, based on an instruction from the control device 5, an electric motor, specifically a servo motor (synchronous AC servo motor) 6 rotates, and the rotation of the servo motor 6 is transmitted to a sheave 8 via a speed reducer 7, and the sheave 8 rotates. As a result, a chain 9 is wound up / down on the sheave 8, and the cargo 2 suspended from a hook 10 at the tip of the chain 9 is raised / lowered.

[0040] The cargo handling device main body 3 is provided with a rotation speed detection unit 11 for detecting the rotation speed of the servo motor 6. The rotation speed of the servo motor 6 detected by the rotation speed detection unit 11 is input to the control device 5. Note that, at the upper part of the cargo handling device main body 3, a hook 12 for suspending the cargo handling device main body 3, for example, from the ceiling of a factory, etc., is provided.

[0041] The operation box 4 is for the user to operate to input an instruction for raising / lowering to the control device 5 in order to raise / lower the cargo 2 with the electric cargo handling device 1. In the present embodiment, the operation box 4 is provided with an operation grip 13, and the user can change the rotation speed of the servo motor 6 according to the operation amount of the operation grip 13, that is, change the lifting / lowering speed of the cargo 2 by the electric cargo handling device 1.

[0042] The operation box 4 is provided with an operation amount detection unit 14 for detecting the operation amount of the operation grip 13. The grip operation amount detected by the operation amount detection unit 14 is input to the control device 5. Here, in order to detect the analog (continuous) operation amount of the operation grip 13 by the user, for example, a potentiometer, a strain gauge, a Hall sensor, etc. are used. Note that it is not limited to the operation grip 13, and other operation means (for example, an operation lever, etc.) for detecting an analog operation amount may be adopted.

[0043] The control device 5 controls the driving of the servo motor 6 of the cargo handling device main body 3 based on an instruction from the operation box 4. In the control device 5, based on the grip operation amount input from the operation amount detection unit 14, the control unit 15 outputs a speed command (rotation speed) of the servo motor 6 to the speed command difference calculation unit 16. The speed command difference calculation unit 16 performs a difference calculation process based on the speed command from the control unit 15 and the current rotation speed of the servo motor 6 detected by the rotation speed detection unit 11 and fed back. The differential speed obtained thereby is amplified by the amplifier 17, converted into a drive command by the motor drive unit 18, and input to the servo motor 6. Thereby, the servo motor 6 is driven, and the electric cargo handling device 1 can raise / lower the cargo 2.

[0044] The control device 5 is provided with a display unit 19, an input unit 20, and a storage unit 21. The display unit 19 is for displaying the rated load (rated weight) of the electric cargo handling device 1, the rotation speed of the servo motor 6, etc. The input unit 20 is for the user to input the maximum weight of the cargo 2 to be carried by the electric cargo handling device 1 to the control unit 15. The storage unit 21 stores a program for executing a setting routine of the weight of the cargo 2 and the rotation speed of the servo motor 6, which will be described in detail later. Note that the control device 5 may be integrated with or separate from the cargo handling device main body 3.

[0045] Here, the differences between the electric load handling device 1 according to the present embodiment and the conventional electric load handling device 113 shown in FIG. 7 will be described. A major difference in the hardware configuration between the electric load handling device 1 according to the present embodiment and the conventional electric load handling device 113 shown in FIG. 7 is that the electric load handling device 1 according to the present embodiment has a display unit 19 for displaying the weight of the load 2, the rotational speed of the servo motor 6, etc., and an input unit 20 for inputting and setting the weight of the load 2 and the desired rotational speed of the servo motor 6.

[0046] As described above, FIG. 9 shows the rotational speed - torque characteristics and the usage area of the servo motor 115 mounted on the conventional electric load handling device 113. Generally, since the load handling operation by the electric load handling device is performed continuously, the usage area in the rotational speed - torque characteristics of the servo motor 115 is set in the continuous operation area (the area defined by the rated rotational speed and the rated torque).

[0047] Specifically, as shown in FIG. 9, in order for the electric load handling device 113 to be able to carry a load 112 up to the rated weight, the usage area of the torque of the servo motor 115 is set in the torque area from 0 to near the rated torque, and the usage area of the rotational speed is set in the rotational speed area from 0 to near the rated rotational speed. As a result, the area shown by the dot pattern in FIG. 9 becomes the usage area in the rotational speed - torque characteristics of the servo motor 115 mounted on the conventional electric load handling device 113. Note that "near" the rated torque means that when the electric load handling device 113 raises a load 112 near the rated weight, an accelerating torque exceeding the rated torque is required at the start (acceleration).

