JPH08119581A - Turning control device of crane - Google Patents

Abstract

PURPOSE: To automatically regulate the maximum turning speed according to the working condition of a crane represented by the operating radius, the hoisting load, etc., and to prevent the turning speed from being changed even when the speed of a prime mover is fluctuated during the work. CONSTITUTION: A crane turning control device consists of an overload preventing device 28 to detect the working condition of a crane, a variable displacement pump 22 to be driven by an engine 20, an engine speed detector 21 to detect the speed of the engine 20, a pilot operation part 2a to change the quantity of rotation of the pump 22, and a control device 29 to control the pilot operation part 22a. The control device 29 calculates the turning speed suitable for the working condition of the crane detected by the overload preventing device 28, and the pilot operation part 22a of the variable displacement pump 22 is driven based on the turning speed and the engine speed detected by the engine speed detector 21, and the maximum turning speed is regulated by controlling the discharge flow rate of the variable displacement hydraulic pump 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turning control device for a crane which is capable of turning and whose working conditions such as working radius and lifting load change depending on the work. The present invention relates to a turning control device for a controlled crane.

[0002]

2. Description of the Related Art In a conventional crane turning control device, when the engine speed is increased during a turning operation in order to increase the speed of a winch operating in a complex manner, the turning speed is entangled and becomes faster, causing a load shake. Difficult to operate. Therefore, a turning control device that suppresses the turning speed based on the work situation when the suspension load, the work radius, and the like become large is disclosed in Japanese Patent Application Laid-Open No. 1-21.
It is disclosed in Japanese Patent No. 85592. The contents will be described below with reference to FIG.

FIG. 8 is a block diagram of the turning control device disclosed in the above publication. In this conventional turning control device,
The boom angle β detected by the boom angle detector 1 and the boom length L detected by the boom length detector 2 are input to the work radius calculator 3, and the work radius calculator 3 calculates the work radius R. This working radius R is input to the rated value calculator 5 and the first function generator 7, and in the first function generator 7, the maximum turning angular velocity ω that the working radius R allows.
max is calculated. On the other hand, the boom length L is also input from the boom length detector 2 to the rated value calculator 5, and the rated value calculator 5
Calculates the rated load from the working radius R and the boom length L, and calculates the rated value Wa by adding the rated load and the boom own weight. The load factor P (W / Wa) is calculated by the divider 6 from the rated value Wa and the load W that is the sum of the crane boom and the suspension load detected by the load detector 4.
A turning angular velocity reduction coefficient K is determined by the second function generator 8 in accordance with the load factor P. Then, the multiplier 9 multiplies the maximum turning angular velocity ωmax by the turning angular velocity reduction coefficient K,
This multiplication value ωmax · K is used as the turning angular velocity upper limit control signal corresponding to the working radius R and the load factor P, and the turning drive mechanism A
Is output to This control signal decreases as the working radius R and the load factor P increase.

The swing drive mechanism A includes a hydraulic pump 10, an electromagnetic flow control valve 11 for limiting the pump discharge flow rate, a control valve 12 for adjusting the direction and flow rate of pressure oil, and a pressure supplied from the control valve 12. The hydraulic motor 13 rotates in the direction and speed according to the oil. Electromagnetic flow control valve 11
Suppresses the flow rate of the pressure oil discharged from the hydraulic pump 10 based on the input turning angular velocity upper limit control signal, thereby limiting the turning angular velocity at the upper limit value and preventing the swinging of the suspended load. When the work radius R and the load factor P are small, the control signal becomes large and the turning angular velocity is not limited, so that the work efficiency is prevented from being lowered.

