JPH0338193B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic circuit for a large crane to which a counterweight truck is detachably connected.

(Prior art) Conventionally, in large cranes, in order to increase the lifting capacity, a counterweight truck is connected to the rear of the upper revolving body, and when the upper revolving body of the crane main body is rotated during swinging work, the counterweight truck is connected to the rear of the upper revolving body. It is known that the wheels of the truck are driven to cause the truck to travel (swing) around the center of rotation of the upper revolving structure.

In conventional large cranes, the hydraulic circuit for driving the upper rotating body of the crane body and the hydraulic circuit for driving the wheels of the truck are independent of each other, so during the above-mentioned turning operation, the rotation speed of the upper rotating body and the rotating speed of the truck are different. The swing speed was likely to become unbalanced, and the upper revolving body and the truck were not able to swing smoothly, resulting in poor crane work accuracy and a significant drop in work efficiency. In addition, when the counterweight truck is removed and used, the oil discharged from the hydraulic pump that supplies pressure oil to the hydraulic motor for driving the wheels of the truck will be returned to the tank, which causes problems such as energy loss. It was hot.

(Object of the Invention) The present invention has been made to solve such conventional problems, and at the same time when the upper rotating body is rotated during turning work in which a counterweight truck is connected, the truck is rotated within its turning radius. The crane can be rotated at a speed commensurate with the crane, and the upper revolving body and the truck can be completely synchronized to rotate smoothly, improving the accuracy of crane work, improving work efficiency, and when using the crane with the truck removed. The present invention provides a hydraulic circuit for a large crane that can effectively utilize the oil discharged from a hydraulic pump that supplies pressure oil to a hydraulic motor for driving wheels of a truck, thereby increasing the energy saving effect.

(Structure of the Invention) The present invention provides a large crane comprising a crane body including a lower traveling body and an upper rotating body, and a counterweight truck removably connected to the rear part of the upper rotating body. 2 variable pumps,
A swing hydraulic motor that swings the upper rotating body of the crane body, a swing control valve that controls the supply and discharge of pressure oil from the first variable pump to the swing hydraulic motor, and a trolley hydraulic pressure that drives wheels provided on the counterweight trolley. A motor, a bogie control valve that controls the supply and discharge of pressure oil from the second variable pump to the bogie hydraulic motor, a swing control valve that controls the operation of the swing control valve and the bogie control valve, and a command pressure from the swing operation valve. A first flow control circuit that controls the discharge amount of the first variable pump by the command pressure, a second flow control circuit that controls the discharge amount of the second variable pump according to the command pressure, and the counterweight truck is connected to the upper revolving structure. pipe joint means for closing the connection of the supply/discharge pipe line from the truck control valve to the truck hydraulic motor when removed from the truck; and a merging circuit for merging the discharged oil of the pump, and the first flow control circuit is in a state in which the command pressure from the swing control valve is guided to the flow rate controller of the first variable pump when the truck is removed from the upper revolving structure. The present invention is characterized in that a switching means is provided for switching the command pressure to a state in which the command pressure is reduced and guided to the flow rate controller of the first variable pump when the truck is connected to the upper revolving body.

With this configuration, during swing work with the counterweight truck connected, the command pressure from the swing control valve is directly guided to the flow rate controller of the second variable pump, whereas it is directed to the flow rate controller of the first variable pump. The above-mentioned command pressure is reduced and inputted via the switching means. The discharge amount of the first variable pump that supplies pressure oil to the swinging hydraulic motor of the upper rotating structure with a small turning radius is the same as that of the second variable pump that supplies pressure oil to the hydraulic motor for driving the wheels of the bogie that has a large turning radius.
This becomes smaller than the discharge amount of the variable pump, the turning speed of the upper revolving body becomes slower than the turning speed of the truck, and both turns are synchronized and turned smoothly. Also,
When only the upper revolving body is rotated with the truck removed, the pipe joint means blocks the supply/drain line from the truck control valve to the truck hydraulic motor, and the oil discharged from the second variable pump is routed through the confluence circuit. The oil is then combined with the oil discharged from the first variable pump and supplied to the swing hydraulic motor. Then, the oil discharged from the second variable pump is effectively used, and the energy saving effect is enhanced, and the rotating speed of the upper rotating body is increased, so that the efficiency of the rotating operation can be increased.