[0048] FIG. 11 shows an example of the rotational speed - torque characteristics and the usage area of the servo motor 6 mounted on the electric handling device 1 according to the present embodiment. As shown in FIG. 11, in the electric handling device 1 according to the present embodiment, an area other than the usage area of the above-described conventional electric handling device 113 is also used. When the weight of the load 2 to be carried by the electric handling device 1 is less than the rated weight, the electric handling device 1 suppresses the torque outputtable by the servo motor 6 by restricting the portable weight (the weight of the load 2 that can be carried). As a result, the electric handling device 1 actively utilizes the torque droop characteristic area (the area sandwiched by the torque droop characteristic straight line S and the horizontal axis, which is also referred to as the high rotational speed area) that has hardly been used in the conventional electric handling device 113, and uses the servo motor 6 at a high rotational speed exceeding the rated rotational speed. By configuring the servo motor 6 to be actively used in the droop characteristic area (high rotational speed area) in this way, when the electric handling device 1 carries a load 2 with a small weight, the lifting and lowering speed of the load 2 can be increased by rotating the servo motor 6 at a speed exceeding the rated rotational speed. And thereby, the lifting and lowering time can be shortened and the work efficiency can be improved.

[0049] In FIG. 11, an example of the torque - rotational speed area of the servo motor 6 used in the electric handling device 1 is shown by a hatched line pattern and a light shaded pattern. In FIG. 11, the area shown by the hatched line pattern is the area of the rotational speed at which the servo motor 6 can operate when a limit (= torque limit) is applied to the weight of the load 2 carried by the electric handling device 1.

[0050] In the electric handling device 1, the control unit 15 calculates the torque of the servo motor 6 required from the weight of the load 2 set by the user, and calculates the area of the rotational speed at which the servo motor 6 can operate shown by the hatched line pattern in FIG. 11. Then, within the calculated area, the user can set the area of the desired rotational speed of the servo motor 6. The area of the rotational speed of the servo motor 6 (user - set area) set by the user is shown by the light shaded pattern in FIG. 11.

[0051] The relationship between the operation amount of the operation grip 13 and the rotation speed of the servo motor 6 at this time is shown in FIG. 12. As shown in FIG. 10, the conventional electric handling device 113 uses the region from 0 to the rated rotation speed (at the maximum operation amount) with respect to the operation amount of the operation grip 102. On the other hand, the electric handling device 1 according to the present embodiment, by restricting the weight of the load 2 that can be transported, in addition to the region from 0 to the rated rotation speed like the conventional electric handling device 113, a region from 0 to the maximum rotation speed at which the servo motor 6 can operate beyond the rated rotation speed is used.

[0052] In FIG. 12, the diagonal line (diagonal line S1) connecting the intersection of the maximum operation amount of the operation grip 13 and the rated rotation speed and the 0 point shows the same characteristics as the characteristics of the rotation speed with respect to the operation amount of the operation grip 102 of the conventional electric handling device 113. In the electric handling device 1 according to the present embodiment, by suppressing the weight of the load 2 that can be transported, characteristics of a diagonal line with a steeper gradient than the diagonal line S1 in FIG. 12 are realized with respect to the operation amount of the operation grip 13.

[0053] Specifically, in the high rotation speed region beyond the rated rotation speed, the lower the weight of the load 2 that can be transported is set, the higher the high-speed rotation of the servo motor 6 becomes possible in the order of the rated rotation speed (diagonal line S1), high-speed rotation speed 1 (diagonal line S2), and high-speed rotation speed 2 (diagonal line S3) as shown in FIG. 12, and the gradients of the diagonal lines S1, S2, and S3 showing the characteristics of the rotation speed with respect to the operation amount of the operation grip 13 become steeper. That is, FIG. 12 shows that the steeper the gradient of the diagonal line showing the characteristics of the rotation speed of the servo motor 6 with respect to the operation amount of the operation grip 13, the higher the rotation speed for the same operation amount.

[0054] When a low-speed rotation operation is required for the servo motor 6 according to the content of the work of transporting the load 2 by the electric handling device 1, the rotation speed of the servo motor 6 can be set below the rated rotation speed, and the servo motor 6 can be operated at a low rotation speed. The characteristics in this case are shown by a diagonal line (diagonal line S4) with a gentler gradient than the diagonal line S1 in FIG. 12. Therefore, the difference between the high-speed rotation and low-speed rotation of the servo motor 6 is that during high-speed rotation, a torque limit corresponding to the weight of the load 2 set is applied to the servo motor 6, and during low-speed rotation, the weight of the load 2 that can be transported becomes the rated weight, and the servo motor 6 can output torque up to the rated torque.

