JPH04143334A - Hydraulic control device for construction machine - Google Patents

Abstract

PURPOSE:To improve responsibility of a pilot changeover valve by providing an output raiser in a controller, raising an electric signal output value input from an electric joy stick, and acting against electromagnetic proportional pressure reducing valves. CONSTITUTION:By operating an electric joy stick 1, an electric signal corresponding to an operating quantity is output to a controller 18. The electric signal output value is raised with an output raiser provided in the controller 18, and actuated to electromagnetic proportional pressure reducing valves 3, 4 during a prescribed time. Through this, a command signal is actuated to pilot pressure receiving parts 11, 12 of a pilot changeover valve 9, and a hydraulic actuator 8 is controlled by operation of the pilot changeover valve 9. Hereby, troubles such as defective hunting property or hunting shock by operation of the electric joy stick 1 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates primarily to a hydraulic control device for controlling various hydraulic actuators installed in construction machines such as hydraulic excavators.

BACKGROUND OF THE INVENTION FIG. 5 is a circuit diagram of a main part of a conventional hydraulic control device. In the figure, 1 is an electric joystick, 2 is a controller, 3 and 4 are electromagnetic proportional pressure reducing valves, 5 and 6 are solenoids of electromagnetic proportional pressure reducing valves 3 and 4, respectively.
7 is a pilot pressure hydraulic source, 8 is a hydraulic actuator, 9
is a pilot switching valve for controlling hydraulic actuator 8, 1
0 and 11 are pilot pressure receiving portions of the pilot switching valve 9, 13 and 14 are throttle portions, 15 is a main pump, and 16 is an oil tank.

Next, a prior art hydraulic control system will be described with reference to FIG. By operating the operating lever 17 of the electric joystick 1 from the neutral position toward the A position or the mouth position, an electric signal is output to the controller 2 in accordance with the amount of operation. The controller 2 makes a judgment based on the electric signal and outputs the electric signal to the solenoid 5 or 6. Since the solenoid 5 or 6 is energized, the electromagnetic proportional pressure reducing valve 3 or 4 is operated. The pilot pressure from the pilot pressure pressure source 7 acts on the pilot pressure receiving section 11 or 12 via the electromagnetic proportional pressure reducing valve 3 or 4.

The pilot switching valve 8 operates to switch between the C position direction and the 2 position direction. Pressure oil from the main pump 15 is supplied to the hydraulic actuator through the pilot switching valve 9 in the C position or the 2nd position.

FIG. 6 is a chart showing the relationship between the output value of the electric signal output from the electric joystick l and the output value of the electric signal output from the controller 2. As shown in FIG. 6, in proportion to the output value of the electric signal output from the electric joystick 1 to the controller 2,
An electric signal is output to the electromagnetic proportional pressure reducing valve 3 or 4.

For example, when the electric signal output from the electric joystick 1 is A, the electric signal output from the controller 2 is B.

FIG. 7 is a chart showing the relationship between the time when the electric joystick 1 is operated and the output values from the electric joystick 1 and the controller 2, respectively. For example, the output value A in FIG.

When an electric signal is input to controller 2 in a step manner up to
Depending on the proportional amplification ratio, a step waveform like the one shown in Figure 7 appears.

Problem to be Solved by this Invention: By operating an electric joystick, an electromagnetic proportional pressure reducing valve is actuated via a controller, and the pilot pressure derived from the electromagnetic proportional pressure reducing valve is applied to a pilot switching valve for controlling a hydraulic actuator. The pilot pressure circuit is connected to the spool inside the pilot switching valve (
In order to ensure the stability of the pilot pressure receiving part of the pilot switching valve, a constriction part (a fifth
The aperture portions 13 and 14) shown in the figure are provided. Therefore, the pipe resistance of the pilot pressure circuit was large, and the response of the pilot switching valve was poor when the electric joystick was operated. Particularly during the cold season, the viscosity of hydraulic oil becomes thicker, causing problems in the operation of construction machinery such as hydraulic excavators.

This invention solves the above-mentioned problems, and when a pilot switching valve is provided with a throttle section provided for the pilot pressure receiving section, or when the above throttle section is not provided but the pilot pressure is received from the pilot valve. It is an object of the present invention to provide a hydraulic control device that can increase the responsiveness of a pilot switching valve to a pilot pressure receiving section when the pipe line resistance of a pilot pipe leading to a pilot pressure receiving section is large.

