JPH09250504A - Vibration control equipment of hydraulic actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the actuator operation speedily follow the operation of control stick while preventing shock and vibration caused in the actuator by sudden return operation of the control stick. SOLUTION: When the speed of return operation is higher than the specified speed after the operation volume of a control stick 7 detected by an operation value sensor 10 is larger than the specified volume, a solenoid valve 3 is opened by outputting driving current ic=io to the solenoid valve 3, and the pressure in a main line Ta is rapidly lowered and the driving force to a boom cylinder 1 is released by flowing out the hydraulic fluid in the main line Ta to the side of a main line Tb, and if the fluctuation of pressure in the main line Ta after being examined is within the specified range, the driving current ic output to the solenoid valve 3 is turned 0 and the solenoid valve 3 is closed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of a vibration preventing device for a hydraulic actuator which prevents an impact or vibration generated in an actuator during a sudden switching operation of a directional control valve.

[0002]

2. Description of the Related Art A construction machine, for example, a driven body of a hydraulic excavator has a large inertia, and a hydraulic circuit element and a hydraulic pipeline forming a driving hydraulic circuit of an actuator for driving them are formed of a rigid body. Therefore, when the operation is suddenly stopped, high pressure and low pressure are alternately generated between the inflow side and the outflow side of the hydraulic oil of the actuator, causing the actuator to vibrate violently and causing discomfort to the operator. The phenomenon of giving is known. Many proposals have heretofore been made in order to solve such problems.

For example, in Japanese Unexamined Patent Publication (Kokai) No. 6-17448, an inflow side and an outflow side of a hydraulic cylinder are connected via an electromagnetic on-off valve, and an operating lever is operated and then returned to a neutral position. When the hydraulic pressure in the main pipe connected to the hydraulic cylinder rises and reaches the working pressure or the holding pressure, the mechanical on-off that occurs when the hydraulic cylinder is stopped by opening the solenoid on-off valve for a predetermined time. An invention of a vibration suppressing device that prevents vibration is disclosed.

[0004]

In the above-mentioned prior art, when the hydraulic pressure in the main pipeline rises and reaches the operating pressure or the holding pressure, the electromagnetic on-off valve is opened, and the inflow side and the outflow side of the hydraulic cylinder are opened. Since the pipeline communicates, despite the fact that the operating rod was operated to apply quick braking, the braking is not applied until the predetermined time elapses, so the driven body does not stop at the position intended by the operator, Operability deteriorates. It should be noted that a predetermined braking force can be obtained by changing the set pressure to a higher set pressure instead of the operating pressure or the holding pressure, but the first impact associated with a sudden operation cannot be avoided.

The present invention solves the above problems in the prior art, and prevents the actuator from shocking or vibrating due to a sudden return operation of the operating rod, while allowing the operation of the actuator to quickly follow the operation of the operating rod. It is an object of the present invention to provide a vibration prevention device for a hydraulic actuator that can achieve the above.

[0006]

In order to solve the above-mentioned problems, the present invention investigates the operating speed of an operating rod, and when the operating speed is equal to or higher than a predetermined value, an actuator is operated via a directional switching valve. The hydraulic oil in the inflow side pipeline to which the hydraulic oil is supplied is opened by opening the switching valve connected to the inflow side pipeline, so that the outflow side pipeline of the actuator or the pipeline constantly connected to the oil tank, etc. When it is discharged into the low pressure side pipe and the pressure oscillation of the hydraulic oil in the inflow side pipe is sufficiently reduced, the switching valve is closed or connected to the pilot receiving part of the hydraulically operated directional switching valve. By the switching operation of the switching valve with a throttle provided in the middle of the pilot line and the switching operation of the electromagnetically operated directional switching valve based on the delay signal obtained by delaying the detection signal that detected the operation amount of the operating rod with the delay circuit. , Slow down the switching operation speed of the direction switching valve It is obtained by way.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is applied to a construction machine, particularly a hydraulic excavator, a wheel loader, etc., and has an effect of shock and vibration generated in a boom cylinder, a turning motor, etc. during a sudden return operation such as boom, turning and the like. To prevent it. That is,
The operating amount of the operating rod for operating the target actuator is monitored, and the change in the operating amount when the operating rod is operated by a predetermined operating amount or more and is returned toward the neutral position is determined. When the value is equal to or more than the value, the high pressure main line of the actuator is connected to the low pressure line via the switching valve, or the direction switching valve that supplies the actuator by switching the direction and flow rate of hydraulic oil is supplied. Controls to decelerate the switching operation. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0008]

