JP2004076904A - Hydraulic cylinder control device of construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure constant operability regardless of variation of a load only by adding a minimum and inexpensive facility. <P>SOLUTION: A regeneration circuit 18 that returns one part of return oil discharged from an arm cylinder 8 in a hydraulic shovel is installed to this cylinder control device. A regeneration valve 19 whose opening degree is controlled by a controller 20 is installed to the regeneration circuit 18. An opening characteristic of the regeneration valve 19 is varied according to a load pressure, so as to keep an actuation speed of an arm cylinder 8 relative to an operation volume of a remote control valve 17 constant. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydraulic cylinder control device that controls the operating speed of a hydraulic cylinder in a construction machine such as a hydraulic shovel, an excavator or a demolition machine having the hydraulic shovel as a base.
[0002]
[Prior art]
A conventional technique will be described by taking a hydraulic cylinder for an arm of a hydraulic shovel as a preferred example of the present invention as an example.
[0003]
In FIG. 6, reference numeral 1 denotes a lower traveling body, and 2 denotes an upper revolving body which is mounted on the lower traveling body 1 so as to be freely rotatable. The excavation attachment 3 is attached to the upper revolving body 2 to constitute a hydraulic shovel.
[0004]
The excavation attachment 3 includes a boom 4 that can be raised and lowered, an arm 5 attached to the tip of the boom 4 so as to be rotatable around a horizontal axis, a bucket 6 attached to the tip of the arm 5, , Bucket hydraulic cylinders 7, 8, and 9, the boom hydraulic cylinder 7 raises and lowers the boom 4, and the arm hydraulic cylinder 8 pushes the arm 5 (movement away from the upper swing body 2). , Pulling (movement in the direction approaching the upper swing body 2), and the bucket hydraulic cylinder 9 performs each operation of rotating the bucket 6.
[0005]
[Problems to be solved by the invention]
Here, when performing an arm pulling operation of pulling the arm 5 in a direction indicated by an arrow from a position ahead of the vertical as shown in the drawing, the arm hydraulic cylinder (hereinafter referred to as the arm cylinder) 8 has the weight of the arm 5 and the bucket 6. A load that is the sum of the load and the stacking load acts in the cylinder extension (arm pulling) direction, and the magnitude of this load changes the arm pulling speed.
[0006]
On the other hand, in recent years, with the diversification of the working environment of the hydraulic excavator, the excavation attachment 3 has many variations, and in many cases, the excavation attachment 3 is heavier than the standard attachment when the machine is shipped. In addition, a special attachment for dismantling may be added to the excavation attachment 3.
[0007]
As a result, in a machine in which the operability is tuned based on the standard attachment, the arm pulling speed becomes faster than the standard lever operation.
[0008]
Under such circumstances, there has been a problem that the arm pulling speed with respect to the lever operation varies, and the operability deteriorates.
[0009]
As a countermeasure against these points, replace the arm cylinder control valve with the one with the meter-out opening characteristic to be obtained, or install it in the meter-out circuit of the control valve so that operability according to the load is obtained. It is conceivable to add a flow control valve and adjust the speed by reducing the meter-out flow during the arm pulling operation according to the load.
[0010]
However, the former method is not practical because the control valve must be replaced with an optimum one every time the load fluctuates. Further, according to the latter method, the cost is increased by adding an expensive flow control valve, so that it is not a good idea.
[0011]
On the other hand, a hydraulic shovel is generally provided with a regeneration circuit for returning oil discharged from the rod side (cylinder contraction side) of the arm cylinder to the head side (cylinder extension side) for the purpose of preventing cavitation during an arm pulling operation. Have been.
[0012]
In a shovel provided with this regeneration circuit, a technique is known in which a regeneration valve is provided in the regeneration circuit, and the cylinder speed is controlled by controlling the meter-out flow rate by controlling the opening of the regeneration valve (see Japanese Patent Application Laid-Open No. HEI 9-163572). 10-18358).
