JPH1045383A - Safety device of construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly perform operation in the automatic stop releasing direction while preventing sudden actuation by making driving speed when a boom is driven in the opposite direction of the prescribed direction faster than driving speed when it is driven in the prescribed direction after a first condition is realized. SOLUTION: For example, when a lever 5a of a crane is operated to the boom side, pressure reduced by a solenoid proportional pressure reducing valve 4 is reduced further by a pilot valve 5, and acts on one pilot port of a control valve 10 through a solenoid valve 8a of a boom raising side oil passage L2. Therefore, the control valve 10 is switched, and delivery oil of a main hydraulic pump 31 is introduced to a hydraulic motor 7, and the hydraulic motor 7 rotates, and a boom raising-lowering winch 21 is driven to the rope winding side. At ordinary boom raising-lowering time, opening of the solenoid proportional pressure reducing valve 4 is adjusted so that pressure of an operating oil passage L1 becomes a maximum value, and driving speed of a boom is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device such as an overload prevention device used for a construction machine such as a crane.

[0002]

2. Description of the Related Art As a safety device for a construction machine, for example, there is a safety device in which when a boom undulation angle reaches a predetermined stop angle θ2 (for example, FIG. 1) when the boom is undulated, the safety device is forcibly stopped. This type of safety device is configured to automatically stop the boom by switching the solenoid valve located in the operating oil passage of the boom to the shut-off position. There was a problem. To prevent this, for example, Japanese Utility Model Laid-Open No. 5-69069.
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-115, the boom speed is reduced when the boom up / down angle reaches a predetermined angle θ1 before reaching the stop angle θ2, and the boom speed is gradually stopped when the boom up / down angle reaches the stop angle θ2. Have been.

[0003]

However, according to the method disclosed in the above-mentioned publication, when the boom is driven in the automatic stop release direction (the downward direction in FIG. 1) when the boom up-and-down angle exceeds θ1, it is not until the angle θ1 is reached. The boom will move slowly, which is inconvenient if you want to move the boom quickly.

[0004] It is an object of the present invention to provide a safety device for a construction machine capable of quickly operating in an automatic stop release direction while preventing abrupt operation.

[0005]