Means for Solving the Problems The means of the present invention taken to solve the above problems are as follows: (1) A. An output increaser is provided in the controller, and an electric signal from an electric joystick is input to the controller. When this occurs, the controller uses an output increaser to increase the electrical signal output value based on the electrical signal, and causes the controller to apply the increased electrical signal output to the electromagnetic proportional pressure reducing valve for a predetermined period of time.

(2) B. In the hydraulic control device for construction machinery as set forth in claim 1, when the output signal output from the electric joystick is shifted from one state to another, the control device according to the amount of shift. The controller outputs a command signal to the electromagnetic proportional pressure reducing valve.

Function (1) A. When the electric joystick is operated, the electric signal output from the electric joystick is input to the controller, and its output is increased by the output increaser.

B. The controller causes the electric signal whose output was increased in step A above to act on the electromagnetic proportional pressure reducing valve for a predetermined instantaneous time t, so that the hydraulic output output from the electromagnetic proportional pressure reducing valve is equal to the output from the controller. Proportionally, it acts on the pilot pressure receiving part of the pilot switching valve. The spool of the pilot switching valve moves quickly for an instant of time t, and then strokes until the oil pressure is balanced to match the specified output.

(2) A. When you want to slightly shift the electric signal output from the controller, or when the electric joystick control lever moves due to shaking of the driver's hand,
The controller described in claim 1 may cause poor inching performance or hunting shock during operation. In order to prevent such troubles from occurring, when the output signal output from the electric joystick is shifted from one state to another, a command signal corresponding to the shift amount is sent from the controller to the electromagnetic proportional pressure reducing valve. Output against.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings. FIG. 1 is a circuit diagram of a main part of a hydraulic control device according to the present invention. In the figure, the same reference numerals are given to the same components as in the prior art. 18 is a controller, 19 is an output increaser provided in the controller 18, and 20 is a shift state detector for electrical signals.

Next, the configuration of the hydraulic control device according to the present invention will be described with reference to FIG. The controller 18 is provided with an output increaser 19, and when an electric signal from the electric joystick 1 is input to the controller 18, the controller 18 causes the output value of the electric signal to be increased by the output increaser 19 based on the electric signal, and the output value of the electric signal is increased. The electric signal output from the controller 18 is made to act on the electromagnetic proportional pressure reducing valve 3 or 4 for a predetermined period of time. Further, the controller 18 is equipped with a shift state detector 20 for electrical signals, so that when the output signal output from the electric joystick 1 is shifted from one state to another, a command signal corresponding to the shift amount is sent to the controller 18. It is configured to output to the electromagnetic proportional pressure reducing valve 3 or 4.

Next, the functions of the hydraulic control device according to the present invention will be described. When the operating lever 17 of the electric joystick 1 is operated, the electric signal output from the electric joystick 1 is input to the controller 18, and its output is increased by the output increaser 19. This increased electrical signal is applied to the electromagnetic proportional pressure reducing valve 3 or 4 by the controller 18 for a predetermined instantaneous time t, so that the hydraulic output from the electromagnetic proportional pressure reducing valve 3 or 4 is reduced by the pressure output from the controller 18. It acts on the pilot pressure receiving part 11 or 12 of the pilot switching valve 9 in proportion to the output. FIG. 2 shows the time when the electric joystick 1 is operated in the hydraulic control device of the present invention and the time when the electric joystick 1 is operated.
It is a chart showing the relationship between the output A from the controller 18 and the output B from the controller 18. Controller 18 as shown in FIG.
The output B from is increased by an instantaneous time t.

FIG. 3 is a chart showing the relationship between the time T when the electric joystick 1 is operated and the stroke S of the spool (not shown) in the pilot switching valve 9 in the present invention. In the diagram of FIG. 3, the dashed-dotted curve 1 is the curve for the hydraulic control device of the prior art, and the solid line f is the curve for the hydraulic control device of the present invention. Also, the solid line f
A virtual line f11 branching from the curve is a curve showing a case where the output increase for a predetermined instantaneous time t is extended and sustained. (Note that the state of the above virtual line fI is indicated by the virtual line f+2 in Fig. 2.) As shown in Fig. 3, in the conventional technology, it took time T1 to move the spool by the stroke S1. According to the present invention, this can be done in a short time T2.

