JP2002068667A - Speed control method and apparatus for hydraulic winch of crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a speed control apparatus for a hydraulic winch using a variable displacement motor having no fear of causing hunting of control although a high speed mode and a low speed mode are switched and selected manually when designated conditions are satisfied regardless of the stroke position of a winch operating lever. SOLUTION: In the hydraulic winch of a crane using a variable capacity motor in which the capacity required for one rotation is switched to switch the rotating speed to the supply flow to a high speed mode and a low speed mode, hoist load computed immediately before the start of lowering the winch operating lever by an overload preventing device is stored as an actual operation hoist load until the end of lowering operation. When the actual operation hoist load is smaller than a designated value, the lowering operation is performed and switching to the high speed mode is manually selected, the variable capacity motor is switched from the low speed mode to the high speed mode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed control method for a hydraulic winch using a variable displacement motor capable of switching a rotation required for a supply flow rate between a high speed mode and a low speed mode by switching a capacity required for one rotation. It concerns the device.

[0002]

2. Description of the Related Art As a speed control technique of a hydraulic winch of a crane using a variable displacement motor for driving a winch drum, a technique disclosed in Japanese Patent Application Laid-Open No. 7-187585 is known. From the neutral position of the operation lever to the predetermined stroke, the relationship between the winch drum rotation speed and the stroke is controlled in the same manner in each speed mode.After the predetermined stroke, the speed mode selected once can be switched to another speed mode in the middle. Is what you do. The switching of the speed mode from the low speed to the high speed is made possible when a predetermined condition set in advance is satisfied. As the predetermined condition, there is described a technology that requires that three conditions of an ON signal of a high-speed mode switching button, a pilot valve lowering pilot pressure signal, and a predetermined rope tension signal be simultaneously satisfied. As a method for detecting the tension, a technique using a suspended load obtained via an overload prevention device is described. The rope tension is used as a condition to limit the load to a predetermined light load that allows high-speed work.

[0003]

However, the value of the suspended load obtained through the overload prevention device fluctuates due to the swing of the suspended load accompanying the operation of the winch. The determination changed depending on whether the condition of the tension allowed the high-speed mode or not, and hunting of control sometimes occurred.

Accordingly, the present invention provides a method for manually switching between high-speed mode and low-speed mode when a predetermined condition is satisfied, regardless of the stroke position of the winch operating lever. An object of the present invention is to provide a hydraulic winch speed control device using a variable displacement motor that does not cause hunting.

[0005]

According to a first aspect of the present invention, there is provided a method for controlling the speed of a hydraulic winch of a crane according to the present invention. In a hydraulic winch of a crane using a variable displacement motor capable of operating, the hoisting load calculated immediately before the lowering operation of the winch operating lever by the overload prevention device is stored as the actual operating hoisting load until the lowering operation ends. Then, when the actual working lifting load is smaller than a predetermined value, a lowering operation is performed, and the switching to the high-speed mode is manually selected, the variable displacement motor is switched from the low-speed mode to the high-speed mode. Features.

According to this method, the hoisting load calculated by the overload prevention device immediately before the start of the lowering operation of the winch operating lever is stored as the actual operating hoisting load until the end of the lowering operation, and the actual operating hoisting load is stored. Is used to determine the switching condition to the high-speed mode, so during the winch lowering operation, regarding the condition of the lifting load, the high-speed mode is allowed,
There is no change in the determination that it is not permitted, and there is no possibility that control hunting will occur.

Further, the speed control device for the hydraulic winch of the crane according to the second aspect of the present invention can switch the rotation speed for the supply flow rate between the high speed mode and the low speed mode by switching the capacity required for one rotation. For a hydraulic winch of a crane using a variable displacement motor, the lifting load is calculated from the boom length, the telescopic boom hoisting angle and the boom moment, and the lifting load calculated just before the winch operation lever lowering operation is started. An overload prevention device that stores the actual operation lifting load until the end of the operation, a lowering operation detecting unit that detects a lowering operation of the winch operation lever, and a switch between a high speed mode and a low speed mode can be manually selected. A hydraulic window comprising mode selection means and motor displacement switching means for switching displacement required for one rotation of the variable displacement motor. A speed control device, wherein the speed control device is configured such that the actual load applied by the overload prevention device is smaller than a predetermined value, and the lowering operation detecting unit detects a lowering operation, And outputting a high-speed mode switching signal to the motor displacement switching means when the mode selection means is selected to be in the high-speed mode.

