Hoisting machine and drive control method for hoisting machine

Abstract

Provided are a hoisting machine and a drive control method for the hoisting machine, by which, in a balancer mode, the task of raising / lowering a load near a limit position can be performed intuitively in a state where a worker is made aware of the limit position.　A motor control means of a hoisting machine 10 is able to control driving of a drive motor 40 in a balancer mode on the basis of a measurement of a load at a load sensor 90. The balancer mode includes a first balancer mode for controlling the driving of the drive motor on the basis of a first torque command value to which an assist torque for assisting with an operating force has been added. Within an upper limit attenuation region UAR, control for decreasing the assist torque is performed in accordance approaching a balancer upper limit position MT2, and within a lower limit attenuation region LAR that is within a predetermined range on the upper side from a balancer lower limit position MB2, control for decreasing the assist torque is performed in accordance with approaching the balancer lower limit position MB2.

Description

Hoisting machine and hoisting machine drive control method

[0001] The present invention relates to a hoist and a drive control method for a hoist.

[0002] Some hoists allow a user to lift or lower a heavy load not by using an operating switch, but by placing a hand on the load and applying a small amount of force to the load, as if lifting or lowering a heavy load with one's own hands. Examples of such hoists are shown in Patent Document 1 and Patent Document 2.

[0003] Patent Document 1 discloses that the weight of the load and the assisting force of the motor are balanced, and an external force (a force sufficiently smaller than the external force used to lift the load) is applied by a worker or the like to move the load up and down, thereby controlling the load to move up and down to any desired height.

[0004] Furthermore, Patent Document 2 discloses control of the drive motor based on a balancer mode similar to the above-mentioned assisting force. In this balancer mode, (1) in the balance position range between the balancer upper limit position and the balancer lower limit position, the drive of the drive motor 40 is controlled based on a first torque command value obtained by adding or subtracting an assist torque that assists the operating force to or from a balance torque in a balanced state where the load P is balanced, and (2) at the balancer upper limit position and the balancer lower limit position, the drive of the drive motor 40 is controlled based on a second torque command value obtained by adding or subtracting a cancel torque in a direction that cancels the operating force to or from the balance torque.

[0005] JP 2019-052007 A

[0006] However, the configurations shown in Patent Documents 1 and 2 do not disclose how to control the speed of the motor when approaching limit positions such as the upper limit position and the lower limit position. In other words, when a load with large inertia reaches a limit position, it suddenly decelerates and stops, and a large impact is applied to the load, but no specific motor control method is disclosed for such situations near limit positions.

[0007] Here, one possible way to control the motor near the limit position is to forcibly decelerate the motor drive before approaching the limit position, so that the load response in balancer mode feels heavy. In this case, if the motor drive speed is fast, the degree of deceleration increases, and the load lifting / lowering operation feels heavy. This effectively notifies the worker that the limit position is approaching, and makes the worker aware of the limit position when lifting / lowering the load.

[0008] On the other hand, if the motor drive speed is slow, the degree of deceleration is small, and the worker does not feel much resistance when lifting or lowering the load. As a result, the worker is not sufficiently informed that the limit position is approaching, and it is not possible to make the worker aware of the limit position when lifting or lowering the load. As a result, the worker may not realize that they are approaching the limit position, and the motor may suddenly stop the moment the limit position is reached, which may cause an impact or the like to the load.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a hoist and a control method for a hoist that, in balancer mode, enables an operator to intuitively perform lifting and lowering of a load near a limit position while being aware of the limit position.

[0010] In order to solve the above problems, according to a first aspect of the present invention, there is provided a hoist that raises and lowers a load by winding up and down a load chain or rope from a hoist main body, the hoist comprising: hoisting means that is arranged on the hoist main body, around which a load chain or rope is wound, and which winds up and down the load chain or rope in response to rotation; a drive motor that generates a driving force for rotating the hoisting means; motor control means that controls the drive of the drive motor; and load detection means that detects the load torque applied to the hoisting means by the load chain or rope that suspends the load and the operating force applied by an operator in the direction of winding up and winding down the load, and the motor control means detects the load torque based on the load torque. The hoist is characterized in that the drive of the drive motor can be controlled in a balancer mode in which torque control is performed based on a first torque command value to which an assist torque that assists the operating force is added, and the balancer mode includes a first balancer mode in which the drive of the drive motor is controlled based on a first torque command value to which an assist torque that assists the operating force is added, and the motor control means controls the magnitude of the assist torque to decrease as the movement moves toward the balancer upper limit position within an upper limit damping region within a predetermined range below the balancer upper limit position in the first balancer mode, and also controls the magnitude of the assist torque to decrease as the movement moves toward the balancer lower limit position within a lower limit damping region within a predetermined range above the balancer lower limit position in the first balancer mode.

[0011] Furthermore, in the above-described invention, it is preferable that the motor control means controls the drive motor to reduce the magnitude of the drive speed as the drive moves toward the balancer upper limit position within an upward speed deceleration region within a predetermined range downward from the balancer upper limit position in the first balancer mode, and also controls the drive motor to reduce the magnitude of the drive speed as the drive moves toward the balancer lower limit position within a downward speed deceleration region within a predetermined range upward from the balancer lower limit position in the first balancer mode.

[0012] In the above-described invention, it is preferable that the upper limit attenuation region coincides with the upper speed deceleration region, and the lower limit attenuation region coincides with the lower speed deceleration region.

[0013] In addition, in the above-mentioned invention, it is preferable that the motor control means, within the upper limit damping region, perform control to proportionally reduce the magnitude of the assist torque as the balancer approaches the upper limit position, and, within the lower limit damping region, perform control to proportionally reduce the magnitude of the assist torque as the balancer approaches the lower limit position.

[0014] Furthermore, in the above-described invention, the balancer mode preferably includes a second balancer mode that controls the drive of the drive motor based on a second torque command value that does not assist the operating force, and when setting the load lifting range, the motor control means preferably sets a first position range, which is a range in which control is performed in the first balancer mode regardless of whether the direction of the operating force is in the winding-up or winding-down direction, and a second position range, which is a range in which control is performed in either the first balancer mode or the second balancer mode, depending on the direction of the operating force in the winding-up or winding-down direction.

[0015] According to a second aspect of the present invention, there is provided a drive control method for a hoist that raises and lowers a load by winding up and down a load chain or rope from a hoist main body, the method comprising: hoisting means that is arranged on the hoist main body, around which a load chain or rope is wound, and that winds up and down the load chain or rope in response to rotation; a drive motor that is arranged on the hoist main body and generates a drive force that rotates the hoisting means; motor control means that is arranged on the hoist main body and controls the drive of the drive motor; and load detection means that detects a load torque applied to the hoisting means by the load chain or rope that suspends the load and an operating force applied by an operator to operate the load in the hoisting / lowering direction, the method comprising the steps of: a load torque detection step of detecting the load torque with the load detection means; and a preset lifting position range based on the load torque detected in the load torque detection step. and a torque control step of controlling drive of the drive motor by motor control means in a range of 0.5 to 1.5 mm, wherein the torque control step is capable of controlling drive of the drive motor in a balancer mode where torque control is performed based on load torque, and the balancer mode includes a first balancer mode where drive of the drive motor is controlled based on a first torque command value to which an assist torque that assists the operating force is added, and the torque control step performs control to reduce the magnitude of the assist torque as the load approaches the balancer upper limit position within an upper limit attenuation range within a predetermined range below the balancer upper limit position in the first balancer mode, and also performs control to reduce the magnitude of the assist torque as the load approaches the balancer lower limit position within a lower limit attenuation range within a predetermined range above the balancer lower limit position in the first balancer mode.

[0016] According to the present invention, it is possible to provide a hoist and a control method for the hoist that, in balancer mode, enables an operator to intuitively perform lifting and lowering operations near a limit position while being aware of the limit position.

