JP3750764B2 - Swivel control device for construction machinery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a turning control device for a construction machine such as a crane.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a so-called pressure control type device is generally well known as a device for controlling the driving of a fluid pressure actuator in accordance with, for example, an operation amount of an operation lever. This will be explained with reference to the turning of the crane. 4 is an overall configuration diagram of the crane, and FIG. 5 is a circuit configuration diagram of a pressure control type turning control device. As shown in FIG. 4, the crane has a traveling body 61, a revolving body 62 mounted on the traveling body 61 and capable of turning, and a boom 63 provided on the revolving body 62. The suspended load 66 is lifted by a hook 65 connected to the rope.
[0003]
As shown in FIG. 5, the hydraulic circuit for turning the revolving structure 62 is for the turning driven by the prime mover 101, the hydraulic pump 3 driven by the prime mover 101, and the pressure oil discharged from the hydraulic pump 3. The hydraulic motor 2, the turning direction control valve 1 for controlling the flow of pressure oil supplied from the hydraulic pump 3 to the turning hydraulic motor 2, the operating lever 5 for the operator to input a turning command, and the operation of the operating lever 5 And a pilot hydraulic power source 7 that supplies pressure oil to a pilot hydraulic circuit that transmits the amount to the directional control valve 1. The direction control valve 1 bleeds to a tank 8 and a throttle 1A that communicates with the main pipelines 6A and 6B connected to the turning hydraulic motor 2 in a neutral position in order to ensure controllability of torque of the turning hydraulic motor 2. And a throttle 1B interposed in the passage of the pressure oil to be turned off.
[0004]
In such a conventional turning control device, when the operation lever 5 is operated to switch the direction control valve 1 to the a position or the b position, the pump pressure of the hydraulic pump 3 increases according to the operation amount of the operation lever 5. When the main pipelines 6A and 6B are gradually shut off and the directional control valve 1 is operated to the a position, pressure oil is supplied to the main pipeline 6B, and when the directional control valve 1 is operated to the b position, Pressure oil is supplied to the path 6 </ b> A side, whereby the driving torque of the turning hydraulic motor 2 can be controlled. On the other hand, when the operating lever 5 is suddenly returned from the operating state to the neutral position, the directional control valve 1 is also switched to the neutral position, but the main conduits 6A and 6B are immediately communicated, so the turning hydraulic motor 2 is suddenly Thus, the state where the revolving body rotates freely (a state where the turn is free) is secured.
[0005]
In this way, by performing pressure control, the swivel body can easily rotate freely with respect to an external load such as a load shake, thereby making it difficult for the load shake to occur and the operator can You can work while feeling the external load.
[0006]
On the other hand, a so-called flow rate control system is also known as a device for controlling the driving of the fluid pressure actuator. FIG. 6 is a circuit configuration diagram of a flow control type turning control device. In FIG. 6, the same components as those in FIG. 5 are given the same reference numerals, and detailed description thereof is omitted. The flow control type turning control device and the pressure control type turning control device control the point that the direction control valve 1 does not have the throttles 1A and 1B and the pressure of the pressure oil bleed off from the direction control valve 1. This is different from the point that the pressure compensating valve 4 is provided. The pressure compensation valve 4 is configured to be able to control the pressure of the bleed-off pressure oil to a pressure corresponding to the driving pressure of the turning hydraulic motor 2 by guiding the driving pressure of the turning hydraulic motor 2.
[0007]
In such a turning control device, since the drive pressure of the turning hydraulic motor 2 and the pressure of the bleed-off pressure oil are equal to each other as described above, the pressure difference before and after the directional control valve 1 is configured. Is constant regardless of the load pressure when the opening area is constant, and the flow rate to the turning hydraulic motor 2 side and the flow rate to be bleed off are distributed according to the opening area ratio of the turning direction control valve 1. Therefore, the flow rate distribution as input by the operator can be performed regardless of the load pressure.
[0008]
On the other hand, in the above-described turning control device of the flow rate control method, the flow rate control function always operates, so that when the operator wants to perform work while feeling the load of the turning hydraulic motor 2, the flow rate control function becomes an obstacle. There is a risk that the inconvenience of poor operability may occur.
[0009]
For this reason, there has been proposed a device for compensating pressure by providing a negative control pressure setting valve in the bleed-off line and reducing the negative control pressure in inverse proportion to the operation amount of the operating lever by this setting valve (Japanese Patent Laid-Open No. Hei 8). -105403). Here, the negative control pressure is the pressure that controls the tilt angle of the hydraulic pump, and the negative control is the negative control maximum pressure that acts on the regulator of the pump at the neutral position of the operation lever to minimize the tilt angle, At the maximum stroke of the control lever, the negative control pressure is minimized and the tilt angle is maximized. In the apparatus described in the above-mentioned Japanese Patent Application Laid-Open No. 8-105403, the flow rate control state (referred to as pressure compensation control in the above publication) is turned on when the negative control pressure setting valve is turned on, and the non-flow rate control state (in the publication described above) This is called non-pressure compensation control. In this way, by making it possible to switch between flow rate control and non-flow rate control, the turning hydraulic motor can be controlled according to the control state desired by the operator.
