JP7120906B2 - crane - Google Patents

Description

The present invention relates to cranes.

Conventionally, a crane uses a jib catch to lock the abdomen of the boom and the abdomen of the jib in order to maintain the posture of embracing the jib. When swinging out the jib from this jib embracing posture, it is usually done after releasing the locking of the jib catch. It may be damaged by excessive force. As a technology to prevent this, there is a jib breakage prevention function.

As a technology related to the jib breakage prevention function, a jib holding detector that includes a physical switch located at the connection between the tip of the boom and the base of the jib is used. A technique for determining whether the jib is in the embracing posture or the swinging posture is disclosed (for example, Patent Document 1).

Patent No. 2733442

By using the holding detector described in Patent Document 1, it is possible to prevent excessive force from being applied to the member. However, the switch of the jib holding detector described in Patent Document 1 is located at the connecting portion where the tip of the boom and the base end of the jib are connected. will be located in Therefore, in order to readjust the switch in order to correctly detect whether the jib is in the embracing posture or the jib swinging posture, the boom must be lowered again, which takes time.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a technique that facilitates adjustment of a jib damage prevention function.

In order to solve the above problems, a representative crane of the present invention includes a jib, a hoisting force measuring unit for measuring the hoisting force for hoisting the jib, and a winding amount measuring unit for measuring the amount of winding of the hoisting rope. and a control unit that sets a threshold according to the winding amount, and disables the hoisting operation of the jib when the hoisting force reaches the threshold , wherein the control unit controls the winding. setting the threshold to a first value when the amount reaches a specified value, and setting the threshold to a second value smaller than the first value when the winding amount does not reach the specified value. Characterized by
Further, a representative crane of the present invention includes a jib, a hoisting force measuring unit for measuring the hoisting force for hoisting the jib, a jib hoisting angle measuring unit for measuring the hoisting angle of the jib, and a boom hoisting angle. a boom hoisting angle measurement unit that sets a threshold according to the hoisting angle, and a control unit that disables the hoisting operation of the jib when the hoisting force reaches the threshold; The boom hoisting angle measuring unit measures an angle equal to or greater than the angle specified as a posture in which the jib and the boom abdomen are separated from each other. a controller that sets the threshold to a first value when the jib hoisting angle measurement unit measures, and sets the threshold to a second value that is smaller than the first value otherwise.

According to the present invention, it is possible to easily adjust the jib damage prevention function.

It is an external appearance side view of a crane. It is a figure which illustrates the situation which member damage arises. FIG. 4 is an enlarged view of a connecting portion between a tower and a jib; 7 is a flow chart showing an operation example of a conventional jib breakage prevention function. It is a figure which shows the position and structure of the winding amount measurement part of 1st Embodiment. It is a figure explaining direction of a pulse sensor of a 1st embodiment, and arrangement relation. 4 is a flowchart showing an operation example of a jib breakage prevention function of the first embodiment; It is a figure which shows the example of a display of the operation panel with which the cockpit of 1st Embodiment is equipped. FIG. 8 is an external side view of the crane of the second embodiment, showing the position and details of a jib hoisting angle measuring section; FIG. 11 is a flow chart showing an operation example of a jib breakage prevention function of the second embodiment; FIG.

<Schematic configuration of the crane>
FIG. 1 is a diagram showing a schematic configuration of a crane, and is a side view when viewed from the right side of the crane. A crane 100 shown in FIG. 1 is a mobile crane that performs a lifting operation of a load via a hook 6 . The crane 100 has an undercarriage 1 and an upper swinging body 2 mounted on the upper portion of the undercarriage 1 so as to be capable of turning. The upper slewing body 2 has a cockpit 5, a boom 20 that swings vertically, and a jib 30 rotatably supported at the tip of the boom 20. As shown in FIG. In addition, in the posture of the boom 20 and the jib 30 shown in FIG. 1, the surface on the side where each rope is not installed (the right side of the boom 20 and the lower side of the jib 30 in FIG. 1) is the abdomen, and the opposite side ( The left side surface of the boom 20 and the upper side surface of the jib 30 in FIG.

A mast 11 is rotatably supported on the upper revolving body 2 , and a pendant rope 12 connects the tip of the mast 11 and the tip of the boom 20 . A boom hoisting rope 16 is wound between the boom hoisting drum 17 and the tip of the mast 11 . By driving the boom hoisting drum 17 , the boom hoisting rope 16 is wound up or let out, the mast 11 is rotated, and the boom 20 is hoisted via the pendant rope 12 .

