JPH10110703A - Oil pressure control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of pulsation of a motor owing to a pressure fluctuation during the stop and the starting of a motor, in an oil pressure control device for a motor for revolution of a crane. SOLUTION: Two lines 6A and 6B through which a hydraulic motor 2 for revolution and a direction control valve 1 for revolution are interconnected are interconnected through an electromagnetic switch valve 9. Pressure sensors 10A and 10B are arranged in the two lines 6A and 6B and connected to a control device 11. The control device 11 fetches a high frequency component signal H1 for a pressure fluctuation from pressure signals P1 and P2 outputted from the pressure sensors 10A and 10B. When the high frequency component signal H1 is generated, the electromagnetic switch valve 9 is controlled such that the lines 6A and 6B are intercommunicated. This constitution prevents the generation of an uncomfortable feeling or a impact due to a pressure fluctuation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device for reducing an impact at the time of stopping and starting an actuator.

[0002]

2. Description of the Related Art Conventionally, various devices have been proposed for preventing a shock when an actuator is stopped when driving a fluid pressure actuator in accordance with an operation amount of an operation lever, for example. For example, in Japanese Utility Model Laid-Open Publication No. 5-40601,
As shown in FIG. 10, the hydraulic pump 31 and the hydraulic motor 3
3, a control valve 32 for switching the flow of pressure oil discharged from the hydraulic pump 31, and a control valve 3
2, an electromagnetic switching valve 43 capable of communicating two pipes 34, 35 connected to a hydraulic motor 33, and a pressure sensor 4 for detecting the pressure in the pipes 34, 35.
There has been proposed a hydraulic control apparatus including a control unit 44 for switching the electromagnetic switching valve 43 based on the detection results of the pressure sensors 41 and 42.

[0003] This hydraulic control device operates as follows. When the operation lever 37 is operated to the side A, the control valve 32 is switched to the position a, and the pressure P1
Occurs, and the hydraulic motor 33 rotates in one direction. In this state, when the operation lever 37 is operated to the neutral position,
The control valve 32 is switched to the position c, and the line 3
4 decreases, but the pressure P2 in the conduit 35 increases. Then, when the rising speed of the pressure P2 exceeds the reference value, the control unit 44 opens the electromagnetic switching valve 43, and the line 34 and the line 35 are communicated, and the pressure difference between the two lines 34, 35 is reduced. . Further, the hydraulic motor 33 is reversed by the stop motion of the inertial body driven by the hydraulic motor 33, and the pipeline 3
Also, when the pressure P1 of 4 rises, if the rate of rise exceeds the reference value, the control unit 44 opens the electromagnetic switching valve 43 to communicate the pipes 34 and 35, and the two pipes 34, 35 Reduce pressure differential. Thereby, when the hydraulic motor 33 is stopped, it is possible to prevent the pressure in the pipelines 34 and 35 from rising sharply and causing an impact on the device.

[0004]

However, in the device described in Japanese Utility Model Application Laid-Open No. H5-40601, when the hydraulic motor 33 is stopped, the pressures P1 and P2 in the pipelines 34 and 35 are prevented from sharply increasing. However, pulsation due to pressure fluctuation cannot be prevented.
That is, when a driving force acts on an actuator such as a hydraulic motor at startup or deceleration, the pressure acting on the pipeline connected to the actuator due to the compressibility of the pressure oil and the inertia of the actuator is as shown in FIG. As shown in the figure, the vibrations are repeatedly generated and reduced in a short time, and converge to a steady state. Therefore, if such pressure fluctuations are not removed, the actuator pulsates when the actuator is started or stopped, not only giving an unpleasant feeling to the operator, but also causing an impact on the device at the time of starting and deceleration,
The operability of the device is deteriorated.

On the other hand, such pressure fluctuations are uniquely determined by the mass of the actuator and the configuration of the hydraulic system. Further, the high-frequency components of the vibration components of the pressure fluctuations cause a shock or the like in the device. It becomes.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic control device capable of eliminating pressure fluctuations occurring in a pipeline connected to an actuator when the actuator is stopped or started.