[0010]
[Problems to be solved by the invention]
In the pressure control method described above, the operator can operate while feeling an external load such as a load swing, and thus it is difficult for the suspended load to swing, but the operational feeling changes depending on the difference in the size of the external load. For example, a large torque is required when lifting a heavy object or when the working radius is relatively large, but not so much when hanging a small object or when the working radius is relatively small, or during slow speed operation or positioning operation. Since a large torque is not required, a change in operation feeling occurs. In addition, when a small weight is suspended or when the working radius is relatively small, it is difficult to feel the external load and the influence of the external load is not so great. It is desired to drive the turning hydraulic motor by a flow rate control system that can obtain the desired speed.
However, it is difficult to provide the pressure control method and the flow rate control method in the same construction machine, and the operator has to operate only by one of the methods.
[0011]
An object of the present invention is to provide a turning control device for a construction machine capable of driving a turning hydraulic motor by arbitrarily switching a pressure control method and a flow rate control method.
[0012]
[Means for Solving the Problems]
(1) Referring to FIGS. 1 to 4 showing an embodiment, the present invention relates to a hydraulic pump 3 and a turning hydraulic motor that drives a turning body 62 by pressure oil discharged from the hydraulic pump 3. 2, turning control of a crane provided with a turning direction control valve 1 for controlling the direction of pressure oil supplied from the hydraulic pump 3 to the turning hydraulic motor 2, and operating means 5 for switching the turning direction control valve 1. A pressure compensation valve 4 which is applied to the apparatus and sets the pressure of a bleed-off circuit communicating from the turning direction control valve 1 to the tank 8 to a pressure corresponding to the driving pressure of the turning hydraulic motor 2; The input / output port is communicated and cut off, and the switching valve 11 whose opening area changes according to the operation amount of the operating means 5 during the switching, and can be operated by the occupant irrespective of the operation of the operating means 5, Pressure operation Or performed by control system, blocking the command means 15 for commanding whether to perform a flow rate control method, when the flow control method by a command unit 15 is commanded, the output port of the swing hydraulic motor 2 by the switching valve 11 When the pressure control method is commanded by the command means 15 , the control means 12 that operates the switching valve 11 between the communication position and the shut-off position so as to change the opening area according to the operation amount of the operation means 5. It is characterized by providing.
(2) The invention of claim 2 is the turning control device of claim 1 , wherein the switching valve 11 is a hydraulic pilot type switching valve, and the control means 12 is connected to the hydraulic pilot port of the hydraulic pilot type switching valve 11. The electromagnetic switching valve 12 is switched to a first position a for supplying pressure for switching 11 to the shut-off position, and a second position b for supplying hydraulic pressure corresponding to the operation amount of the operating means 5 to the hydraulic pilot port; The command means is characterized by comprising a switch 15 for commanding switching of the electromagnetic switching valve 12 to the first position a or the second position b.
(3) The invention of claim 3 is the turning control device of claim 1 , further comprising a detecting means 23 for outputting an electric signal corresponding to the operation amount of the operating means, wherein the switching valve is the electromagnetic switching valve 110, The control means 12 has a first table 21 for supplying a signal for switching the switching valve 110 to the cutoff position b to the signal supply terminal of the electromagnetic switching valve 110, and a signal corresponding to the operation amount of the operating means 5 to the signal supply terminal. The command means is composed of a switch 24 that commands switching between the first table 21 and the second table 22.
[0013]
In the section of the means for solving the above-described problems for explaining the configuration of the present invention, the drawings of the embodiments of the invention are used for easy understanding of the present invention. It is not limited.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a hydraulic circuit diagram showing a configuration of a turning control device for a construction machine according to an embodiment of the present invention. As shown in FIG. 1, the hydraulic circuit of the turning control device for a construction machine according to the present embodiment includes a prime mover 101, a hydraulic pump 3 driven by the prime mover 101, and pressure oil discharged from the hydraulic pump 3. The swivel hydraulic motor 2 that is driven, the swivel direction control valve 1 that controls the flow of pressure oil supplied from the hydraulic pump 3 to the swivel hydraulic motor 2, and the pressure oil bleed off by the direction control valve 1 A pressure compensation valve 4 for controlling pressure, an operation lever 5 for an operator to input a turning command, and a pilot hydraulic power source 7 for supplying pressure oil to a pilot hydraulic circuit for transmitting an operation amount of the operation lever 5 to the direction control valve 1; It has. The pressure compensation valve 4 is configured to be able to control the pressure of the bleed-off pressure oil to a pressure corresponding to the driving pressure of the turning hydraulic motor 2 by guiding the driving pressure of the turning hydraulic motor 2.
