JPS6030639B2 - horizontal retractable crane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a horizontal retractable crane that uses a hydraulic cylinder for a retractor for horizontally moving a suspended load.

A horizontal retractable crane is used to transport a suspended load at a predetermined location onto a hoist, and it is well known that a retracting device is required to move the suspended load in the horizontal direction.

Conventionally, there are rack and pin type, screw rod and nut type, rope type and hydraulic type as this retracting device, but the most widely used type in recent years is the so-called mechanically driven retracting device of the screw rod and nut type. It is.
This mechanically driven retracting device requires a large number of parts such as a drive motor, pinion, gear, screw nut, rod, etc., and has the drawback that the structure is complicated. For this reason, in a situation where larger cranes are planned, hydraulic type cranes that can simplify and rationalize the structure are attracting attention.An example of a horizontal retractable crane using a hydraulic retracting device. Referring to FIG. 1, reference numeral 1 denotes a mast. A main boom 2 is attached to the mast so that it can be rotated freely, and is connected to a retracting device (hydraulic cylinder) 5 via a pin 3 and a trunnion turtle.

This hydraulic cylinder 5 rotates the main boom 2,
By rotating the top boom IQ, which is rotatably attached to the tip of the top boom IQ, the goods 8 suspended from the rope 9 wound with the sheave gun sound provided at the tip of the top boom turtle 8 are It is configured to release suspended cargo crabs onto the hopper turtle 2 by operating a rope 9 that moves in the horizontal direction.The hydraulic circuit of the hydraulic cylinder 5 is as shown in FIG. During extrusion (when moving in direction C), the operator moves the servo valve in the direction of the dotted arrow using the control lever.

As a result of this movement, the pressure oil discharged from the hydraulic pump group 4 driven via the electric motor 3 is maintained at a constant pressure by the relief valve group. Head side force a inside the hydraulic cylinder box through
supplied to At the same time, the pressure of the pressure oil discharged from the side of the rod inside the hydraulic cylinder is controlled by the pressure control valve 2.
It is returned to the hydraulic tank via the servo valve. Furthermore, when the hydraulic cylinder 5 is retracted (when moving in direction B), when the servo valve 8 is moved in the direction of the solid line arrow, the pressure oil flows in the direction of the solid line arrow and is supplied to the rod side 7b inside the hydraulic cylinder 5. At the same time, the pressure oil in the head side 7a is removed by the pressure control valve 28.
' and is returned to the oil tank via the servo valve group 8.

The operation method of the hydraulic cylinder 5 will be explained with reference to FIG. The hydraulic cylinder 5 is made to extend and contract.This operation allows the main boom 2 connected to the hydraulic cylinder 5 to be raised vertically and the suspended load 8 to be moved horizontally. The operator 22 himself operates the control lever 17 to detect the swing 24 of the load and eliminate the swing 24.

Especially when pulling in, if the suspended load 8 is ore, etc., the hopper 1
It is necessary to stop the swinging 24 of the suspended load 2 on top of the suspended load 2 and allow the suspended load 8 to fall. Therefore, in order to eliminate swinging of the suspended load, the operator not only needs to be skilled, but also because the load applied to the hydraulic cylinder reverses between positive and negative, making the operation of the pressure control valve installed in the hydraulic circuit unstable. There is a risk that this will cause problems in rock farming and significantly impede work efficiency.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a horizontal retractable crane which eliminates the above-mentioned drawbacks and allows the crane to operate smoothly and improve the efficiency of the hydraulic circuit.

The inventor has confirmed through experiments that when starting and stopping a crane, a large impact load is generated when the servo valve is switched by the operator's control lever operation, and that the oil temperature increases during low-speed operation. It was found that the impact load changes with the set pressure of the relief valve, as shown in Fig.

The present invention includes a detector that detects the pressure and expansion/contraction speed of the load acting on the hydraulic cylinder, a pressure oil flow control valve that adjusts the expansion/contraction speed of the hydraulic cylinder according to the detected value of the expansion/contraction speed, and a The present invention is characterized in that it is provided with a calculator that calculates a pressure setting value that defines the driving force of the hydraulic cylinder from the detection gutter, and a pressure control valve that adjusts the hydraulic pressure to match the pressure setting value.

Embodiments of the present invention will be described below with reference to the drawings.

The hydraulic cylinder that operates the main boom is also shown in the figure "When pushing out the hydraulic cylinder 6 (when moving in the C direction), the main solenoid valve 25 and the solenoid valve 2 are operated in the direction of the dotted arrow.