The crane turning control device disclosed in Japanese Utility Model Laid-Open No. 3-49291 is constructed as shown in FIG. The swing motor 24 is driven by the discharge oil of the variable displacement hydraulic pump 22 driven by the engine 20. The tilting amount of the pump 22 is adjusted according to the pressure acting on the pilot operating part 22a, and this pressure is adjusted by the electromagnetic proportional pressure reducing valve 23 based on the engine speed detected by the engine speed detector 21. It When the engine speed is high, the output pressure of the electromagnetic proportional pressure reducing valve 23 is low, which reduces the pump tilt amount and the discharge flow rate per revolution of the pump 22. On the other hand, when the engine speed is low, the electromagnetic proportional pressure reducing valve 23
Output pressure increases, which increases the pump tilt amount and increases the discharge flow rate per one rotation of the pump.
The increase / decrease amount of the pump displacement amount depending on the engine speed is irrespective of the change of the rotation speed of the engine 20.
The flow rate of the pressure oil discharged from is determined so as to be constant, and therefore, the turning angular velocity is limited to a predetermined upper limit value, thereby facilitating the turning operation.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The turning control device described in Japanese Patent No. 5592 controls the maximum turning angular velocity determined by the load of the suspended load and the working radius by controlling the discharge flow rate of the hydraulic pump 10 supplied to the turning motor by the electromagnetic flow control valve 11. Is defined by. Therefore, for example, when the engine speed is increased in an attempt to increase the hoisting speed of the suspended load by performing a combined operation of turning and hoisting of the suspended cargo in a state where the engine speed is low, the angular velocity of the swirl increases to a specified maximum value. .
As a result, even if the maximum turning angular velocity is specified to prevent swinging of the load due to start / stop of turning, within the range where the maximum turning angular velocity is reached, the turning angular velocity changes due to changes in the discharge flow rate of the hydraulic pump due to fluctuations in the engine speed. Changes.

Further, in the turning control device described in Japanese Utility Model Laid-Open No. 3-49291, the maximum turning speed can always be kept constant regardless of the change in the engine speed, but the maximum turning speed is the same as in a crane. With work machines that have a long boom, the working radius changes significantly when the elevation angle of the boom is changed,
Due to the change in the working radius, the moving speed of the suspended load due to the turning greatly differs even if the turning speed is constant. Compared to the case where the boom elevation angle is large and the working radius is small, when the boom elevation angle is small and the working radius is large, the position of the load hung by the wire rope at the tip of the boom is far from the turning center, so the moving speed of the suspended load is It is faster than when the working radius is small. Therefore, it is necessary for the worker to appropriately control the flow rate of the pressure oil supplied to the swing motor using the control valve to adjust the swing speed.

The object of the present invention is to improve the operability by automatically adjusting the maximum turning speed in accordance with the working condition of the crane such as the working radius and the lifting load, and to change the rotational speed of the prime mover during working. Even so, it is to provide a turning speed control device for a crane, in which the turning speed does not change.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIGS. 1 and 2 showing an embodiment. The present invention is a working state detecting means 28 for detecting a working state of a crane.
A variable displacement pump 22 driven by a prime mover 20 and capable of changing a discharge flow rate by changing a pump displacement amount, a displacement amount changing means 22a for changing the displacement amount of the variable displacement pump 22, and the displacement amount. The present invention is applied to a turning control device for a crane, which includes a control means 29 for controlling the changing means 22a and a prime mover rotation speed detection means 21 for detecting the rotation speed of the prime mover 20. In the invention of claim 1, the control means 29 is provided with flow rate calculating means 29a, 29z for calculating a flow rate according to a turning speed suitable for the working state of the crane detected by the working state detecting means 28, and Tilt amount calculating means 29c for calculating the tilt amount of the variable displacement pump 22 based on the flow rates calculated by the flow rate calculating means 29a, 29z and the prime mover rotational speed detected by the prime mover rotational speed detecting means 21. By configuring the above, the above-mentioned object is achieved. According to the second aspect of the invention, the working state detecting means 28 detects the working radius of the crane. According to a third aspect of the present invention, the work state detecting means 28 detects the suspension load of the crane. Explaining in association with FIG. 4, in the invention of claim 4, the turning speed changing means 34, 29i for arbitrarily setting the turning speed with the turning speed based on the flow rate calculated by the flow rate calculating means 29a, 29z as an upper limit. Is provided. The invention of claim 5 is shown in FIG.
Referring to FIG. 6, the working state detecting means 28 for detecting the working state of the crane, the variable displacement pump 22 driven by the prime mover 20 and capable of changing the discharge flow rate by changing the pump tilting amount, and the variable A tilt amount changing means 22a for changing the tilt amount of the displacement pump 22, a control means 29C for controlling the tilt amount changing means 22a, a prime mover rotation speed detecting means 21 for detecting the rotation speed of the prime mover, and a prime mover. First rotation speed command means 31 for setting the minimum value of the rotation speed
c, second rotation speed command means 31b for increasing the prime mover rotation speed with respect to the minimum value of the prime mover rotation speed set by the first rotation speed command means 31c, and the first and second rotation speed commands It is applied to a turning control device for a crane, which is provided with a maximum rotation speed selection means 30 for selecting a large command value from the command values commanded by the means 31c and 31b and rotationally driving the prime mover 20 with the command value. . In the invention of claim 5, the control means 29C includes first flow rate calculating means 29a, 29z for calculating a flow rate according to the turning speed suitable for the working state of the crane detected by the working state detecting means 28. , The first rotation speed command means 31
Second flow rate calculating means 29j for calculating a flow rate according to the maximum turning speed that can be exhibited based on the rotation speed command value set by c, and the first and second flow rate calculating means 29.
a minimum flow rate selection means 29k for selecting a smaller flow rate among the flow rates calculated by a, 29z, and 29j,
A tilt amount calculating means for calculating the tilt amount of the variable displacement pump 22 is provided based on the flow rate selected by the minimum flow rate selecting means 29k and the prime mover rotational speed detected by the prime mover rotational speed detecting means 21. By doing so, the above object is achieved. In the invention of claim 6, as shown in FIG. 7, the flow rate calculation means 29m limits the calculated flow rate to a predetermined value when the detection value of the work state detection means 28 is less than or equal to a predetermined value. According to a seventh aspect of the invention, the work state detecting means 28 is an overload preventing device.