According to a first aspect of the present invention, there is provided a boom which can be raised and lowered, and when the first condition is satisfied when the boom is driven in a predetermined direction, the boom drive speed is reduced. Thereafter, when the second condition is satisfied, the present invention is applied to a safety device for a construction machine that stops the boom. And the first
After the above condition is satisfied, the boom is provided with speed control means for driving the boom in a direction opposite to the predetermined direction faster than the driving speed when driving the boom in the predetermined direction, thereby solving the above problem. I do. The invention according to claim 2 has a boom that can be raised and lowered, and when the boom is driven in the raising direction, the boom driving speed is reduced when the boom raising and lowering angle reaches a first predetermined angle. The present invention is applied to a safety device for a construction machine that stops a boom when a second predetermined angle that is larger than the first predetermined angle is reached. When the boom hoisting angle is larger than the first predetermined angle, a speed control means for increasing the driving speed in the lowering direction of the boom faster than the driving speed in the raising direction is provided. The invention according to claim 3 has a boom that can be raised and lowered, and when the boom is driven in the lowering direction, the boom driving speed is reduced when the boom raising and lowering angle reaches a third predetermined angle. The present invention is applied to a safety device for a construction machine that stops the boom when a fourth predetermined angle smaller than the third predetermined angle is reached. When the boom hoisting angle is smaller than the third predetermined angle, a speed control means is provided for increasing the driving speed in the raising direction of the boom faster than the driving speed in the lowering direction. The invention according to claim 4 has a boom that can be raised and lowered, and reduces the boom drive speed when the load factor of the construction machine according to the boom raising and lowering angle increases to a first predetermined value.
The present invention is applied to a safety device of a construction machine that stops a boom when a load factor reaches a second predetermined value larger than the first predetermined value. And, when the load factor is larger than the first predetermined value, a speed control means is provided for increasing the drive speed in the direction of decreasing the load factor of the boom to the drive speed in the direction of increasing. The invention according to claim 5 has a boom that can be raised and lowered, and reduces the boom drive speed when the critical working radius ratio of the construction machine according to the boom raising / lowering angle rises to a first predetermined value. The present invention is applied to a safety device for a construction machine that stops a boom when a second predetermined value that is larger than the first predetermined value is reached. When the limit operation radius ratio is larger than the first predetermined value, a speed control unit is provided for increasing the drive speed in the direction of decreasing the limit operation radius ratio of the boom in the direction of increasing the drive speed. The limit work radius ratio is equivalent to the ratio of the limit work radius calculated from the boom hoisting angle and the boom acting force to the actual work radius, and becomes 100% when the actual work radius reaches the limit work radius. Value. According to a sixth aspect of the present invention, a boom that can be raised and lowered and a first physical quantity that defines a driving speed of the boom are calculated, and when the first condition is satisfied when the boom is driven in a predetermined direction, the calculation is performed based on the calculation result. The boom drive speed is reduced by the first boom operating means for stopping the boom when the second condition is satisfied, and a second physical quantity defining the boom drive speed is calculated. A second boom operating means for reducing the boom driving speed based on a calculation result when the third condition is satisfied while the boom is being driven, and thereafter stopping the boom when the fourth condition is satisfied. Applied to safety devices. And
When the drive speed defined by the first physical quantity is lower than the drive speed defined by the second physical quantity, the first boom operating means is operated, and the drive speed defined by the second physical quantity is reduced to the first physical quantity. Control means for activating the second boom operation means when the drive speed is lower than the drive speed defined by the physical quantity of the first boom operation means. The driving speed at the time of driving in the opposite direction is faster than the driving speed at the time of driving in the predetermined direction, and after the third condition is satisfied, the boom operates in the direction opposite to the predetermined direction. The driving speed at the time of driving in the predetermined direction is higher than the driving speed at the time of driving in the predetermined direction. According to a seventh aspect of the present invention, there is provided a rope which is hung around the end of a boom and has a hook attached to a lower end thereof, and a winch which raises / lowers the hook by winding / lowering the rope. When the distance between the hook and the boom tip is reduced to the first predetermined distance, the winding speed is reduced.
Is applied to a safety device of a construction machine that stops winding when a second predetermined distance smaller than the predetermined distance is reached. When the distance between the hook and the end of the boom is smaller than the first predetermined distance, a speed control means is provided for making the rope lowering speed higher than the hoisting speed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic side view of the crawler crane according to the present embodiment. A boom 1 is connected to the front part of the crane body so as to be able to be raised and lowered, and the boom 1 is raised and lowered through a boom raising and lowering rope 22 by driving a boom raising and lowering winch 21 provided on the main body. A hoisting / lowering rope 24 pulled out from a hoisting / lowering winch 23 of the main body is wound around a sheave 1 a provided at an upper end of the boom 1, and a hook 25 is attached to a lower end thereof. Hook 2
5 is lifted and lowered via the hoisting / lowering rope 24 by driving the winch 23.

FIG. 2 shows a hydraulic / electric circuit for raising and lowering the boom of the crawler crane. Reference numeral 31 denotes a main hydraulic pump, and its discharge oil is guided to a hydraulic motor 7 for driving a boom hoisting winch via a control valve 10. Reference numeral 32 denotes an operating hydraulic pump whose discharge pressure is controlled by the control valve 10 via the electromagnetic proportional pressure reducing valve 4, the pilot valve 5 and the solenoid valve 8a or 8b.
Act on pilot ports. The pilot valve 5 is operated by a lever 5a. The electromagnetic proportional pressure-reducing valve 4 adjusts the pressure of the operating oil passage L <b> 1 leading to the pilot valve 5 according to the opening thereof, and is controlled in opening by a signal from the controller 3. Solenoid valves 8a, 8b
Is for opening / closing the operation oil passages L2a, L2b between the pilot valve 5 and the control valve 10, respectively, and is controlled by a signal from the controller 3.