Then, the pressure oil discharged from the hydraulic pump pump driven via the electric motor 3 is transferred to the main solenoid valve 2 as shown by the dotted arrow.
6 is supplied to the head side 7a of the hydraulic cylinder 5 through a check valve 38a and a pilot check valve 3 arranged in parallel with the proportional electromagnetic flow control valve 29'. At the same time, the pressure oil discharged from the rod side 7b of the hydraulic cylinder 5 flows through the pilot check valve 30 opened by the electromagnetic valve 26 and the proportional electromagnetic flow control valve 29, and then merges with the pressure oil from the oil pump 14 again. This is to form a differential circuit to reduce the difference in speed between pushing and retracting, which is caused by the difference in area between the head side 7a and the rod side 7b of the hydraulic cylinder 5.
On the other hand, when the hydraulic seeder 5 is retracted (when moving toward town), the main solenoid valve 25 is operated in the direction of the solid line arrow, contrary to when the hydraulic seeder 5 is pushed in.

Then, the pressure oil discharged from the oil pump 14 flows into the same machine as above in the direction of the solid line arrow, and is supplied to the rod side 7b of the hydraulic cylinder 5. At the same time, the pressure oil discharged from the head side 7a flows through the check valve. 30', proportional solenoid flow control valve 2
9' and the main solenoid valve 25 and returned to the hydraulic tank. When the hydraulic cylinder 5 expands and contracts, the set pressure of the pressure oil discharged from the hydraulic pump 1 is also adjusted by the proportional solenoid pressure control valve 28 combined with the main relief valve 15 for overload prevention and the solenoid valve 27. Ru.

At this time, the pressure of the proportional electromagnetic pressure control valve 28 is set by an electric signal 32' input via the amplifier 3. Furthermore, the speed of expansion and contraction of the hydraulic cylinder 5 is adjusted by the amount of oil supplied to the hydraulic cylinder 6 and the amount of oil discharged. be done. Next, the load acting on the hydraulic cylinder 5 is detected by a load meter 381 attached to the tip of the piston rod 6 of the hydraulic cylinder 5, as shown in FIG. The pressure is detected by seven pairs of pressure detectors 39a and 39b provided on both sides thereof.

Furthermore, the expansion and contraction speed of the hydraulic cylinder 5 is controlled by a screw rod 36 connected to a pick-up tool attached to the tip of the piston rod 6.
1 is converted into a rotation angle ~ This rotation angle is transferred to the speed increaser 3.
7, and the rotation angle change is detected by the speed detector 33. The minute voltages detected by each of the detectors 38, 398, and 39b are introduced into the arithmetic unit 35. Next, the operating method of this embodiment will be explained with reference to FIG. 7.
In response to this detection, the initial input voltage signal 32'a is applied to the amplifier 3.
2a, "This input operates the proportional electromagnetic flow control valves 29, 2@'.

By operating the control valves 29 and 29', the amount of oil from the hydraulic source 23 is regulated and introduced into the hydraulic cylinder 5, causing the hydraulic cylinder 5 to expand and contract. The proportional electromagnetic flow control valves 29, 2
Since the electric signal 32'a input to the hydraulic cylinder 9' is corrected, the hydraulic syringe 5 can be expanded and contracted as operated by the operator 22. Furthermore, the load F of the hydraulic cylinder 5,
The pressures P, , P2 are detected by the detectors 38, 39a, 39b, and the detected values are calculated by the following formula '1' by the calculator 35, and the driving force is adjusted to match the load F acting on the hydraulic cylinder 5. By inputting the input electric signal 32'b corresponding to the operating pressure Po to the proportional electromagnetic pressure control valve 28 via the amplifier 32b, the set pressure P of the hydraulic circuit is adjusted.
The hydraulic cylinder 5 can be operated smoothly by changing o.

P.

= 2 points on tripod...Q1 However, Po: Setting pressure of the hydraulic circuit [of X9] F: Load applied to the hydraulic cylinder [
k9] Flow rate in Qmi piping [Funo S] 1: Piping length [vertical] d; Piping diameter [ka] K; Loss coefficient in piping g: Gravitational acceleration [Node S2] P2: - Hydraulic cylinder head Internal pressure [k9] P. Pressure inside the rod of the hydraulic cylinder [k9 point] Specific gravity of the oil [kg no.] N; Pressure receiving area on the rod side of the hydraulic cylinder [ground] N: Pressure receiving area on the head side of the hydraulic cylinder [ground] '1} formula can be obtained as follows.

First, the pressure inside the rod of the hydraulic cylinder P, and F, P2
The relationship is as follows. P. =Shi(F+P2・A2
)------ '21 Now, considering the case where n=2A, the equation {2) becomes as follows. P. = Mother or 2
--... ■' On the other hand, the set pressure Po of the hydraulic circuit can be obtained from the following equation based on the force balance relationship of the hydraulic circuit.

P.

=P. Tensa fin medium and small... (3'kono'3} formula {2)
By substituting ', we obtain equation {11.