(Example) The overall configuration of a large crane will be explained with reference to FIG. In FIG. 4, the crane main body 1 includes a lower traveling body 2, an upper revolving body 3, a main jib 4, a lifting device 5,
It is equipped with a mast 6, a main jib guy line 7, a mast guy line 8, etc. The counterweight truck 10 is provided with a plurality of wheels 11 on the lower part thereof so as to be freely steerable around a vertical axis and rotatable around a horizontal axis, and a counterweight 12 is mounted on the upper part.
This truck 10 is removably connected to the rear part of the upper revolving body 3 of the crane main body 1 via a connecting member 9 such as a beam, and is connected to a guy line 13 for a counterweight truck suspended from the upper end of the mast 6. They are detachably connected.

Figure 1 shows the hydraulic circuit of the main parts of the large crane. In FIG. 1, 14 is a first variable pump, 15 is a second variable pump, and discharge pipes 16 and 17 of both pumps 14 and 15 are connected to a confluence pipe 18.
The confluence pipe line 18 is provided with a check valve 19 that allows the confluence from the second variable pump 15 to the first variable pump 14 and prevents the reverse flow. 20 is a swing control valve, 21 is a bogie control valve, 22
2 is a swing hydraulic motor for rotating the upper revolving structure 3 shown in FIG. 4; 23 is a truck hydraulic motor for driving the wheels 11 of the counterweight truck 10;
Reference numeral 4 indicates a tank, and a truck hydraulic motor 23 is detachably connected to the truck control valve 21 via a pipe joint means 25 such as a quick coupling puller.

The swing operation valve 26 includes a variable pressure reducing valve operated by a swing operation lever 27, and outputs a command pressure according to the operating direction and operating angle of the lever 27 to the operating pipes 28 and 29. Although a spool valve type directional control valve may be used for the swing control valve 20 and the bogie control valve 21, normally they are used to switch the flow direction of pressure oil and control the supply pressure to the hydraulic motors 22 and 23. A pressure control valve (eg, a 4-check valve) is used. In addition, the bogie control valve 21 receives a turning command pressure guided to the operating pipes 30 and 31 and a command pressure guided to the operating pipe for a travel control valve (not shown) that controls the traveling of the lower traveling body 2 of the crane main body 1. It is now possible to switch between them.

On the other hand, a pipe line 33 is connected to the operating pipe lines 28 and 29 via a high pressure selection valve 32.
are the first flow control pipe 34 and the second flow control pipe 35
The pipe line 35 is connected to the flow rate controller 15a of the second variable pump 15. Above pipe line 3
4 is connected to a pipe line 37 via a switching means 36, and this pipe line 37 is connected to the flow rate controller 14a of the first variable pump 14. The switching means 36
is equipped with an electromagnetic switching valve 38, a proportional pressure reducing valve 39, a passage 40, and a high pressure selection valve 41, and the electromagnetic switching valve 38 is in a left position where the pipe line 34 is communicated with the passage 40, and in a position where the pipe line 34 is in a proportional pressure reducing position. The high pressure selection valve 41 selects a high pressure between the pressure led to the passage 40 and the pressure led from the proportional pressure reducing valve 39 and leads it to the conduit 37. ing.

Next, the effect will be explained.

When performing a turning operation with the counterweight truck 10 connected to the upper revolving structure 3, the wheels 11 of the truck 10 are directed in the turning direction by a steering means (not shown). At this time, manually or the above-mentioned trolley 10
Detecting the connection, the electromagnetic switching valve 38 of the switching means 36 is automatically excited and switched to the right position. In this state, when the swing operation lever 27 is operated, for example, to the left, the left pipe 28 is moved from the swing operation valve 26 to the left side.
A command pressure Pi ₁ is guided to, the swing control valve 20 is switched by this command pressure Pi ₁ , the oil discharged from the first variable pump 14 is guided to the swing hydraulic motor 22, and the motor 22 is rotated in the forward direction. The upper rotating body 3 of the crane main body 1 is rotated to the left. Further, the command pressure Pi ₁ is also guided to the operation pipe 30, and this command pressure
The bogie control valve 21 is switched by Pi ₁ , and the second
The oil discharged from the variable pump 15 is supplied to the truck hydraulic motor 23.
The motor 23 is rotated in the forward direction, and the trolley 10 is
The wheels 11 of the truck 10 are driven, and the truck 10
The vehicle travels or turns integrally with the vehicle.