According to this configuration, the overload prevention device calculates the lifting load from the boom length, the boom angle, and the boom moment, and calculates the lifting load calculated immediately before the start of the lowering operation of the winch operation lever. The actual lifting load is stored until the end of the lowering operation, and the actual lifting load is used to determine the conditions for switching to the high-speed mode. Regarding the load condition, the judgment whether the high-speed mode is allowed or not is not changed, and there is no possibility that control hunting will occur.

[0009]

FIG. 1 shows a hydraulic and electric circuit diagram of a speed control device for a hydraulic winch of a crane according to an embodiment of the present invention.

1 is a hydraulic pump for driving the winch, 2 is a relief valve for setting the maximum pressure of the driving oil pressure, 3
Is a pilot operated valve, 4 is a counterbalance valve, and 5 is a variable displacement motor for driving a winch drum. The capacity of the variable displacement motor 5 can be changed by a displacement control cylinder 12.
1 is in the low-speed mode in the state of FIG.

Reference numeral 6 denotes a winding-side oil passage connecting the pilot-type operation valve 3 and the variable hydraulic motor 5, and the counter balance valve 4 is interposed. Reference numeral 7 denotes a lowering-side oil passage that connects the pilot-type operation valve 3 and the variable displacement motor 5. 11 is the upper oil passage 6 or the lower oil passage 7
Among them, a shuttle valve for supplying the hydraulic pressure on the high pressure side to the displacement control cylinder 12, and a hydro valve 13 which is switched by a pilot pressure. When the pilot pressure is not applied, the hydraulic valve 13 communicates the extension-side oil chamber 14 of the displacement control cylinder 12 with the tank. When the pilot pressure is applied, the pressure from the shuttle valve 11 reduces the displacement of the displacement control cylinder 12 to the capacity. Switching is performed so as to act on the extension-side oil chamber 14 of the control cylinder 12. At that time, the variable displacement motor 5 is switched to the high-speed mode.

Reference numeral 21 is a pilot hydraulic pump, 22 is a pressure reducing valve, and 23 is a solenoid switching valve. Reference numeral 24 denotes a pilot oil passage connecting the hydro valve 13 and the solenoid switching valve 23. When the solenoid switching valve 23 is energized, the hydraulic pressure of the pilot hydraulic pump 21 is reduced by the pressure reducing valve 22, Acting on the hydrovalve 13, the hydrovalve 13 is switched.

Reference numeral 25 denotes a winch operating lever, 26 denotes a pilot valve, and 27 denotes a lowering side 3 of the pilot type operating valve 3.
A lower-side pilot oil passage connecting A to the pilot valve 26, and a lower-side pilot oil passage 28 connecting the hoist-side 3B of the pilot-type operation valve 3 to the pilot valve 26.

Reference numeral 30 denotes an overload prevention device, 31 denotes a boom length detector, 32 denotes a boom angle detector, 33 denotes a boom moment detector, and 34 denotes a lowering pressure detector of the lowering-side pilot oil passage 27. Thus, it functions as a lowering operation detecting means. The overload prevention device 30 outputs a high-speed command signal to a high-speed command signal line 35 described later based on signals from the boom length detector 31, the boom angle detector 32, the boom moment detector 33, and the lowering pressure detector 34. I do.

Reference numerals 41 and 42 denote high-speed mode selection switches. Reference numeral 41 denotes a panel switch attached to the operation panel of the cabin. Reference numeral 42 denotes a lever switch attached to the winch operation lever 25. The panel switch 41 is of a self-holding type, while the lever switch 42 is of an automatic resetting type. 43 is a relay coil, 44 is a relay switch driven by the relay coil 43, 45 is an indicator lamp, 46 is a power supply,
47 is an output line to the solenoid switching valve 23.