[0055] Next, the method for calculating the maximum (highest) rotational speed of the servo motor 6 and the maximum (highest) lifting and lowering speed of the load 2 when transported by the electric load handling device 1 will be described. For example, when the servo motor 6 rotates at a high speed exceeding the rated rotational speed, from FIG. 11, the output torque T showing the characteristic (torque droop characteristic straight line S) of the torque of the servo motor 6 dropping can be expressed by the following linear equation. C Here, -a (a > 0) indicates the slope of the torque droop characteristic straight line S, and T0 indicates the virtual torque value at the rotational speed of 0 obtained by extending the torque droop characteristic straight line S. Note that the minus sign "-" of the slope -a of the torque droop characteristic straight line S indicates that the torque droop characteristic straight line S is a straight line equation with a downward slope on the right shoulder. (8) T = -a·N + T0 Here, -a (a > 0) indicates the slope of the torque droop characteristic straight line S, and T0 indicates the virtual torque value at the rotational speed of 0 obtained by extending the torque droop characteristic straight line S. Note that the minus sign "-" of the slope -a of the torque droop characteristic straight line S indicates that the torque droop characteristic straight line S is a straight line equation with a downward slope on the right shoulder.

[0056] When the rotational speed of the servo motor 6 is N C the torque T mc at that time is, from the above formula (8) (9) T mc = T0 - a·N C Therefore, from the above formula (9), the rotational speed N C of the servo motor 6 is expressed by the following formula (10). (10) N C = (T0 - T mc ) / a

[0057] Next, from the above formula (3), the torque T C when the load 2 with a weight of W mc is lifted by the electric load handling device 1 can be expressed by the following formula (11). (11) T mc = r·W C / (η·R)

[0058] The torque T of the above formula (11) mc is substituted into the above formula (10), and when the servo motor 6 operates to lift and lower the load 2 with a weight W C by the electric handling device 1, the rotational speed N C at which the servo motor 6 can operate is calculated by the following formula (12). (12) N C ={T0 - r·W C / (η·R)} / a

[0059] The above formula (12) indicates that by setting the weight W C of the load 2, the rotational speed N C at which the servo motor 6 can operate at that time can be calculated. Also, considering the radius r of the sheave 8 and the reduction ratio R of the speed reducer 7 as fixed values in the above formula (12), the lighter the weight W C of the load 2, the higher the rotational speed N C of the servo motor 6. When the servo motor 6 rotates at the rotational speed N C , the operable lifting and lowering speed V C of the load 2 is obtained by substituting N C calculated by the above formula (12) into the above formula (4). (13) V C =2πrN C / R The above formula (13) indicates that the lifting and lowering speed of the load 2 by the electric handling device 1 increases in proportion to the rotational speed N C of the servo motor 6.

[0060] From the above, it can be seen that the torque T mc required when lifting and lowering the load 2 with the maximum weight by the electric handling device 1 can be calculated by the above formula (11), the rotational speed N C of the servo motor 6 at this time can be calculated by the above formula (12), and the lifting and lowering speed V C can be calculated by the above formula (13) respectively.

[0061] Next, based on the above-described content, in the electric cargo handling device 1 according to the present embodiment, a method for a user to input and set the maximum weight W of the cargo 2 to be transported by the electric cargo handling device 1 and the maximum rotational speed of the servo motor 6 using the display unit 19 and the input unit 20 will be described with reference to FIG. 13.

[0062] The control device 5 of the electric cargo handling device 1 according to the present embodiment is configured to be able to execute a setting routine for the weight of the cargo 2 and the rotational speed of the servo motor 6 shown in FIG. 13 and described in detail below.

[0063] The program of this setting routine is stored in the storage unit 21 of the control device 5, and is started when a setting start key (not shown) provided in the input unit 20 is pressed by the user, and the following steps S1 to S7 are executed by the control unit 15. Here, as a specific example, it is assumed that the hardware specifications of the electric cargo handling device 1 are set as follows. Rated load (maximum weight of the cargo 2 that can be transported by the electric cargo handling device 1): 300 [kg] Rated rotational speed (rated rotational speed) of the servo motor 6: 3000 [rpm] Maximum rotational speed (maximum rotational speed) of the servo motor 6: 6000 [rpm]

[0064] Step S1: The control unit 15 causes the display unit 19 to display the value of the rated load of the electric cargo handling device 1, and also displays a message prompting the user to input the maximum weight of the cargo 2 to be transported by the electric cargo handling device 1 (see FIG. 14(a)). Note that FIG. 14(a) shows a state in which the value of the rated load, 300 [kg], is displayed on the display unit 19 as a specific example.