[0017] 1 is a perspective view showing the overall configuration of a hoist according to an embodiment of the present invention. FIG. 2 is a diagram showing the control configuration of the hoist shown in FIG. 1. FIG. 3 is a diagram showing the configuration of a cylinder operating device for the hoist shown in FIG. 1. FIG. 4 is a diagram showing a part of the control flow of the hoist shown in FIG. 1, showing steps S01 to S10. FIG. 5 is a diagram showing a part of the control flow of the hoist shown in FIG. 1, showing steps S11 to S15. FIG. 6 is a diagram showing a part of the control flow of the hoist shown in FIG. 1, showing steps S16 to S29. FIG. 7 is a diagram showing a part of the control flow of the hoist shown in FIG. 1, showing steps S30 to S40. FIG. 8 is a diagram showing an upper limit length and a lower limit length in the hoist shown in FIG. 1. FIG. 9 is a diagram showing the relationship between speed and position in an upper speed deceleration region or an upper speed deceleration region in the hoist shown in FIG. 1. FIG. 10 is a diagram showing the relationship between a torque command value and position, where (A) shows a state in which a force is applied in the lifting direction within the upper limit attenuation region, and (B) shows a state in which a force is applied in the push-down direction within the lower limit attenuation region.

[0018] Hereinafter, a hoist 10 and a drive control method for the hoist 10 according to an embodiment of the present invention will be described with reference to the drawings.

[0019] <1. Configuration of the hoist 10> Fig. 1 is a perspective view showing the overall configuration of the hoist 10. Fig. 2 is a diagram showing the control configuration of the hoist 10. As shown in Fig. 1, the hoist 10 mainly comprises a hoist main body 20, an upper hook 30, a cylinder operating device 150, and a chain bucket 170 that holds the wound-up load chain C1.

[0020] The hoist main body 20 can be suspended from a predetermined location, such as a ceiling, via an upper hook 30. The hoist main body 20 includes a housing 21 that accommodates various components. Specifically, the housing 21 contains a drive motor 40, a speed reduction mechanism 50, a brake mechanism 60, a load sheave 70 for winding up the load chain C1, an upper limit switch 80, a lower limit switch 81, a load sensor 90, a control unit 100, and a driver 110. The load chain C1 and load sheave 70 can be replaced by a hoist main body consisting of a rope and a winding drum (not shown). In this case, the wound rope is held by the winding drum, eliminating the need for a chain bucket 170. The load sheave 70 and winding drum correspond to a hoisting means.

[0021] The drive motor 40 is a motor that provides a driving force to drive the load sheave 70. In this embodiment, the drive motor 40 is a servomotor equipped with a detector (encoder 41) for detecting a position (the rotational position of a rotor, not shown), and is preferably an AC servomotor. Note that a synchronous motor is preferable as the AC servomotor, but an induction motor may also be used.

[0022] The reduction mechanism 50 is a part that reduces the speed of the drive motor 40 and transmits the rotation to the load sheave 70. The brake mechanism 60 is a part that can release the braking force by electromagnetic force when the drive motor 40 is operating, but is also a part that generates braking force so as to hold the load P even when the drive motor 40 is not operating.

[0023] The load sheave 70 is a part that winds up and down the load chain C1, and is provided with a plurality of chain pockets along its outer periphery into which the metal rings of the load chain C1 fit.

[0024] The upper limit switch 80 is a switch for detecting the limit position (mechanically and structurally set upper limit position) when the load chain C1 is wound up, and the lower limit switch 81 is a switch for detecting the limit position (mechanically and structurally set lower limit position) when the load chain C1 is wound down.

[0025] The load sensor 90 is a load sensor that measures the load applied to the upper hook 30. In other words, the load sensor 90 is a sensor that measures and detects the total load of the load on the hoisting machine main body 20, the load on the load chain C1 (the portion that is not on the floor, etc.), and the load on the load P. By subtracting the weight of the main body, etc. from the total load measured and detected using this load sensor 90, it is possible to detect (calculate) the load applied to the load sheave 70 via the load chain C1. The load sensor 90 is attached, for example, to a mounting shaft that attaches the upper hook 30 to the hoisting machine main body 20.

[0026] The load sensor 90 may be a load cell equipped with a strain gauge. The load sensor 90 may be located anywhere, such as between the upper hook 30 and the crane trolley, between the lower hook 160 and the load P, or between the end of the load chain C1 and the lower hook 160, as long as it can detect and measure the load applied to the load sheave 70 by the load chain C1 suspending the load P. The load sensor 90 may be a crane scale or other device other than a load cell, but it must have the accuracy and responsiveness required for balancer control. The load sensor 90 and a portion of the control unit 100 that calculates the load torque applied to the load sheave 70 from the signal from the load sensor 90 correspond to the load detection means.

[0027] The control unit 100 is a part that provides the driver 110 with command values ​​for the control mode (speed control mode, torque control mode), position, speed, torque, etc. The control unit 100 and the driver 110 correspond to motor control means. The control unit 100 may be, for example, a computer equipped with a CPU (Central Processing Unit), memory 101 (RAM (Random Access Memory), ROM (Read Only Memory), internal storage, external storage device, etc.), input / output interface, etc. The memory 101 stores a control program for operating in a switch operation mode and a balancer mode, which will be described later.

[0028] The driver 110 controls the power supplied from an external source to an appropriate level based on the current value of the drive motor 40, the output of the encoder 41, and command values ​​for motor drive control given by the control unit 100, and supplies that power to the drive motor 40 to rotate the drive motor 40. In this embodiment, since the drive motor 40 is a servo motor, the driver 110 is a servo driver that has at least a speed control mode and a torque control mode and is configured to selectively perform speed control or torque control based on commands from the control unit 100. In torque control, the torque of the drive motor 40 is controlled and the rotational speed of the drive motor 40 can be limited.

[0029] The cylinder operating device 150 is an operating device that is held by the operator's hand and is connected to the lower end of the load chain C1. A lower hook 160 for hanging a load P is connected to the cylinder operating device 150. FIG. 3 is a diagram showing the configuration of the cylinder operating device 150. As shown in FIG. 3, the cylinder operating device 150 includes an operation mode selector switch 151, a movable grip 152, and a displacement sensor 153. The operating device is not limited to an operating device connected to the lower hook 160, but may also be an operating device (pendant switch) suspended by a cable from the main body of the hoist, or may be a wireless remote control device.

[0030] The operation mode changeover switch 151 is a switch for switching the operation mode of the drive motor 40, and a switch signal of the operation mode changeover switch 151 is output to the control unit 100. In this embodiment, there are at least two operation modes: a switch operation mode and a balancer mode. By pressing the operation mode changeover switch 151, the control unit 100 can switch the operation mode of the drive motor 40 between the switch operation mode, the balancer mode, or another mode. The control unit 100 outputs a speed control command or a torque control command to the driver 110 (servo driver) so that the drive motor 40 is controlled by speed control in the switch operation mode and by torque control in the balancer mode.

[0031] The movable grip 152 is the part that is operated when operating in the switch operation mode. The movable grip 152 is provided so as to be slidable in the vertical direction, and is held in a neutral position by a biasing means such as a spring. The movable grip 152 can be slid upward or downward from the neutral position against the biasing means. The displacement sensor 153 outputs a detection signal corresponding to the amount of sliding to the control unit 100. The control unit 100 then controls the speed of the drive motor 40 based on the detection signal.

[0032] The chain bucket 170 is a part that stores and holds the unloaded (already wound) load chain C1 that is located on the opposite side of the load sheave 70 from the lower hook 160.

