JPS6151491A - Jib derrick device for jib crane - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a jib hoisting device for a jib hoisting crane equipped with an inverter-controlled electric hoisting winch.

- Page [Prior Art] Fig. 2 shows an example of a crane having a hoisting jib. An A-frame 4, a control panel 11, etc. are mounted, and a jib 5 is attached to the front part of the revolving structure 1 so as to be able to rise and fall freely around a jib foot 23. , a priddle 1 hung on a guide sheep 17 at the top of the A frame 4, and further connected to a sheep block 19 at the top of the A frame and the top of the jib 5 via a pendant rope 8.
A plurality of jibs 5 are hung between the jib 8 and the jib 5, and the jib 5 is raised and lowered by the operation of the hoisting winch 3.

Further, the hoisting rope 6 that is wound up and let out by the hoisting winch 2 is attached to a jib point sheep 20 at the top of the jib 5.
, the sheep 21 of the hook 9, and the other jib point sheep 22 at the top of the jib 5, and the end thereof is connected to the jib 5.

In such a lane, when the hoisting rope 7 is wound up at a constant speed by the hoisting winch 3, the horizontal movement speed of the hoisted load is the jib angle θ (the fourth
(see figure) becomes a dog as it becomes larger, and when the jib 5 is near the upright position, the suspended load rapidly approaches the revolving structure 1 and is dangerous. In particular, in a crane in which the driver's seat is located in front of the revolving structure 1, there is a risk that the suspended load will collide with the driver's seat. As a means to solve such problems, a pole change motor or a parent-child motor is used as the drive device for the hoisting winch 3, and a mini-to-sinch is installed that operates when the jib angle reaches a certain angle. There is also a configuration that automatically switches the rotational speed of No. 3 to a lower speed side, but it is not possible to select a speed other than the preset speed. Unfortunately, if the speed of the motor is controlled by inverter control, the operator can manually adjust the speed to solve the problem, but in this case, manual operation is required, which is inconvenient.

[Problem that the invention seeks to solve]

In view of the above-mentioned points, the present invention is to automatically regulate the jib hoisting speed according to the jib angle, and to
1491(2) The purpose is to solve the problem that it is not possible to freely select the ups and downs speed within the specified range.

[Means for solving problems]

In order to solve the above problems, the crane jib hoisting device of the present invention includes an electric motor whose speed is controlled by an inverter device as a drive device of the hoisting winch, and at least one motor that outputs a signal when a preset angle is reached.
The inverter device includes a circuit that transmits power for frequency setting directly to a frequency setting potentiometer when there is no output of the signal emitted by the angle detector; and at least one circuit that transmits a frequency setting power source to a frequency setting potentiometer via a resistor when the signal is output from the frequency setting potentiometer.

[Effect]

With the above configuration, the crane jib hoisting device of the present invention can freely select the hoisting and hoisting speed within the regulated range while regulating the jib hoisting speed in stages according to the jib angle.

〔Example〕

An embodiment of the crane jib hoisting device of the present invention will be described below.
This will be explained with reference to FIGS. 1 to 5.

In the present invention, in the jib crane shown in FIG. It is controlled by.

Here, in a general jib crane, the horizontal movement speed vH of the suspended load when the jib is raised and lowered is (1) to (5)
) can be obtained by solving the equation.

v,, = dR/dt
−(1) d l / d t = V/n
,,, (2)t”=(H-Y
)2+(R+X)2...(3)L"
= H” + R”
...(4) θ= tu-' ()(/R)
...(5) Here, the above (1) to (
Each symbol other than the above in formula 5) means the following, which is also shown in FIG.

-6-,・r R; Horizontal distance t from the center of the jib foot 23 of the jib 5 to the center of the jib point sheep 20; The center of the guide sheep 17 and the jib point sheep 20
Distance V to the center of the hoisting rope 7; Take-up speed n of the hoisting rope 7; Multiply number L of the hoisting rope 7; Length X of the jib 5; From the center of the jib foot 23 to the center of the guide sheep 17 at the top of the A frame 4 horizontal distance Y; jib foot 2
Vertical distance H from the center of 3 to the center of the guide sheep 17 at the top of the A frame 4; Vertical height from the center of the jib foot 23 to the center of the jib point sheave 20 In this embodiment, as a jib angle detector, As shown in FIG. 3, a striker 1 is attached to the end of the jib foot 23.
4 is fixed, and a limit switch 13 is fixed on the rotating body side close to the striker 14. When the jib 5 rotates to a certain angle, the switching lever 13a of the limit switch 13 comes into contact with the striker 14, and the limit switch 13 is fixed. 13 is switched to detect that the jib page 5 has reached a certain set angle.

FIGS. 1(L) and 1(b) show a control circuit for the electric motor 27 for driving the hoisting winch 3 (generally, a squirrel cage induction motor is used as this electric motor),
FIG. 1(,) shows an inverter circuit, and FIG. 1(b) shows a circuit that controls the inverter circuit. The limit switch 13 turns off when a certain set angle is detected],
LS is a relay that is excited when limit switch [3] is turned on.

U is an operation switch SW1.U which instructs the electric motor 27 to rotate in the opposite direction of winding and unwinding of the hoisting rope (that is, in the direction of raising and lowering the tip of the jib, respectively). It consists of a switch SW2 and a potentiometer 25 for commanding the rotation speed, and when the potentiometer 23 is operated with one handle, one of the switches SW1 and SW is turned on depending on the direction of rotation of the electric motor. RU and RD are relays for raising and lowering the jib, respectively. In addition, what is shown by the code|symbol Ka or b of each relay is an a contact or a b contact of each relay.