[0008] The controller 3 also includes an angle sensor 2 attached to the boom 1 for detecting the elevation angle of the boom 1.
A load cell 9 for detecting the tension of the boom hoisting rope 22, pressure switches 6a and 6b which are turned on when the pressures of the operating oil passages L2a and L2b on the boom raising and lowering sides are equal to or higher than predetermined values, respectively. Limit switches 33a and 33b that are turned on when the angles reach predetermined stop angles θ2 (FIG. 1) and θ4 (FIG. 4), respectively, and a rotary encoder 34 that detects the amount and direction of rotation of the sheave 1a are connected. .

Although not shown, the crane is provided with a hydraulic circuit for driving the hoisting / lowering winch 23. This hydraulic circuit has substantially the same configuration as the hydraulic circuit of FIG. 1, and a proportional electromagnetic pressure reducing valve, a solenoid valve and a pressure switch (all function similarly to those of FIG. 1) are connected to the controller 3. . Further, a detector for detecting that the hook 25 has reached the solid line position in FIG. 8 (hereinafter, referred to as a first hook overwinding) and a detector for detecting that the hook 25 has reached the broken line position (hereinafter, the second hook excess winding). Called a volume)
Is provided. Since these detectors are well known, detailed description is omitted.

In the crane constructed as described above, when the lever 5a is operated, for example, to the boom raising side, the pressure reduced by the electromagnetic proportional pressure reducing valve 4 is further reduced by the pilot valve 5, and the boom raising side oil passage L2a Act on one pilot port of the control valve 10 through the solenoid valve 8a (at this time, at the communication position). As a result, the control valve 10 is switched, the discharge oil of the main hydraulic pump 31 is guided to the hydraulic motor 7, and the hydraulic motor 7 rotates, and the boom hoist winch 21 is driven to the rope retraction side. As a result, the boom 1 is driven via the hoisting / lowering rope 24 in the raising direction (the direction of the arrow in FIG. 1). When the lever 5a is operated to lower the boom, the boom 1 is rotated in the lowering direction (the direction of the arrow in FIG. 4) by the same operation as described above.

At the time of normal boom raising and lowering, the opening of the electromagnetic proportional pressure reducing valve 4 is adjusted so that the pressure in the operation oil passage L1 becomes a maximum value. As the pressure in the operation oil passage L1 increases, the switching amount of the control valve 10 for the same lever operation amount increases, and the driving speed of the boom 1 increases.

The winch / winding winch 23 is also driven to rotate in a hoisting direction or a lowering direction in response to a lever operation (not shown), and a hook 25, ie, a suspended load, is wound via a hoisting / lowering rope 24. 26 is raised and lowered.

The above is the basic operation of the crane. The operation including the safety function will be described below. (1) Automatic Boom Raising Stop In this embodiment, when the up-and-down angle (ground angle) of the boom 1 reaches the stop angle θ2 (FIG. 1) during driving in the boom raising direction, the solenoid valve 8a is forcibly switched to the shut-off position. To shut off the oil passage L2a and automatically stop the boom 1. At that time, in order to prevent the boom 1 from suddenly stopping, the drive speed of the boom 1 is reduced when the boom up / down angle reaches θ1 before reaching the θ2. The drive speed is reduced by adjusting the pressure of the operation oil passage L1 by the electromagnetic proportional pressure reducing valve 4, and this pressure adjustment is performed based on, for example, a map shown in FIG. This map associates the pressure of the operation oil passage L1 with the boom undulation angle, and the operation oil passage pressure decreases linearly as the boom undulation angle increases from θ1 to θ2. According to this, after the boom angle reaches θ1, the boom 1 gradually decelerates, and when the angle reaches θ2, the boom 1 can be stopped without giving any shock, thereby preventing load swing and the like. it can.

On the other hand, if the boom 1 is driven downward when the boom angle exceeds θ1, control using the above map is not performed. In this case, the electromagnetic proportional pressure-reducing valve 4 is controlled such that the pressure in the operation oil passage L1 becomes the maximum value regardless of the boom raising / lowering angle, and the boom 1 quickly rotates from the beginning. Therefore, the boom 1 can be quickly set to a desired angle.