[0065] Step S2: The control unit 15 determines whether the user has operated the input unit 20 to input the value of the maximum weight of the cargo 2. If the input of the value of the maximum weight is confirmed, the control unit 15 proceeds to the next step S3; if not, this step S@ is repeatedly executed.

[0066] Step S3: The control unit 15 causes the display unit 19 to display the value of the maximum weight of the load 2 input by the user operating the input unit 20 (see Fig. 14(a)). Note that Fig. 14(a) shows, as a specific example, the state where the value "200" of the maximum weight of the load 2 has been input by the user and is displayed on the display unit 19.

[0067] Step S4: Based on the value of the maximum weight of the load 2 input by the user and the graph showing the rotational speed-torque characteristics of the servo motor 6 in Fig. 11, the control unit 15 calculates the maximum rotational speed at which the servo motor 6 can operate and the maximum lifting / lowering speed of the load 2 by the electric load handling device 1, and causes the display unit 19 to display them.

[0068] Specifically, the control unit 15 substitutes the value of the maximum weight (W C ) of the load 2 input by the user into the above formula (12), thereby calculating the maximum rotational speed (N C ) at which the servo motor 6 can operate, that is, the maximum rotational speed (N C ) of the servo motor 6 that can be set in the electric load handling device 1. Further, the control unit 15 substitutes the calculated value of the maximum rotational speed (N C ) into the above formula (13), thereby calculating the maximum lifting / lowering speed (V C ) of the load 2 by the electric load handling device 1.

[0069] In this step S4, the control unit 15 causes the display unit 19 to display the calculated values of the maximum rotational speed (N C ) and the maximum lifting / lowering speed (V C ), and also causes the display unit 19 to display a message prompting the user to input the desired maximum rotational speed of the servo motor 6 (see Fig. 14(b)). Note that Fig. 14(b) shows, as a specific example, the value 5000 [rpm] of the maximum rotational speed (N C ) of the servo motor 6 that can be set in the electric load handling device 1 and the value 400 [mm / Sec] of the maximum lifting / lowering speed (V C ) of the load 2 at this time, which are displayed on the display unit 19.

[0070] Step S5: The control unit 15 determines whether the user has operated the input unit 20 to input the value of the desired maximum rotational speed of the servo motor 6, specifically, whether the user has input the value of the maximum rotational speed (N C ) within the rotational speed range below which the servo motor 6 can operate. If the input of the desired maximum rotational speed value is confirmed, the control unit 15 proceeds to the next step S6; if not, the control unit 15 repeats the execution of this step S5.

[0071] Step S6: The control unit 15 causes the display unit 19 to display the value of the desired maximum rotational speed of the servo motor 6 input by the user by operating the input unit 20 (see Fig. 14(b)). Fig. 14(b) shows, as a specific example, the state where the value "4000" (≤ 5000 [rpm]) of the desired maximum rotational speed of the servo motor 6 is input by the user and displayed on the display unit 19.

[0072] Step S7: The control unit 15 sets (stores in the storage unit 21) the value of the desired maximum rotational speed (4000 [rpm]) input by the user as the maximum rotational speed of the servo motor 6 in the electric handling device 1, and ends this setting routine.

[0073] Through the above setting routine, the user can lift and lower the load 2 weighing 200 [kg] by rotating the servo motor 6 at a maximum rotational speed of 4000 [rpm] using the electric handling device 1. That is, with the electric handling device 1, the user can continuously change the rotational speed of the servo motor 6 within the range of 0 to 4000 [rpm] by adjusting the operation amount of the operation grip 13, and lift and lower the load 2 weighing 200 [kg]. As described above, according to the electric handling device 1, the rotational speed of the servo motor 6 and the lifting and lowering speed of the load can be suitably set according to the weight of the load 2, and the transportation time of the load 2 can be shortened.

[0074] When the maximum weight of the load 2 carried by the electric handling device 1 is less than the rated load, by executing the setting routine of the weight of the load 2 and the rotational speed of the servo motor 6 described above, the electric handling device 1 can move the load 2 up and down at a speed higher than the up and down speed when moving the load 2 up and down with the servo motor 6 operating at the rated rotational speed.

[0075] In addition, in the above step S2, when the value of the maximum weight of the load 2 input by the user exceeds the rated load, it is preferable that the control unit 15 adopts the value of the rated load as the maximum weight of the load 2 and executes steps S3 to S7.