A load cell 50 connected to the jib hoisting rope 15 is positioned on the lower back side of the boom 20 . The jib hoisting rope 15 is connected to the jib pendant rope 14 connected to the tip of the jib 30 via a spreader 41 . With this configuration, the load cell 50 functions as a hoisting force measuring unit that can obtain the hoisting force for hoisting the jib 30 by measuring the tension of the jib hoisting rope 15 .

The upper revolving body 2 is also provided with a jib hoisting drum 60 and a front drum 53 . The jib hoisting rope 15 is wound around the jib hoisting drum 60 , and when the jib hoisting drum 60 is driven, the jib hoisting rope 15 is wound up or let out, and the jib 30 is hoisted through the jib pendant rope 14 . Moreover, the suspended load suspended by the hook 6 moves vertically by driving the front drum 53 .

A jib catch 22 for connecting with the abdomen of the jib 30 is provided on the abdomen of the boom 20 . The jib catch 22 locks the abdomen of the boom 20 and the abdomen of the jib 30 when they face each other.

The crane 100 also has a control unit 10 that controls each operation described below. The control unit 10 is a base on which, for example, an arithmetic processing unit, a main storage device, an auxiliary storage device, etc. are installed. Each action is performed.

For example, the posture in which the jib 30 is swung out as shown in FIG. 1 is called a swung out posture. On the other hand, the posture in which the abdomen of the boom 20 and the abdomen of the jib 30 face each other (the posture of FIG. 2A described later) is called the facing posture.

<Example of damage to crane members>
FIG. 2 is a diagram illustrating a situation in which each member of the crane is damaged. FIG. 2A is a schematic diagram showing a situation when the jib 30 is raised from the face-to-face posture to the swing-out posture in the assembly process of the crane 100 (partially omitted). When the abdomen of the boom 20 and the abdomen of the jib 30 are locked by the jib catch 22, originally, the locking by the jib catch 22 is released before the jib 30 is raised and swung out. On the other hand, if for some reason the jib hoisting drum 60 is driven to raise the jib 30 without releasing the locking by the jib catch 22, the tension of the jib pendant ropes 14 is applied to the jib 30 and the boom 20. , jib catch 22, etc., and they may be damaged.

FIG. 2(B) is a diagram showing a state in which the boom 20 is laid down in the process of removing the crane 100. As shown in FIG. When the abdomen of the boom 20 and the abdomen of the jib 30 are locked by the jib catch 22, the jib pendant rope 14 is stretched as the boom 20 tilts forward when the boom 20 is lowered from the standing state. . For this reason, the jib pendant rope 14 is loosened while being laid down, but if the jib pendant rope 14 is not loosened for some reason, the jib 30, boom 20, etc. may be damaged in the same manner as described above.

The control unit 10 has a jib damage prevention function for preventing members such as the jib 30 from being damaged by tension applied to the jib pendant rope 14 . The jib breakage prevention function is a function that disables the winding operation of the jib hoisting rope 15 when the load cell 50 detects a tension equal to or greater than a certain threshold value (for example, 9.0 t) in the swinging posture. In addition, when the abdomen of the jib 30 and the abdomen of the boom 20 are facing each other, if tension is applied to the rope while the abdomens are locked by the jib catch 22, each member will be damaged as described above. there is a possibility. Therefore, the jib breakage prevention function of the present embodiment sets the tension threshold value to a small value (for example, 2.5t) in order to prevent member breakage in the face-to-face posture. Then, when the tension of the rope reaches this small threshold value, the winding operation of the jib hoisting rope 15 is disabled, thereby preventing damage to the member.

<Conventional face-to-face orientation detection method and operation of jib breakage prevention function>
Here, a conventional implementation for detecting whether the abdomen of the jib 30 and the abdomen of the boom 20 face each other or is in a swinging posture will be described. Here, the reference numerals of the crane 100 shown in FIG. 1 are used as they are for explanation.

FIG. 3 is an enlarged view of the connecting portion (region R1 shown in FIG. 1) between boom 20 and jib 30. As shown in FIG. FIG. 3 also shows an enlarged view of the local region R2 when the crane 100 is viewed from the opposite direction (left direction) ("R2 enlarged view" in the figure). The enlarged view of R2 shows a facing posture in which the abdomen of the boom 20 and the abdomen of the jib 30 face each other.