1 is a boom cylinder drive hydraulic circuit diagram according to a first embodiment of the present invention. In the figure, 1 is a boom cylinder, 2 is a pressure sensor for detecting the hydraulic pressure of _a main pipeline Ta for supplying hydraulic oil to the bottom side of the boom cylinder 1, and 3 is connected between the main pipelines T _a and T _b. An electromagnetic opening / closing valve, 4 is a direction switching valve for switching the direction and flow rate of the hydraulic oil supplied to the boom cylinder 1, and 5 and 6 are operating hydraulic pumps and pilot hydraulic pressures that are the supply sources of hydraulic oil and pilot oil, respectively. Pump, 7 is an operating rod operated to drive the boom cylinder 1, 8
(A, b) is switched according to the operating direction of the operating rod 7, and the pilot oil from the pilot hydraulic pump 6 is supplied to the corresponding pilot receiving portion of the direction switching valve 4, and 9 is the oil that has consumed power. The recirculating oil tank, 10 is an operation value sensor for detecting the operation direction and operation amount of the operation rod 7, and 11 is an electromagnetic sensor which executes a calculation process described later based on the detected value data from the pressure sensor 2 and the operation value sensor 10, It is a controller that outputs a driving current i _c to the solenoid of the on-off valve 3 at a proper time.

FIG. 2 is a schematic diagram showing how to obtain an operation value according to the operation direction of the operation rod 7. In this embodiment, the operation value is obtained by setting the operation value θ to 0 when the operation rod 7 is at the neutral position,
The sign of the operation value θ is positive when the operating rod 7 is pushed forward and the boom cylinder 1 is operated in the extending direction, and the operating value when the operating rod 7 is pulled toward you and the boom cylinder 1 is contracted The sign of θ is set to be negative. As the operation value sensor 10, a well-known displacement detector that detects the operation direction and the operation amount of the operation rod 7 can be used.

Next, the operation of this embodiment will be described. The vibration preventing device for the boom cylinder of the present embodiment is configured so as to prevent the occurrence of vibration that occurs in the boom cylinder 1 when the operating rod 7 is suddenly operated, but it is typically generated when the boom cylinder 1 is suddenly stopped. As represented by the vibration prevention operation for preventing the occurrence of vibration, the operation of the boom cylinder sudden stop vibration prevention control will be described below.

FIGS. 3 and 4 are flow charts of vibration prevention control during boom cylinder sudden stop. First, looking at the output value from the operation value sensor 10, the value of the operation value θ (t) at the current time is registered as the first operation value counter value θ ₁ (S1).
In the next step S2, it is determined whether or not the time t has passed the time Δt. If the judgment result is negative, wait for the time Δt to elapse, and if the judgment result is yes,
The value of the operation value θ (t) at that time is registered as the second operation value counter value θ ₂ (S3).

Next, the magnitude of the absolute value of the first operation value counter value θ ₁ is checked to determine whether it is equal to or greater than the minimum operation value θ _min (S4). If the determination result is correct, that is, if the operation rod 7 has been operated in the left or right direction by the minimum operation value θ _min or more, the process proceeds to step S5 and the sign of the first operation value counter value θ ₁ ( sign) and the first operation value counter value θ
The product of the difference between ₁ and the second operation value counter value θ ₂ is calculated, and it is determined whether the product is greater than or equal to a predetermined operation amount difference δ ₁ . That is, it is determined whether or not the operating rod 7 has been returned at a predetermined speed or higher. Here, the product of the first operation value counter value θ _{1 and} the sign (sign) is to make the determination processing of step S5 effectively function regardless of whether the operation rod 7 is operated in the left or right direction. This is so that it can be done.