[0010]

According to the first aspect of the invention, based on the working state of the crane detected by the working state detecting means 28, the flow rate calculating means (29a, 29z) determines the flow rate according to the turning speed suitable for the working state. calculate. Further, the tilt amount calculating means 29c calculates the tilt amount of the pump 22 for discharging the flow rate calculated by the flow rate calculating means 29z at the prime mover rotational speed detected by the prime mover rotational speed detecting means 21, and the calculation thereof. The tilting amount changing means 22a is controlled on the basis of the determined value, and the tilting amount of the variable displacement hydraulic pump 22 is adjusted to regulate the turning speed. According to the second aspect of the present invention, the working radius of the crane is detected by the working state detecting means 28, and the detected working radius is input to the flow rate calculating means 29a, 29z of the control means 29, where the turning is suitable for the working radius. The flow rate according to the speed is calculated. In the invention of claim 3, the working state detecting means 28 detects the hanging load of the hanging load of the crane, and the detected hanging load is input to the flow rate calculating means 29a, 29z of the control means 29.
Therefore, the flow rate according to the turning speed suitable for the suspension load is calculated. In the invention of claim 4, the turning speed changing means (3
4, 29i), the turning speed is arbitrarily set with the turning speed based on the calculated flow rate as the upper limit. According to the invention of claim 5, the first flow rate calculating means 29 is based on the working state of the crane detected by the working state detecting means 28.
a and 29z calculate the flow rate according to the turning speed suitable for the working state. In the second flow rate calculation means 29j,
The flow rate according to the maximum turning speed that can be exerted is calculated based on the command value of the prime mover rotation speed commanded by the first rotation speed command means 31c. And the minimum flow rate selection means 29k
And the first and second flow rate calculating means 29a, 29z, 29
A smaller flow rate is selected from the flow rates calculated in j. The displacement amount calculating means 29c calculates a pump displacement amount for discharging the flow rate based on the flow rate selected by the minimum flow rate selecting means 29k and the prime mover rotation speed detected by the prime mover rotation speed detecting means 21. The tilting amount changing means 22a is controlled based on the calculated value to adjust the tilting amount of the variable displacement hydraulic pump 22 to define the turning speed. Claim 6
In the invention, when the detection value of the work state detecting means 28 is equal to or less than the predetermined value, the flow rate calculated by the flow rate calculating means 29m is limited to the predetermined value. In the invention of claim 7, the working state of the crane is detected by the overload prevention device, and based on the detected signal, the flow rate calculating means 29a of the control device 29 determines the turning speed and the turning speed suitable for the working state. The corresponding flow rate is calculated.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used for the purpose of making the present invention easy to understand. It is not limited to.

[0012]