The conventional crane 100 includes a semicircular striker 31 and a limit switch 32 located at the connecting portion between the boom 20 and the jib 30, as shown in the R2 enlarged view. In this configuration, when the abdomen of the boom 20 faces the abdomen of the jib 30 (in the case of the attitude shown in the enlarged view of R2), the striker 31 and the limit switch 32 are out of contact. On the other hand, when the jib 30 rotates about the shaft 33 with respect to the boom 20 and the abdomen of the boom 20 and the abdomen of the jib 30 are separated from each other to enter the swinging posture, the striker 31 and the limit switch 32 come into contact with each other, and the limit is reached. The switch 32 is turned on. The conventional crane 100 detects whether the limit switch 32 is turned on or off to determine whether it is in the face-to-face orientation or the swinging orientation.

FIG. 4 is a diagram showing an operation example of a conventional jib damage prevention function by the control unit 10. As shown in FIG. When the jib hoisting rope 15 is wound up (S001), the controller 10 determines whether the limit switch 32 has come into contact with the striker 31 (S002). If the limit switch 32 is in contact with the striker 31 (S002: Yes), the controller 10 assumes that the jib is in the swinging posture and sets the activation threshold value of the jib damage prevention function to, for example, 9.0t (S003). . On the other hand, when the limit switch 32 is not in contact with the striker 31 (S002: No), the control unit 10 assumes that the state is the face-to-face posture, and sets the activation threshold value of the jib damage prevention function to a value smaller than 9.0t ( Here, it is set to 2.5t) (S004).

The control unit 10 acquires the tension value applied to the jib hoisting rope 15 from the load cell 50, and determines whether this tension value is less than the actuation threshold set in step S003 or step S004 (S005). When the tension value reaches the operation threshold value (S005: No), the control unit 10 disables the winding operation of the jib hoisting rope 15 (S006).

If the tension value has not reached the operation threshold value (S005: Yes), or after disabling the winding operation (after S006), the control unit 10 returns the process to step S001. That is, the control unit 10 repeatedly executes the operation shown in FIG.

<First Embodiment>
Next, the problem in the conventional configuration will be explained, and the aspect of the first embodiment for solving this problem will be explained.

When the crane is relocated to another site, it is necessary to install a suitable boom and jib for the site, so the combination of the boom and jib is changed according to the site. In the conventional configuration described above, the striker 31 and the limit switch 32 are positioned at the joints between the boom and the jib, respectively. It is necessary to adjust the positional relationship in order to make normal contact. Therefore, opportunities for physical adjustment increase.

Moreover, in order to confirm whether contact/non-contact between the striker 31 and the limit switch 32 is performed normally, it is necessary to actually raise the boom 20 and swing out the jib 30 . If contact/non-contact is not performed normally, the striker 31 and the limit switch 32 must be readjusted. However, since the striker 31 and the limit switch 32 are positioned high when the boom 20 is erected, readjustment is necessary. To do this, the boom 20 must be turned down again, which takes time. Moreover, depending on the site, it may be difficult to secure a place to lay down the boom 20 .

In order to solve such a problem, the crane 100 of the first embodiment uses a pulse sensor attached to the jib hoisting drum 60 instead of the conventional striker 31 and limit switch 32 to detect the jib swing, thereby detecting the jib hoisting rope. By detecting the winding amount of 15, jib swing detection is performed. The crane 100 of the first embodiment sets a threshold value for the tension of the jib hoisting rope 15 according to the winding amount, and disables the hoisting operation of the jib 30 when the tension of the jib hoisting rope 15 reaches the threshold value. and control.

FIG. 5A is a diagram showing the arrangement position of the winding amount measuring unit 61 for measuring the winding amount of the jib hoisting rope 15. FIG. FIG. 5B is an enlarged view of the local region R3 shown in FIG.

The winding amount measuring unit 61 is positioned outside the right side surface of the jib hoisting drum 60, as shown in FIG. 5(A). For example, if the jib hoisting drum is arranged near the foot position F (see FIG. 1) of the boom 20, the jib hoisting drum may be positioned on the right side of the jib hoisting drum. In other words, the winding amount measuring section 61 may be arranged at the upper revolving body 2 of the crane 100 or at the foot position of the boom 20 directly connected to the upper revolving body 2 .