[0033] 2. Control flow of the drive motor 40 Next, a control flow (drive control) of the drive motor 40 according to this embodiment in the hoist 10 having the above-described configuration will be described with reference to Fig. 4 to Fig. 7. Note that the following steps are executed or determined by the control unit 100.

[0034] The control unit 100 determines whether the upper limit switch 80 is activated (step S01). If the upper limit switch 80 is activated, the cylinder operating device 150, the lower hook 160, and the load P are hoisted up to their upper limit positions.

[0035] Therefore, if it is determined in step S01 that the upper limit switch 80 is not activated (No), it is determined that winding is possible, and the drive motor 40 is set to "enabled" in the winding direction (written in the predetermined memory 101) (step S02). On the other hand, if it is determined in step S01 that the upper limit switch 80 is activated (Yes), it is determined that further winding is not possible, and the drive motor 40 is set to "disabled" in the winding direction (written in the predetermined memory 101) (step S03).

[0036] After steps S02 and S03, the control unit 100 determines whether the lower limit switch 81 is activated (step S04). If the lower limit switch 81 is activated, the cylinder operating device 150, the lower hook 160, and the load P are all lowered to their lowest positions. If the determination in step S04 determines that the lower limit switch 81 is not activated (No), it is determined that lowering is possible, and the drive motor 40 is set to "enabled" in the lowering direction (written in the predetermined memory 101) (step S05). On the other hand, if the determination in step S04 determines that the lower limit switch 81 is activated (Yes), it is determined that further lowering is not possible, and the drive motor 40 is set to "disabled" in the lowering direction (written in the predetermined memory 101) (step S06).

[0037] After steps S05 and S06, the control unit 100 reads the load measured by the load sensor 90 (step S07). In step S07, the read load value is subjected to appropriate filtering or the like and written to a predetermined memory 101. The filtering may be performed by an amplifier or the like provided in the load sensor 90 instead of by the control unit 100, or may be performed by both. Note that step S07 corresponds to a load torque detection step. The control unit 100 calculates the load torque from the load written to the memory 101 using equations (4) and (5) described below.

[0038] Next, the control unit 100 reads the position information output from the driver 110 (servo driver) (step S08). This position information indicates the amount of payout of the load chain C1 output by the driver 110 based on information from the encoder 41, which detects the rotation of the drive motor 40 so that the driver 110 (servo driver) can control the drive motor 40 in speed control mode or torque control mode. The output of the encoder 41 may be input directly to the control unit 100, and the amount of payout of the load chain C1 may be calculated.

[0039] The payout amount corresponds to the lift position, and the direction in which the payout amount increases is the winding down direction, and the direction in which the payout amount decreases is the winding up direction.When the payout amount is large, the lift position is lower, and when the payout amount is small, the lift position is upper.

[0040] Next, the control unit 100 determines whether the load read in step S07 is a preset overload (step S09). If the determination in this step determines that the load read in is not an overload (within the rated load range) (No), the control unit 100 proceeds to step S11, which will be described later. On the other hand, if the determination in step S09 determines that the load read in is an overload (Yes), the control unit 100 determines that the load is an overload and executes overload (abnormality) processing (step S10). Note that the overload (abnormality) processing is processing to prohibit the drive motor 40 from being driven, or to perform an emergency stop if the drive motor 40 is in operation. At the same time, the control unit 100 issues a warning or notification of the overload using a buzzer, display, or other means. After the processing in step S10, the control unit 100 proceeds to the determination in step S23, which will be described later.

[0041] If it is determined in step S09 that the load read above is not an overload (within the rated load range) (No), a confirmation process is performed on the operation mode changeover switch 151 (step S11). In step S11, the operation mode memory (memory 101) is rewritten to "balancer mode" or "switch operation mode" in a flip-flop manner in response to a signal from the operation mode changeover switch 151.

[0042] After the confirmation process is performed, the control unit 100 reads the operation mode memory (memory 101) and determines whether the mode is the balancer mode (step S12). If the determination in step S12 determines that the mode is the balancer mode (Yes), the control unit 100 proceeds to step S13. On the other hand, if the determination in step S12 determines that the mode is the switch operation mode rather than the balancer mode (No), the control unit 100 proceeds to step S30, which will be described later.

[0043] If it is determined in step S12 that the balancer mode is selected (Yes), the setting information (memory 101) from steps S02 and S03 is referenced to determine whether or not driving the drive motor 40 in the winding direction is "enabled" (step S13). If it is determined that driving the drive motor 40 in the winding direction is not possible (No), the balancer mode (torque control) involving winding and unwinding of the drive motor 40 cannot be executed, and therefore a stop process is performed to stop the balancer mode (step S14). The stop process in step S14 includes a process of switching the operation mode memory from "balancer mode" to "switch operation mode." After this stop process, the process proceeds to step S23 (see FIG. 7), which will be described later.

[0044] On the other hand, if it is determined in step S13 that the drive motor 40 can be driven in the winding direction (Yes), the setting information (memory 101) in steps S05 and S06 is referenced to determine whether or not the drive motor 40 can be driven in the winding down direction (step S15). If it is determined in this determination that the drive motor 40 cannot be driven in the winding down direction (No), the balancer mode (torque control) involving winding up and down of the drive motor 40 cannot be executed, and therefore the stop processing of step S14 described above is performed.

[0045] If it is determined in step S15 that drive in the winding down direction is "enabled" (Yes), the control unit 100 outputs a torque control mode (balancer mode) command to the driver 110 (servo driver) and executes (continues) drive control in the balancer mode (step S16). When executing the balancer mode, the following values ​​of motor torque Tm0, operating force Ws by the operator, and increased / decreased motor torque Th are calculated. This calculation is performed based on the following formula. Note that the units below can be converted as appropriate. Note that steps S16 to S22 correspond to the torque control step, but other steps related to drive control of the drive motor 40 may also be included in the torque control step. Step S16 also corresponds to the setting step.

[0046] First, let wcm (kg) be the weight of the wound load chain C1, wc0 (kg) be the unit weight of the load chain C1, L (m) be the payout length of the load chain C1, and L0 (m) be the total length of the load chain C1. Then, wcm can be calculated as follows: wcm = wc0 × (L0 - L) ... (Equation 1)

[0047] The weight of the hoisting machine main body 20 is defined as wh (kg). Note that this wh does not include the weight of the load chain C1. The load measured by the load sensor 90 (load cell) is defined as Wl (N), and the gravitational acceleration is defined as g. Then, using Equation 1, the load w to be hoisted can be calculated as follows: w = Wl / g - (wh + wcm) (Equation 2)

[0048] If the load value (set value) of the load sensor 90 stored in the memory 101 at the start of the balancer mode is WlO (N), the set load wO to be hoisted is calculated as follows. Of the setting steps, the step of writing the load value (set value) WlO into the memory 101 at the start of the balancer mode is the set weight setting step. The load value (set value) WlO may be written into the memory when a signal from the operation mode changeover switch 151 is confirmed in the above-mentioned step S11, that is, before switching to the balancer mode executed in step S16, and the set weight setting step may also be called the setting step. wO = WlO / g - (wh + wcm) ... (Equation 3)

[0049] Here, according to (Equation 1), w0, the set load to be hoisted, fluctuates depending on the payout length L of the load chain C1. Therefore, to prevent w0, the set load to be hoisted, from fluctuating depending on the payout length L of the load chain C1, it may be divided into two parts and stored in memory 101: (A) "the part of the load chain C1 corresponding to the payout length L," which is the part where the load fluctuates, and (B) the remaining part. Note that if the weight of (A) "the part of the load chain C1 corresponding to the payout length L" is small enough to be ignored compared to w0, the weight of (A) may be ignored.