【Example】

-First Embodiment- A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a circuit diagram of this embodiment, and FIG. 2 is a control block diagram of this embodiment. In the figure, 20 is an engine serving as a power source of a crane, 21 is an engine speed detector for detecting the speed of the engine 20, 22 is a variable displacement hydraulic pump driven by the engine 20, and is connected to a pilot operating portion 22a. By applying a desired pilot pressure, the displacement amount of the pump changes, and the discharge amount per one rotation of the pump can be changed. Reference numeral 23 denotes an electromagnetic proportional pressure reducing valve whose pressure reduction amount is controlled by the magnitude of the current that acts, which is provided in an operation circuit 22b that connects the pilot operating portion 22a of the hydraulic pump 22 and the hydraulic power source 22c.
Adjust the pilot pressure acting on a. Reference numeral 25 is a control valve for controlling the direction and flow rate of the pressure oil discharged from the hydraulic pump 22 and supplied to the turning hydraulic motor 24, and 28 is an overload prevention device, which is a boom elevation angle β, a boom length L, a suspension load W.
Etc. are detected, and the working radius and the load of the suspended load, etc. of the working machine in the current working state are displayed and an alarm is displayed to indicate the stable or unstable state of the working machine. This overload prevention device is obliged to be installed as an alarm device for preventing the crane from falling over, for example. The control device 29 detects the value of the engine speed detector 21 that detects the speed of the engine 20, and
The electromagnetic proportional pressure reducing valve 23 is controlled based on the detected value of the overload prevention device 28. The hydraulic pump 27 is a hydraulic pump that is a drive source of an actuator other than the turning driven by the engine 20, such as a hoisting winch.

As shown in FIG. 2, the control device 29 described above has a working radius R calculated by the overload prevention device 28.
First function generator 29 for calculating the turning speed V based on
a and a flow rate calculator 29z for calculating the flow rate Q required to obtain the turning speed V. The turning speed V is set based on a value that can prevent the crane from tipping over due to the centrifugal force of the suspended load due to the turning operation. The flow rate Q is obtained by multiplying the turning speed V, the displacement volume q per one rotation of the turning motor 24, and the reduction ratio α1 of the turning drive system.

Further, the control device 29 includes a second function generator 29b for calculating the engine speed N from the pulse train signal S detected by the engine speed detector 21, and a flow rate Q calculated by the flow rate calculator 29z. The operation of the pump displacement amount calculator 29c for calculating the pump displacement amount θ by dividing the detected engine speed N and the pilot operation part 22a of the pump 22 corresponding to the calculated pump displacement amount θ. It has a third function generator 29d for calculating the pressure P and a fourth function generator 29e for calculating the control current of the electromagnetic proportional pressure reducing valve 23 corresponding to the calculated working pressure P.

Turning control in this embodiment will be described. The overload prevention device 28 multiplies the detected cosine value of the boom elevation angle β by the boom length L to calculate and output the working radius R,
The engine speed detector 21 outputs a pulse train signal S at intervals that are inversely proportional to the speed of the engine 20, and these output signals are input to the control device 29. When the working radius R is input to the first function generator 29a, the working radius R
The optimum turning speed V according to the above is determined. When the turning speed V is input to the flow rate calculator 29z,

## EQU1 ## The calculation of Q = V × q × α1 (1) is performed and the flow rate Q required to obtain the turning speed V is obtained.
Is calculated. Here, α1 is a flow rate calculation coefficient corresponding to the reduction ratio of the reduction gear interposed between the swing motor 24 and the swing structure (not shown).

When the pulse train signal S of the engine 20 is input to the second function generator 29b, the engine speed N is determined. In the pump displacement amount calculator 29c, the flow rate calculator 2
Flow rate Q calculated by 9z and engine speed N (rp
m) and

## EQU2 ## Calculation of θ = Q × α2 / N (2) is performed to calculate the pump displacement amount θ required to obtain the flow rate Q at the detected engine speed N.

Here, α2 is the pump 22 and the engine 20.
It is a flow rate calculation coefficient according to the reduction ratio of the reduction gear interposed between and.

The pump displacement amount θ calculated by the pump displacement amount calculator 29c is input to the third function generator 29d, and the third function generator 29d calculates the displacement amount of the pump 22. The working pressure P acting on the pilot operating portion 22a in order to change the pump displacement amount θ is calculated. Then, the control current I to be applied to the electromagnetic proportional pressure reducing valve 23 to obtain the working pressure P is calculated by the fourth function generator 29e,
It is output to the electromagnetic proportional pressure reducing valve 23. Therefore, the electromagnetic proportional pressure reducing valve 23 outputs a pressure so as to obtain a pump tilting amount that provides a swirling speed suitable for the working radius R, whereby the pump 22 discharges pressure oil at a flow rate suitable for the working radius R. .

According to the first embodiment, the flow rate of the pressure oil discharged from the pump 22 is suitable for the working radius R when the control valve 25 is fully opened regardless of the engine speed. Since the flow rate Q is controlled so that the turning radius becomes large, the moving speed of the suspended load is kept within a predetermined range and is not affected by the engine speed, and as a result, the occurrence of load swing can be prevented. At the same time, since the turning speed can be easily adjusted, the burden on the operator can be reduced.