FIG. 2 is a block diagram of a portion of the overload prevention device 30 related to a hydraulic winch speed control device. Reference numeral 50 denotes a lifting load calculating unit which receives signals of the boom length L, the boom angle θ, and the boom moment M from the boom length detector 31, the boom angle detector 32, and the boom moment detector 33. Receiving and always calculate the lifting load. 55 is an actual operation lifting load calculation unit that receives the lifting load from the lifting load calculation unit 50 and the lowering operation signal from the lowering pressure detector 34;
The actual working lifting load is calculated. In other words, the actual operation lifting load calculation unit 55 sets the lifting load immediately before the lowering operation signal is input as the actual operation lifting load from when the lowering operation signal is input until the lowering operation signal is not input. This is output to the load comparing section 52 described later.

Reference numeral 51 denotes a limit load storage unit which stores a predetermined value and outputs the value to the load comparison unit 52. As the predetermined value, a light load suitable for setting the variable displacement motor 5 to the high speed mode and lowering it at a high speed is set. The load comparing unit 52 compares the actual lifting load output from the actual lifting load calculating unit 50 with the value output from the limited load storage unit 51, and determines that the actual lifting load is a predetermined value. If it is smaller than this, an output signal is output to an output unit 53 described later. The output unit 53 has a built-in switch 54 for connecting the high-speed command signal line 35 to the ground side when the output unit 53 operates, and when the output signal from the load comparison unit 52 is received, the built-in switch 54 is turned on. To operate.

FIG. 3 is a graph showing the relationship between the lower lever stroke of the winch operating lever of the hydraulic winch speed control device and the winch speed.

There is a dead zone between the lever strokes S0 and S1, though the stroke is slight, and the subsequent strokes are related so that the winch speed increases in accordance with the lever stroke. In the low speed mode, the winch speed increases along the line AB during the stroke S1-S2, and does not change between the strokes S2-S3. In high-speed mode, stroke S1
The winch speed increases along the line A-D during -S2, and does not change during the stroke S2-S3.

Since it is possible to switch between the low speed mode and the high speed mode between the lever strokes S1-S3, an area sandwiched between the AC line representing the low speed mode and the AE line representing the high speed mode is defined. This is indicated by hatching with broken lines.

The operation of the hydraulic winch speed control device of the above embodiment will be described below. (When the lifting load is smaller than a predetermined value) When the high speed mode selection switch (41 or 42) is not operated, that is, when the low speed mode is selected, the winch operation lever 2
5 is operated to the lowering side, the pilot operated valve 3
Is switched to the lowering side 3A, and the hydraulic oil from the hydraulic pump 1 is supplied to the variable displacement motor 5 through the lowering side oil passage 7. At this time, since the variable displacement motor 5 is in the low speed mode, the winch speed according to the lever stroke has a relationship represented by the line AC in the low speed mode in FIG.

When the winch operating lever 25 is operated to the lowering side, a pilot oil pressure is generated in the lowering-side pilot oil passage 27.
Outputs a lowering operation signal to the overload prevention device 30. The actual operation lifting load calculation unit 55 inside the overload prevention device 30 illustrated in FIG. 2 calculates the lifting load calculated by the lifting load calculation unit 50 immediately before the input of the lowering operation signal by the input of the lowering operation signal. It is output to the load comparison unit 52 as the actual working lifting load. The load comparing section 52 outputs an output signal to the output section 53 since the actual lifting load is smaller than the predetermined value. The built-in switch 54 built in the output unit 53 is operated, and the high-speed command signal line 35 is connected to the ground.

In this state, the high-speed mode switch (4
1 or 42) is operated and the relay coil 4
3, the power from the power supply 46 flows, and the relay switch 44 is turned on. Power is supplied from the power supply 46 to the solenoid switching valve 23 via the output line 47, and the solenoid switching valve 23 is switched. Then, the pilot hydraulic pressure of the pilot hydraulic pump 21 is applied to the hydro valve 13 via the pilot oil passage 24. When the hydro valve 13 is switched, the hydraulic pressure of the lower oil passage 7 acts on the extension-side oil chamber 14 of the displacement control cylinder 12 to switch the variable displacement motor 5 to the small displacement side where the high-speed mode is set. Since the variable displacement motor 5 rotates at a high speed, the winch speed is high.

To explain the above operation with reference to the graph shown in FIG. 3, the operation is shifted from an arbitrary point P on AC in the low-speed mode to a point Q on AE in the high-speed mode.