[0013]
However, in this known technique, the cylinder speed is reduced by narrowing the opening of the regeneration valve in a range where the lever operation amount is small, and the cylinder is slowly started to smoothly perform leveling work by horizontal pulling of the arm and the like. It is not possible to obtain appropriate operability.
[0014]
Accordingly, the present invention provides a hydraulic cylinder control device for a construction machine that can ensure constant operability irrespective of load fluctuations only by adding minimal and inexpensive equipment.
[0015]
[Means for Solving the Problems]
The invention according to claim 1 is provided with a regeneration circuit for re-supplying a part of the return oil from the hydraulic cylinder operated by the operating means to the drive side of the cylinder, and a regeneration valve is provided in the regeneration circuit. And an operation amount detection means for detecting an operation amount of the operation means, a load pressure detection means for detecting a load pressure of the hydraulic cylinder, and an operation amount and a load pressure of the operation means detected by the two detection means. Control means for performing the following controls (A) and (B) accordingly.
[0016]
(A) The opening of the regeneration valve is increased in accordance with an increase in the operation amount of the operation means.
[0017]
(B) The characteristics relating to the operation amount and the opening degree of the regeneration valve are changed in accordance with the load pressure such that the relation between the operation amount of the operation means and the cylinder operating speed becomes substantially constant regardless of the load pressure.
[0018]
According to a second aspect of the present invention, in the configuration of the first aspect, a regeneration valve is provided in a regeneration circuit of the hydraulic cylinder for an arm that pushes and pulls the arm in the excavation attachment of the hydraulic shovel, and the opening of the regeneration valve is controlled by the control means. This is configured to control the cylinder operating speed on the arm pulling side by controlling.
[0019]
According to a third aspect of the present invention, in the configuration of the first or second aspect, a hydraulic pilot valve whose opening changes in accordance with the pilot pressure is used as the regeneration valve, and the control means controls the pilot pressure of the regeneration valve. It has an electromagnetic proportional valve and a controller that sends a signal to the electromagnetic proportional valve to change the opening of the regeneration valve.
[0020]
According to the above configuration, the characteristic of the opening degree change of the regeneration valve with respect to the operation amount of the operation means changes according to the load pressure, and the relationship between the operation amount and the cylinder speed is controlled to be substantially constant irrespective of the change in the load pressure. Therefore, in the operation affected by the load (the arm pulling operation frequently used in the hydraulic shovel in claim 2), at the time of a large load in which the cylinder speed is increased, the opening of the regeneration valve is reduced to reduce the meter-out flow rate. In addition, it is possible to suppress an increase in speed due to the influence of a load, and to secure a constant operability.
[0021]
In addition, since the meter-out flow rate is controlled by using the originally provided regeneration valve and the cylinder speed is controlled, equipment to be added is minimized (the electromagnetic proportional valve and the electromagnetic proportional valve Controller software for controlling the system).
[0022]
Therefore, compared to the case where the control valve is replaced or an expensive flow control valve is added, the practicability is high and the cost is low.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
[0024]
In the following embodiments, a case is described in which a hydraulic excavator is applied and operability of an arm pulling operation is improved.
[0025]
1, the same parts as those in FIG. 6 are denoted by the same reference numerals.
[0026]
FIG. 1 illustrates a circuit in which a control valve 11 for an arm cylinder and control valves 12 and 13 for other hydraulic actuators are connected in tandem and driven by a common hydraulic pump 14.
[0027]
Reference numeral 15 denotes a center bypass line connecting the bleed-off flow paths of the control valves 11 to 13, reference numeral 16 denotes a cut valve that opens and closes the center bypass line 15 at the most downstream side, and reference T denotes a tank.
[0028]
Reference numeral 17 denotes a remote control valve as operating means for controlling the arm cylinder control valve 11. By operating the remote control valve 17, the control valve 11 is switched between a neutral position A, a cylinder contraction position B, and a cylinder extension position C. Be replaced.
[0029]
A regeneration circuit 18 is connected to a meter-out flow path of the arm cylinder control valve (hereinafter simply referred to as a control valve) 11, and the return oil from the rod-side (reduction-side) oil chamber 8 b of the arm cylinder 8 during the arm pulling operation. Is rotated to the head side (extension side oil chamber 8a) through the regeneration circuit 18 so that the arm pulling operation is performed at a high speed and cavitation is prevented. .