On the other hand, the inverter device 15 of the electric motor 27 has an input terminal R.
, S, and T, and output variable frequency AC output to the motor 27 through the output terminals U, V, and W, E is the ground terminal, and a is the starting signal self-holding. A relay terminal, b is a frequency setting signal input terminal, C is a common terminal for the control circuit, d and e are rotation direction command input terminals, f and g are control power supply terminals, and h is a start signal input terminal. Numeral 25 is a frequency setting potentiometer that can set the speed of the electric motor 13.

In this circuit, if the limit switch 13 does not detect that the angle of the jib 5 has reached the predetermined set angle, that is, if the angle θ of the jib 5 is below the predetermined angle, Limit switch 13 is in the on state. Therefore, the control power output from the control power supply terminal f is directly input to the potentiometer 25. In this state, when the handle of the operation switch Sae is operated and the switch SW is turned on and turned to the conductive state, the coil of the relay 9-page RU is energized, so each contact RUa of the inverter circuit is closed, the C terminal of the inverter 15 and the C terminal and the h terminal, the C terminal and the d terminal, and the f terminal and the potentiometer 2
5 are brought into conduction, and the motor 27 rotates in a fixed direction (hereinafter this direction will be referred to as the upward direction). This rotational speed is determined by the maximum hoisting speed V of the electric motor 27 depending on how the operating switch handle is turned. You can freely choose up to. Further, when the handle of the operation switch 24 is turned in the opposite direction to turn on the switch SW and become conductive, the coil of the relay RD is energized, so each contact RDa of the inverter circuit is closed, and the C terminal of the inverter 15 is turned on. , the C terminal and the h terminal, the C terminal and the C terminal, and the f terminal and the potentiometer 25 are in a conductive state, and the motor 27 moves in the opposite direction to when the switch SW1 is on (hereinafter, this direction is referred to as the downward direction). Rotate to. This rotational speed is also determined by the maximum hoisting (lowering) speed V of the electric motor 27 depending on how the knob of the operation switch 24 is turned. You can freely choose up to. In addition,
When the coil of relay RU is energized, the b contact RUb connected in series with relay RD opens, and the operation of relay RD on page 10 is prohibited. RDb is opened and operation of relay RU is inhibited.

On the other hand, when the jib angle exceeds the predetermined set angle, the limit switch 13 is turned off, the relay LS is no longer excited, and the control power output from the control power terminal f is transmitted to the potentiometer 23 through the resistor 26. input via The resistance value of this resistor 26 is determined as follows.

First, the potentiometer 2 when the circuit from the control power supply terminal f to the potentiometer 25 does not pass through the resistor 26.
If the output voltage from the potentiometer 25 is El, and the output voltage from the potentiometer 25 via the resistor 15 is R2, then the following equation holds true.

R1 However, R1 is the maximum resistance value of the potentiometer 25, R2
indicates the resistance value of the resistor 26. That is, when the jib angle exceeds the set angle, the frequency set voltage is outputted by R1/(R1+R,) times as much as when the jib angle does not exceed the set angle. Therefore, the set speed is R1/(
R1 + R2), the resistance value of resistor 15 is R
Set it to 2.

By determining the resistance value of the resistor 26 as described above, as shown in FIG. The horizontal movement speed increases rapidly as the working radius becomes shorter (that is, as the jib angle θ increases), but when the jib angle θ exceeds the above-mentioned certain value, the speed is automatically reduced. Curve A allows the speed to be averaged and prevents the speed from increasing rapidly. Note that the operator must press operation switch 2.
By operating the potentiometer 25 of No. 4, the speed can be freely selected within the range where the horizontal movement speed curve A is the maximum speed.

In the above embodiment, the circuit from the control power supply terminal f of the inverter circuit to the potentiometer 25 is two circuits, one directly connected and the other via a resistor, but two or more resistors with different resistance values are connected. By changing the mounting angle with respect to the jib and installing limit switches in the number corresponding to the resistance, the horizontal movement speed of the suspended load can be averaged for each jib angle. I can do it.

〔Effect of the invention〕

As described above, in the present invention, at least one angle detector that outputs a signal when a preset angle is reached is provided, and the inverter device does not output the signal emitted by the angle detector. at least one circuit that conveys the frequency setting power supply to the frequency setting potentiometer directly when the frequency setting potentiometer is in use; By having one circuit, the jib hoisting speed can be regulated and averaged in stages according to the jib angle, and the hoisting speed can be freely selected within the regulated range.

[Brief explanation of drawings]

The drawings show one embodiment of the jib hoisting device of the jib crane of the present invention, FIGS. 1(a) and (b) are control circuit diagrams of the electric motor for jib hoisting, and FIG. 2 is a front view showing the entire jib crane on one page. , Fig. 3 is a front view showing the vicinity of the rotation center of the jib, Fig. 4 is a dimensional diagram of each part of the crane used to explain the principle of the present invention, and Fig. 5 is a jib angle and horizontal movement of a suspended load in one embodiment. FIG. 3 is a diagram showing the relationship with speed in comparison with a conventional example. 3... Lifting winch, 5 river jib, 13... Limit switch, 14... Striker, 15... Inverter device, 25... Potentiometer, 26... Resistor.

Claims (1)

[Claims] An electric motor whose speed is controlled by an inverter device is provided as a drive device for the hoisting winch, and at least one angle detector is provided that outputs a signal when the jib reaches a preset angle, and the inverter device is provided with an electric motor for detecting the angle. one circuit that directly transmits the frequency setting power to the frequency setting potentiometer when there is no output of said signal emitted by the angle detector; and a resistor to the frequency setting potentiometer when there is an output of said signal emitted by said angle detector. and at least one circuit for transmitting power for frequency setting through the hoisting device for a crane.