In this embodiment, the first function generator 2
The turning speed V is calculated from the working radius R at 9a, and the flow rate Q based on the turning speed V is calculated by the flow rate calculator 29z. However, the inertial force of the suspended load at the time of turning, the shake of the load due to the centrifugal force, etc. In consideration of the load W of the suspended load, the turning speed V may be calculated, and the flow rate Q may be calculated based on the turning speed V.

-Second Embodiment- FIG. 3 shows a controller 29A of the second embodiment. The same parts as those in FIG. 2 are designated by the same reference numerals, and the differences will be mainly described. The control device 29A calculates a reduction coefficient K of 1 or less based on the suspension load W detected by the overload prevention device 28, and a fifth function generator 29f and the fifth function generator 29.
The controller 29 of the first embodiment is provided with a multiplier 29g that calculates the flow rate Q1 by multiplying the decrease coefficient K calculated by f and the flow rate Q calculated by the flow rate calculator 29z based on the turning speed V. It is added.

The operation of the control device 29A in the second embodiment will be described. Based on the reduction coefficient K calculated by the fifth function generator 29f and the turning speed V, the flow rate calculator 2
The flow rate Q calculated by 9z is multiplied by the multiplier 29g to calculate the flow rate Q1 which is equal to or less than the flow rate Q defined by the working radius R. Then, based on the flow rate Q1, the pump tilting amount θ1, the working pressure P1 applied to the pilot operating portion 22a to obtain the pump tilting amount θ1, and the electromagnetic proportional pressure reducing valve 23 to obtain the working pressure P1. The control current I1 to be calculated is calculated in the same manner as in the first embodiment described above. As a result, the pump displacement amount is controlled and the turning speed is regulated.

The reduction coefficient K determined by the fifth function generator 29f is preset in consideration of the turning speed, the inertial force due to the suspension load, the centrifugal force, the work radius and the overturning moment due to the suspension load, and the like. It is a value.

In the second embodiment constructed as described above,
Since the turning speed is controlled based on the hanging load W and the working radius R, compared with the first embodiment, the swinging of the hanging load due to the start and stop of the turning does not easily occur regardless of the weight of the hanging load, and the operability is further improved. Can be improved and the burden on the operator can be reduced.

In the present embodiment, the fifth function generator 2
Although the reduction coefficient K due to the suspension load is determined by 9f, the suspension load W detected by the fifth function generator 29f is determined.
Speed V that does not fall due to centrifugal force based on
May be calculated, and the first function generator 29a may calculate a reduction coefficient of 1 or less from the size of the working radius.

-Third Embodiment- FIG. 4 shows a control device 29B of a third embodiment. The same parts as those in FIG. 2 are designated by the same reference numerals, and the differences will be mainly described. In the third embodiment, a turning speed changing dial 34 that outputs a signal according to the operation amount is provided, and a reduction coefficient K1 of 1 or less is output according to the operation amount X of the turning speed changing dial 34. The function generator 29i and the multiplier 29h that calculates the flow rate Q2 by multiplying the flow rate Q based on the turning speed V by the reduction coefficient K1 are attached to the control apparatus 29 of the first embodiment to configure the control apparatus 29B. To do.

The operation of the control device 29B in the third embodiment will be described. When the operation amount X, which is the output value of the turning speed change dial 34, is input to the sixth function generator 29i,
A reduction coefficient K1 corresponding to the manipulated variable is calculated. A reduction coefficient K1 calculated by the sixth function generator 29i,
The flow rate Q calculated by the flow rate calculator 29z based on the turning speed V is multiplied by the multiplier 29h to calculate the flow rate Q2 which is equal to or less than the flow rate Q defined by the working radius R. Then, in order to obtain the pump displacement amount θ2 and the pump displacement amount θ2 based on the flow rate Q2, the pilot operating portion 22a
Control pressure I2 to be applied to the electromagnetic proportional pressure reducing valve 23 in order to obtain the working pressure P2 to be applied to
Is calculated in the same manner as in the first embodiment described above. As a result, the pump displacement amount is controlled and the turning speed is regulated.

In the third embodiment constructed as described above,
The turning speed change dial 34 allows the operator to arbitrarily set the turning speed within the range of the turning speed V determined by the work radius. Therefore, when performing positioning work by turning, the turning speed change dial 34 turns the turning speed. Since the fine operation can be performed by limiting the upper limit of, the operation becomes easy.