[0030]
The regeneration circuit 18 is provided with a regeneration valve 19 for adjusting the amount of the regeneration oil.
[0031]
The regenerative valve 19 is configured as a hydraulic pilot valve whose opening changes in accordance with the pilot pressure supplied from the pilot line 21, and is set so that the opening becomes smaller (the throttle becomes stronger) as the pilot pressure becomes higher. I have.
[0032]
As a control means for controlling the opening degree of the regeneration valve 19, a controller 20, an electromagnetic proportional valve 21 controlled by an electric signal from the controller 20 to control the pilot pressure of the regeneration valve 19, and a regeneration valve A load pressure sensor 22 for transmitting a signal for determining the opening degree of the valve 19 and a pilot pressure sensor 23 for detecting an arm pull-side pilot pressure Pi (corresponding to the operation amount) of the remote control valve 18 and transmitting the pilot pressure to the controller 20 are provided. .
[0033]
The load pressure sensor 22 detects the pressure of the compression-side oil chamber 8 b of the arm cylinder 8, that is, the pressure (load pressure) applied by the load that combines the weight of the arm 5 and the bucket 6 with the load (load pressure). The characteristic of the opening of the regeneration valve with respect to the operation amount of the remote control valve is determined in accordance with the detected load pressure. In order to obtain the opening of the regeneration valve according to the determined characteristic, a command signal (current) is sent from the controller 20 to the electromagnetic proportional valve 21. Is output.
[0034]
The operation of this point will be described with reference to FIG.
[0035]
First, in step S1, the arm pull-side pilot pressure Pi taken from the pilot pressure sensor 23 is compared with a preset reference pressure (for example, 0.5 MPa). Since the pulling operation amount is small, the cylinder speed is low, and there is no need for control, the control is terminated.
[0036]
On the other hand, if the arm pull-side pilot pressure Pi is larger than the reference pressure, control is determined to be necessary and the process proceeds to step S2, where the load pressure set in advance based on the load pressure taken from the load pressure sensor 22 is determined. / The maximum value Ia and the minimum value Ib of the command current are determined from the characteristics of the command current value.
[0037]
Next, in step S3, based on the determined current maximum value Ia and minimum value Ib, control for changing the command current value between the two values Ia and Ib in accordance with the arm pull-side pilot pressure Pi (operation amount). A map is created, and a current based on this control map is sent to the electromagnetic proportional valve 21 in step S4.
[0038]
As a result, the opening area of the regeneration valve 19 and the synthetic opening (total meter-out opening) obtained by combining this with the meter-out opening of the control valve 11 are automatically controlled according to the arm pulling pilot pressure Pi based on the control map. Is done.
[0039]
The broken lines in FIGS. 3 and 4 show the regeneration valve and the synthetic opening characteristics when such control is not performed, and the solid line, the one-dot chain line and the two-dot chain line show three examples of the regeneration valve and the synthetic opening characteristics when control is performed.
[0040]
With this control, during the arm pulling operation, the relationship between the operation amount of the remote control valve 17 (arm pulling pilot pressure Pi) and the opening degree of the regeneration valve changes according to the load pressure.
[0041]
That is, the amount of the regenerated oil (meter-out flow rate) that is discharged from the contraction-side oil chamber 8b of the arm cylinder 8 and diverted to the extension-side oil chamber 8a is suppressed in accordance with the increase in the load. The rate of increase of the arm pulling operation speed with respect to the increase of the arm pulling pilot pressure Pi is suppressed as compared with the case of no control.
[0042]
In this way, the speed of the arm pulling operation with respect to the operation amount of the remote control valve is kept almost constant irrespective of the load fluctuation, and good operability can be secured.
[0043]
Moreover, according to this device, the regeneration valve 19 originally provided in the arm cylinder circuit is used, and the opening of the regeneration valve 19 is controlled in accordance with the load. Only the control software of the controller 20 that controls the proportional valve 21, the load pressure sensor 22, and the electromagnetic proportional valve 21 according to the load pressure is required. Further, the control valve 19 can be used as it is without changing the opening characteristics.