[0050] Here, the force with which the operator lifts or pushes down on the load P, the cylinder operating device 150, or the lower hook 160 is defined as the operating force Ws (N). This operating force Ws is calculated as follows: Ws = WlO - Wl (Equation 4) In Equation 4, when the operator tries to lift the load P or the like, the load Wl measured by the load sensor 90 becomes smaller (lighter) than the set value WlO, so the operating force Ws is positive. On the other hand, when the operator tries to push down the load P or the like, the load Wl measured by the load sensor 90 becomes larger (heavier) than WlO, so the operating force Ws is negative.

[0051] In the balancer mode, the motor torque Tm0 (Nm) of the drive motor 40 that balances the set load w0 (kg) to be hoisted is calculated by the following formula, where i is the reduction ratio of the reduction mechanism 50 and r (m) is the radius of action of the load sheave 70. The motor torque Tm0 corresponds to the balance torque. Tm0 = (1 / i) x r x g x w0 (Formula 5)

[0052] The formula for calculating the increased or decreased motor torque Th (Nm) of the drive motor 40 from the operating force Ws is as follows: Th=(1 / i)×r×Ws (Formula 6)

[0053] As described above, in step S16, the motor torque Tm0, operating force Ws, and increasing / decreasing motor torque Th that balance the set load w0 to be hoisted, which was set and registered at the time the balancer mode was started, are determined. Then, in step S17, it is determined whether the length L of the load chain C1 unwound from the load sheave 70 is equal to or less than the balancer upper limit length UL (or equal to or greater than the balancer upper limit position in terms of the lifting position). Here, the length L of the load chain C1 unwound from the load sheave 70 is the distance between the upper limit position MT1 at which the upper limit switch 80 activates and the top of the cylinder operating device 150, as shown in FIG. 8 . The balancer upper limit length UL is the distance between the upper limit position MT1 at which the upper limit switch 80 activates and the balancer upper limit position MT2, which is the upper limit position in the balancer mode.

[0054] The balancer upper limit position MT2 is a software-defined upper limit position for the lift of the cylinder operating device 150 (the lower hook 160 and the load P). The balancer upper limit position MT2 may be determined by user settings or calculated using a predetermined calculation formula. When the balancer upper limit position MT2 is determined each time by user settings, it can be set using the switch operation mode described below.

[0055] If, in the judgment of step S17 above, it is determined that the payout length L of the load chain C1 is less than the balancer upper limit length UL (if Yes), then it is determined whether the operator's operating force Ws calculated by (Equation 4) is greater than 0 (positive) (step S18).

[0056] That is, as described in the above (Equation 4), when the operating force Ws is positive, the operator is applying force to the load P in the direction of lifting the load P (hoisting direction). Therefore, when it is determined in step S18 that the operator's operating force Ws is greater than 0 (positive), the control unit 100 creates a torque command value Tm shown in the following equation (7) (step S19). Tm = Tm0 - Kl × Th (Equation 7)

[0057] In this way, the lifting position range of the load P is set to a position range above the balancer upper limit position MT2, and within this set position range, it is determined whether or not to perform restriction control depending on the direction of the operating force Ws.If restriction is necessary, the torque command value Tm calculated using equation (7) is output from the control unit 100 to the driver 110 (servo driver) to control the torque of the drive motor 40.

[0058] The control unit 100 then outputs the generated torque command value Tm to the driver 110, and the driver 110 drives the drive motor 40 with power based on the torque command value Tm. The torque command value Tm calculated by (Equation 7) corresponds to the second torque command value, and the value of "-Kl x Th" in (Equation 7) corresponds to the cancel torque. As described above in (Equation 4), the value of "-Kl x Th" becomes a negative value when the operator applies a force in a direction lifting the load P and a positive value when the operator applies a force in a direction pushing the load down. Adding the cancel torque "-Kl x Th" to the motor torque Tm0, which balances the set load w0 to be hoisted, can restrict the lifting and lowering of the load P. However, if the answer to step S18 is Yes, since the operating force Ws is positive (greater than 0), the value of "-Kl x Th" becomes a negative value based on (Equation 6).

[0059] In the above formula, Kl is a gain that represents the amplification factor, but if the value of gain Kl is less than the mechanical efficiency (η), the motor torque value corresponding to the torque command value "-Kl x Th" of the torque command value Tm generated by the drive motor 40 in response to the operating force Ws of the operator will become small and will be overwhelmed by the operating force Ws, which may result in insufficient position regulation. Therefore, it is preferable and reliable to set the value of gain Kl to be equal to or greater than the mechanical efficiency (η), for example, "1."

[0060] In equation (7), the increased or decreased motor torque Th corresponding to the operator's operating force Ws is subtracted from the motor torque Tm0 of the drive motor 40 in a balanced state. Therefore, even if the operator tries to lift the load P with the operating force Ws, the drive motor 40 is driven with the torque command value Tm in a state where the operating force Ws is canceled. Therefore, the load P will not move in the lifting direction despite the operator's attempt to lift it.

[0061] Depending on the specifications of the hoist 10, the value of "-Kl x Th" may be set to a fixed value on the upper and lower limit sides to an extent that allows the operator to recognize that the balancer upper limit position MT2 or the balancer lower limit position MB2 has been reached, i.e., to an extent that the operation feels heavy or even heavier.

[0062] After step S19, the control unit 100 performs a determination in step S23, which will be described later.

[0063] Also, if it is determined in step S17 that the payout length L of the load chain C1 is greater than the balancer upper limit length UL (below the balancer upper limit position MT2 based on the lifting position) (No), then it is determined whether the payout length L of the load chain C1 is greater than the balancer lower limit length LL (below the balancer lower limit position MB2 based on the lifting position) (step S20).

[0064] 8, the balancer lower limit length LL is the length (distance) between the upper limit position MT1 at which the upper limit switch 80 operates and the balancer lower limit position MB2, which is the lower limit position in the balancer mode. The range between the balancer upper limit position MT2 and the balancer lower limit position MB2 corresponds to the first position range and the balancer intermediate position range. The range between the upper limit position MT1 and the balancer upper limit position MT2 and the range between the lower limit position MB1 and the balancer lower limit position MB2 correspond to the second position range.

[0065] The balancer lower limit position MB2, like the balancer upper limit position MT2, is a software lower limit position for lowering (paying out) the cylinder operating device 150 (the lower hook 160 and the load P) (paying out the load chain C1). The balancer lower limit position MB2 is located above the lower limit position MB1 at which the lower limit switch 81 activates. The balancer lower limit position MB2 may be determined by user settings or calculated using a predetermined formula. Preferably, the signal from either the upper limit switch 80 or the lower limit switch 81 serves as a reset signal for the reference position of the payout length (lifting position) of the load chain C1. However, depending on the specifications of the hoist 10, neither the upper limit switch 80 nor the lower limit switch 81 is an essential component, and only the balancer upper limit position MT2 or the balancer lower limit position MB2 may be set.

[0066] In the judgment of step S20 above, if it is determined that the payout length L of the load chain C1 is equal to or greater than the balancer lower limit length LL (based on the lifting position, equal to or less than the balancer lower limit position MB2) (if Yes), then it is determined whether the operator's operating force Ws is less than 0 (negative) (step S21).

[0067] That is, as described in the above (Equation 4), when the operating force Ws is negative, it means that the operator is applying force to the load P in a direction that pushes down the load. Therefore, when it is determined in step S21 that the operator's operating force Ws is less than 0 (negative), the control unit 100 proceeds to the above-mentioned step S19. That is, the torque command value Tm shown in (Equation 7) is created.

[0068] Then, the control unit 100 outputs the generated torque command value Tm to the driver 110, and the driver 110 drives the drive motor 40 with power based on the torque command value Tm.