[0007]

FIG. 1 shows an embodiment of the present invention.
Referring to FIG. 2, a hydraulic pump 3, an actuator 2 driven by hydraulic oil discharged from the hydraulic pump 3, and a control valve for controlling the flow of hydraulic oil supplied from the hydraulic pump 3 to the actuator 2 An electromagnetic switching valve 9 which is applied to a hydraulic control device having an operating lever 5 for switching the control valve 1 and which communicates and shuts off two pipe lines 6A and 6B respectively connected to the inlet / outlet ports of the actuator 2; Pressure detector 1 that detects the pressure of the pressure oil in two pipe lines 6A and 6B and outputs pressure signals P1 and P2, respectively.
0A, 10B and two pipelines when a high-frequency component is generated based on a high-frequency component of a predetermined value or more among the frequencies of the fluctuation values of the pressure signals P1, P2 detected by the pressure detectors 10A, 10B. The above object is attained by providing the control means 11 for controlling the electromagnetic switching valve 9 so as to communicate the 6A and 6B. The pressure signal P1,
The frequency of the fluctuation value of P2 is a frequency that can be operated by the operator.

According to the present invention, the pressure detectors 10A, 10A
When a high-frequency component causing a shock or the like is generated among the fluctuation values of the pressure signals P1 and P2 detected by B, the electromagnetic switching valve 9 is controlled so as to communicate the two pipelines 6A and 6B. You. Thereby, the impact and pulsation of the actuator based on the high-frequency components in the fluctuation values of the pressure signals P1 and P2 are removed.

In the meantime, in the section of the means for solving the above-mentioned problem which explains the constitution of the present invention, the drawings of the embodiments of the present invention are used in order to make the present invention easy to understand. However, the present invention is not limited to this.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram illustrating a configuration of a hydraulic control device according to an embodiment of the present invention, FIG. 2 is a diagram illustrating a detailed configuration of a control unit described later, and FIG. 3 is used by the hydraulic control device according to the present embodiment. 1 is a side view showing a configuration of a crane to be used. As shown in FIG. 3, the mobile crane includes a traveling body 61, a revolving revolving body 62 mounted on the traveling body 61, and a boom 63 supported up and down by the revolving body 62.
A sheave 64 provided at the tip of the boom 63; and a hook 65 connected to a wire rope via the sheave 64.
Consists of A suspended load 66 is suspended from the hook 65.

As shown in FIG. 1, a hydraulic circuit for turning the revolving unit 62 of the mobile crane includes a hydraulic pump 3 driven by a prime mover 13 and a swivel driven by pressure oil discharged from the hydraulic pump 3. Directional control valve 1 for controlling the flow of pressurized oil supplied from hydraulic pump 3 to slewing hydraulic motor 2, operating lever 5 for the operator to input a slewing command, and operating lever 5 The pilot valves 12A and 12B to be operated and the pilot valve 1
A pilot hydraulic pressure source 7 for supplying pressure oil to 2A and 12B;
Hydraulic oil tank 8, relief valve 4, and two pipelines 6A, 6B connected to the inlet / outlet port of turning hydraulic motor 2.
An electromagnetic switching valve 9 for communicating and shutting off the two pipes 6A and 6B via throttles, and a pressure sensor 10 for measuring the oil pressure of the pressure oil in the pipes 6A and 6B and outputting pressure signals P1 and P2.
A, 10B and a control unit 1 for controlling opening and closing of the electromagnetic switching valve 9
It consists of 1. A pressure control valve 14 is provided in a pipeline between the turning direction control valve 1 and the hydraulic oil tank 8. The pressure control valve 14 controls the pressure in the center bypass passage of the turning direction control valve 1, that is, the pressure oil that is bleed off. When the turning direction control valve 1 is neutral, the pressure oil from the pump is actuated. When the turning direction control valve 1 is operated after returning to the oil tank 8, the flow rate of the center bypass passage is gradually reduced according to the operation amount.

As shown in FIG. 2, the control unit 11 includes a difference unit 20 for calculating a difference signal S1 between the pressure signals P1 and P2,
A high-pass filter 21 that extracts a high-frequency component signal H1 of 1 Hz or more from the difference signal S1, a multiplier 22 that multiplies the high-frequency component signal H1 by a gain K, and calculates an absolute value of the high-frequency component signal K · H1 multiplied by the gain K And an absolute value calculator 23.