If the result of the determination in step S4 or step S5 is negative, that is, if the operating rod 7 was operated in either of the left and right directions by a smaller operation amount than the minimum operation value θ _min before the time Δt, When the operating rod 7 is returned at a speed slower than a predetermined speed, the boom cylinder 1 does not vibrate significantly, so the value of the second operation value counter value θ ₂ is set to the first operation value counter value θ ₁ To perform update registration (S6). Then, the procedure returns to step S2, waits for the time Δt to elapse, and the above-described calculation and determination processing is repeated based on the updated new second operation value counter value θ ₂ . If the determination result of step S5 is correct, the value of the drive current i _c output to the solenoid of the solenoid opening / closing valve 3 is set to i ₀ , the solenoid opening / closing valve 3 is opened, and the output of the pressure sensor 2 at the current time is output. The value P (t) is taken in and registered as the first pressure counter value P ₁ , and the time t is registered as the valve opening time t ₀ (S7).

Turning to FIG. 4, in step S8, it is determined whether or not the time t has passed by the time Δt. If the judgment result is negative, wait for the time Δt to elapse, and if the judgment result is correct, the output value P (t) of the pressure sensor 2 at that time is fetched and the second pressure counter It is registered as the value P ₂ (S9). Next, it is determined whether or not the time t has elapsed from the valve opening time t _{0 for a} time t ₁ which is longer than the time Δt to some extent (S10). If the result of the determination is yes, the process proceeds to step S16, If the determination result is negative, the magnitude of the absolute value of the difference between the second pressure counter value P ₂ and the first pressure counter value P ₁ is examined to determine whether or not the pressure difference is equal to or less than a predetermined pressure difference δ ₂ (S11). ). If the determination result is correct, it can be determined that the pressure fluctuation in the main pipe line T _a (T _b ) connected to the boom cylinder 1 has become sufficiently small.
Waiting for t to elapse (S12), and if time Δt elapses, the output value P (t) of the pressure sensor 2 at that time
Is taken in and registered as the third pressure counter value P ₃ (S13).

The change in pressure difference between time t and time (t + Δt), that is, (P ₁ -P ₂ )-(P ₂ -P ₃ ) = P
₁ + P ₃ calculates the value of -2P _2, by examining the magnitude of the absolute value, it is determined whether or not a predetermined pressure difference change [delta] ₃ or less (S14). If the result of the determination in step S11 or S14 is negative, the main conduit T _a (T
_Since the pressure fluctuation or pressure oscillation in _b ) is large, the second pressure counter value P ₂ is moved to the first pressure counter value P ₁ to be updated and registered (S15), and the procedure returns to step S8 to return to the above-mentioned main pipeline T _a. The determination process of the pressure fluctuation of the internal pressure P (t) or the magnitude of the pressure vibration is repeated. If the result of the determination in step S14 is correct, that is, if the rate of change of the pressure P (t) in the main pipeline T _a has decreased to some extent, or in the determination in step S10, the time t is the time from the valve opening time t ₀ to the time If it is determined that only t _{1 has} elapsed, the value of the drive current i _c output to the solenoid of the electromagnetic opening / closing valve 3 is set to 0, and the electromagnetic opening / closing valve 3 is closed (S16) to prevent vibration of the boom cylinder during sudden stop. The control process ends.