[0076] The above-described setting routine is such that the user operates the input unit 20 to input the maximum weight of the load 2, and the control unit 15 calculates the necessary torque (limiting torque) T mc from the maximum weight based on the above formula (11), and further calculates the maximum rotational speed (N C ) at which the servo motor 6 can operate using the above formula (12). However, the setting routine is not limited to this. The user directly inputs the limiting torque (T mc ), that is, the value of the torque of the servo motor 6 required to lift the load 2 to be carried by the electric handling device 1, from the input unit 20, and the control unit 15 uses this directly input limiting torque to calculate the maximum rotational speed (N C ) at which the servo motor 6 can operate from the above formula (10).

[0077] In addition, the input of the limiting torque by the user is not only to input the value of the limiting torque (T mc ), but it is also possible to input, for example, the rated torque of the servo motor 6 as 100% in terms of the rated torque ratio [%]. In this case, the limiting torque T l [%] of the rated torque ratio input by the user, assuming the rated torque of the servo motor 6 is T R , can be expressed using the above formula (11) as T l =(T mc / T R )×100[%] and can be represented.

[0078] Therefore, when the limit torque T of the rated torque ratio is input by the user, the control unit 15 can calculate the torque T of the servo motor 6 required for lifting and lowering the load 2 by the following equation (14). l When the limit torque T of the rated torque ratio is input by the user, the control unit 15 can calculate the torque T of the servo motor 6 required for lifting and lowering the load 2 by the following equation (14). mc can be calculated by the following equation (14). (14) T mc =(T R ·T l ) / 100 Therefore, even when the limit torque T of the rated torque ratio is input by the user, the control unit 15 can calculate the maximum rotational speed (N l ) at which the servo motor 6 can operate from the above equation (10). C ) at which the servo motor 6 can operate from the above equation (10).

[0079] Also, in step S5 above, when the value of the desired maximum rotational speed of the servo motor 6 input by the user exceeds the maximum rotational speed (N C ) at which the servo motor 6 can operate, it is preferable that the control unit 15 adopts the value of the maximum rotational speed (N C ) as the desired maximum rotational speed of the user and executes steps S6 and S7. Also, in such a case, the control unit 15 may be configured to display, on the display unit 19, a message prompting the user to input a value equal to or lower than the maximum rotational speed (N C ) as the desired maximum rotational speed of the servo motor 6.

[0080] Also, the above-described setting routine is configured such that the desired maximum rotational speed input by the user is set as the maximum rotational speed of the servo motor 6 in the electric load device 1. However, it is not limited to this. For example, steps S5 and S6 may be omitted, and the value of the maximum rotational speed (N C ) at which the servo motor 6 can operate, calculated in step S4, may be set as the maximum rotational speed of the servo motor 6 in the electric load device 1 in step S7, and the setting routine may be terminated.

[0081] Further, the above-described setting routine is configured such that in step S5, the user operates the input unit 20 to input a value of the desired maximum rotational speed of the servo motor 6, in step S6, the value of the desired maximum rotational speed is displayed on the display unit 19, and in step S7, the value of the desired maximum rotational speed input by the user is set as the maximum rotational speed of the servo motor 6. However, the present invention is not limited thereto. Since the lifting and lowering speed of the load 2 by the electric material handling device 1 can be calculated from the rotational speed of the servo motor 6, and the rotational speed of the servo motor 6 can also be calculated from the lifting and lowering speed of the load 2 by the electric material handling device 1 (see the above formula (13)), in step S5, the user operates the input unit 20 to input a value of the desired maximum lifting and lowering speed of the load 2 by the electric material handling device 1, in step S6, the value of the desired maximum lifting and lowering speed is displayed on the display unit 19, and in step S7, the value of the desired maximum lifting and lowering speed input by the user is set as the maximum lifting and lowering speed of the load 2 by the electric material handling device 1.

[0082] In addition, by adding a weight sensor for detecting the weight of the load 2 to the electric material handling device 1, when the weight of the load detected by the weight sensor exceeds the weight of the load 2 set in the above-described setting routine, the control unit 15 may be configured to prohibit the lifting operation of the load 2.

[0083] Further, by adding a torque sensor for detecting the torque of the servo motor 6 to the electric material handling device 1, when the weight of the load 2 estimated from the torque of the servo motor 6 detected by the torque sensor exceeds the weight of the load 2 set in the above-described setting routine (when the torque detected by the torque sensor exceeds the limit torque input by the user to the control unit 15 as described above), the control unit 15 may be configured to prohibit the lifting operation of the load 2.