[0069] When a load is pushed down, the sign of Th is opposite to that when the load is lifted. Therefore, in (Equation 7), when "-Kl x Th" corresponding to the operator's operating force Ws is added to the motor torque Tm0 of the drive motor 40 in a balanced state, the drive motor 40 is driven at a torque command value Tm in a state where the operating force Ws pushing down the load is canceled. Therefore, the load P will not move in the downward direction, even though the operator is trying to push it down (lower the load).

[0070] In this way, the lifting position range of the load P is set to either or both of the position ranges above the balancer upper limit position MT2 and the balancer lower limit position MB2, and it is determined in steps S17 and S20 whether the load P is within the set position range (corresponding to the lifting position range confirmation step). Then, in steps S18 and S21, it is determined whether or not to perform restriction control depending on the direction of the operating force Ws within the set position range. If restriction is required, in step S19, the torque command value Tm calculated using (Equation 7) is output from the control unit 100 to the driver 110 (servo driver) to control the torque of the drive motor 40 (corresponding to the first / second balancer mode selection step).

[0071] Furthermore, depending on the specifications of the hoist 10, the value of "-Kl x Th" may be set to a fixed value on the upper limit side and the lower limit side to an extent that the operator can recognize that the balancer upper limit position MT2 or the balancer lower limit position MB2 has been reached, i.e., to an extent that the operation feels heavy.

[0072] Furthermore, if the judgment in step S20 above determines that the payout length L of the load chain C1 is smaller than the balancer lower limit length LL (above the balancer lower limit position MB2 based on the lifting position) (No), the control unit 100 determines whether the length L of the load chain C1 is equal to or smaller than the upper limit damping length UD (step S22).

[0073] Here, the upper limit damping length UD is the length (distance) between the upper limit position MT1 at which the upper limit switch 80 operates and the upper limit damping start position MT3 at which the assist force in the direction to lift the load P (hoisting direction) is gradually weakened. In the following description, the region between the balancer upper limit position MT2 and the upper limit damping start position MT3 is referred to as the upper limit damping region UAR. In this embodiment, this upper limit damping region UAR coincides with a speed deceleration region (upper speed deceleration region USR; described below) that forcibly decelerates the speed at which the load P advances in the direction to be lifted (hoisting direction). However, the upper speed deceleration region USR and the upper limit damping length UD may not coincide with each other and may be set to be separate regions.

[0074] If, in the judgment of step S22 above, it is determined that the length L of the load chain C1 is greater than the upper limit damping length UD (if Yes), the control unit 100 then determines whether the operator's operating force Ws calculated by (Equation 4) is greater than 0 (positive) (step S23), as in step S18.

[0075] If it is determined in step S23 that the operating force Ws is equal to or less than 0 (No), the process proceeds to step S24, which will be described next. On the other hand, if it is determined in step S23 that the operating force Ws is greater than 0 (Yes), the process proceeds to step S27, which will be described later.

[0076] Furthermore, if the judgment in step S22 above determines that the length L of the load chain C1 is greater than the upper limit damping length UD (if No), and if the judgment in step S23 determines that the operating force Ws is 0 or less (if No), the control unit 100 then determines whether the length L of the load chain C1 is greater than or equal to the lower limit damping length LD (step S24).

[0077] Here, the lower limit damping length LD is the length (distance) between the upper limit position MT1 at which the upper limit switch 80 operates and the lower limit damping start position MB3 at which the assist force in the direction pushing down the load P (the lowering direction) is gradually weakened. In the following description, the region between the balancer lower limit position MB2 and the lower limit damping start position MB3 is referred to as the lower limit damping region LAR. In this embodiment, this lower limit damping region LAR coincides with a speed deceleration region (downward speed deceleration region LSR; described below) that forcibly decelerates the speed at which the load P advances in the direction pushing down (the lowering direction). However, the downward speed deceleration region LSR and the lower limit damping region LAR may not coincide with each other and may be set to be separate regions.

[0078] Furthermore, if it is determined in the judgment of step S24 above that the length L of the load chain C1 is greater than or equal to the lower limit damping length LD (if Yes), the control unit 100 determines whether the operator's operating force Ws calculated by (Equation 4) is less than 0 (negative) (step S25), as in step S21.

[0079] If it is determined in step S25 that the operating force Ws is equal to or greater than 0 (No), the process proceeds to step S26, which will be described next. On the other hand, if it is determined in step S25 that the operating force Ws is less than 0 (Yes), the process proceeds to step S27, which will be described later.

[0080] Furthermore, if it is determined in step S24 that the length L of the load chain C1 is smaller than the lower limit damping length LD (if No), and if it is determined in step S25 that the operating force Ws is equal to or greater than 0 (if No), the control unit 100 creates a torque command value Tm as shown in the following (Equation 8) and transmits it to the driver 110 (step S26). Note that the torque command value Tm in the following (Equation 8) corresponds to the first torque command value. Also, this step S26 corresponds to the balance control step. Tm = Tm0 + Kh × Th (Equation 8) Note that in the above (Equation 8), "Kh × Th" corresponds to the assist torque.

[0081] In the above equation, Kh is a gain representing the amplification factor, which is determined experimentally in consideration of the mechanical efficiency of the drive motor 40, acceleration, etc. This gain Kh is set to a value sufficiently larger than 1, for example, so that the ratio of the value of Kh×Th to Tm0 is approximately 5 to 20%, in order to improve operability in balancer mode. Note that Kh during winding and Kh during winding down may be different values, for example, winding Khu may be smaller than winding down Khd.

[0082] As is clear from equation (8), the control unit 100 calculates the torque command value Tm by adding the assist torque "Kh x Th" obtained by multiplying the motor torque Th corresponding to the operating force Ws by a predetermined gain Kh to the motor torque Tm0 of the drive motor 40 that balances with the set load w0 to be hoisted. Therefore, the load P can be moved up and down with a light force.

[0083] In this way, the torque command value Tm is output from the control unit 100 to the driver 110 in the first balancer mode, where it is calculated using (Equation 8) or (Equation 10) described later when assisting, and in the second balancer mode, where it is calculated using (Equation 7) when not assisting. Furthermore, since the lifting position ranges controlled in the first balancer mode and the second balancer mode can be set and registered, it becomes possible to restrict the direction of winding up and down at the balancer upper limit position MT2 and / or balancer lower limit position MB2 without interrupting torque control of the drive motor 40.

[0084] Furthermore, when the load P is being lifted (hoisting command operation), if the payout length L of the load chain C1 exceeds the balancer upper limit length UL but is equal to or less than the upper limit damping length UD (if the upper end of the cylinder operating device 150 is located within the upper speed deceleration region USR), the upper end of the cylinder operating device 150 will immediately reach the balancer upper limit position MT2, which is the software upper limit position. If the load P is being lifted upward in this upper speed deceleration region USR, the load P will be suddenly decelerated or stopped when the upper end of the cylinder operating device 150 reaches the balancer upper limit position MT2.

[0085] Similarly, when the load P is being pushed down (lowering command operation), if the payout length L of the load chain C1 is shorter than the balancer lower limit length LL but equal to or greater than the lower limit damping length LD (when the upper end of the cylinder operating device 150 is located within the downward speed deceleration region LSR), the upper end of the cylinder operating device 150 will immediately reach the balancer lower limit position MB2, which is the soft lower limit position. If the load P is pushed down in this downward speed deceleration region LSR, the load P will be suddenly decelerated or stopped when the upper end of the cylinder operating device 150 reaches the balancer lower limit position MB2.

[0086] Therefore, when the upper end of the cylinder operating device 150 enters the upper speed deceleration region USR, which is located in front of the balancer upper limit position MT2 (lower position), and the lower speed deceleration region LSR, which is located in front of the balancer lower limit position MB2 (upper position), it is preferable that the control unit 100 controls the drive motor 40 so as to forcibly decelerate the load P.