In this way, by determining F, P2, and Q with the detector, the set pressure Po can be determined. Note that P is necessary when determining the set pressure Po in the case of the sheep 2A mentioned above. By controlling the main relief valve 15 using the pressure Po set in this way, it is possible to reduce the shock especially when starting and stopping.The experimental results of this example and the conventional product are The diagrams are as shown in FIGS. 8 and 9, where the broken line A indicates the conventional product and the solid line B indicates the present embodiment.

From this figure, according to this example, the impact load at startup is approximately 1
'3, it is clear that the rise in oil spillage is respectively reduced by about 20%. Figure 10 shows another embodiment, which differs from the above embodiment (Figure 6) in that it includes two proportional electromagnetic flow control valves that adjust the amount of weight supplied to the hydraulic sill during extrusion and retraction. In addition to reducing the number of valves to one, the valve is operated using two simple solenoid valves.

Note that among the symbols shown in FIG. i0, the same symbols as those shown in FIG. 5 indicate the same parts. Next, the operation of this embodiment will be explained.

When the hydraulic cylinder 5 is pushed out (when moving in the C direction), the pressure oil flows as shown by the dotted arrow, and performs the same effect as in the above embodiment.

On the other hand, when the hydraulic cylinder 5 is retracted (when moving in the D direction), the pressure oil flows as shown by the solid arrow. That is, when the main solenoid valve 25 and the solenoid valves 26, 48, and 41 are operated in the direction of the solid arrow, the pressure oil passes through the solenoid valve 25 and the check valve 30 to the rod side of the hydraulic cylinder 5. b. At the same time, the oil discharged from the head side 78 is discharged from the check valve 30'.
Solenoid valve 41, proportional force magnetic flow control valve 29 and main solenoid valve 2
5 and then returned to the oil tank. In this case, the rod side 7b
The pressure oil supplied to the head side 7a and the pressure oil discharged from the head side 7a are completely isolated from the solenoid valve 40' so that they do not merge in the middle of the hydraulic circuit. As described above, even in a hydraulic circuit using one proportional electromagnetic flow control valve 29 and two simple electromagnetic valves 407 and 41, the same effects as in the above embodiment (FIG. 5) can be obtained.

As explained above, the present invention detects the load, pressure, and speed of the hydraulic cylinder, and controls the driving force of the hydraulic cylinder based on the electrical signal from this detected value. In addition to ensuring smooth operation,
It is possible to prevent oil temperature from rising and improve the efficiency of the hydraulic circuit.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a horizontal retractable crane, Figure 2 is a hydraulic circuit diagram of a subordinate hydraulic cylinder used in the crane, Figure 3 is a block diagram of the conventional operation method, and Figure 4 is a hydraulic circuit diagram. Fig. 5 is a diagram showing an example of the hydraulic circuit of the hydraulic cylinder used in the horizontal retractable crane of the present invention, and Fig. 6 is a diagram showing the relationship between the relief setting pressure and the load of the hydraulic cylinder. Circuit diagram for detecting speed "Figure 7 is a block diagram showing the operating method of the crane of the present invention, Figures 8 and 9 are explanatory diagrams, and Figure g0 is a hydraulic diagram showing another embodiment related to the present invention. It is a hydraulic circuit diagram of the cylinder. ...Hydraulic cylinder "28... Proportional electromagnetic pressure control valve ~ 29,2'... Proportional electromagnetic flow control valve ~ 33.
...speed detector, 38...load detector, 3 crab a,
39b... pressure detector. Figure 4 Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Dance Figure 8 Figure Tsutomu q Figure Younger brother '0 figure

Claims (1)

[Claims] 1 A mast, a main boom rotatably attached to the mast, a hydraulic cylinder that pushes out and retracts the main boom in the horizontal direction, and a hydraulic device that supplies pressure oil to drive the hydraulic cylinder. A horizontal retractable crane equipped with a load detector for detecting the load; a flow control valve for adjusting the amount of oil supplied to the hydraulic cylinder according to the output of the speed detector so as to zero the difference between the speed command signal and the output of the speed detector; The output of each of the detectors is taken in, and based on each output value, the set pressure of the hydraulic system is determined such that when the output of the load detector is negative, the set pressure is a small positive value, and the load is detected. The set pressure increases in proportion to the increase in the output of the pressure detector, and further increases or decreases by increasing or decreasing the sum of the value proportional to the output of the pressure detector and the value proportional to the square of the output of the speed detector. A horizontal pressure control valve characterized in that it is provided with a computing unit that calculates the set pressure calculated by the computing unit, and a pressure control valve that adjusts the pressure of the pressure oil supplied to the hydraulic cylinder so that the set pressure calculated by the computing unit is achieved. Retractable crane.