[0084] Here, as shown in the above formula (7), when trying to use the servo motor 6 at the maximum power factor with the radius r of the sheave 8 in the electric handling device 1 being a fixed value, the reduction ratio of the speed reducer 7 needs to be in a directly proportional relationship with the weight of the load 2. In the conventional electric handling device 113 of FIG. 7, when trying to change the rated load of the electric handling device 113 without replacing the mounted servo motor 115, it was necessary to replace the speed reducer 108 with a speed reducer having a different reduction ratio according to the increase or decrease of the rated load.

[0085] In contrast, in the electric handling device 1 according to the present embodiment, as shown in FIG. 11, since the servo motor 6 is used in a region of a high rotational speed exceeding the rated rotational speed, the lifting speed can be changed without replacing the servo motor 6 and the speed reducer 7 to cope with a change in the weight of the load 2. Therefore, even if there is a change in the rated load of the electric handling device 1, it can be coped with without changing the hardware specifications of the electric handling device 1.

[0086] As described above, the electric handling device 1 according to the present embodiment does not require a change in the hardware specifications and can unify the hardware specifications. Therefore, the manufacturing cost and the management cost can be significantly reduced. Further, even after the product is shipped, an optimal lifting speed can be set according to the weight of the load 2.

[0087] (First Modification Example of the First Embodiment) FIG. 2 is a diagram showing a first modification example of the electric handling device 1 according to the first embodiment. The electric handling device 1 according to the first embodiment may be configured to include an operation switch 22 and a button operation detection unit 23 instead of the operation grip 13 of the operation box 4 and the operation amount detection unit 14.

[0088] The operation switch 22 includes an up command button 22a that is operated by the user and outputs ON (rise) / OFF (stop) information to the button operation detection unit 23, and a down command button 22b that outputs ON (fall) / OFF (stop) information. The button operation detection unit 23 detects the ON / OFF information output from the operation switch 22 and transmits it to the control unit 15.

[0089] In the electric handling device 1 shown in FIG. 1, when the user operates the operation grip 13 of the operation box 4, the operation amount detection unit 14 detects the analog operation amount of the operation grip 13. Therefore, the servo motor 6 can continuously adjust the rotation speed from 0 to the maximum rotation speed according to the operation amount of the operation grip 13 (see FIG. 12).

[0090] On the other hand, in the electric handling device of the first modification shown in FIG. 2, when the user operates the operation switch 22, the button operation detection unit 23 detects the ON / OFF information. Therefore, when the ON information is input from the button operation detection unit 23 to the control unit 15, the control unit 15 drives the servo motor 6 at a preset fixed rotation speed. Specifically, it is desirable that the servo motor 6 operates at the desired maximum rotation speed of the servo motor 6 set in the setting routine of the weight of the load 2 and the rotation speed of the servo motor 6 described in the first embodiment. When the OFF information is input from the button operation detection unit 23 to the control unit 15, the control unit 15 stops the servo motor 6.

[0091] (Second modification of the first embodiment) FIG. 3 is a diagram showing a second modification of the electric handling device 1 according to the first embodiment. The electric handling device 1 according to the first embodiment may further include a weight sensor 24 and a weight detection unit 25.

[0092] The weight sensor 24 is disposed between the operation box 4 and the hook 10 and detects the weight of the load 2. The weight detection unit 25 transmits the information on the weight of the load 2 detected by the weight sensor 24 to the control unit 15.

[0093] In the electric load handling device according to the second modified example shown in FIG. 3, the weight of the load 2 lifted by the user operating the operation grip 13 is detected by the weight sensor 24. The control unit 15 acquires the weight of the load 2 detected by the weight sensor 24 via the weight detection unit 25, averages it, and stores it in the storage unit 21. After that, the control unit 15 calculates the difference between the weight of the load 2 detected by the weight sensor 24 when the user directly holds and raises / lowers the load 2 by hand and the weight of the load 2 stored in the storage unit 21. The control unit 15 detects the user's operating force and operating direction from the differential weight obtained by this differential calculation, and can perform a floating operation of driving the servo motor 6 in proportion to the user's operating force to move the lifting mechanism 6-10 in the vertical direction.

[0094] Also, in the electric load handling device according to the second modified example, the weight of the load 2 can be directly detected by the weight sensor 24 as described above. For this reason, when attempting to lift a load 2 that exceeds the weight of the load 2 set in the setting routine of the weight of the load 2 and the rotational speed of the servo motor 6 described above with the electric load handling device, it can also be configured to detect this with the weight sensor 24 and the control unit 15 prohibits the lifting of the load 2.