(2) Automatic stop of boom lowering (2-1) Automatic stop by boom angle Similarly, when the boom up / down angle reaches the stop angle θ4 (FIG. 4) during driving of the boom lowering direction, the solenoid valve 8b is forcibly shut off. The position is switched to the position, the oil passage L2b is shut off, and the boom 1 is automatically stopped. At this time, in order to prevent the boom 1 from suddenly stopping, the angle θ before the boom undulation angle reaches θ4 is set.
At the time point when the speed becomes 3, the drive speed of the boom 1 is reduced. In this case, for example, a map as shown in FIG. 5 is used. Note that θ2>θ1>θ3> θ4.

If the boom 1 is driven upward when the boom angle is less than θ3, the above-mentioned map is not used, and the pressure in the operation oil passage L1 becomes the maximum pressure regardless of the boom angle. The electromagnetic proportional pressure reducing valve 4 is controlled, and the boom 1 quickly rotates from the beginning. Therefore, the boom 1 can be quickly set to a desired angle.

(2-2) Automatic stop based on load factor The controller 3 sequentially calculates the load factor (%) of the crane based on the boom hoisting angle, the tension of the boom hoisting rope 22, and other parameters. When the load factor reaches 100% while the boom is being driven in the lowering direction (direction for increasing the load factor), the boom 1 is forcibly stopped. At that time, in order to prevent sudden stop of the boom 1,
When the load factor becomes 90% according to the map of FIG. 6, the driving speed of the boom 1 is reduced. According to this, after the load factor reaches 90%, the boom 1 gradually decelerates to 1
When it reaches 00%, it can be stopped without giving any shock, and it is possible to prevent load swing and the like.

On the other hand, if the boom 1 is driven in the raising direction (the direction of decreasing the load factor) when the load factor is greater than 90%, the above-mentioned map is not used, and the pressure of the operation oil passage L1 becomes the maximum pressure. The electromagnetic proportional pressure-reducing valve 4 is controlled such that the boom 1 rotates quickly from the beginning. Therefore, the boom 1 can be quickly set to a desired angle.

(2-3) Automatic stop based on the limit work radius ratio The controller 3 calculates the limit work radius and the actual work radius based on the boom hoisting angle, the tension of the boom hoisting rope 22, and other parameters. Is calculated as the work limit radius ratio. Then, the boom 1 is lowered (the direction in which the marginal work radius ratio is increased).
When the limit working radius ratio reaches 100% when the motor is driven, that is, when the actual working radius reaches the limit working radius, the boom 1 is forcibly stopped. At that time, in order to prevent the boom 1 from suddenly stopping, the drive speed of the boom 1 is reduced when the limit work radius ratio becomes 90% according to the map of FIG. According to this, after the limit work radius ratio reaches 90%, the boom 1 gradually decelerates to 10%.
When it reaches 0%, it can be stopped without giving any shock, and the load swing can be prevented.

On the other hand, if the boom 1 is driven in a direction to decrease the critical working radius ratio when the critical working radius ratio is larger than 90%, the above-mentioned map is not used, and the pressure of the operating oil passage L1 becomes the maximum pressure. The electromagnetic proportional pressure-reducing valve 4 is controlled such that the boom 1 rotates quickly from the beginning. Therefore, the boom 1 can be quickly set to a desired angle.

At the time of the boom lowering drive, the minimum value of the operating oil passage pressure obtained from each map with respect to the boom angle, the load factor, and the limit operation radius ratio is selected, and is set to this minimum value (boom drive). The proportional solenoid pressure reducing valve 4 is controlled (at the lowest speed). According to this,
Even if the boom is forcibly stopped due to any of the factors, the boom drive speed can be reliably reduced in advance.

(3) Hook Overwind Automatic Stop Although the automatic stop function of the boom has been described above, in the present embodiment, overwinding of the hoisting / lowering rope 24 (hereinafter referred to as hook overwinding) is also described. The same control is performed.
That is, when the hoisting / lowering rope 24 is being retracted (while the hook is being lifted), the hook 25 reaches the position shown by the broken line in FIG. 8 and the distance between the hook 25 and the sheave 1a is H2 (FIG. 8).
, The solenoid valve is forcibly switched to the shut-off position, and the hoisting / lowering winch 23 is automatically stopped. At that time, in order to prevent the winch 23 from suddenly stopping, when the hook 25 reaches the solid line position, that is, when the distance between the hook 25 and the sheave 1a becomes H1 before becoming H2, the driving of the winch 23 is performed. Decrease speed. The drive speed is reduced by, for example, controlling the electromagnetic proportional pressure reducing valve using a map as shown in FIG. 9 and adjusting the pressure of the operating oil passage. According to this, after the distance between the hook 25 and the sheave 1a reaches H1, the winch hoisting speed gradually decreases, and when the distance reaches H2, hoisting can be stopped without giving a shock. Deflection can be prevented.