During this swing, the command pressure Pi ₁ guided to the operation pipe 28 is controlled according to the operation amount of the lever 27, and the switching amount of the swing control valve 20 and the bogie control valve 21 is controlled according to the command pressure Pi ₁ . At the same time, the pressure of the pressure oil supplied to the swing hydraulic motor 22 and the truck hydraulic motor 23 is controlled, and the driving pressure of each motor 22, 23 is controlled.

Further, the rotation command pressure Pi ₁ is guided from the pipe 28 to the flow rate controller 15a of the second variable pump 15 via the high pressure selection valve 32, the pipe 33, and the pipe 35,
This pressure Pi ₁ controls the discharge amount Q ₂ of the second variable pump 15 as shown in FIG. Speed is controlled.

On the other hand, the command pressure Pi ₁ guided from the pipe 28 to the pipe 33 via the high pressure selection valve 32 is inputted to the switching means 36 via the pipe 34. At this time, the electromagnetic switching valve 38 of the switching means 36 is switched to the right position, so the command pressure Pi ₁ is inputted to the proportional pressure reducing valve 39 via the electromagnetic switching valve 38, and the proportional pressure reducing valve 39 reduces the pressure to a predetermined pressure Pi _2. After _being reduced _to The flow rate is controlled as shown by the solid line in the diagram, and accordingly, the flow rate supplied to the swing hydraulic motor 22 is controlled, and the swing speed of the upper revolving structure 3 is controlled.

Since the electromagnetic switching valve 38 is switched to the right position when the bogie 10 turns in the connected state, the turning command pressure Pi ₁ is directly guided to the flow rate controller 15a of the second variable pump 15. ,
The swing command pressure Pi ₁ is reduced to a pressure Pi ₂ by the proportional pressure reducing valve 39 and then introduced to the flow rate controller 14 a of the first variable pump 14 . At this time, the pressure from Pi ₁ to the pressure
The degree of depressurization to Pi ₂ is as follows: Carriage 1 with a large turning radius
Required flow rate of the hydraulic motor 23 for the truck that rotates the
It is determined by the ratio between Q ₂ and the required flow rate Q ₁ of the swing hydraulic motor 22 that swings the upper swing structure 3 with a small swing radius, and this ratio can be determined by changing the area ratio of the proportional pressure reducing valve 39, etc. This can be easily selected, and by this selection, the turning speed of the upper revolving body 3 and the traveling speed of the truck 10 can be completely synchronized, and both can be smoothly turned as one.

Next, when rotating only the upper revolving body 3 with the truck 10 removed, the truck 10 is removed from the crane main body 1 and the truck hydraulic motor 23 is removed from the pipe joint 25 portion. At this time, the electromagnetic switching valve 38 of the switching means 36 is automatically or manually demagnetized and held at the illustrated position. In this state, if the turning operation lever 27 is operated, for example, to the left,
Similarly to the above, the command pressure Pi ₁ is guided from the swing operation valve 26 to the operation conduit 28, and the swing control valve 20 is switched by the command pressure Pi ₁ .

On the other hand, the command pressure Pi ₁ is applied to the flow rate control of the first variable pump 14 via the high pressure selection valve 32, the pipe 33, the first control pipe 34, the electromagnetic switching valve 38, the passage 40, the high pressure selection valve 41, and the pipe 37. It is guided to the flow rate controller 15a of the second variable pump 15 via the conduit 35. At this time, the command pressure Pi ₁ guided to the first control pipe 34 is guided to the pipe 37 via the passage 40, so it is not subjected to the pressure reducing action by the proportional pressure reducing valve 39, and is therefore guided to the flow rate controller 14a. The pressure Pi ₂ is Pi ₂ = Pi ₁ , and this pressure Pi ₂
As a result, the discharge amount Q ₁ of the first variable pump ₁₄ is controlled as shown by the broken line in FIG. It is supplied to the swing hydraulic motor 22 through the.