[0087] Therefore, the control unit 100 performs deceleration processing of the drive motor 40 (step S27) when the load P is being lifted (a hoisting command operation) and the operating force Ws is determined to be greater than 0 in the judgment of step S23 (if Yes). The control unit 100 also performs deceleration processing of the drive motor 40 in step S27 when the load P is being pushed down (a lowering command operation) and the operating force Ws is determined to be less than 0 in the judgment of step S25 (if Yes). The image of the speed deceleration in the upper speed deceleration region USR and the lower speed deceleration region LSR is as shown in Figure 9. Although Figure 9 shows a state in which the speed is decelerated proportionally, the drive motor 40 may be controlled so that the speed is decelerated in a state other than proportional speed deceleration.

[0088] Furthermore, in this embodiment, as described above, the upper speed deceleration region USR is made to coincide with the upper limit attenuation region UAR, so that when the upper end of the cylinder operating device 150 is in the upper speed deceleration region USR, the upper end of the cylinder operating device 150 will also be in the upper limit attenuation region UAR. Furthermore, in this embodiment, as described above, the lower speed deceleration region LSR is made to coincide with the lower limit attenuation region LAR, so that when the upper end of the cylinder operating device 150 is in the lower speed deceleration region LSR, the upper end of the cylinder operating device 150 will also be in the lower limit attenuation region LAR.

[0089] Therefore, in addition to the deceleration process of the drive motor 40 in step S27, the control unit 100 generates a torque command value Tm as shown in the following (Equation 9) (step S28): Tm=Tm0+Kh'×Th (Equation 9) Note that the process of step S28 may be performed before the process of step S27.

[0090] Here, Kh' in the above (Equation 9) is a coefficient for providing a torque command value Tm that changes in the upper limit damping region UAR or the lower limit damping region LAR, as shown in Figures 10A and 10B. Therefore, as is clear from a comparison with the above (Equation 8), the coefficient Kh' is a variable that varies depending on the position within the upper limit damping region UAR or the lower limit damping region LAR, unlike the coefficient Kh, which is a fixed value. Note that in Figures 10A and 10B, Kh' is a variable that changes the torque command value Tm linearly within the upper limit damping region UAR or the lower limit damping region LAR. However, Kh' may be a variable that causes a change other than a linear function, such as an exponential function.

[0091] When the torque command value Tm as shown in Equation 9 is transmitted to the driver 110 to control and drive the drive motor 40, the assisting force provided by the drive motor 40 to assist the operating force Ws gradually weakens as the upper end of the cylinder operating device 150 approaches the balancer upper limit position MT2 or the balancer lower limit position MB2. Moreover, the decrease in the assisting force occurs whether the moving speed of the load P is high or low.

[0092] Therefore, the operator feels an increasing heaviness in the response when applying the operating force Ws to the load P as the load approaches the balancer upper limit position MT2 or the balancer lower limit position MB2. This allows the operator to intuitively understand that the upper end of the cylinder operating device 150 (load P) is approaching the balancer upper limit position MT2 or the balancer lower limit position MB2, not only when the load P is moving at high speed but also when the load P is moving at low speed.

[0093] After executing the processes of steps S10, S14, S19, S26, and S28, the control unit 100 determines whether to stop the drive control of the drive motor 40, which is in the balancer mode or switch operation mode, in response to an abnormality signal or input of a command (not shown) (step S29). If it is determined that the drive control should be stopped (Yes), the control unit 100 transitions to a process (not shown), such as a maintenance mode, based on the command, and terminates the drive control program. On the other hand, if it is determined in step S29 that the drive control should not be stopped (continue) (No), the control unit 100 returns to the determination of step S01 and continues the drive control.

[0094] Next, the switch operation mode will be described. If it is determined in step S12 that the balancer mode is not selected (No), the switch operation mode is executed (continued) (step S30). That is, an execution program for the switch operation mode is read from the memory 101, and a command for the speed control mode is output to the driver 110 (servo driver).

[0095] Next, the control unit 100 checks the displacement sensor 153 provided in the cylinder operating device 150 (step S31). That is, the position of the movable grip 152 is confirmed by the displacement sensor 153. Then, the winding-up and winding-down are set based on the sliding position of the movable grip 152.

[0096] Next, the control unit 100 refers to the setting information (memory 101) from steps S02 and S03 to determine whether or not the drive motor 40 can be driven in the film winding direction (step S32). That is, the same determination as in step S13 is made. If it is determined in step S32 that the drive motor 40 cannot be driven in the film winding direction (No), the control unit 100 determines whether or not a command to perform film winding has been issued (step S33). That is, this determination is made based on the confirmation result (memory 101) of whether or not the movable grip 152 has been slid in the film winding direction in step S31.

[0097] Here, it has already been determined in step S32 that the drive motor 40 on the winding side cannot be driven, i.e., it is "impossible." Therefore, if it is determined in step S33 above that a command to wind up has been issued (if Yes), processing is then performed to stop the drive motor 40 in the winding direction and to activate the brake mechanism 60 (step S34).

[0098] On the other hand, if it is determined in step S32 that the drive motor 40 can be driven in the film winding direction (Yes), and if it is determined in step S33 that there is no command to wind the film (No), the control unit 100 then refers to the setting information (memory 101) in steps S05 and S06 to determine whether or not the drive motor 40 can be driven in the film winding direction (step S35). That is, the control unit 100 makes the same determination as in step S15. If it is determined in step S35 that the drive motor 40 cannot be driven in the film winding direction (No), the control unit 100 determines whether or not there is a command to wind the film (step S36). That is, the control unit 100 makes this determination based on the result of the determination (memory 101) in step S31 of whether or not the movable grip 152 has been slid in the film winding direction.

[0099] Here, it has already been determined in step S35 that the drive motor 40 on the winding side cannot be driven, i.e., "impossible." Therefore, if it is determined in step S36 above that a command to wind up has been issued (Yes), processing is then performed to stop the drive motor 40 in the winding direction and to activate the brake mechanism 60 (step S37).

[0100] On the other hand, if it is determined in step S35 that the drive motor 40 can be driven in the winding direction (Yes), the control unit 100 creates a speed command and outputs it to the driver 110 (step S38). This speed command is created based on the value of the memory 101 that stores the detection signal from the displacement sensor 153 that detects the sliding position of the movable grip 152 in step S31.

[0101] Next, regarding the driving range of the drive motor 40, it is determined whether or not there is a need (request) to set an upper limit length UL and a lower limit length LL as shown in Figure 8 (step S39). That is, depending on the operating environment of the cylinder operating device 150, it may be preferable to change the software settings of the upper limit position and the lower limit position. Therefore, in step S39, whether or not there is a request to set the upper limit length UL and the lower limit length LL (resetting) is determined, for example, based on the length of the ON signal from the change-over switch.

[0102] If it is determined in step S39 that the upper limit length UL and the lower limit length LL need to be set (Yes), the upper limit length UL and the lower limit length LL are set (step S40). In other words, the operating range of the cylinder operating device 150 is determined by software. After the processing of step S40, the control unit 100 determines whether to stop (continue) the drive control of the drive motor 40, as described in step S23 above.

[0103] Also, if the judgment in step S39 determines that there is no need to set the upper limit length UL and the lower limit length LL (if No), the control unit 100 determines whether to stop (continue) the drive control of the drive motor 40, as described in step S23 above.

[0104] The above-described control flow is executed when the drive motor 40 of the hoisting machine 10 is driven.