On the other hand, when the lowering operation (hook lowering operation) of the winch 23 is performed in a state where the distance between the hook 25 and the sheave 1a is less than H1, the control using the above map is not performed. In this case, regardless of the distance between the hook 25 and the sheave 1a, the electromagnetic proportional pressure-reducing valve is controlled such that the operating oil passage pressure becomes the maximum value, and a quick lowering operation is performed from the beginning.

FIGS. 10 to 12 show flowcharts for realizing the above operation. This control is performed by the controller 3
10 and FIG. 11 include the above operations (1) and (2), and the flow of FIG. 12 includes the operation (3). These flows are called and executed periodically from a main routine (not shown).

Referring to FIG. 10 and FIG.
At 1, the boom hoisting angle detected by the angle sensor 2 and the tension of the hoisting rope 22 detected by the load cell 9 are input. In step S2, the load factor (%) of the crane, the critical working radius, and the critical working radius ratio (%) are calculated from the input information and various information stored in the controller 3. In step S3, the pressure of the operation oil passage L1 corresponding to the load factor is obtained from the map of FIG. 6, and the operation oil passage pressure corresponding to the limit work radius ratio is obtained from the map of FIG. In step S4, the smaller of the two operating circuit pressures determined above is selected and stored as the first control pressure.

In step S5, the operating oil passage pressure corresponding to the current boom hoisting angle is obtained from the map shown in FIG. 3 or FIG. 5, and this is stored as the second control pressure. Step S
6 shows the current boom undulation angle (hereinafter referred to as θ) in FIG.
If θ1 <θ, it is determined in step S7 whether the pressure switch 6a is on or off. Pressure switch 6
If a is on, it is determined that the boom 1 is being driven in the up direction, and the process proceeds to step S8, where the opening of the electromagnetic proportional pressure reducing valve 4 is controlled so as to have the second control pressure obtained in step S5. . Thus, the speed of the boom 1 on the raising side is reduced. In step S9, it is determined whether the limit switch 33a is on or off. If the limit switch 33a is off, that is, if the boom angle has not yet reached θ2, the process returns. If the limit switch 33a is ON, that is, if the boom angle reaches θ2, the process proceeds to step S10, and the solenoid valve 8a is switched to the shut-off position. As a result, the control valve 10 returns to the neutral position, and the boom 1 is forcibly stopped.

If it is determined in step S7 that the limit switch 33a is off, the boom 1
Is not driven in the up direction, and step S1
Proceed to 1. In step S11, the opening of the electromagnetic proportional pressure-reducing valve 4 is controlled so as to become the first control pressure obtained in step S4. In step S12, it is determined whether any of the load factor and the limit work radius ratio has reached 100%, and if negative, the process returns. When step S12 is affirmed, the solenoid valve 8b is switched to the shut-off position in step S12, and the boom 1 is stopped.

Since the map shown in FIG. 3 is not used in the control after step S11, when both the load factor and the limit work radius ratio are less than 90%, the boom 1 is driven at the maximum speed even if θ1 <θ. Is driven in the downward direction.

On the other hand, if it is determined in step S6 that θ1 ≧ θ, the process proceeds to step S14, where it is determined whether the pressure switch 6b is on or off. If the pressure switch 6b is on, that is, if the boom 1 is being driven in the lowering direction, the process proceeds to step S15, and the opening of the electromagnetic proportional pressure reducing valve 4 is set so that the first and second control pressures become smaller. Control. In other words, when the boom 1 is moving in the lowering direction, the problems are the load factor, the limit working radius ratio, and the boom lowering angle limit. The electromagnetic proportional pressure-reducing valve 4 is controlled by using (the value that makes the boom drive speed the slowest).