In FIG. 5, the operator pushes the operating rod 7 forward so as to extend the boom cylinder 1 (θ
(t)> 0) The pressure P in the main pipe line T _a when a constant operation amount larger than the minimum operation value θ _min is maintained and then a sudden return operation is performed.
It is a wave form diagram which shows the fluctuation | variation of (t) and the output value of drive current i _c . The operation of this embodiment will be specifically described with reference to FIG. Since the directional control valve 4 by the operation of pushing forward the operating rod 7 by the operator is switched to the right switching position, oil discharged from the hydraulic pressure pump 5 into main conduit T _a flows, the pressure P (t) is When it rises rapidly and the operation of the operating rod 7 by the operator reaches a certain amount of operation, after some vibration,
Converges to a constant pressure value. After that, when the operating rod 7 is suddenly returned at time t, (θ ₁ −θ ₂ )> δ ₁ is satisfied, so that the determination result of step S5 is accordingly and the drive current i _c = i ₀ . The solenoid of the electromagnetic opening / closing valve 3 is energized to open the electromagnetic opening / closing valve 3.

As a result, the pressure in the main pipe line T _a drops rapidly (a). However, at this time, since the direction switching valve 4 has not been closed yet, the discharge oil of the working hydraulic pump 5 has flowed into the main pipe line _Ta side through the partial direction switching valve 4,
Although the discharge oil is refluxed to the oil tank 9 via the solenoid valve 3 and the direction switching valve 4, since resisted by the diaphragm action and the like of the electromagnetic valve 3 and the direction switching valve 4, the pressure in the main line T _a P (t) does not decrease until near 0. When the operation value θ (t) becomes 0 due to the return operation of the operation rod 7, the direction switching valve 4 is closed, so that the hydraulic circuit communicating with the boom cylinder 1 is connected to the main pipelines T _a and T _b and the electromagnetic passage communicating between them. There is only a closed circuit composed of the on-off valve 3. Although the boom cylinder 1 has a relatively large inertia, the flow of the hydraulic oil receives a resistance due to the throttling action of the electromagnetic opening / closing valve 3 or the like, so that the boom cylinder 1 is quickly stopped.

At this time, the pressure in the main pipe line T _b is equal to the main pipe line T _a.
Has become higher than the pressure P (t) of the inner hydraulic fluid main conduit T _b are slightly compressed by the inside pressure. The main pipeline T that was compressed when the boom cylinder 1 stopped extending
The hydraulic oil in _b exerts stress in the direction in which the boom cylinder 1 contracts in an attempt to return to the original volume. Thus, the boom cylinder 1 begins to shrink, the pressure P in the main line T _a (t) is increased (b). Thus, the main conduit T _a ,
Although T _b communicates with each other through the open / close solenoid valve 3, the main pipeline T
The pressure in _a (T _b ) repeatedly oscillates for a while, and eventually converges to a constant value. The pressure fluctuation in the main conduit T _b is similar to the fluctuation of the pressure P (t) in the main conduit T _a and has a waveform of opposite phase.

When the vibration of the pressure P (t) in the main pipeline T _a converges, the absolute value of the pressure fluctuation (P ₂ -P ₁ ) and the absolute value of the pressure difference change (P ₁ + P ₃ -2P ₂ ) The value decreases and the procedure S
Since the determination results of 12 and S14 are correct, the drive current i _c = i ₀ output from the controller 11 becomes 0, and the electromagnetic on-off valve 3 is closed. Note that when the time t ₁ elapses after the solenoid on-off valve 3 is opened, the main pipeline T
regardless of the presence or absence of the vibration of the pressure P (t) in _a, the solenoid valve 3
Is closed. This is because when the frequency of vibration of the pressure P in the main line T _a (t) is close to the natural frequency of the composed closed circuit by the main line T _a, T _b and the electromagnetic valve 3, the electromagnetic on-off This is because when the valve 3 is closed to increase the frequency of the vibration of the pressure P (t) in the main pipeline T _a , the vibration of the pressure P (t) in the main pipeline T _a converges earlier.

