JP2737779B2 - Hydraulic drive - Google Patents

Description

The present invention relates to a hydraulic drive device provided in a hydraulic machine such as a hydraulic shovel of the present invention. <Prior Art> FIG. 4 is an explanatory diagram showing a basic configuration of a conventional hydraulic drive device. As shown in this figure, the conventional hydraulic drive device
A hydraulic source 4, an actuator 6 driven by pressure oil supplied from the hydraulic source 4, a directional control valve 3 for controlling the driving of the actuator 6, and an operation command signal for driving the directional control valve 3 And an operation lever 1 for outputting. Reference numeral 2 denotes a signal line for communicating the operation lever 1 with the direction control valve 3, and reference numeral 5 denotes a line for communicating the direction control valve 3 and the actuator 6. If this hydraulic drive device is provided in, for example, a hydraulic shovel, the actuator 6
Denotes a boom cylinder, an arm cylinder, a bucket cylinder, a swing motor, a traveling motor, and the like. In such a hydraulic drive device, the relationship between the stroke of the operation lever 1 and the stroke of the spool of the direction control valve 3 is uniquely set as shown in FIG. 5, that is, at a constant rate of change. Accordingly, the relationship between the stroke of the operation lever 1 and the flow rate flowing through the actuator 6 is as shown in FIG. In FIG. 5, reference numeral 13 denotes a limit point of a dead zone of a stroke of the operation lever 1; and 14, a limit of a dead zone of a flow rate flowing to the actuator 6 with respect to a stroke of a spool of the directional control valve 3, that is, the directional control valve 3 This shows the point at which it begins to open. Reference numeral 15 shown in FIG. 6 denotes a limit point of a dead zone of a flow rate flowing through the actuator 6 with respect to a stroke of the operation lever 1. <Problems to be Solved by the Invention> As described above, in the conventional hydraulic drive device, as shown in FIG. 5, the relationship between the stroke of the operation lever 1 and the stroke of the spool of the direction control valve 3. As shown in FIG. 6, the limit point 15 of the dead zone of the flow rate flowing through the actuator 6 with respect to the stroke of the operation lever 1 is largely located far from 0, and therefore, as shown in FIG. It takes time from the operation of the operation lever 1 to the actuation of the actuator 6, which causes a problem in follow-up performance, and inevitably reduces the metering area of the stroke of the operation lever 1, making it difficult to expect good reliability. There is a defect. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances in the related art, and has as its object to provide a hydraulic drive device capable of reducing a limit point of a dead zone of a flow rate flowing to an actuator with respect to a stroke of an operation lever. is there. <Means for Solving the Problems> In order to achieve this object, the present invention provides a control means for inputting an operation command signal for an operation lever and outputting a drive signal to a directional control valve. A first setting means for setting a change rate of a stroke of the spool of the directional control valve to a stroke of the lever to be sufficiently large; and a change rate of a stroke of the spool of the directional control valve to the stroke of the operation lever in the first setting means. A second setting means for setting a value smaller than the setting, a detecting means for detecting a start time of the opening operation at which the directional control valve starts to open, and outputting a detection signal to the control means; When the lever is operated beyond the limit point of the dead zone of the stroke of the operation lever and the detection signal of the detection means is not input, the first setting means A drive signal corresponding to the set change rate is output to the direction control valve, and a drive signal corresponding to the change rate set by the second setting means is output to the direction control valve when the detection signal of the detection means is input. Configuration. <Operation> Since the hydraulic drive device of the present invention is configured as described above, after the operation lever is operated and until the detection signal is not output from the detection unit, the control unit sets the first setting unit. A drive signal corresponding to a sufficiently large rate of change set by the above is output to the directional control valve, and the relatively small operation lever 1
The stroke reaches the critical point of the dead zone of the flow rate flowing to the actuator with respect to the spool of the directional control valve, that is, the opening operation start time at which the directional control valve starts to be opened. At this time, a drive signal corresponding to a relatively small change rate set by the second setting means from the control means, for example, a change rate equivalent to the conventional one in consideration of normal work, is output to the directional control valve, As a result, the limit point of the dead zone of the flow rate flowing to the actuator with respect to the stroke of the operation lever can be reduced, that is, the time point at which the directional control valve starts opening can be shortened. <Example> Hereinafter, a hydraulic drive device of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing the structure of one embodiment of the present invention, and FIG.