In step S16, it is determined whether one of the load factor and the limit operation radius ratio has reached 100% or the limit switch 33b has been turned on. If the result is negative, the process returns. If the result is affirmative, the process returns to step S13. Then, the boom 1 is stopped by switching the solenoid valve 8b to the shut-off position.

On the other hand, in step S14, the pressure switch 6b
Is off, that is, when the boom 1 is driven in the raising direction or stopped, the process proceeds to step S17. θ1 ≧
When the boom 1 is driven in the upward direction at θ, there is no problem.
The electromagnetic proportional pressure-reducing valve 4 is controlled so that the operating oil passage pressure becomes the maximum value (the boom driving speed becomes the fastest).

Next, the processing for the overwinding of the hook will be described with reference to FIG. In the main routine not shown, hook 2
The rotary encoder 34 until the sheave-hook distance changes from H1 to H2 based on the number of times the hoisting / lowering rope 25 is hung between the sheave 1 and the sheave 1a (preliminarily input).
(Hereinafter referred to as a reference count number) is calculated and stored.

In FIG. 12, in step S21, the first
It is determined whether or not the hook overwinding is ON, that is, whether or not the hook 25 is located above the solid line position in FIG. 8. If the determination is negative, a predetermined pulse counter is reset in step S29. If step S21 is affirmed, step S22 is reached.
The pulse counter of the rotary encoder 34 is counted by the pulse counter.

In step S23, it is determined whether or not the second hook overwinding is ON, that is, whether or not the hook 25 has reached the position indicated by the broken line in FIG. 8, and if not, the flow proceeds to step S24.
In step S24, the percentage of the current pulse count to the stored reference count is calculated. This is equivalent to the sheave-hook distance. In step S25, the operation oil pressure is obtained from the calculation result in step S24 using the map shown in FIG. In step S26, it is determined whether or not the pressure switch provided in the winding operation circuit of the rope 24 is on. If it is on, it is determined that the winding of the rope 24 is being performed, and the process proceeds to step S27. The electromagnetic proportional pressure-reducing valve is controlled so as to have the obtained operating oil passage pressure.

On the other hand, if the pressure switch is off, the process proceeds to step S28. Here, the control based on the above map is not performed, and the electromagnetic proportional pressure reducing valve is controlled so that the operating oil passage pressure becomes the maximum value (so that the lowering speed of the rope 24 becomes the highest). If it is determined in step S23 that the second hook overwinding is ON, the solenoid valve is switched to the shut-off position in step S30, the control valve is returned to the neutral position, and the hoisting / lowering winch 23 is stopped.

In the above description, the pressure switches are provided in the operation oil passages in both the boom raising and lowering directions. However, the same control can be performed by providing the pressure switches only in the raising oil passages. Instead of the pressure switch, for example, a rotation sensor may be provided in the hydraulic motor 7 to detect the rotation direction, and thereby determine the boom up / down direction or the hook lifting / lowering. Alternatively, the up-and-down direction of the boom may be determined from a temporal change in the signal of the angle sensor 2. The maps in FIGS. 3, 5, 6, 7 and 9 show examples, and the manner of deceleration of the boom or hook is not limited to these.

[0037]