Next, FIG. 4 is a chart showing a state in which when the electric signal output from the electric joystick 1 is shifted from A2 to A'2, the electric signal output from the controller 18 is shifted from B2 to ]3+2. .

As shown in FIG. 4, when the electric signal output from the controller 18 is shifted by a small amount, or when the operating lever 17 of the electric joystick 1 moves due to unintentional shaking of the hand, an output increaser 19 is provided. controller 1
8 may cause poor operation and hunting shock. In order to prevent such troubles from occurring, when the output signal output from the electric joystick 1 is shifted from one state to another, a command signal corresponding to the shift amount is sent to the controller 18°.
output to the electromagnetic proportional pressure reducing valve 3 or 4. Thereby, troubles such as poor inching performance and hunting shock during the above operation can be prevented.

Effects of the Invention A solenoid proportional pressure reducing valve is actuated via a controller by operating an electric joystick, and the pilot pressure derived from the electromagnetic proportional pressure reducing valve is made to act on a pilot switching valve for controlling a hydraulic actuator. In the circuit, in order to ensure the stability of the spool in the pilot switching valve, a constriction part is provided near the boat of the pilot pressure receiving part of the pilot switching valve. Therefore, the pipe resistance of the pilot pressure circuit was large, and the response of the pilot switching valve was confusing when the electric joystick was operated. Particularly during the cold season, the viscosity of hydraulic oil becomes thicker, causing problems in the operation of construction machinery such as hydraulic excavators.

However, in the hydraulic control device according to the present invention, when the electric signal from the electric joystick is input to the controller, the controller increases the electric signal output value with the output increaser based on the electric signal, and the increased electric signal is The pump roller acts on the electromagnetic proportional pressure reducing valve for a predetermined period of time. As a result, if the pilot switching valve is equipped with a constriction part provided for the pilot pressure receiving part, or if the constriction part is not provided but the pilot pipe is connected to the pilot pressure receiving part from the pilot valve. When road resistance is large, responsiveness of the pilot switching valve to the pilot pressure receiving section can be made faster.

Further, when the output signal output from the electric joystick is shifted from one state to another, the controller outputs a command signal corresponding to the shift amount to the electromagnetic proportional pressure reducing valve. This makes it possible to prevent problems such as poor inching performance and hunting shock when operating the electric joystick.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of the main parts of the hydraulic control device according to the present invention, FIG. 2 is a chart showing the relationship between time and output when operating the electric joystick according to the present invention, and FIG. A chart showing the relationship between the time when the joystick is operated and the spool stroke, Fig. 4 is a chart showing the electric joystick and a state in which the output from the controller is shifted, and Fig. S is a diagram showing a conventional hydraulic control device. Part circuit diagram, Figure 6 is a diagram showing the output from the electric joystick and controller, Figure 7 is a diagram showing the output from the electric joystick and controller.
The figure is a chart showing the relationship between time and output when operating an electric joystick in the prior art. 1-----------------1~--Electric joystick 2, 18--------Controller 3, 4----------1 Solenoid proportional pressure reducing valve 7
−−−−−−−−−−−−−−−−−−−−−Pilot pressure hydraulic power source 8−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− −−−−−−−−−−−−−
------Pilot switching valve 11.12-1--Pilot pressure receiving part 13.14-1--Restriction part 19-------1 Output riser 20
−−−−−−−−−−−−−−−−Shift state detector and above

Claims (2)

[Claims] (1) By operating the electric joystick, an electric signal is output to the controller according to the amount of operation,
In a hydraulic control device, a command signal is applied from a controller to a pilot pressure receiving part of a pilot switching valve via an electromagnetic proportional pressure reducing valve in response to the electric signal, and a hydraulic actuator is controlled by the operation of the pilot switching valve. The controller is provided with an output increaser, and when an electric signal from the electric joystick is input to the controller, the controller increases the electric signal output value with the output increaser based on the electric signal, and the increased electric signal output is sent to the controller. A hydraulic control device for construction machinery, characterized in that the electromagnetic proportional pressure reducing valve is made to act only for a predetermined time. (2) In the hydraulic control device for construction machinery according to claim 1, when the output signal output from the electric joystick is shifted from one state to another, a command signal corresponding to the shift amount is transmitted. A hydraulic control device for construction machinery, characterized in that a controller outputs an output to an electromagnetic proportional pressure reducing valve.