JPH10110704A - Oil pressure control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of pulsation due 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: An oil pressure control device comprises a switch valve 9 to intercommunicate or disconnect two lines 6A and 6B through which a hydraulic motor 2 for revolution and a direction control valve 1 for revolution are intercoupled; a throttle 12: and a switch circuit 11 consisting of a high pressure selecting valve 10 to select the high pressure sides of the lines 6A and 6B, a throttle 12, and an oil reservoir 13. Resistance R of the throttle 12 and capacity V of the oil reservoir 13 are set so as to cut off the high frequency component, having 1Hz or less, of the pressure fluctuation components of the lines 6A and 6B. Since, when a high frequency component is contained in the pressure fluctuations of the lines 6A and 6B, the switch circuit 11 is operated to switch a switch valve 9 to an opening position and the lines 6A and 6B are intercommunicated, this constitution prevents the generation of an impact or an uncomfortable feeling due to the pressure fluctuations of the lines 6A and 6B.

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. 8, a hydraulic pump 31 and a hydraulic motor 33
A control valve 32 for switching the flow of the pressure oil discharged from the hydraulic pump 31;
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 and FIG.
A hydraulic pump 3, an actuator 2 driven by hydraulic oil discharged from the hydraulic pump 3, a control valve 1 for controlling the flow of hydraulic oil supplied from the hydraulic pump 3 to the actuator 2, and an operation lever for switching the control valve 1 5 and a high-pressure selection valve 10 for selecting the high-pressure side hydraulic oil of the two pipelines 6A and 6B respectively connected to the inlet / outlet ports of the actuator 2, and the two pipelines 6A. , 6
A switching valve 9 that switches between an open position for communicating B and a closed position for shutting off B, and a switching valve 9 that is switched to an open position based on a high frequency component that is equal to or greater than a predetermined frequency of the pressure fluctuation from the high pressure selection valve 10. A switching circuit 11 for switching the switching valve 9 to the closed position based on the frequency component of the pressure fluctuation below the component
The above object is achieved by providing the above. According to the invention of claim 2, the switching circuit 11 includes the throttle 12 and the oil reservoir 1
3 is provided. According to the invention of claim 3, the frequency of the pressure fluctuation is a frequency that can be operated by the operator.

According to the first aspect of the present invention, the two pipes 6
When the fluctuations in the pressures of A and 6B are at a predetermined high frequency, the switching circuit 11 moves the switching valve 9 to the open position by the pressure from the high-pressure selection valve 10, whereby the two pipelines 6A and 6B communicate. Is done. On the other hand, when the pressure fluctuations of the two pipe lines 6A and 6B are lower than a predetermined high frequency, the high pressure selection valve 1
The switching circuit 11 moves the switching valve 9 to the closed position by the pressure from 0, whereby the two pipe lines 6A and 6B are shut off. Thus, the impact and pulsation of the actuator 2 based on the high-frequency components of the pressure fluctuations of the two conduits 6A and 6B 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 showing a configuration of a hydraulic control device according to an embodiment of the present invention, FIG. 2 is a diagram showing a detailed configuration of a switching circuit 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 6 supported on the revolving body 62 so as to be able to move up and down.
3, a sheave 64 provided at the tip of the boom 63, and a hook 6 connected to a wire rope via the sheave 64.
5 A suspended load 66 is suspended from the hook 65.

As shown in FIG. 1, the hydraulic circuit for turning the revolving unit 62 of the mobile crane includes a hydraulic pump 3 driven by a motor 14 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.
, A switching valve 9 for communicating and shutting off the two pipelines 6A and 6B, and a high-pressure selection valve connected between the two pipelines 6A and 6B for selecting a high-pressure side of each of the pipelines 6A and 6B. And a switching circuit 11 for selectively supplying the pressure oil from the high-pressure selection valve 10 to the ports 9A and 9B of the switching valve 9.

As shown in FIG. 2, the switching circuit 11 supplies the pressure of the high-pressure pipes 6A and 6B selected by the high-pressure selection valve 10 to the ports 9A and 9B of the switching valve 9, respectively. 11B and a throttle 1 provided in the conduit 11B
2 and an oil sump 13.