Further, the command pressure Pi ₁ is guided to the flow rate controller 15a of the second variable pump 15 via the second control line 35, and the discharge amount Q ₂ of the second variable pump 15 is controlled as shown in FIG. However, since the discharge oil of the second variable pump 15 during this turning is blocked by the pipe joint 25, the discharge oil flows into the confluence pipe 18, passes through the check valve 19, and becomes the discharge oil of the first variable pump 14. be merged. This combined oil is then guided to the swing hydraulic motor 22 via the swing control valve 20. That is, the oil discharged from the first variable pump 14 and the oil discharged from the second variable pump 15 are combined and supplied to the swing hydraulic motor 22 .

In this way, when rotating only the upper rotating body 3 with the truck 10 removed, the oil discharged from the first variable pump 14 and the oil discharged from the second variable pump 15 are supplied to the swing hydraulic motor 22. By merging and supplying the oil, the oil discharged from the second variable pump 15 can be effectively used to increase the energy saving effect, and a large flow of oil can be supplied to the swing hydraulic motor 22, and the rotational speed of the motor 22 can be increased. In other words, the turning speed can be increased, and the efficiency of turning work can be increased.

(Effects of the Invention) As described above, the present invention provides the discharge amount of the first variable pump that supplies pressure oil to the swing hydraulic motor of the upper rotating body with a small swing radius during swing work with the counterweight truck connected. can be made smaller than the discharge amount of the second variable pump that supplies pressure oil to the hydraulic motor for driving the wheels of the bogie with a large turning radius, and the turning speed of the upper revolving body and the turning speed of the cart can be synchronized and smooth. It can be rotated and the accuracy of turning work can be improved. In addition, when rotating only the upper revolving body with the bogie removed, the pipe joint data blocks the supply/discharge pipe from the bogie control valve to the bogie hydraulic motor, and the second variable The oil discharged from the pump can be combined with the oil discharged from the first variable pump and supplied to the swing hydraulic motor, thereby making it possible to increase the swing speed of the upper revolving structure and significantly increasing the efficiency of swing work. Moreover, the oil discharged from the second variable pump can be used effectively, and the energy saving effect can be enhanced.

[Brief explanation of drawings]

Fig. 1 is a hydraulic circuit diagram showing an embodiment of the present invention, Figs. 2 and 3 are control characteristics of the discharge amount of the first variable pump and the second variable pump, and Fig. 4 shows an example of a large crane. It is an overall side view. 1... Crane body, 2... Lower running body, 3...
...Upper revolving body, 10...Counterweight truck,
11...Wheel, 14...First variable pump, 14a
...Flow rate controller, 15...Second variable pump, 15
a...Flow rate controller, 18... Merging pipe, 20...
Swing control valve, 21... Bogie control valve, 22... Swing hydraulic motor, 23... Hydraulic motor for bogie, 25...
...pipe joint, 26...swivel control valve, 34...first flow rate control line, 35...second flow rate control line, 36...
...Switching means, 38...Solenoid switching valve, 39...Proportional pressure reducing valve.

Claims (1)

[Claims] 1. In a large crane consisting of a crane body equipped with a lower traveling body and an upper rotating body, and a counterweight truck removably connected to the rear of the upper rotating body,
a first variable pump, a second variable pump, a swing hydraulic motor that swings the upper rotating body of the crane body, a swing control valve that controls supply and discharge of pressure oil from the first variable pump to the swing hydraulic motor, and a counterweight. a truck hydraulic motor that drives wheels provided on the truck; a truck control valve that controls supply and discharge of pressure oil from a second variable pump to the truck hydraulic motor;
a swing operation valve that controls the operation of the swing control valve and the bogie control valve; a first flow rate control circuit that controls the discharge amount of the first variable pump according to the command pressure from the swing operation valve; A second flow rate control circuit that controls the discharge amount of the second variable pump, and a pipe that closes the connection of the supply and discharge pipe from the truck control valve to the truck hydraulic motor when the counterweight truck is removed from the upper revolving structure. It is equipped with a joint means and a merging circuit for merging the discharge oil of the second variable pump with the discharge oil of the first variable pump on the upstream side of each of the control valves, and the first flow rate control circuit includes the above-mentioned truck connected to the upper revolving structure. The command pressure from the swing operation valve is guided to the flow rate controller of the first variable pump when the truck is removed from the swing control valve, and the command pressure is reduced and the flow rate of the first variable pump is controlled when the truck is connected to the upper revolving structure. A hydraulic circuit for a large crane, characterized in that it is provided with a switching means for switching between a state in which the information is guided to a controller.