[0105] <3. Effects> As described above, the hoist 10 and the control method for the hoist 10, which raises and lowers a load P by winding up and lowering the load chain C1 from the hoist main body 20, include: a load sheave 70 that is arranged on the hoist main body 20, has the load chain C1 wound around it, and winds up and lowers the load chain C1 in response to its rotation; a drive motor 40 that is arranged on the hoist main body 20 and generates a driving force to rotate the load sheave 70; motor control means (control unit 100 and driver 110) that is arranged on the hoist main body 20 and controls the drive of the drive motor 40; and load detection means (load sensor 90 and part of control unit 100) that detects the load torque applied to the load sheave 70 by the load chain C1 that suspends the load P and the operating force Ws with which the operator operates the load in the winding up and winding down direction.

[0106] The motor control means (control unit 100 and driver 110) can control the drive of the drive motor 40 in a balancer mode in which torque control is performed based on the load torque, and the balancer mode includes a first balancer mode in which the drive of the drive motor is controlled based on a first torque command value (torque command value (Tm) calculated by the above (Equation 8)) to which an assist torque that assists the operating force Ws is added. Furthermore, the motor control means (control unit 100 and driver 110) controls the magnitude of the assist torque to decrease as the movement moves toward the balancer upper limit position MT2 within an upper limit damping region UAR within a predetermined range downward from the balancer upper limit position MT2 in the first balancer mode, and also controls the magnitude of the assist torque to decrease as the movement moves toward the balancer lower limit position MB2 within a lower limit damping region LAR within a predetermined range upward from the balancer lower limit position MB2 in the first balancer mode.

[0107] Therefore, in the balancer mode, when assisting according to the operating force Ws while lifting the load P toward the balancer upper limit position MT2, if a predetermined portion, such as the upper end of the cylinder operating device 150, is located within the upper limit attenuation region UAR, the assist torque (assist force) according to the operating force Ws is reduced as shown in (Equation 9). Therefore, as the load P approaches the balancer upper limit position MT2, the assist force provided by the drive motor 40 to assist the operating force Ws gradually weakens. Therefore, the operator feels a heavier response when applying the operating force Ws to the load P as the load P approaches the balancer upper limit position MT2. This allows the operator to intuitively recognize that the upper end of the cylinder operating device 150 (load P) is approaching the balancer upper limit position MT2, not only when the load P is moving at high speed but also when the load P is moving at low speed. This allows the operator to notice the end of the lifting operation of the load P.

[0108] Furthermore, even when the load P approaches the balancer lower limit position MB2, the assist force provided by the drive motor 40 to assist the operating force Ws gradually weakens. Therefore, the operator feels a heavier response when applying the operating force Ws to the load P as the load P approaches the balancer lower limit position MB2. This allows the operator to intuitively understand that the upper end of the cylinder operating device 150 (load P) is approaching the balancer lower limit position MB2, not only when the load P is moving at high speed but also when the load P is moving at low speed. This allows the operator to notice the end of the load P pushing down.

[0109] Furthermore, in this embodiment, as described above, the assist force provided by the drive motor 40 to assist the operating force Ws gradually weakens as the load P approaches the balancer upper limit position MT2 or the balancer lower limit position MB2. Therefore, even when the load P is moving at a low speed, the decrease in assist force causes the worker to feel a heavier resistance. Therefore, even when the load P is moving at a low speed at which it is difficult to tell whether it is decelerating or not, the worker can intuitively understand that the load P is approaching the balancer upper limit position MT2 or the balancer lower limit position MB2. Therefore, by suddenly stopping or suddenly decelerating the load P when it reaches the balancer upper limit position MT2 or the balancer lower limit position MB2, it is possible to prevent an impact from being applied to the load P.

[0110] In addition, in this embodiment, the motor control means (control unit 100 and driver 110) controls the drive motor 40 to reduce the drive speed as it moves toward the balancer upper limit position MT2 within an upper speed deceleration region USR within a predetermined range downward from the balancer upper limit position MT2 in the first balancer mode, and also controls the drive motor 40 to reduce the drive speed as it moves toward the balancer lower limit position MB2 within a downward speed deceleration region LSR within a predetermined range upward from the balancer lower limit position MB2 in the first balancer mode.

[0111] When control is performed in this manner, when a load P is being lifted, the motor control means (control unit 100 and driver 110) not only controls to weaken the assist force but also controls to reduce the drive speed of the drive motor 40 within the upper speed deceleration region USR, making it possible to stop the load P at the balancer upper limit position MT2 without applying much impact to the load P.

[0112] In this embodiment, the upper limit attenuation region UAR coincides with the upper speed deceleration region USR, and the lower limit attenuation region LAR coincides with the lower speed deceleration region LSR. This reduces the processing load on the control unit 100 compared to when the upper limit attenuation region UAR and the upper speed deceleration region USR do not coincide, and when the lower limit attenuation region LAR and the lower speed deceleration region LSR do not coincide.

[0113] In addition, in this embodiment, the motor control means (control unit 100 and driver 110) performs control to proportionally reduce the magnitude of the assist torque within the upper limit damping region UAR as it moves toward the balancer upper limit position MT2, and also performs control to proportionally reduce the magnitude of the assist torque within the lower limit damping region LAR as it moves toward the balancer lower limit position MB2.

[0114] When controlling in this manner, it is possible to reduce the processing load on the control unit 100 compared to when control other than proportionally reducing the assist torque is performed, such as using an exponential function.

[0115] Furthermore, in this embodiment, the balancer mode includes a second balancer mode that controls the driving of the drive motor 40 based on a second torque command value (torque command value Tm calculated by (Equation 7)) that does not assist the operating force, and when setting the load lifting range, the motor control means (control unit 100 and driver 110) sets a first position range, which is a range in which control is performed in the first balancer mode regardless of whether the direction of the operating force is the winding-up or winding-down direction, and a second position range, which is a range in which control is performed in either the first balancer mode or the second balancer mode, depending on the direction of the operating force, whether it is the winding-up or winding-down direction.

[0116] Therefore, at the balancer upper limit position MT2 and the balancer lower limit position MB2, the second torque command value is calculated based on (Equation 7). Therefore, even at the balancer upper limit position MT2 and the balancer lower limit position MB2, the drive motor 40 is driven based on a torque command value including a torque component in a direction that cancels the operating force Ws, so that the control command for the drive motor 40 does not become complicated. Furthermore, when the drive motor 40 stops at the balancer upper limit position MT2 and the balancer lower limit position MB2, a force greater than or equal to the torque command value is not applied, so that it is possible to prevent unnecessary impacts from being applied to structural parts such as the hoisting machine main body 20.

[0117] <Modifications> Although the embodiments of the present invention have been described above, the present invention can be modified in various other ways, which will be described below.

[0118] In the above-described embodiment, the drive motor 40 is controlled to reduce the speed throughout the entire upper speed deceleration region USR and the lower speed deceleration region LSR. However, for example, the drive motor 40 may be controlled to reduce the speed only in a portion of at least one of the upper speed deceleration region USR and the lower speed deceleration region LSR.

[0119] Furthermore, in this embodiment, the control unit 100 performs control to reduce the assist force (assist torque) as shown in (Equation 9) in both the lifting state of the load P in the upper limit damping region UAR and the pressing state of the load P in the lower limit damping region LAR. However, it is also possible to perform control to reduce the assist force (assist torque) as shown in (Equation 9) only in either the lifting state of the load P in the upper limit damping region UAR or the pressing state of the load P in the lower limit damping region LAR.

[0120] Furthermore, in the above-described embodiment, the calculated values ​​in each of the formulas (Equation 1) to (Equation 9) may be corrected as necessary. For example, heat is generated when the drive motor 40 is used, and the characteristics of the magnets and coil wires that make up the motor change with temperature. Therefore, predetermined corrections may be made to each of the above formulas (Equation 1) to (Equation 9) taking into account these temperature-dependent changes in characteristics.