[0095] Note that the function of detecting an overload in this way and prohibiting the lifting of the load 2 can also be realized by using a torque sensor that detects the torque of the servo motor 6 and a torque detection unit that transmits information on the torque detected by the torque sensor to the control unit 15, constantly monitoring the torque of the servo motor 6, and prohibiting the lifting of the load 2 when an overload torque is detected. In this case, it may also be configured to constantly monitor the current flowing through the servo motor 6 without using a torque sensor, and prohibit the lifting of the load 2 when it is determined that the value of the torque estimated from the current is an overload torque.

[0096] (Second Embodiment) FIG. 4 is a diagram showing the configuration of an electric load handling device according to the second embodiment of the present invention. Regarding the electric load handling device according to the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted, and different parts will be described. As shown in FIG. 4, the electric load handling device 26 according to the second embodiment includes a wireless operation switch (pendent switch) 27 and a wireless receiving unit 28 instead of the operation box 4, the operation grip 13, and the operation amount detection unit 14 in the electric load handling device 1 according to the first embodiment.

[0097] The wireless operation switch 27 is for the user to operate the load handling device main body 3 by wireless communication. The wireless operation switch 27 includes an up command button 22a that is operated by the user and outputs ON (rise) / OFF (stop) information to the wireless receiving unit 28, and a down command button 22b that also outputs ON (lower) / OFF (stop) information. The wireless receiving unit 28 receives the ON / OFF information output from the wireless operation switch 27 and transmits it to the control unit 15.

[0098] The user can operate the electric load handling device 26 using the wireless operation switch 27 at a location away from the electric load handling device 26 to perform the transportation work of the load 2. In the electric load handling device 26, when the user operates the wireless operation switch 27, the wireless receiving unit 28 receives the ON / OFF information. Therefore, when the control unit 15 receives the ON information from the wireless receiving unit 28, it drives the servo motor 6 at a preset fixed rotation speed. Specifically, it is desirable that the servo motor 6 operates at the desired maximum rotation speed of the servo motor 6 set in the setting routine of the weight of the load 2 and the rotation speed of the servo motor 6 described in the first embodiment. When the control unit 15 receives the OFF information from the wireless receiving unit 28, it stops the servo motor 6.

[0099] According to each of the above embodiments, it is possible to realize an electric load handling device 1, 26 and a drive control method of a servo motor 6 that can preferably set the rotation speed of the servo motor according to the weight of the load or preferably set the lifting speed of the load to shorten the load transportation time.

[0100] The electric load handling devices 1 and 26 according to the above embodiments show an example in which the present invention is applied to a load handling device used in an industrial production line. However, since the present invention reviews the usage method of the servo motor and attempts to maximize the capabilities originally possessed by the servo motor, it can also be applied to other devices related to load handling devices equipped with servo motors.

[0101] According to the above embodiments, by maximizing the capabilities and characteristics of the servo motor 6, even when the weight of the load 2 to be transported changes, without changing the hardware configuration of the electric load handling devices 1 and 26, the lifting speed of the electric load handling devices 1 and 26 can be set to an optimal value according to the weight of the load 2. Therefore, quick transportation work becomes possible, improving work efficiency, and the portable weight and operating speed of the load 2 can be optimized without changing the hardware specifications of the electric load handling devices 1 and 26.

[0102] According to the above embodiments, the electric load handling device manufacturer no longer needs to manufacture and manage multiple types of electric load handling devices with different hardware configurations, so the manufacturing cost and management cost can be significantly reduced. On the other hand, even when the weight of the load to be transported changes after the user of the electric load handling device purchases the electric load handling device of the present invention, the lifting speed of the electric load handling device can be optimized according to the changed weight. Therefore, when the load becomes lighter, the lifting speed can be increased to improve work efficiency, and there is also the advantage that there is no need to newly purchase an electric load handling device with different specifications according to the changed weight of the load.