According to the first aspect of the present invention, when the first condition is satisfied while the boom is driven in a predetermined direction, the boom drive speed is reduced, and when the second condition is satisfied, the boom is driven. In the stop, after the first condition is satisfied, the drive speed when the boom is driven in the direction opposite to the predetermined direction is set to be faster than the drive speed when the boom is driven in the predetermined direction. Abrupt stop of the boom can be prevented, and the boom can be quickly moved to the safe side (auto stop release side).
Can be driven. According to the invention of claim 2, when the boom is driven in the raising direction, the boom drive speed is reduced when the elevation angle reaches the first predetermined angle, and the boom elevation angle is larger than the first predetermined angle. A method for stopping a boom when a second predetermined angle is reached, wherein the boom undulation angle is the first
When the angle is larger than the predetermined angle, the driving speed in the lowering direction of the boom is set to be faster than the driving speed in the raising direction, so that abrupt stop of the boom can be prevented and the lowering direction of the boom can be quickly reduced (automatic stop release). Side). According to the invention of claim 3, when the boom is driven in the lowering direction, the boom drive speed is reduced when the up-and-down angle reaches the third predetermined angle, and the boom up-and-down angle is smaller than the third predetermined angle. When the boom angle is smaller than the third predetermined angle, the driving speed in the raising direction of the boom is made faster than the driving speed in the lowering direction. In addition, the boom can be prevented from suddenly stopping, and the boom can be quickly driven in the raising direction (the automatic stop release side). Claim 4
According to the invention, the boom drive speed is reduced when the load factor of the construction machine increases to the first predetermined value, and the boom is stopped when the load factor reaches the second predetermined value larger than the first predetermined value. When the load factor is larger than the first predetermined value, the drive speed in the direction to decrease the load factor of the boom is made faster than the drive speed in the direction to increase, so that the same effect as described above is obtained. Can be According to the fifth aspect of the present invention, the boom drive speed is reduced when the limit work radius ratio rises to the first predetermined value, and the limit work radius ratio reaches the second predetermined value larger than the first predetermined value. Then, in the one that stops the boom, the limit work radius ratio is the first
Is larger than the predetermined value, the drive speed in the direction of decreasing the limit working radius ratio of the boom is set to be faster than the drive speed in the direction of increasing, so that the same effect as described above can be obtained. According to the invention of claim 6, the first and the second are provided.
Decelerate and stop the boom under the conditions of
In the case where the boom is similarly decelerated and stopped under the fourth condition, the slower one of the boom drive speed when the first condition is satisfied and the boom drive speed when the third condition is satisfied is selected. Control.
The same effect as described above can be obtained, and at the same time, the boom drive speed can be reliably reduced when necessary. According to the invention of claim 7, when the distance between the hook and the boom tip reaches the first predetermined distance at the time of hoisting, the hoisting speed is reduced, and the distance between the hook and the boom tip is smaller than the first predetermined distance. When the distance between the hook and the end of the boom is smaller than the first predetermined distance, the hoisting speed of the rope is set to be higher than the hoisting speed. / The abrupt stop of the lowering winch can be prevented, and the hook can be quickly driven to the safe side (the automatic stop release side).

[Brief description of the drawings]

FIG. 1 is a schematic side view of a crane according to an embodiment of the present invention, illustrating a function of automatically stopping a boom raising direction.

FIG. 2 is a hydraulic / electrical circuit diagram for driving the boom of the crane.

FIG. 3 is a diagram showing a map for determining an operation oil passage pressure from a boom undulation angle.

FIG. 4 is a schematic side view of the crane, illustrating a boom lowering direction automatic stop function.

FIG. 5 is a diagram showing a map for determining an operation oil passage pressure from a boom undulation angle.

FIG. 6 is a diagram showing a map for determining an operation oil passage pressure from a load factor.

FIG. 7 is a diagram showing a map for determining an operation oil passage pressure from a limit work radius ratio.

FIG. 8 is a schematic side view of a crane illustrating a hook overwinding prevention function.

FIG. 9 is a diagram showing a map for determining an operating oil passage pressure from a hook-sheave distance.

FIG. 10 is a flowchart illustrating a boom automatic stop function.

FIG. 11 is a flowchart following FIG. 10;

FIG. 12 is a flowchart illustrating a hook overwinding prevention function.

[Explanation of symbols]

 Reference Signs List 1 boom 1a sheave 2 angle sensor 3 controller 4 electromagnetic proportional pressure reducing valve 5 pilot valve 6a, 6b pressure switch 7 hydraulic motor 8a, 8b solenoid valve 9 load cell 10 control valve 21 boom hoisting winch 22 boom hoisting rope 23 hoisting / lowering winch 24 Hoisting / lowering rope 25 Hook 26 Suspended load 31 Main hydraulic pump 32 Operating hydraulic pump 33a, 33b Limit switch 34 Rotary encoder L1, L2a, L2b Operating oil passage

Claims (7)