The winding amount measuring unit 61 includes two pulse sensors 601 and 602 as shown in FIG. 5B. The pulse sensors 601 and 602 detect unevenness of the fins 62 which are evenly distributed around the jib hoisting drum 60 .

Specific irradiation directions and arrangement relationships of the pulse sensors 601 and 602 will be described with reference to FIG. The pulse sensors 601, 602 are oriented to direct the laser radiation perpendicular to the fins 62 formed on the outer side surface of the jib luffing drum 60, as shown in FIG. 6A.

Also, the positional relationship between the pulse sensors 601 and 602 will be described with reference to FIG. 6(B). When one of the pulse sensors (the pulse sensor 601 in the example of FIG. 6(B)) is positioned at the center of the convex portion, the pulse sensors 601 and 602 (in the example of FIG. 6(B)) In this case, the pulse sensor 602) is positioned at the boundary of the unevenness. With such an arrangement relationship, when the pulse sensor 602 detects that a convex portion has changed to a concave portion while the pulse sensor 601 is detecting a convex portion, the jib hoisting drum 60 rotates in the direction of the arrow A1. It can be determined that Conversely, when the pulse sensor 602 detects that the concave portion has changed to the convex portion while the pulse sensor 601 is detecting the convex portion, it can be determined that the jib hoisting drum 60 is rotating in the direction of the arrow A2. can. Thus, by providing two pulse sensors and arranging them in the positional relationship shown in FIG. Furthermore, the drum dimensions and the machine body dimensions of the jib hoisting drum 60 are stored in advance in the storage device in the control unit 10, and from the rotation amount of the drum detected by the pulse sensor 601 (or the pulse sensor 602), A winding amount (winding length) and a payout amount (payout length) of the jib hoisting rope 15 can be calculated. In this embodiment, the pulse sensor is used to measure the amount of rotation of the jib hoisting drum 60. However, as a means for measuring the amount of rotation of the jib hoisting drum 60, if the amount of rotation of the jib hoisting drum 60 can be calculated, any It may be in such a mode. For example, other means such as attaching a rotary encoder via a flange and using this rotary encoder for measurement may be used.

FIG. 7 is a diagram showing an operation example of the jib damage prevention function in the first embodiment. Each operation shown in FIG. 7 is also repeatedly performed in the same manner as in FIG. Also, each step within the dashed frame shown in FIG. 7 operates in the same manner as steps S003 to S006 in FIG.

When the jib hoisting rope 15 is wound up (S101), the controller 10 determines whether the tension of the jib hoisting rope 15 is greater than or equal to a first predetermined value (S102). This is synonymous with determining whether the jib hoisting rope 15 is in a taut state without slack. Assume it is in tension. In addition, since the tension value detected by the load cell 50 is also related to the weight of the jib hoisting rope 15 and the jib pendant rope 14 itself, the controller 10 adjusts the first predetermined tension as the jib length increases. Set a larger value. In this case, it is assumed that a table in which the length of the jib is associated with the first predetermined value is stored in advance in the storage device within the control unit 10 . The first predetermined value may be input by the operator in the cockpit 5 as an initial value.

If the tension is 0.5t or more (S102: Yes), the control unit 10 uses the winding amount measuring unit 61 attached to the jib hoisting drum 60 to measure the amount of winding of the jib hoisting rope 15. Start or continue the measurement to integrate the amount of winding so far (S103). In this manner, the winding amount measuring section 61 starts measuring the winding amount when the tension of the jib hoisting rope 15 exceeds a first predetermined value (0.5 t in this example) in accordance with the command from the control section 10. Start. The winding amount measuring unit 61 measures the winding amount of the jib hoisting rope 15 by detecting unevenness of the fins 62 of the jib hoisting drum 60 with the pulse sensors 601 and 602 as described above.

On the other hand, if the tension is less than 0.5t (S102: No), the control unit 10 either does not start measuring the winding amount of the jib hoisting rope 15, or resets the integrated value to 0.0m. (S104).