[0015]
Further, a switching valve 11 for switching communication and non-communication of the main pipelines 6A and 6B is connected to the two main pipelines 6A and 6B connected to the turning hydraulic motor 2. The switching valve 11 is normally switched to the position a for communicating the main pipelines 6A and 6B by the biasing force of the spring 11c. Here, the switching valve 11 is provided with a throttle 11B in which the throttle area is changed in the process of switching between the a position and the b position. As shown in FIG. As the pressure (pressure signal) of the pressure oil supplied to the pilot port 11A increases, the opening area of the throttle 11B decreases. FIG. 2B is a diagram showing the relationship between the stroke of the directional control valve 1 and the opening area.
[0016]
Connected to the pilot port 11A of the switching valve 11 is a selection valve 12 for selectively supplying the pilot oil from the pilot hydraulic power source 7 and the pilot pressure oil generated by the operation of the operation lever 5 to the pilot port 11A. . The selection valve 12 is normally switched to the position a for supplying the pressure oil of the pilot hydraulic source 7 to the pilot port 11A by the biasing force of the spring 12c, and the solenoid portion 12A is excited by the switch 15 provided in the cab. Thus, the pilot pressure oil generated by the operation of the operation lever 5 is switched to the b position for supplying the pilot port 11A. The pilot pressure oil is selected by the shuttle valve 10 and supplied to the pilot port 11A of the switching valve 11.
[0017]
In this embodiment, the turning hydraulic motor 2 is driven by the flow rate control method when the selection valve 12 is switched to the a position, and by the pressure control method when the selection valve 12 is switched to the b position.
[0018]
Next, the operation of the present embodiment will be described.
First, in a state in which the switch 15 is off, that is, in a state in which the selection valve 12 is switched to the position a, the pressure oil from the pilot hydraulic source 7 directly enters the pilot port 11A of the switching valve 11 via the selection valve 12. Supplied. As a result, the switching valve 11 is switched to the b position regardless of the operation amount of the operation lever 5, and the main pipelines 6A and 6B are shut off. In this state, the turning control device according to the present embodiment is a flow rate control type hydraulic circuit including the direction control valve 1 and the pressure compensation valve 4 as shown in the prior art of FIG. Therefore, as described above, the flow rate to the turning hydraulic motor 2 side and the flow rate to be bleed off are distributed according to the opening area ratio of the turning direction control valve 1 regardless of the load pressure. Regardless of the flow, the flow can be distributed as entered by the operator.
[0019]
On the other hand, when the switch 15 is turned on, the solenoid portion 12A is excited and the selection valve 12 is switched to the b position. In this state, the pilot pressure corresponding to the operation amount of the operation lever 5 is supplied to the pilot port 11 </ b> A of the switching valve 11 through the check valve 10. Thereby, the main pipelines 6A and 6B are communicated with each other by the aperture 11B having an opening area corresponding to the operation amount of the operation lever 5. In this state, the turning control device according to the present embodiment is a circuit equivalent to the pressure control type hydraulic circuit shown in the prior art of FIG. Accordingly, when the operation lever 5 is operated to operate the direction control valve 1 to the a position side or the b position side, the pump pressure of the hydraulic pump 3 rises according to the operation amount of the operation lever 5, and the main valve is operated by the switching valve 11. The paths 6A and 6B are gradually cut off. Therefore, the driving torque of the turning hydraulic motor 2 can be controlled in the same manner as the pressure control method of FIG. On the other hand, when the operation lever 5 is suddenly returned to the neutral position from the operation state, the direction control valve 1 is also switched to the neutral position, but the switching valve 11 is switched to the position a and the main pipelines 6A and 6B are immediately communicated. Therefore, the turning hydraulic motor 2 does not stop abruptly, and a state in which the turning body freely rotates (turning free state) is ensured. Therefore, it becomes easy for the swivel body to freely rotate with respect to an external load such as a load swing, thereby making it difficult for the swing to occur, and an operator can work while feeling an external load such as a load swing. it can.
[0020]
As described above, in this embodiment, the turning body can be turned by the pressure control method by turning on the switch 15, so that it is possible to prevent load swinging when a heavy object is suspended. In addition, the operator can perform a turning operation while feeling a turning load, thereby improving the operability. Further, since the turning body can be turned by the flow rate control method by turning off the switch 15, the operation lever 5 is used when carrying out a slow speed operation or positioning operation when hanging a small weight object, at a small work radius. The revolving body can be rotated at a speed corresponding to the operation amount, thereby improving the operability.