Fourth Embodiment A fourth embodiment will be described with reference to FIGS. In the fourth embodiment, in addition to the configuration shown in FIG. 1 described above, as shown in FIG. 5, a first engine rotation speed setting device 31a for setting the rotation speed of the engine 20, for example, an accelerator pedal, and a second engine rotation speed setting device 31a. An engine speed setting device 31b, for example, an accelerator grip, and a third engine speed setting device 31c that sets a minimum value of the engine speed, for example, an engine speed setting device 31 including a fuel lever, and those engine speeds. A maximum rotation speed selection device 30 for selecting a maximum rotation speed setting value among the rotation speeds set by the setting device 31, and a third
The engine speed setting device 31c includes a minimum rotation speed detector 32 that detects the set value and outputs the set value to the control device 29C, and a control release switch 33 that stops the operation of the control device 29C.

Further, as shown in FIG. 6, the control device 29C is different from the control device 29 of FIG. 1 in that the maximum discharge flow rate Qmax of the pump 22 at the minimum rotation speed which is the output signal Nmin of the engine minimum rotation speed detector 32. The discharge flow rate calculator 29j for calculating the flow rate and the flow rate Q output from the flow rate calculator 29z
And a flow rate Qmax are compared with each other, and a comparator 29k for outputting the smaller value as the flow rate Q3 is additionally provided. The discharge flow rate calculator 29j is

## EQU3 ## Calculation of Qmax = Nmin × qmax × α2 (3) is performed. However, qmax is the maximum displacement of the pump,
α2 is a flow rate calculation coefficient.

The operation of the fourth embodiment thus constructed is as follows. The following description will be given under the following conditions. (1) The optimum turning speed at the working radius R is 5 rpm,
The minimum engine speed set by the third engine speed setting device 31c (fuel lever) is 1000 rp.
m. (2) At an engine speed of 1000 rpm, the turning speed is limited to 2.5 rpm even if the displacement amount of the pump is maximized.

Under these conditions, when the engine speed is set to 2000 rpm by operating the first engine speed setting device (accelerator pedal) 31a, the flow rate of the pump is increased and the turning speed is increased to 5 rpm. .
Therefore, the moving speed of the suspended load suddenly increases, and the swinging of the load occurs. Therefore, in the present embodiment, the maximum discharge flow rate Qmax that can be output at the minimum engine speed Nmin is calculated by the discharge flow rate calculator 29j based on the above-described equation (3), and based on the optimum turning speed V at the working radius R. The flow rate Q and the pump maximum discharge flow rate Qmax at the engine speed Nmin are compared by the comparator 29k, and Q>
In the case of Qmax, the comparator 29k selects the flow rate Qmax. Therefore, the tilt amount of the pump 22 in this case is defined by the flow rate Qmax.

When it is desired to stop such control depending on the work content or the wishes of the operator, the control is released by turning on the control release switch 33, and the turning is performed according to the change in the rotational speed of the prime mover. The speed is variable.

According to the fourth embodiment, the accelerator pedal 31a and the accelerator grip 31 are provided in order to increase the winding speed, for example, during the combined operation of winding and turning.
Even if the engine speed is increased in b, the turning speed is limited in accordance with the minimum speed defined by the fuel lever, so that fluctuations in the turning speed are suppressed, and the vibration of the load can be effectively prevented.

-Fifth Embodiment- Another embodiment for obtaining substantially the same effect as the above-mentioned fourth embodiment will be described with reference to FIG. In the first to third embodiments described above, the turning speed V calculated by the first function generator 29a is set to have a larger value as the working radius R becomes smaller. . In this case, for example, assuming that the optimum turning speed V at a relatively small work radius R is 5 rpm, the current engine speed 100
It is assumed that the maximum turning speed V that can be obtained at 0 rpm is 2.5 rpm. In this state, if the engine speed is suddenly increased to the maximum speed of 2000 rpm, the pump discharge flow rate increases accordingly, the swirling speed V rapidly increases to 5 rpm, and the swinging of the load easily occurs. Therefore, instead of the control device 29A having the first function generator 29a shown in FIG.
By using the control device 29D having the first function generator 29m as shown in FIG. When the working radius R is relatively small, the first function generator 29m
By limiting the calculated turning speed to, for example, the maximum turning speed that can be exhibited when the engine speed is relatively low (in the previous example, about 3 rpm, which is the maximum turning speed at an engine speed of 1200 rpm), Even if the engine speed changes, the turning speed does not change significantly, and it is possible to prevent the shake of the load from occurring. The first
Since the constituent actions other than the function generator 29m of (1) are the same as those shown in FIG. 2, description thereof will be omitted here. With this configuration, it is possible to obtain substantially the same effect as that of the fourth embodiment with a simple configuration without using the discharge flow rate calculator 29j and the comparator 29k shown in the fourth embodiment. Also, when the turning speed V is determined from the load W of the suspended load by the first function generator 29a, the swing speed V can be limited to the predetermined value when the load W of the suspended load is equal to or less than the predetermined value.