[0121] Furthermore, in the above-described embodiment, the control unit 100 determines the motor torque Tm0 of the drive motor 40 that balances the set load w0 to be hoisted up, based on (Equation 5). As described above, the set load w0 to be hoisted up is a value calculated from the load (load) Wl0 of the load sensor 90 that is stored in the memory 101 at the start of the balancer mode, as explained in (Equation 3). However, the motor torque Tm0 may also be determined from the load w to be hoisted up that is calculated from the load (load) Wl measured by the load sensor 90 at a predetermined measurement timing, for example, including the present, rather than at the start of the balancer mode.

[0122] When such a load to be hoisted w is used, the formula for calculating the motor torque Tm0 is as follows: Tm0=(1 / i)×r×g×w (Formula 10) The motor torque Tm0 calculated by this (Formula 10) may be substituted into the above-mentioned (Formula 7) and (Formula 8) to calculate the torque command value Tm.

[0123] Furthermore, in the above-described embodiment, the control unit 100 controls the driving of the drive motor 40 at the balancer upper limit position MT2 and the balancer lower limit position MB2 based on (Equation 7). However, since the motor torque Tm0 calculated by (Equation 10) based on the load w to be hoisted is balanced including the operating force Ws, the gain Kl in (Equation 7) may be set to 0. Even if the gain Kl is set to 0 in this way, the lifting or lowering of the load P can be stopped due to the relationship of mechanical efficiency (transmission efficiency).

[0124] Furthermore, in the above-mentioned (Equation 8), the torque command value Tm is calculated by adding the assist torque "Kh x Th" to the motor torque Tm0, but the torque command value Tm may be calculated (Equation 11) so that the torque command value increases or decreases in proportion to the operating force Ws and the motor torque Tm0. Tm = Khr x Ws x Tm0 ... (Equation 11) The torque command value Tm in (Equation 11) is obtained by adding the motor torque "(Khr x Ws - 1) x Tm0" to the motor torque Tm0, and the motor torque "(Khr x Ws - 1) x Tm0" corresponds to the assist torque. Khr is a gain that represents the amplification rate, and is a coefficient that is determined in advance according to the specifications of the hoist.

[0125] By calculating the torque command value Tm using (Equation 11), the load P can be raised or lowered at an acceleration proportional to the operating force Ws within the range permitted by the specifications of the drive motor 40, regardless of the magnitude of the load of the load P. Drive control in balancer mode can be performed by selecting or combining (Equation 8) or (Equation 11) depending on the type of lifting or lowering work for the load P or the load of the load P. The maximum rotation speed (hoisting speed) of the drive motor 40 is set to a predetermined value in advance. Like the gain Kh, the gain Khr may be set to different values ​​for hoisting and lowering, or may be increased or decreased depending on the magnitude of the load of the load P, for example, by reducing the increase in acceleration when the load is above a predetermined value, so as to be set according to the work environment in which the hoist is used.

[0126] 10...hoisting machine, 20...hoisting machine main body, 21...housing, 30...upper hook, 40...drive motor, 41...encoder, 50...reduction mechanism, 60...brake mechanism, 70...load sheave, 80...upper limit switch, 81...lower limit switch, 90...load sensor, 100...control unit (corresponding to part of motor control means), 101...memory, 110...driver (corresponding to part of motor control means), 150...cylinder operating device (corresponding to operating device), 151...operation mode changeover switch, 152...movable grip (operation means and slide means), 153...displacement sensor, 160...lower hook, 170...chain bucket, C1...load chain, L...feeding length, LAR...lower limit damping area, LD...lower limit damping length, LL...lower limit length, LSR...lower speed deceleration area, MT1...upper limit position, MT2...balancer upper limit position, MT3...upper limit damping start position, MB1...upper limit position, MB2...balancer lower limit position, MB3...lower limit damping start position, P...load, UAR...upper limit damping area, UD...upper limit damping length, UL...upper limit length, USR...upper speed deceleration area

Claims

1. A hoist for raising and lowering a load by winding up and down a load chain or rope from a hoist main body, comprising: hoisting means arranged on the hoist main body, around which the load chain or rope is wound and which winds up and down the load chain or rope in response to rotation; a drive motor for generating a drive force for rotating the hoisting means; motor control means for controlling the drive of the drive motor; and load detection means for detecting a load torque applied to the hoisting means by the load chain or rope that suspends the load and an operating force applied by an operator in the direction of winding up and lowering the load, wherein the motor control means is capable of controlling the drive of the drive motor in a balancer mode in which torque control is performed based on the load torque, and the balancer mode includes a first balancer mode in which the drive of the drive motor is controlled based on a first torque command value to which an assist torque that assists the operating force is added, and the motor control means is a hoisting machine, characterized in that, within an upper limit damping region within a predetermined range downward from a balancer upper limit position in the first balancer mode, a control is performed to reduce the magnitude of the assist torque as the balancer moves toward the balancer upper limit position, and, within a lower limit damping region within a predetermined range upward from a balancer lower limit position in the first balancer mode, a control is performed to reduce the magnitude of the assist torque as the balancer moves toward the balancer lower limit position.

2. A hoist as claimed in claim 1, characterized in that the motor control means performs control to reduce the magnitude of the drive speed of the drive motor as the balancer moves towards the balancer upper limit position within an upward speed deceleration region within a specified range downward from the balancer upper limit position in the first balancer mode, and performs control to reduce the magnitude of the drive speed of the drive motor as the balancer moves towards the balancer lower limit position within a downward speed deceleration region within a specified range upward from the balancer lower limit position in the first balancer mode.

3. A hoist according to claim 2, characterized in that the upper limit damping region coincides with the upper speed deceleration region, and the lower limit damping region coincides with the lower speed deceleration region.

4. A hoist as claimed in claim 1, characterized in that the motor control means performs control to proportionally reduce the magnitude of the assist torque as it approaches the balancer upper limit position within the upper limit damping region, and performs control to proportionally reduce the magnitude of the assist torque as it approaches the balancer lower limit position within the lower limit damping region.

5. A hoist as claimed in claim 1, wherein the balancer mode includes a second balancer mode in which the drive of the drive motor is controlled based on a second torque command value that does not assist the operating force, and the motor control means, when setting the lifting / lowering range of the load, sets a first position range in which control is performed in the first balancer mode regardless of whether the direction of the operating force is in the winding up or winding down direction, and a second position range in which whether control is performed in the first balancer mode or the second balancer mode is selected depending on the direction of the operating force in the winding up or winding down direction.

6. A drive control method for a hoisting machine which raises and lowers a load by winding up and lowering a load chain or rope from a hoisting machine main body, comprising: hoisting means which is arranged on the hoisting machine main body, around which the load chain or rope is wound and which winds up and lowers the load chain or rope in response to rotation; a drive motor which is arranged on the hoisting machine main body and generates a drive force for rotating the hoisting means; motor control means which is arranged on the hoisting machine main body and controls the drive of the drive motor; and load detection means which detects the load torque applied to the hoisting means by the load chain or rope which suspends the load and the operating force applied by an operator in the direction of winding up and lowering the load, comprising: a load torque detection step of detecting the load torque by the load detection means; and a torque control step of controlling the drive of the drive motor by the motor control means within a preset lifting position range based on the load torque detected in the load torque detection step, a torque control step of controlling the driving of the drive motor in a balancer mode in which torque control is performed based on the load torque, and the balancer mode includes a first balancer mode in which the driving of the drive motor is controlled based on a first torque command value to which an assist torque that assists the operating force is added; and the torque control step of controlling the magnitude of the assist torque to be reduced as the load moves toward the balancer upper limit position within an upper limit damping region within a predetermined range downward from the balancer upper limit position in the first balancer mode, and further controlling the magnitude of the assist torque to be reduced as the load moves toward the balancer lower limit position within a lower limit damping region within a predetermined range upward from the balancer lower limit position in the first balancer mode.

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