[0044]
For this reason, the cost can be reduced as compared with a case where a new expensive meter-out control valve is added, and there is no need to replace the control valve 19 with one having a different opening characteristic according to the load.
[0045]
By the way, in the above embodiment, the arm pulling operation of the excavator has been described as an object to be controlled. However, the present invention is not limited to this, and can be applied particularly to the entire operation in the direction in which a load is applied. It can also be applied to operations.
[0046]
Further, the present invention is not limited to a hydraulic excavator, and can be applied to an excavator, a demolition machine, and the like that are configured using a hydraulic excavator as a base.
[0047]
【The invention's effect】
As described above, according to the present invention, the characteristic of the opening degree change of the regeneration valve with respect to the operation amount of the operation means changes according to the load pressure, and the relationship between the operation amount and the cylinder speed is substantially constant regardless of the change in the load pressure. In the case of large loads where the cylinder speed becomes faster, the operation affected by the load is controlled to reduce the meter-out flow rate by reducing the opening of the regeneration valve, thereby suppressing the speed increase due to the load and maintaining a constant Operability can be ensured.
[0048]
In particular, according to the second aspect of the present invention, a constant operability can be ensured for the arm pulling operation frequently used in the hydraulic excavator, so that the practical effect is high.
[0049]
In addition, since the meter-out flow rate is controlled by using the originally provided regeneration valve and the cylinder speed is controlled, equipment to be added is minimized (the electromagnetic proportional valve and the electromagnetic proportional valve Controller software for controlling the system).
[0050]
Therefore, compared to the case where the control valve is replaced or an expensive flow control valve is added, the practicability is high and the cost is low.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a cylinder control device according to an embodiment of the present invention.
FIG. 2 is a flowchart for explaining the operation of the embodiment.
FIG. 3 is a diagram showing a control example of a regeneration valve opening according to the embodiment.
FIG. 4 is a diagram showing an example of controlling a meter-out synthetic aperture according to the embodiment.
FIG. 5 is a diagram showing an example of controlling an arm pulling speed according to the embodiment;
FIG. 6 is an overall side view of a hydraulic shovel to which the present invention is applied.
[Explanation of symbols]
8. Arm cylinder (hydraulic cylinder)
18 Regeneration circuit 19 Regeneration valve 20 Controller 21 constituting control means Electromagnetic proportional valve 22 Load pressure sensor (command means)

Claims (3)

A regeneration circuit is provided for re-supplying a part of the return oil from the hydraulic cylinder which is telescopically operated by the operation means to the drive side of the cylinder, a regeneration valve is provided in the regeneration circuit, and the operation of the operation means is performed. An operation amount detecting means for detecting the amount, a load pressure detecting means for detecting the load pressure of the hydraulic cylinder, and the following (A) ( A hydraulic cylinder control device for a construction machine, comprising: control means for performing the control of B).
(A) The opening of the regeneration valve is increased in accordance with an increase in the operation amount of the operation means.
(B) The characteristic relating to the opening of the regeneration valve with respect to the operation amount is changed in accordance with the load pressure so that the relation between the operation amount of the operation means and the cylinder operating speed is substantially constant regardless of the load pressure. A regeneration valve is provided in a regeneration circuit of a hydraulic cylinder for an arm that pushes and pulls an arm in an excavation attachment of a hydraulic shovel, and a control means controls an opening of the regeneration valve to control a cylinder operating speed on an arm pull side. The hydraulic cylinder control device for a construction machine according to claim 1, wherein the hydraulic cylinder control device is configured as follows. As the regenerative valve, a hydraulic pilot valve whose opening changes according to the pilot pressure is used, and the control means includes an electromagnetic proportional valve that controls the pilot pressure of the regenerative valve, and the electromagnetic proportional valve controls the opening of the regenerative valve. The hydraulic cylinder control device for a construction machine according to claim 1 or 2, further comprising a controller that sends a signal to change the hydraulic cylinder.

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