Here, the pressure oscillation phenomenon will be described. FIGS. 4A and 4B are explanatory diagrams of pressure oscillation. In FIG. 4A, the hydraulic motor 2 is replaced with a hydraulic cylinder in order to simplify the configuration. When pressure oil having a flow rate Q flows from the turning direction control valve 1 into the hydraulic cylinder, the pressure P in the hydraulic cylinder increases upon receiving the flow rate Q due to the compressibility of the pressure oil. Then, a thrust F is generated by the pressure P, and the object m causes an acceleration motion by the thrust. The speed of the object m is obtained by integrating this acceleration, and the speed increases the volume in the hydraulic cylinder, the rate of compressing the oil decreases, and the pressure P
Goes down. Then, a vibration phenomenon occurs due to the repetition of these. This phenomenon is represented by a vibration model as shown in FIG. 4B, which is considered to be the same as a general spring-mass system including a spring and a mass (mass).

Next, this phenomenon will be described with reference to the hydraulic motor 2 for turning. The turning direction control valve 1 includes an operation lever 5
Is supplied to the turning hydraulic motor 2 according to the input. Actually, a reduction gear, a bearing, a sliding surface (not shown), etc. (not shown) act as frictional resistance during movement in the turning hydraulic motor 2, so that the pressure waveform statically rises to the right as shown in FIG. . FIG. 6 shows a pressure waveform on the high load side of the pipelines 6A and 6B for supplying the hydraulic oil to the turning hydraulic motor 2 with the above-described vibration phenomenon. These pressure fluctuations affect the acceleration of the turning hydraulic motor 2 and cause not only discomfort to the operator but also a shock at the time of starting and deceleration.

On the other hand, the operator normally performs the turning operation relatively slowly to ensure safety. Also, the response frequency of the lever input is 1H even during danger avoidance such as in an emergency.
If it is sufficient to have about z, the response frequency of pressure control required by the operator is sufficient to be about 1 Hz or less, and a frequency component higher than 1 Hz can be considered to be outside the control range of the operator.

Therefore, in the present embodiment, the high-pass filter 21 of the control unit 11 shown in FIG.
The component below Hz is removed, and the electromagnetic switching valve 9 is opened and closed based on the high-frequency component H1 filtered by the high-pass filter 21.

Hereinafter, the operation of the present embodiment will be described. Operate the operation lever 5 to turn the turning direction control valve 1 to a
When the position is switched to the position or the position b, pressure oil is supplied from the hydraulic pump 3 to the turning hydraulic motor 2, and the turning hydraulic motor 2 rotates. When the operation lever 5 is operated to switch the turning direction control valve 1 to the position c, the hydraulic oil from the hydraulic pump 3 is shut off, and the turning hydraulic motor 2 stops. When the operation lever 5 is operated, that is, when the turning hydraulic motor 2 is started or stopped, the pressure of the pressure oil in the pipelines 6A and 6B fluctuates, and the pressure sensors 10A and 10B change the pressure. The detected pressure signal P1,
At P2, a high-frequency component signal H1 of 1 Hz or more as shown in FIG. 6 is generated. At this time, the pressure signals P1 and P2 are input to the differentiator 20 of the control unit 11 to calculate the differential signal S1, and further input to the high-pass filter 21, where the high-frequency component signal H1 exceeding 1 Hz among the differential signals is filtered. Taken out. This high frequency component signal H1 is shown in FIG. The high frequency component signal H1 is further multiplied by a gain K in a multiplier 22, and an absolute value signal | K · H1 | is obtained in an absolute value calculator 23. The electromagnetic switching valve 9 is opened and closed based on the absolute value signal | K · H1 |.

FIG. 8 shows the open / close state of the electromagnetic switching valve 9 based on the high frequency component signal H1 shown in FIG. As shown in FIG. 8, the electromagnetic switching valve 9 opens and closes according to the fluctuation of the high frequency component signal H1. That is, when the pressure in the pipelines 6A and 6B fluctuates at a high frequency, the electromagnetic switching valve 9 repeatedly opens and closes according to the fluctuation of the high frequency component signal H1. Therefore, the fluctuation of the acceleration of the turning hydraulic motor 2 based on the high frequency component of the pressure fluctuation is attenuated by the opening and closing of the electromagnetic switching valve 9. Therefore, it is possible to prevent the pulsation of the turning hydraulic motor 2 from giving an uncomfortable feeling to the operator, and it is possible to eliminate an impact based on the pressure fluctuation at the time of starting or stopping the turning hydraulic motor 2.