After step S103 or step S104, the control unit 10 determines that the integrated value of the winding amount of the jib hoisting rope 15, that is, the winding amount after the measurement of winding is started is the specified value (here, 0.5 m). ) or more (S105). This specified value (=0.5m) is a value that indicates whether the abdomen of the boom 20 and the abdomen of the jib are separated from each other and has entered the swinging posture. and so on.

When the integrated value reaches 0.5 m (S105: Yes), the control unit 10 treats it as having entered the swinging posture or has already been in the swinging posture, and sets the activation threshold value of the jib damage prevention function to the first value. , for example, 9.0t (S003). On the other hand, when the integrated value does not reach 0.5 m (S105: No), the control unit 10 treats the boom 20 and the jib 30 as facing each other, and sets the activation threshold value of the jib damage prevention function to the above-mentioned A second value smaller than the first value, for example 2.5t, is set (S004).

The control unit 10 acquires the tension value of the jib hoisting rope 15 from the load cell 50 and determines whether this tension value is less than the actuation threshold set in step S003 or step S004 (S005). When the tension value reaches the operation threshold value (S005: No), the control unit 10 disables the winding operation of the jib hoisting rope 15 (S006). As a control for disabling, the control unit 10 may notify the operator in the cockpit 5, or fix the hoisting lever operated by the operator so that the hoisting operation can no longer be performed. may be controlled. Alternatively, the control unit 10 may control the jib 30 not to raise and lower even if the operation of the raising and lowering lever is detected.

FIG. 8 is a diagram showing a display example of the operation panel 501 provided in the cockpit 5, the display of which is controlled by the control unit 10. As shown in FIG. FIG. 8A shows a display example when the tension value of the jib hoisting rope 15 does not exceed the operation threshold value, and FIG. 15 is a display example when the tension value of 15 exceeds the activation threshold. As shown in FIGS. 8A and 8B, this screen includes an upper display bar 801 and a lower display bar 802 .

The display bar 801 at the top indicates a bar area below the activation threshold in green or blue (lightly shaded in FIG. 8), and indicates a bar area in excess of the activation threshold in red (dark shaded in FIG. 8). ing. In other words, the boundary 803 that separates each color serves as the activation threshold. The operator can confirm the current activation threshold by confirming the position of this boundary 803 .

A lower display bar 802 is a bar that indicates the current tension value in a scale. If the current tension value is less than the actuation threshold, the operation panel 501 displays the current tension value by changing the color of the bar to green or blue as shown in FIG. 8(A). On the other hand, if the current tension value is greater than or equal to the actuation threshold, the operation panel 501 displays the current tension value by changing the color of the bar to red, as shown in FIG. 8(B).

In the present embodiment, the notification is given by display, but in addition to this, an audio notification such as a buzzer sound or a warning message, or a combination of display and audio may be used. In addition, the display modes such as the screen and the colors to be used shown in FIG. 8 are merely examples.

Aspects of the first embodiment provide the following advantages.
・Instead of using the conventional limit switch to detect the swing, the winding amount measuring unit 61 provided near the jib hoisting drum 60 is used to detect the swing, thereby reducing the trouble of adjusting the boom by lowering it again. be able to. In addition, since the winding amount measuring unit of the first embodiment is arranged at the upper revolving body of the crane or at the foot position of the boom directly connected to the upper revolving body, the operator can easily perform the adjustment. accessible and easy to make adjustments.
・The monitoring of the amount of winding and unwinding of a rope using a pulse sensor has already been performed for other purposes such as a lift gauge, and this can be used. Therefore, since it is not necessary to provide new parts to implement the first embodiment, the number of parts can be reduced.
・By applying the first embodiment, when the combination of the boom and jib is changed, correction can be made without the physical adjustment of contact/non-contact as with conventional strikers and limit switches. This can be handled by adjusting values and parameters (software adjustment). Therefore, opportunities for physical adjustment can be reduced.

<Second embodiment>
In the second embodiment, the jib hoisting angle is detected and the jib hoisting operation is performed in accordance with the control that disables the jib hoisting operation according to the rope winding amount described in the first embodiment. refers to the control that disables

FIG. 9(A) is a diagram showing the configuration of the crane 100 according to the second embodiment, and FIG. 9(B) shows the details of the region R4 shown in FIG. It is a figure which illustrates a jib hoisting angle measuring part.