During the winch lowering operation in the high-speed mode,
As long as the operation of the winch operation lever 25 toward the lowering side is continued, the high-speed command signal line keeps the ON state of the built-in switch. The ON state is maintained. That is, the overload prevention device 30 shown in FIG.
Even if the lifting load calculated by the internal lifting load calculator 50 fluctuates due to vibration of the lifting load, the actual operation lifting load calculator 55 calculates the lifting load immediately before the lowering operation signal is input. Since the load is output to the load comparator 52 as the actual lifting load, the load comparator 52 continuously outputs an output signal, and the output unit 53 maintains the ON state of the built-in switch 54. Therefore, there is no danger of hunting accompanying the switching of the high-speed command signal line 35.

Switching from the high-speed mode to the low-speed mode is performed by O
N mode high-speed mode changeover switch (41 or 4)
It can be performed by operating 2) to the OFF side. That is, a high-speed mode changeover switch (4 in this case)
1 and 42) are turned off, electricity from the power supply 46 does not flow through the output line 47, and the solenoid switching valve 23 is connected to the pilot hydraulic pump 21.
The hydraulic valve 13 stops applying the hydraulic pressure of the lowering-side oil passage 7 to the extension-side oil chamber 14 of the displacement control cylinder 12. Then, the variable displacement motor 5 is in a low speed mode, that is, has a large capacity and rotates at a low speed.

As described above, switching from the high-speed mode to the low-speed mode is performed by the high-speed command signal line 35 of the overload prevention device.
Can be switched irrespective of the state of. In other words, it is possible to switch regardless of whether the winch operation lever 25 is operated and the lifting load.

The above operation has been described in connection with the case where the winch operation lever 25 is operated to the lowering side and then the high-speed mode selection switch (41 or 42) is selected.
If the winch operation lever 25 is operated to the lowering side after the high-speed mode selection switch is selected and operated first, the electric power of the power supply 46 is connected to the high-speed command signal line 35 immediately after the winch operation lever 25 is operated. Flows, and the operation of the winch in the high-speed mode is performed in the same manner as described above.
That is, in the graph of FIG.
The winch operation along the line -E will be performed. When the high-speed mode selection switch (41 or 42) is not operated (when the lifting load is larger than a predetermined value), the winch speed according to the lever stroke is represented by the low-speed mode line AC in FIG. This is the same as when the lifting load is smaller than the predetermined value.

When the winch operating lever 25 is operated to the lowering side, the load comparing section 52 inside the overload prevention device 30 shown in FIG. No output signal is output to 53. Output unit 5
The internal switch 54 built in 3 is not operated, and the high-speed command signal line 35 is not connected to the ground.

In this state, the high-speed mode switch (4
1 or 42), the electricity from the power supply 46 does not flow through the relay coil 43, so that the relay switch 44
Remains OFF. Accordingly, since the solenoid switching valve 23 is not energized, the variable displacement motor 5 is not switched to the high-speed mode.

As a result, the lowering operation in the high-speed mode with a large lifting load is prevented, so that troubles such as damage to the variable displacement motor 5 due to abnormally high pressure can be prevented.

During the winch lowering operation in the low speed mode, the high speed command signal line 35 maintains the OFF state of the built-in switch 54 as long as the winch operating lever 25 continues to be operated on the lower side. The OFF state of the relay switch 44 is maintained. That is, even if the lifting load calculated by the lifting load calculator 50 inside the overload prevention device 30 shown in FIG. Since the lifting load immediately before the input of the lowering operation signal is output to the load comparing section 52 as the actual working lifting load, the load comparing section 52 does not continuously output the output signal, and the output section 53 is built-in. The OFF state of the switch 54 is maintained. Therefore, the high-speed mode changeover switch (4
Even if (1 or 42) is ON, there is no danger of hunting accompanying switching of the high-speed command signal line 35.

[0033]

As described above, according to the method for controlling the speed of the hydraulic winch of the crane according to the first aspect of the present invention, the overload preventing device immediately before the lowering operation of the winch operating lever is started. The calculated hoisting load is stored as the actual hoisting load until the end of the lowering operation, and the actual hoisting load is used to determine the conditions for switching to the high-speed mode. As a result, the determination of whether the high-speed mode is permitted or not permitted does not change with respect to the condition of the lifting load, and there is no possibility that hunting of control will occur.