Incidentally, in these embodiments described above,
In the first function generator 29a, the turning speed V is determined so as to prevent the crane from tipping over due to the centrifugal force of the suspended load due to the turning operation. However, after satisfying this condition, the working radius is large or small. Instead, the moving speed of the boom tip may be constant. Further, if the above conditions are satisfied, the operator may arbitrarily set a value frequently used for each work radius.

In the configuration of the above embodiment, the engine 2
0 is the prime mover, the overload prevention device 28 is the working state detecting means, the pilot operating part 22a is the tilt amount changing means, the engine speed detector 21 is the prime mover speed detecting means, and
The function generator 29a and the flow rate calculator 29z function as the flow rate calculating means and the first flow rate calculating means, and the pump displacement amount calculator 29
c is the tilt amount calculating means, the sixth function generator 29i, the turning speed changing dial 34 is the turning speed changing means, the engine speed setting device 31 is the rotation speed commanding device, and the third engine speed setting device. 31c is the first rotation speed command means, the second engine rotation speed setting device 31b is the second rotation speed command means, the discharge flow rate calculator 29j is the second flow rate calculation means, and the comparator 29k is the minimum flow rate. Each of the selection means is configured.

[0038]

According to the present invention, the following effects can be obtained. (1) Calculate the turning speed suitable for the working condition of the crane,
The flow rate required to obtain the turning speed is adjusted by adjusting the tilting amount of the pump based on the number of revolutions of the prime mover. In addition to the appropriate turning speed desired by the user, the turning speed does not change with the change in the number of revolutions of the prime mover, it is possible to prevent the swinging of the suspended load, and the turning speed can be easily set. Therefore, workability is improved. (2) By calculating the turning speed of the crane based on the working radius of the crane detected by the working state detection means, the moving speed of the suspended load may be too fast even when working in a state where the working radius is large. Since it does not occur, the swinging of the load is less likely to occur, and the turning speed is easily adjusted, so that the operability is improved and the burden on the operator can be reduced. (3) By calculating the turning speed of the crane based on the hoisting load detected by the work state detecting means, the crane becomes unusable due to centrifugal force and inertial force generated in the hoisting load that is affected by the turning speed and the load of the hoisting load. It is possible to prevent the load from becoming unstable when the turning is stopped due to a large inertial force. (4) Since the turning speed based on the flow rate calculated by the flow rate calculating means can be arbitrarily reduced by using the turning speed changing means, the operator can change the turning speed according to the work content, so that the operability is improved. In addition, fine operation becomes possible. (5) The flow rate according to the turning speed based on the detection value of the work state detection means and the flow rate according to the maximum turning speed that can be exhibited based on the rotation speed command value of the first rotation speed command means are compared. By controlling the pump displacement by selecting a smaller flow rate among these values, in the case where the flow rate required for the turning speed based on the detection value of the work state detection means cannot be obtained from the current prime mover rotation speed, Even if the engine speed is increased by the second engine speed commanding means, the turning speed does not change. Therefore, in order to increase the hoisting speed during the combined operation of hoisting and hoisting of the suspended load at low engine speed, rotation of the engine is performed. Even if the number is increased, the turning speed does not increase, so there is no shaking of the load, and stable work is possible. (6) When the flow rate calculated by the flow rate calculation means is less than or equal to a predetermined value detected by the work state detection means, the change in the turning speed due to an increase in the prime mover rotational speed is suppressed by limiting the flow rate to a predetermined value. The use of the second flow rate calculation means and the minimum flow rate selection means makes it possible to prevent the shake of goods from occurring with a simple configuration. (7) By using the work state detection means as an overload prevention device that is obliged to be installed as a safety device for a crane, the present invention can be easily implemented without requiring major modification.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a turning control device for a crane according to the present invention.

FIG. 2 is a block diagram showing details of a control device 29 of the first embodiment.

FIG. 3 is a block diagram showing details of a control device 29A of a second embodiment of the crane turning control device according to the present invention.