The second embodiment has a jib hoisting angle measuring unit 70 that measures the hoisting angle of the jib 30 and a boom hoisting angle measuring unit 80 that measures the hoisting angle of the boom 20 . Positioning the jib hoisting angle measuring unit 70 and the boom hoisting angle measuring unit 80 on the lower side rather than on the upper side reduces the influence of external force such as wind force, thereby increasing the accuracy. Therefore, the jib hoisting angle measuring unit 70 is provided at a position closer to the foot position F1 than the center C1 of the jib 30, and the boom hoisting angle measuring unit 80 is also located closer to the center C2 of the boom 20. , is provided at a position closer to the position F2 of the foot.

The jib hoisting angle measuring unit 70 includes a first angle sensor 701 and a second angle sensor 702 as shown in FIG. 9B. In the second embodiment, the first angle sensor 701 and the second angle sensor 702 are angle measurement units that measure an angle range that is smaller than the range in which the jib 30 can be raised and lowered. Also, the first angle sensor 701 and the second angle sensor 702 are sensors that measure ranges different from each other. The reason why a plurality of angle sensors are provided and the measurement ranges are made different from each other will be described later. The same type of sensor is used for the first angle sensor 701 and the second angle sensor 702, but different types of sensors may be used.

The jib hoisting angle measuring unit 70 also has a belt 703 . The belt 703 is used to prevent the first angle sensor 701 and the second angle sensor 702 from falling, and to bind wiring between each of these angle sensors and the controller 10 along the framework member of the jib 30 .

For the first angle sensor 701, a conventional sensor that is also used as a moment limiter, which is another safety device of the crane 100, is used. It is also assumed that the boom hoisting angle measuring unit 80 also uses the conventionally provided sensor as it is.

In the second embodiment, the angle of the boom 20 with respect to the ground that can be regarded as the standing posture of the boom 20 is defined in advance, and this value is stored in the storage device within the control unit 10 . Here, as an example, this angle with respect to the ground is assumed to be around 89 degrees to 90 degrees. In short, the standing posture refers to the operation angle before swinging out. In addition, the angle of the jib 30 with respect to the ground at which the abdomen of the boom 20 and the abdomen of the jib 30 can be regarded as separated is defined in advance, and this value is similarly stored in the storage device within the control unit 10. . Here, as an example, the angle with respect to the ground is assumed to be around -82.5 degrees to -85 degrees (at this time, the boom 20 is assumed to be in a standing posture). In the second embodiment, when the current ground angle of the boom 20 (referred to as the boom angle) and the current ground angle of the jib 30 (referred to as the jib angle) are equal to or greater than these prescribed angles, the swing attitude is assumed. and That is, in the second embodiment, as an example, if the boom angle is 89 degrees or more and the jib angle is -85 degrees or more, it is assumed to be the swinging posture.

On the other hand, the first angle sensor 701, which is conventionally installed in the jib 30, exclusively measures the jib angle during normal work, so the measurement range is from -15 degrees to 95 degrees with respect to the ground. Therefore, only the first angle sensor 701 cannot detect the angle (=approximately -82.5 degrees to -85 degrees) at which the abdomens are separated from each other. In order to solve this problem, it is possible to use an angle sensor that measures a wider angle, but in this case, the measurement accuracy becomes rough, and it also affects the operation accuracy of the moment limiter, which is another safety device. . Therefore, in the second embodiment, the two angle sensors 701 and 702 are alternately arranged to widen the measurement range of the jib angle without lowering the measurement accuracy. That is, the first angle sensor 701 measures the jib angle when the jib is in the normal work posture, and the second angle sensor 702 measures the jib angle when the jib is swinging out. It should be noted that such an aspect is merely an example. In the second embodiment, as shown in FIG. 9(B), the sensors are installed so that the vertical direction (orientation of the top and bottom) is reversed. The second angle sensor 702 may be installed so as to be able to detect an angle (approximately -82.5 degrees to -85 degrees). In the second embodiment, two angle sensors, the first angle sensor 701 and the second angle sensor 702, are used. A single angle sensor capable of measuring a wide angle range may be used as long as the measurement accuracy is acceptable. Moreover, when using several angle sensors, a part of measurement range of each sensor may overlap.

FIG. 10 is a diagram showing an operation example of the jib damage prevention function in the second embodiment. Each step shown in FIG. 10 is also repeatedly performed in the same manner as in FIGS. 10 are the same as steps S004 to S006 in FIGS. 4 and 7. The steps in FIG.