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 conduits 6A, 6A selected by the high-pressure selection valve 10 shown in FIGS.
The switching circuit 11 is configured so that the switching valve 9 switches to the open position only for the high-frequency component of 1 Hz or more of the pressure fluctuation of B. That is, as described above, the switching valve 9 is switched to the open position by supplying the pressure from the high pressure selection valve 10 to the port 9A, and the switching valve 9 is switched to the closed position by supplying the pressure to the port 9B. At this time, a temporary delay system is formed by the throttle 12 and the oil reservoir 13, and the switching valve 9 is switched based on the high-frequency component of the pressure fluctuation selected by the high-pressure selection valve 10. This will be described with reference to FIG.

As shown in FIG. 7, the resistance of the diaphragm 12 is R,
The capacity of the oil reservoir 13 is V, and the pressure from the high pressure selection valve 10 is P
i, assuming that the pressure acting on the port 9B of the switching valve 9 is Po, the pressure output value Po with respect to the pressure input value Pi is:

(Equation 1) Here, K is the bulk modulus of oil. Converting equation (1) into a time function,

(Equation 2) Becomes As is apparent from equation (2), the rise time constant T of the system shown in FIG.

(Equation 3) Becomes The relationship between the time constant T and the cutoff frequency F is

(Equation 4) And from equation (4):

(Equation 5) Is obtained, and the time constant T for the target cutoff frequency F is determined. Therefore, the resistance R of the throttle 12 and the oil sump 1
3, the time constant T and the cutoff frequency F can be arbitrarily set. And
In the present embodiment, the resistance R of the throttle 12 and the capacity V of the oil reservoir 13 are adjusted so that the cutoff frequency F is 1 Hz or less.

The operation of the embodiment will be described below. 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, a pressure difference between the pressure oils in the pipe lines 6A and 6B is generated, and the pressure fluctuates. The selection valve 10 switches. The pressure from the high-pressure selection valve 10 is input to the port 9A and the port 9B according to the frequency of the pressure fluctuation. That is, since the cutoff frequency F is set to 1 Hz by the resistance R of the throttle 12 and the capacity V of the oil reservoir 13, when the pressure fluctuation is 1 Hz or less, the pressure from the high pressure selection valve 10 is applied to the ports 9A and 9B. Acting substantially simultaneously, the switching valve 9 maintains the state switched to the closed position. On the other hand, when the pressure fluctuation is 1 Hz or more, when the pressure from the high pressure selection valve 10 acts on the port 9A via the line 11A, the pressure does not act on the port 9B due to a temporary response delay of the line 1B. , The switching valve 9 is switched to the open position, whereby the line 6A and the line 6B are communicated.

As described above, in the present embodiment, when the pressure in the pipelines 6A and 6B fluctuates at a high frequency, the switching valve 9 opens and closes according to the pressure fluctuation selected by the high-pressure selection valve 10. repeat. 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 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.

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 correspondence between the above embodiment and the claims, the turning hydraulic motor 2 forms an actuator.

[0022]

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 conduits at the entrance and exit of the actuator. Pulsation can be eliminated to prevent an uncomfortable feeling for the operator, and an impact based on pressure fluctuation at the time of starting or stopping the actuator can be eliminated. In particular, since the opening and closing of the two entrance / exit lines is controlled by the pressure oil on the high pressure side of the entrance / exit lines of the actuator, electric sensors and circuits are not required, and a highly reliable device can be provided. it can.

[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 switching circuit.

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 diagram for explaining the operation of the throttle and the oil reservoir;

FIG. 8 is a circuit diagram of a conventional hydraulic control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Direction control valve for turning 2 Hydraulic motor for turning 3 Hydraulic pump 4 Pressure control valve 5 Operating lever 6A, 6B Pipe 7 Pilot hydraulic source 8 Hydraulic oil tank 9 Switching valve 10 High pressure selection valve 11 Switching circuit 11A, 11B Pipe 12 Throttle 13 Oil sump 11 Control device

Claims (3)

[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 between the control valves. A hydraulic control device including an operation lever, a high-pressure selection valve for selecting pressure oil on a high-pressure side of two pipes respectively connected to an inlet / outlet port of the actuator, and an open position communicating the two pipes. A switching valve that switches between a closed position and a shutoff position, and among the frequencies of pressure fluctuations from the high-pressure selection valve, switches the switching valve to the open position based on a high-frequency component that is greater than or equal to a predetermined value, and A switching circuit for switching the switching valve to a closed position based on a frequency component of the pressure fluctuation. 2. The hydraulic control device according to claim 1, wherein the switching circuit includes a throttle and an oil reservoir. 3. The hydraulic control device according to claim 1, wherein the frequency is a frequency that can be operated by an operator.