FIG. 3 is a diagram showing the relationship between the stroke of the operation lever obtained in this embodiment and the stroke of the direction control valve, and FIG. 3 is a diagram showing the relationship between the stroke of the operation lever obtained in this embodiment and the flow rate flowing through the actuator. It is. In this embodiment, as shown in FIG. 1, an actuator which is driven by a hydraulic pressure source 4 and pressure oil supplied from the hydraulic pressure source 4 to actuate a load (not shown) as shown in FIG. 6a, 6b, 6c and these actuators 6a, 6
The directional control valves 3a, 3b, 3c for controlling the driving of the b, 6c and the operating lever 1 for outputting an operation command signal for driving the directional control valves 3a, 3b, 3c are provided. Then, an operation command signal of the operation lever 1 is input between the operation lever 1 and the direction control valves 3a, 3b, 3c, and the direction control valve
A control unit 7 for outputting a drive signal to the drive units 3a, 3b and 3c is provided. This control means 7 is a first setting means for setting a sufficiently large change rate of the stroke of the spool of the direction control valves 3a, 3b, 3c with respect to the stroke of the operation lever 1,
For example, a characteristic line drawn by a straight line having a relatively large inclination in FIG.
Lever stroke and directional control valves 3a, 3b, as shown at 20
First setting means for setting the relationship of the spool stroke 3c; and a directional control valve 3 for the stroke of the operating lever 1.
A second setting means for setting the change rates of the strokes of the spools a, 3b, and 3c to be smaller than those set by the first setting means, for example, as shown by a characteristic line 21 drawn by a straight line having a relatively small inclination in FIG. Such as lever stroke and direction control valve 3a,
There is provided second setting means for setting the relationship between the spool strokes 3b and 3c. As shown in FIG. 2, the characteristic line 20 and the characteristic line 21 are connected, for example, at the limit point 14 of the dead zone of the flow rate flowing to the actuators 6a, 6b, 6c with respect to the spool stroke of the directional control valves 3a, 3b, 3c. It is. The passage 22 is located above the directional control valves 3a, 3b, 3c.
a, 22b, 22c are formed, and outside the directional control valves 3a, 3b, 3c, the pipes 23a, 23b, 23c communicate with the above-mentioned passages 22a, 22b, 22c, respectively, and communicate with the pipe 23a. Shuttle valve
24a, a shuttle valve 24b that communicates the pipe 23b and the pipe 23c.
And a pipe line 25 connecting the shuttle valve 24a and the shuttle valve 24b.
And is connected to the control means 7, and the shuttle valve 24a
Is provided with a pressure detector 27 for detecting the pressure of the pipe line 26 connected to. Passages 22a, 22b, 22 of the above-described directional control valves 3a, 3b, 3c
c, pipes 23a, 23b, 23c, shuttle valves 24a, 24b, pipe 25,
26, and the pressure detector 27, the actuators 6a, 6b, 6c for the stroke of the spool of the directional control valves 3a, 3b, 3c
The detection means outputs the detection signal to the control means 7 by detecting the limit point of the dead zone of the flow rate flowing through the control means 7, that is, the limit point 14 shown in FIG. The operation in the embodiment configured as described above is as follows. For example, when the operation lever 1 is driven to drive the actuator 6a, the operation command signal
The control means 7 determines that the stroke of the operating lever 1 is at the limit point 13 of the dead zone of the lever stroke shown in FIG.
Is reached, a drive signal corresponding to a sufficiently large change rate set by the first setting means, that is, a drive signal corresponding to the characteristic line 20 shown in FIG. 2 is output to the drive unit of the direction control valve 3a. I do. In response to this, the direction control valve 3a is switched to be driven, for example, to the upper position in FIG. When the passage 22a of the direction control valve 3a reaches a position where the passage 22a communicates with the pipe 23a, the pressure oil of the hydraulic pressure source 4 is supplied to the passage 22a, the pipe 23a, and the shuttle valve 24a.
a, guided to the pressure detector 27 through the pipe 26, it is detected that the dead zone limit point 14 shown in FIG. 2 has been reached, that is, the opening operation start time when the directional control valve 3a starts to open is detected, The detection signal is output to the control means 7. At this time, the control means 7 outputs a drive signal corresponding to the relatively small change rate set by the second setting means, that is, a drive signal similar to the conventional one corresponding to the characteristic line 21 shown in FIG.