FIG. 6 shows the case where the operator pulls the operating rod 7 toward you (θ (t) <0), maintains a constant operating amount larger than the minimum operating value θ _min , and then suddenly returns it. Main pipeline T
is a waveform diagram showing an output value of the fluctuation and the drive current i _c of the pressure P (t) in _a. As shown in the figure, the pressure P (t) in the main pipe line T _a is caused by the operation of pulling the operation rod 7 by the operator.
After slowly rising, when the operation of the operating rod 7 reaches a certain operation amount, it is affected by the pressure fluctuation in the main pipe line T _b , and after a slight pressure fluctuation, converges to a constant pressure value. When the operating rod 7 is abruptly returning operation at time t, since in conjunction therewith electromagnetic valve 3 begins to close the direction switching valve 4 as well as opened, the pressure P in the main line T _a (t) is soared After that, the vibration is repeated for some time due to the same reason as described above, and eventually converges to a constant value.

As described above, in this embodiment, the operating rod 7 is operated by a constant operating amount larger than the minimum operating value θ _min, and then a sudden returning operation is performed to the neutral position side, and | θ ₁ −θ ₂ |
When> δ ₁ , the operator determines that the boom cylinder 1 is about to be stopped quickly, and immediately opens the electromagnetic opening / closing valve 3 to release the hydraulic oil driving the boom cylinder 1 from the main pipe on the opposite side. Since the oil is discharged to the oil tank 9 and the oil tank 9, the movement of the boom cylinder 1 can be quickly followed by the operating state of the operating rod 7, and extremely excellent responsiveness to the returning operation of the operating rod 7 can be realized, and the solenoid opening / closing valve can be realized. By the braking force on the boom cylinder 1 due to the throttle action of 3, the boom cylinder 1 can be stopped without generating a large shock or vibration even when the operating rod 7 is suddenly returned and operated.

FIG. 7 is a boom cylinder drive hydraulic circuit diagram according to the second embodiment of the present invention. In the figure, 12
Is _a discharge direction switching valve that switches the discharge direction of the hydraulic oil in the main pipelines T _a and T _b to the oil tank 9, and 13 is a throttle provided in the oil path between the oil tank 9 and the discharge direction switching valve 12. Is. In addition, the same reference numerals are given to the portions which are the same as or can be regarded as the same as those in the first embodiment, and the duplicate description thereof will be omitted. The same applies to the following description. Next, the operation of this embodiment will be described with reference to the flow charts of the vibration prevention control during boom stop of the boom cylinder shown in FIGS. 8 and 9.

The first registered operation value θ (t) at the current time
Operation value Counter value θ₁Absolute value of | θ₁| And the first operation
Value counter value θ₁And after the time t passes by the time Δt
The second operation value counter that registered the operation value θ (t) at the time
Value θ₂Difference (θ₁−θ ₂) And sign (θ₁) With
Check the values and_minAnd δ₁Was less than
In the case of steps S21 to S26, the process shown in FIG.
The description is omitted because it is the same as the operation procedure S1 to S6 according to the embodiment.
In short, the judgment result of step S24 and the judgment result of step S25
Same with each other, that is, | θ₁│ ≧ θ_minAnd (θ₁−θ₂)
・ Sign (θ₁) ≧ δ₁Or the process of step S27
Explain.

At this time, whether the sign (θ ₁ ) is positive or negative is checked, and if it is positive, the drive current i _{ca is set} to i ₀ and the switching position of the discharge direction switching valve 12 is switched to the left switching position. The time t of the hour is registered as the valve opening time t ₀ (S28). If sign (θ ₁ ) is negative, drive current i
The switching position of the discharge direction switching valve 12 is switched to the right switching position by setting _cb to i ₀ , and the time t at this time is registered as the valve opening time t ₀ (S29).