FIG. 4 is a block diagram showing details of a control device 29B of a third embodiment of the turning control device for a crane according to the present invention.

FIG. 5 is a circuit diagram showing a fourth embodiment of a turning control device for a crane according to the present invention.

FIG. 6 is a block diagram showing details of a control device 29C of a fourth embodiment.

FIG. 7 is a block diagram showing a control device 29D of a fifth embodiment of the crane turning control device according to the present invention.

FIG. 8 is a block diagram showing an example of a conventional turning control device for a crane.

FIG. 9 is a circuit diagram showing an example of a conventional turning control device for a crane.

[Explanation of symbols]

Reference Signs List 20 engine (motor) 21 engine speed detector (motor speed detection means) 22 variable displacement pump 22a pilot operating part (tilt amount changing means) 28 overload prevention device (working state detection means) 29 control device (control means) ) 29A to 29D Control device (control means) 29a First function generator (flow rate calculation means, first flow rate calculation means) 29c Pump tilt amount calculator (tilt amount calculation means) 29i Sixth function generator (Rotation speed changing means) 29j Discharge flow rate calculator (second flow rate calculating means) 29k Comparator (minimum flow rate selecting means) 31 Engine speed setting device (rotation speed commanding device) 31b Second engine speed setting device ( Second rotation speed command means) 31c Third engine rotation speed setting device (first rotation speed command means) 34 Swing speed change dial (swing speed change means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Naruzawa City, 650 Jinrachi-cho, Tsuchiura City, Ibaraki Prefecture Hitachi Construction Machinery Co., Ltd. Tsuchiura Factory

Claims (7)

[Claims] 1. A work state detecting means for detecting a work state of a crane, a variable displacement pump driven by a prime mover and capable of changing a discharge flow rate by changing a pump displacement amount, and a displacement amount of the variable displacement pump. In the turning control device of the crane, which comprises: tilting amount changing means for changing the tilting amount, control means for controlling the tilting amount changing means, and prime mover rotation speed detecting means for detecting the rotation speed of the prime mover, Is a flow rate calculating means for calculating a flow rate according to a turning speed suitable for the working state of the crane detected by the working state detecting means, a flow rate calculated by the flow rate calculating means, and detected by the prime mover rotation speed detecting means. A turning control device for a crane, comprising: a tilting amount calculating means for calculating the tilting amount of the variable displacement pump based on the generated engine speed. 2. The turning control apparatus for the crane according to claim 1, wherein the working status of the crane detected by the working status detection means is a working radius. 3. The turning control apparatus for the crane according to claim 1, wherein the work status of the crane detected by the work status detection means is a suspension load. 4. The turning speed changing means for setting the turning speed arbitrarily with an upper limit of the turning speed based on the flow rate calculated by the flow rate calculating means is provided. A turning control device for a crane according to claim 1. 5. A work state detection means for detecting a work state of a crane, and a variable displacement pump driven by a prime mover and capable of changing a discharge flow rate by changing a pump tilt amount.
A tilt amount changing means for changing the tilt amount of the variable displacement pump, a control means for controlling the tilt amount changing means, a prime mover rotation speed detecting means for detecting a rotating speed of the prime mover, and a prime mover rotation speed First rotation speed command means for setting a minimum value,
Of the second rotation speed command means for increasing the prime mover rotation speed with respect to the minimum value of the prime mover rotation speed set by the first rotation speed command means, and among the command values commanded by these rotation speed command means A crane turning device having a maximum rotation speed selecting means for selecting a large command value and rotationally driving the prime mover at the command value, the control means is a crane operation detected by the work state detecting means. First flow rate calculation means for calculating a flow rate according to the turning speed suitable for the state, and flow rate according to the maximum turning speed that can be exhibited based on the rotation speed command value set by the first rotation speed command means. A second flow rate calculating means for calculating, and a minimum flow rate selecting means for selecting a smaller flow rate of the flow rates calculated by the first and second flow rate calculating means, and the minimum flow rate selecting means. Based on the flow rate selected by the means and the prime mover rotational speed detected by the prime mover rotational speed detecting means, a tilting amount calculating means for calculating the tilting amount of the variable displacement pump is provided. Turning control device. 6. The flow rate calculation means limits the calculated flow rate to a predetermined value when the detection value of the work state detection means is a predetermined value or less. A turning control device for a crane according to any one of the above. 7. The turning control device for a crane according to claim 1, wherein the work state detection means is an overload prevention device.