[0021]
In the above embodiment, the position of the switching valve 11 is switched by turning on / off the switch 15, but as shown in FIG. 3, a proportional electromagnetic valve 110 is provided instead of the switching valve 11, and an operation lever is provided. 5, two tables 21 and 22 indicating the relationship between the stroke and voltage, a sensor 23 for detecting the stroke of the operation lever 5, and a changeover switch 24 for switching a signal from the sensor 23 input to the tables 21 and 22. It may be provided so that the switching valve 11 is switched. When the changeover switch 24 is switched to the a position, the table 21 that outputs a voltage signal for switching the changeover valve 11 to the b position is selected regardless of the stroke size, and the changeover switch 24 is switched to the b position. If so, the table 22 that outputs a voltage signal that is directly proportional to the size of the stroke is selected. Thus, the turning hydraulic motor 2 can be driven by the flow rate control method when the changeover switch 24 is switched to the a position and by the pressure control method when the changeover switch 24 is switched to the b position.
[0022]
In the correspondence between the above embodiment and the claims, the operation lever 5 constitutes the operation means, and the selection valve 12, the hydraulic pressure source 7 and the shuttle valve 10 constitute the control means. The switches 15 and 24 constitute command means. Further, the sensor 23 constitutes detection means, and the s tables 21 and 22 constitute control means.
[0023]
【The invention's effect】
As described above in detail, according to the present invention, when the flow rate control method is commanded by the command means , the input / output port of the turning hydraulic motor is blocked by the switching valve, thereby placing importance on the fine operability by the pressure compensation valve. When the pressure control method is commanded by the command means , the input / output port of the turning hydraulic motor is communicated before the operation means is operated by the switching valve , and when operated, the input / output port is switched according to the operation amount. The opening area of the valve is reduced, and the pressure control method emphasizes anti-loading performance. Therefore , the turning body can be driven by the control method desired by the operator when the operator instructs the turning control method by the command means .
[Brief description of the drawings]
FIG. 1 is a hydraulic circuit diagram showing a configuration of a turning control device according to an embodiment of the present invention. FIG. 2 is an opening area diagram of a switching valve and a directional control valve. Fig. 4 is a hydraulic circuit diagram showing the configuration of the crane according to the present invention. Fig. 4 is an overall configuration diagram of the crane. Fig. 5 is a hydraulic circuit diagram showing the configuration of the pressure control type swing device. Hydraulic circuit diagram indicating
DESCRIPTION OF SYMBOLS 1 Direction control valve for turning 2 Hydraulic motor for turning 3 Hydraulic pump 4 Pressure compensation valve 6A, 6B Main line 5 Operation lever 7 Pilot hydraulic power source 11 Switching valve 12 Selection valve

Claims (3)

A hydraulic pump;
A turning hydraulic motor for driving the turning body by the pressure oil discharged from the hydraulic pump;
A turning direction control valve for controlling the direction of pressure oil supplied from the hydraulic pump to the turning hydraulic motor;
In a turning control device for a construction machine comprising an operation means for switching the turning direction control valve,
A pressure compensation valve for setting a pressure of a bleed-off circuit communicating with the tank from the turning direction control valve to a pressure corresponding to a driving pressure of the turning hydraulic motor;
The input / output port of the turning hydraulic motor is communicated and shut off, and a switching valve whose opening area changes according to the operation amount of the operating means in the middle of the switching,
Command means that can be operated by the occupant regardless of the operation of the operation means, and commands whether the turning operation is performed by the pressure control method or the flow rate control method;
When the flow control method is commanded by the command means, the switching valve shuts off the input / output port of the turning hydraulic motor, and when the pressure control method is commanded by the command means , the operation means And a control means for operating the switching valve between the communication position and the shut-off position so as to change the opening area in accordance with the amount of operation. Claim 1 In the turning control device of
  The switching valve is a hydraulic pilot switching valve,
  The control means supplies a pressure for switching the switching valve to the shut-off position to a hydraulic pilot port of the hydraulic pilot type switching valve. 1 And an electromagnetic selection valve that is switched to a second position for supplying the hydraulic pressure corresponding to the operation amount of the operating means to the hydraulic pilot port,
  The command means moves the electromagnetic selection valve to the first 1 A swing control device for a construction machine, comprising a switch for instructing switching to the second position or the second position. Claim 1 In the turning control device of
  The switching valve is an electromagnetic switching valve;
  It further comprises detection means for outputting an electrical signal corresponding to the operation amount of the operation means,
  The control means supplies a signal for switching the electromagnetic switching valve to the shut-off position to a signal supply terminal of the electromagnetic switching valve. 1 And a second table for supplying a signal corresponding to the operation amount of the operation means to the signal supply terminal,
  The turning control device for a construction machine, wherein the command means is composed of a switch for commanding switching between the first and second tables.

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