[Claims] A boom that can be raised and lowered, the boom drive speed is reduced when a first condition is satisfied when the boom is driven in a predetermined direction, and the boom is reduced when a second condition is satisfied. In the safety device for a construction machine to be stopped, after the first condition is satisfied, a driving speed when the boom is driven in a direction opposite to the predetermined direction is faster than a driving speed when the boom is driven in the predetermined direction. A safety device for a construction machine, comprising: 2. A boom that can be raised and lowered, and when the boom is driven in a raising direction, the boom driving speed is reduced when the boom raising and lowering angle reaches a first predetermined angle. In a safety device for a construction machine that stops the boom when a second predetermined angle that is larger than the predetermined angle is reached, when the boom undulation angle is larger than the first predetermined angle, the drive speed of the boom in the lowering direction is reduced. A safety device for a construction machine, comprising speed control means for increasing a driving speed in a raising direction. 3. A boom that can be raised and lowered, and when the boom is driven in a lowering direction, the boom driving speed is reduced when the boom raising and lowering angle reaches a third predetermined angle. A safety device for a construction machine that stops the boom when a fourth predetermined angle smaller than the predetermined angle is reached, wherein when the boom undulation angle is smaller than the third predetermined angle, the driving speed of the boom in the raising direction is reduced. A safety device for a construction machine, comprising speed control means for increasing a driving speed in a lowering direction. 4. A boom that can be raised and lowered, and when the load factor of the construction machine according to the boom hoisting angle increases to a first predetermined value, the boom driving speed is reduced, and the load factor is reduced to the first predetermined value. A safety device for a construction machine that stops the boom when it reaches a second predetermined value that is larger than the second predetermined value. When the load factor is larger than the first predetermined value,
A safety device for a construction machine, comprising: speed control means for increasing a driving speed of the boom in a direction of decreasing the load factor in a direction of increasing a driving speed of the boom. 5. A construction machine having a boom that can be raised and lowered, and when the critical working radius ratio of the construction machine according to the boom raising / lowering angle rises to a first predetermined value, the boom driving speed is reduced, and the critical working radius ratio is reduced to the first working value. A safety device for a construction machine that stops the boom when a second predetermined value greater than a first predetermined value is reached, wherein the limit operation radius of the boom is determined when the limit operation radius ratio is larger than the first predetermined value. A safety device for a construction machine, comprising: speed control means for increasing a driving speed in a direction of decreasing a ratio to a driving speed of a direction of increasing the driving speed. 6. An up-and-down boom and a first physical quantity defining a drive speed of the boom are calculated, and the first boom is driven when the boom is driven in a predetermined direction.
When the condition (1) is satisfied, the boom driving speed is reduced based on the calculation result, and thereafter, when the second condition is satisfied, a first boom operating means for stopping the boom; A physical quantity is calculated, and when the third condition is satisfied while the boom is driven in the predetermined direction, the boom driving speed is reduced based on the calculation result, and thereafter, when the fourth condition is satisfied, the boom is stopped. A safety device for a construction machine having a second boom operation means for causing the first physical quantity to be lower than the second physical quantity when the driving speed defined by the first physical quantity is lower than the first physical quantity.
Control means for operating the second boom operation means when the drive speed defined by the second physical quantity is lower than the drive speed defined by the first physical quantity. The first boom operating means, after the first condition is satisfied, sets a driving speed when the boom is driven in a direction opposite to the predetermined direction to a driving speed when the boom is driven in the predetermined direction. The second boom operating means may further include, after the third condition is satisfied, a drive speed when the boom is driven in a direction opposite to the predetermined direction and a drive speed when the boom is driven in the predetermined direction. A safety device for construction machinery, wherein the speed is higher than the speed. 7. A rope which is hung around a tip of a boom and has a hook attached to a lower end thereof, and a winch which raises / lowers the hook by hoisting / lowering the rope,
When the distance between the hook and the end of the boom reaches a first predetermined distance during the winding of the rope, the winding speed is reduced, and the distance between the hook and the end of the boom is a second predetermined distance smaller than the first predetermined distance. A safety device for a construction machine that stops hoisting when the distance between the hook and the boom tip is smaller than the first predetermined distance; speed control for making the lowering speed of the rope faster than the hoisting speed. A safety device for a construction machine, characterized by comprising means.