Explanation of Reference Numerals

[0103] 1, 100, 113 Electric load handling device 2, 112 Load 10, 111 Hook 8, 109 Sheave 9, 110 Chain 12 Hook 15 Control unit 19 Display unit 20 Input unit 21 Memory unit 18, 106 Motor drive unit 17, 105 Amplifier 16, 116 Speed command difference calculation unit 6, 115 Servo motor 7, 108 Reducer 4, 101 Operation box 13, 102 Operation grip 11, 114 Rotational speed detection unit 22 Operation switch 23 Button operation detection unit 22a Upward command button 22b Downward command button 24 Weight sensor 25 Weight detection unit 27 Wireless operation switch 28 Wireless reception unit

Claims

1. A servo motor that supplies power for transporting a load, and a control unit that controls the drive of the servo motor. In an electric load handling device having these, it has an input unit for the user to input information to the control unit, the control unit calculates the maximum rotational speed at which the servo motor can operate or the maximum lifting and lowering speed of the load at which the electric load handling device can operate based on the weight of the load input from the input unit by the user or the torque required to lift the load with the servo motor input from the input unit by the user and the torque characteristic with respect to the rotational speed of the servo motor, and drives the servo motor with the maximum rotational speed or the maximum lifting and lowering speed as an upper limit. An electric load handling device characterized by this.

2. It has a display unit for displaying the maximum rotational speed or the maximum lifting and lowering speed calculated by the control unit, the control unit drives the servo motor with the desired maximum rotational speed of the servo motor or the desired maximum lifting and lowering speed of the load input from the input unit by the user within the range of the maximum rotational speed or the maximum lifting and lowering speed as an upper limit. The electric load handling device according to Claim 1, characterized by this.

3. It has a weight sensor for detecting the weight of the load, when the weight of the load input from the input unit by the user exceeds the weight of the load detected by the weight sensor, the control unit prohibits the upward movement of the load by the electric load handling device. The electric load handling device according to Claim 2, characterized by this.

4. It has torque detection means for detecting the torque of the servo motor, when the weight of the load input from the input unit by the user exceeds the weight of the load estimated from the torque of the servo motor detected by the torque detection means, or when the torque required to lift the load with the servo motor input from the input unit by the user exceeds the torque of the servo motor detected by the torque detection means, the control unit prohibits the upward movement of the load by the electric load handling device. The electric load handling device according to Claim 2, characterized by this.

5. operation means for the user to operate the electric load handling device, and an operation amount detection unit for detecting the analog operation amount of the operation means by the user. The control unit adjusts the rotation speed of the servo motor steplessly from 0 to the maximum rotation speed or adjusts the lifting and lowering speed of the load-carrying object steplessly from 0 to the maximum lifting and lowering speed according to the operation amount of the operation means detected by the operation amount detection unit. The electric load-carrying device according to claim 2, characterized in that.

6. An operation means for a user to operate the electric load-carrying device, An on / off operation detection unit that detects an on / off operation of the operation means by the user, and has, When the on operation of the operation means is detected by the on / off operation detection unit, the control unit drives the servo motor at a predetermined rotation speed or drives the servo motor so as to carry the load-carrying object at a predetermined lifting and lowering speed. The electric load-carrying device according to claim 2, characterized in that.

7. Wireless operation means for a user to operate the electric load-carrying device by wireless communication, A wireless receiving unit that receives an operation signal from the wireless operation means and transmits it to the control unit. The electric load-carrying device according to claim 2, characterized in that it has.

8. A sheave for winding up a chain for suspending the load-carrying object, A speed reducer that transmits the rotation of the servo motor to the sheave, and has, When the torque drop characteristic of the servo motor is shown by the following torque drop characteristic straight line, T = -a·N + T ０ However, T: Output torque of the servo motor a: Slope of the torque drop characteristic straight line N: Rotation speed of the servo motor T ０ : Virtual torque value at rotational speed 0 obtained by extending the torque drop characteristic line The control unit calculates the maximum rotation speed or the maximum lifting and lowering speed based on the following formula. The electric load-carrying device according to claim 2, characterized in that. N Ｃ = {T ０ - r·W Ｃ / (η·R)} / a V Ｃ = 2πrN Ｃ / R However, N Ｃ : the maximum rotational speed V Ｃ : the maximum lifting speed W Ｃ : The weight of the load r: Radius of the sheave R: Reduction ratio of the speed reducer η: Transmission efficiency of the speed reducer

9. A drive control method for a servo motor provided in an electric load-carrying device, Based on the weight of the load-carrying object input by the user or the torque required to lift the load-carrying object by the servo motor input by the user, and the rotation speed and torque characteristics of the servo motor, calculating the maximum rotation speed at which the servo motor can operate or the maximum lifting and lowering speed of the load-carrying object at which the electric load-carrying device can operate; Driving the servo motor with the desired maximum rotation speed of the servo motor input by the user or the desired maximum lifting and lowering speed of the load-carrying object input by the user as an upper limit within the range of the maximum rotation speed or the maximum lifting and lowering speed. A drive control method for a servo motor, characterized by including.

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