According to the speed control device for a hydraulic winch of a crane according to the second aspect of the present invention, the overload prevention device calculates a lifting load from a boom length, a boom hoisting angle and a boom moment, and also calculates a winch. The lifting load calculated immediately before the start of the lowering operation of the operating lever is stored as the actual operating lifting load until the end of the lowering operation, and the actual operating lifting load is used for determining the switching condition to the high-speed mode. Therefore, during the winch lowering operation, regarding the condition of the lifting load, the determination that the high-speed mode is allowed or not is not changed, and there is no possibility that the control hunting occurs. As described above, according to the invention of the present application, the lifting load calculated by the overload prevention device apparently changes due to vibration of the lifting load or the like, but the lifting load once lifted by the crane is actually the lifting load. It pays attention to the fact that it does not change until it is lowered. The lifting load calculated immediately before the lowering operation of the winch operation lever is stored as the actual lifting load until the lowering operation is completed, and is used for speed control. . Thereby, stable speed control of the hydraulic winch using the variable displacement motor has become possible. Therefore, its practical value is high.

[Brief description of the drawings]

FIG. 1 is a hydraulic and electric circuit of a speed control device for a hydraulic winch of a crane according to an embodiment of the present invention.

FIG. 2 is a block diagram of a portion related to a speed control device of a hydraulic winch of the overload prevention device.

FIG. 3 is a graph showing a relationship between a lever stroke and a winch speed.

[Explanation of symbols]

1 hydraulic pump, 2 relief valve, 3 pilot operated valve, 4 counterbalance valve, 5 variable displacement motor,
6 upper oil passage, 7 lower oil passage, 11 shuttle valve,
12 capacity control cylinder, 13 hydro valve, 14 extension side oil chamber, 21 pilot hydraulic pump, 22 pressure reducing valve,
23 solenoid switching valve, 24 pilot oil passage, 25
Winch operating lever, 26 pilot valve, 27 lower pilot oil passage, 28 upper pilot oil passage, 3
0 Overload prevention device, 31 Boom length detector, 32
Boom angle detector, 33 Boom moment detector, 3
4 lowering pressure detector, 35 high-speed command signal line, 41
42 high-speed mode selection switch, 43 relay coil, 44 relay switch, 45 indicator lamp, 46 power supply, 47 output line, 50 lifting load calculation unit, 51 limit load storage unit, 52 load comparison unit, 53
Output unit, 54 Built-in switch, 55 Actual operation lifting load calculation unit

Claims (2)

[Claims] In a hydraulic winch of a crane using a variable displacement motor capable of switching a rotation required for a supply flow rate between a high speed mode and a low speed mode by switching a capacity required for one rotation, a winch operation is performed by an overload prevention device. The hoisting load calculated immediately before the start of the lowering operation of the lever is stored as the actual working hoisting load until the end of the lowering operation, the actual working hoisting load is smaller than a predetermined value, the lowering operation is performed, and A speed control method for a hydraulic winch of a crane, wherein the variable displacement motor is switched from a low speed mode to a high speed mode when switching to the high speed mode is manually selected. 2. A hydraulic winch for a crane using a variable displacement motor capable of switching a rotation speed with respect to a supply flow rate between a high speed mode and a low speed mode by switching a capacity required for one rotation. And an overload prevention device that calculates the lifting load from the boom moment and stores the lifting load calculated immediately before the start of the lowering operation of the winch operation lever as the actual operation lifting load until the lowering operation ends. Lowering operation detecting means for detecting a lowering operation of an operating lever; mode selecting means capable of manually selecting switching between a high speed mode and a low speed mode; and a motor capacity for switching the capacity required for one rotation of the variable displacement motor. Switching means for controlling the speed of the hydraulic winch, wherein the speed control device is stored in the overload prevention device. When the actual operation lifting load is smaller than a predetermined value, the lowering operation detecting means detects a lowering operation, and the mode selecting means is selected to be a high speed mode, the high speed mode switching to the motor capacity switching means is performed. A speed control device for a hydraulic winch of a crane, which outputs a signal.