Thereby, the directional control valve 3a is driven at the same speed as in the case of performing a conventional normal operation, the pressure oil of the hydraulic source 4 is supplied to the actuator 6a via the directional control valve 3a, and the return oil is supplied to the directional control valve. It is returned to the tank via 3a, the actuator 6a is driven, and the load (not shown) operates. In this embodiment, the first setting means of the control means 7 extends from when the operation lever 1 is operated as described above to when the flow rate flowing to the actuator 6a relative to the spool of the direction control valve 3 reaches the dead zone limit point 14. The drive signal corresponding to the sufficiently large change rate set in the step (1) is output to the direction control valve 3a, so that the limit point 15 of the dead zone of the flow rate flowing through the actuator 6a with respect to the stroke of the operation lever 1 is set as shown in FIG. Small, ie close enough to zero. In the embodiment configured as described above, the operation lever 1
Since the limit point 15 of the dead zone of the flow rate flowing through the actuator 6a for the stroke of the stroke can be reduced, the time from operating the operation lever 1 to driving the actuator 6a can be shortened. <Effect of the Invention> Since the hydraulic drive device of the present invention is configured as described above, the limit point of the dead zone of the flow rate flowing through the actuator with respect to the stroke of the operation lever can be reduced, that is, the direction control valve is The opening start time can be earlier, so that the followability of the actuator drive to the operation of the operation lever can be improved as compared with the conventional case, and the metering area of the operation lever stroke can be increased. This has the effect of being able to secure a large value as compared with that of the prior art and improving reliability. Further, a detecting means for detecting a limit point of a dead zone of a flow rate flowing to the actuator with respect to a stroke of the spool of the directional control valve, that is, a time point at which the directional control valve starts to open, is provided, and a control means is provided in accordance with a detection signal output from the detecting means. Controls the driving of the directional control valve, so that the directional control valve is set by the second setting means even though the directional control valve does not start to open, that is, although the directional control valve does not reach the limit point of the dead zone. Control the drive of the directional control valve in accordance with the relatively small rate of change, or even though the directional control valve is open, i.e., beyond the dead zone limit point Thus, it is possible to prevent a situation in which the driving of the directional control valve is controlled at a relatively large rate of change set by the first setting means, whereby the fluid flows to the actuator. It is possible to realize highly accurate control of the amount.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing a configuration of an embodiment of a hydraulic drive device according to the present invention, and FIG. 2 is a stroke and directional control valve of an operating lever obtained in the embodiment shown in FIG. FIG. 3 is a diagram showing the relationship between the stroke of the operating lever obtained in the embodiment shown in FIG. 1 and the flow rate flowing through the actuator, and FIG. 4 is a diagram showing the basics of a conventional hydraulic drive device. FIG. 5 is a diagram showing the configuration, FIG. 5 is a diagram showing the relationship between the stroke of an operation lever and the stroke of a directional control valve obtained by the conventional hydraulic drive device shown in FIG. 4, and FIG. FIG. 5 is a diagram showing a relationship between a stroke of an operation lever obtained by the hydraulic drive device and a flow rate flowing to the actuator. 1 ... operation lever, 3a, 3b, 3c ... directional control valve, 4 ...
Hydraulic source, 6a, 6b, 6c Actuator 7, Control means 13, 14, 15 Limit point 20, Characteristic line 21, Characteristic line 22a, 22b, 22c Passage 23a , 23b, 23c, 25, 26 ...
… Line, 24a, 24b …… shuttle valve, 27 …… pressure detector.

Claims (1)

(57) [Claims] A hydraulic source, an actuator driven by pressure oil supplied from the hydraulic source, a directional control valve for controlling the driving of the actuator, and an operating lever for outputting an operation command signal for driving the directional control valve. A hydraulic drive device provided with control means for inputting an operation command signal for the operation lever and outputting a drive signal to the direction control valve, wherein the control means comprises a spool for the direction control valve with respect to a stroke of the operation lever. First setting means for setting the change rate of the stroke of the control lever sufficiently large, and second setting means for setting the change rate of the stroke of the spool of the directional control valve with respect to the stroke of the operation lever to be smaller than that set by the first setting means.
And a detecting means for detecting a start time of the opening operation at which the direction control valve starts to open and outputting a detection signal to the control means. When the operation is performed beyond the limit point of the dead zone of the stroke and the detection signal of the detection means is not input, a drive signal corresponding to the change rate set by the first setting means is output to the direction control valve; When the operation lever is operated beyond the limit point of the dead zone of the stroke of the operation lever and the detection signal of the detection unit is input,
A hydraulic drive device for outputting a drive signal corresponding to a change rate set by the second setting means to the direction control valve.