Further, since the absolute value of the high frequency component signal H1 is calculated by the absolute value calculator 23, and the electromagnetic switching valve 9 is opened and closed based on the absolute value, the pressure change is not affected irrespective of starting or stopping. Impact can be eliminated.

In the above-described embodiment, an example in which the present invention is applied to the hydraulic circuit for driving the turning hydraulic motor 2 for driving the upper turning body 62 of the crane has been described. However, the present invention is not limited to this. Instead, the present invention can be applied to any hydraulic circuit using an actuator driven by hydraulic pressure.

In the above embodiment, the control unit 11 is provided with the high-pass filter 21. However, as shown in FIG. 9, a high-pass filter 21A may be provided outside the control unit 11. In this case, in FIG. 9, only one high-pass filter 21A is provided for convenience, but in practice, a high-pass filter is provided for each of the pressure sensors 10A and 10B.

In the correspondence between the above-described embodiment and the claims, the turning hydraulic motor 2 constitutes an actuator, the pressure sensors 10A and 10B constitute pressure detectors, and the control section 11 constitutes control means.

[0023]

As described above in detail, according to the present invention, the high-frequency component of the pressure fluctuation at the time of starting or stopping the actuator is removed by connecting the inlet / outlet pipe of the actuator. The pulsation can be eliminated to prevent the operator from feeling uncomfortable, and the impact based on the pressure fluctuation at the time of starting or stopping the actuator can be eliminated. In particular, since the respective pressures of the actuator entrance / exit lines are detected as electric signals to open / close the actuator entrance / exit lines, the high-frequency component to be cut off can be easily changed arbitrarily. That is, in order to realize the same hydraulically, a switching circuit of a first-order lag system including the throttle and the capacity of the oil reservoir is required,
In that case, in order to change the cutoff frequency, it is necessary to change the throttle and the oil reservoir capacity, and it is difficult to adjust the cutoff frequency.
On the other hand, according to the present invention, the cutoff frequency can be easily adjusted electrically.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram according to an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram showing a detailed configuration of a control unit.

FIG. 3 is an overall configuration diagram of a crane to which the present invention is applied.

FIG. 4 is a diagram for explaining pressure oscillation.

FIG. 5 is a diagram showing static characteristics of pressure when a hydraulic motor is driven.

FIG. 6 is a dynamic characteristic diagram of pressure when a hydraulic motor is driven.

FIG. 7 is a graph showing a high-frequency component signal.

FIG. 8 is a graph showing an absolute value of a high-frequency component signal.

FIG. 9 is a hydraulic circuit diagram showing a modification of the present embodiment.

FIG. 10 is a circuit diagram of a conventional hydraulic control device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 direction control valve for turning 2 hydraulic motor for turning 3 hydraulic pump 4 pressure control valve 5 operating lever 6A, 6B pipeline 7 pilot hydraulic source 8 hydraulic oil tank 9 electromagnetic switching valve 10A, 10B pressure sensor 11 control device 20 differentiator 21 High-pass filter 22 Multiplier 23 Absolute value calculator

Claims (2)

[Claims] 1. A hydraulic pump, an actuator driven by hydraulic oil discharged from the hydraulic pump, a control valve for controlling a flow of hydraulic oil supplied from the hydraulic pump to the actuator, and switching the control valve. A hydraulic control device comprising an operation lever, an electromagnetic switching valve for communicating and shutting off two pipes respectively connected to the inlet / outlet ports of the actuator, and detecting pressure of pressure oil in the two pipes, respectively. And a pressure detector that outputs a pressure signal, and based on a high frequency component that is equal to or greater than a predetermined value among the frequencies of the fluctuation values of the pressure signal detected by the pressure detectors, the high frequency component is generated. Control means for controlling the solenoid-operated directional control valve so as to communicate the two pipelines. 2. The hydraulic control device according to claim 1, wherein the frequency is a frequency that can be operated by an operator.