When the jib hoisting rope 15 is wound up (S201), the control unit 10 acquires measured values from the jib hoisting angle measuring unit 70 and the boom hoisting angle measuring unit 80, respectively. Then, the control unit 10 determines whether the boom angle is 89 degrees or more and the jib angle is -85 degrees or more (S202).

If the determination result in step S202 is affirmative (S202: Yes), the controller 10 treats the abdomen of the boom 20 and the abdomen of the jib 30 as being separated from each other and enters the swinging posture, and activates the jib breakage prevention function. A threshold is set to, for example, 9.0t (S003). On the other hand, if the determination result in step S202 is negative (S202: No), the control unit 10 sets the activation threshold of the jib damage prevention function to 2.5t (S004).

Since the operations of subsequent steps S005 and S006 are the same as those of FIGS. 4 and 7, description thereof is omitted.

In the second embodiment as well, when changing the combination of the boom and jib, it is possible to adjust the correction values and parameters related to the angle sensor (software adjustment). Compared to , the opportunity for physical adjustment can be reduced.

The aspects described in the first and second embodiments above and the conventional aspects using strikers and limit switches may be combined with each other.

In the first and second embodiments described above, the tension of the hoisting rope is measured using the load cell to derive the hoisting force for hoisting the jib. In addition to this, the hoisting force for hoisting the jib may be estimated by measuring the load applied to the jib hoisting drum. good too. A method of indirectly deriving the undulation force by measuring such characteristic data may be employed. In other words, the hoisting force measurement unit of the first and second embodiments measures a value that changes in response to the hoisting force that hoists the jib, and is capable of deriving the hoisting force. It doesn't matter if there is.

As described above, by applying the above embodiment, the operator can easily access the adjustment portion when adjusting the jib damage prevention function. This makes it possible to easily adjust the jib damage prevention function. In addition, opportunities for physical adjustment can be reduced, and correction values, parameters, and the like can be adjusted by software, and from this point of view as well, the jib damage prevention function can be easily adjusted.

10: Control unit 14: Jib pendant rope 15: Jib hoisting rope 20: Boom 22: Jib catch 30: Jib 50: Load cell 60: Jib hoisting drum 61: Winding amount measuring unit 62: Fin 70: Jib hoisting angle measuring unit 80 : Boom hoisting angle measuring unit 100: Crane 501: Operation panel 601: Pulse sensor 602: Pulse sensor 701: First angle sensor 702: Second angle sensor

Claims (5)

jib and
a hoisting force measurement unit that measures the hoisting force that hoists the jib;
a winding amount measuring unit for measuring the winding amount of the hoisting rope;
a control unit that sets a threshold according to the winding amount, and disables the hoisting operation of the jib when the hoisting force reaches the threshold;
has
The controller sets the threshold value to a first value when the winding amount reaches a specified value, and sets the threshold value to be smaller than the first value when the winding amount does not reach the specified value. A crane characterized by a second value. jib and
a hoisting force measurement unit that measures the hoisting force that hoists the jib;
a winding amount measuring unit for measuring the winding amount of the hoisting rope;
a control unit that sets a threshold according to the winding amount, and disables the hoisting operation of the jib when the hoisting force reaches the threshold;
In a crane having
The crane according to claim 1, wherein the winding amount measuring section is arranged at a foot position of an upper revolving body of the crane or a boom directly connected to the upper revolving body. jib and
a hoisting force measurement unit that measures the hoisting force that hoists the jib;
a winding amount measuring unit for measuring the winding amount of the hoisting rope;
a control unit that sets a threshold according to the winding amount, and disables the hoisting operation of the jib when the hoisting force reaches the threshold;
has
The crane, wherein the winding amount measuring unit includes a pulse sensor attached to a jib hoisting drum that pays out or winds the hoisting rope. jib and
a hoisting force measurement unit that measures a hoisting force that hoists the jib;
a winding amount measuring unit for measuring the winding amount of the hoisting rope;
a control unit that sets a threshold according to the winding amount, and disables the jib hoisting operation when the hoisting force reaches the threshold;
has
The crane, wherein the winding amount measuring unit starts measuring the winding amount when the hoisting force exceeds a first predetermined value. A crane according to claim 4 ,
The crane, wherein the control unit sets the first predetermined value to increase as the length of the jib increases.

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