Next, moving to FIG. 9, in step S30 when sign (θ ₁ ) is positive, the sign of the time change ΔP / Δt of the pressure P (t) in the main pipeline T _a is checked and To determine whether is correct. If ΔP / Δt> 0, the drive current i _{ca is set} to 0 and the drive current i _{cb is set} to i ₀ to switch the switching position of the discharge direction switching valve 12 from the left switching position to the right switching position (S31). The time t is the time t ₀ from the valve opening time t _0.
It is determined whether or not only _{2 has} elapsed (S32). If the determination result is negative, wait until the time t ₂ elapses from the valve opening time t _0. If the determination result is correct, the drive current i _{cb is set} to 0 (S33), and the boom cylinder The processing of the vibration prevention control at the time of sudden stop is completed. In sign (θ ₁₎ procedure in the case of negative S34, examines the sign of the time variation [Delta] P / Delta] t of the pressure P (t) in the main conduit T _a, it is determined whether negative or not. If ΔP / Δt <0, the drive current i _cb is 0,
The drive current i _{ca is set} to i ₀ and the switching position of the discharge direction switching valve 12 is switched from the right switching position to the left switching position (S35). Then, it is determined whether or not the time t has passed the time t ₂ from the valve opening time t ₀ (S36). If the judgment result is negative, wait until the time t _{2 has} elapsed from the valve opening time t ₀ , and if the judgment result is yes,
The drive current i _{ca is set} to 0 (S37), and the processing of the vibration prevention control during sudden stop is completed.

In FIG. 10, the operator pushes the operating rod 7 forward to extend the boom cylinder 1 (θ
(t)> 0) The drive current i of the present embodiment when a sudden return operation is performed after maintaining a constant operation amount larger than the minimum operation value θ _min.
ca, the output value of the i _cb, main line T pressure in _a P (t), main path fluctuation and the boom cylinder 1 of T pressure in _b P _r (t)
FIG. 7 is a waveform diagram showing the transition x of FIG. The operation of this embodiment will be specifically described with reference to FIG. When the operator pushes the operation rod 7 forward, the main pipeline T
pressure in _a P (t) is rising rapidly, the boom cylinder 1 is extended. After the operation of the operation rod 7 by the operator reaches a certain operation amount, the pressure P (t) vibrates for a while. On the other hand, the pressure P _r (t) in the main pipeline T _b gradually rises during this period and then oscillates for a while.

After that, when the operating rod 7 is suddenly returned by the operator, in the conventional example having no discharge direction switching valve 12, the direction switching valve 4 starts to close, so that the pressure P in the main pipe line T _a is reduced. ′ (T) decreases rapidly with some time delay, while the pressure P _r ′ (t) in the main line T _b increases rapidly with some time delay. Then, as described above, the main pipeline T
_{Due to} the expansion and contraction of the _a and T _b walls, the pressure P ′ (t) in the main pipeline T _a
And the pressure P _r ′ (t) in the main pipe line T _b repeats large vibrations in the opposite phase, whereby the boom cylinder 1 also repeats large stretching vibrations.

On the other hand, in this embodiment, (θ ₁ −θ ₂ )
When it is determined that ≧ δ ₁ , the drive current i _ca = i ₀ is output to the left solenoid of the discharge direction switching valve 12, the discharge direction switching valve 12 is switched to the left switching position, and the main pipeline T _a opens the throttle 13. Since it communicates with the oil tank 9 via the main pipe line T
pressure in _a P (t) rapidly decreases in conjunction with the sudden returning operation of the operating rod 7. On the other hand, the pressure P _r (t) in the main pipe line T _b rapidly increases due to the closing operation of the direction switching valve 4 and the inertial force of the boom, so that the extension motion of the boom cylinder 1 is suddenly braked. Therefore, it is possible to minimize the increase in the extension displacement x of the boom cylinder 1 after the operation rod 7 is suddenly returned.

Thus, when the extension of the boom cylinder 1 is stopped, the pressure P _r (t) in the main pipeline T _b is high and the pressure P (t) in the main pipeline T _a is low. A pressure for contracting the pressure receiving surface of the cylinder 1 acts on the pressure receiving surface, and the boom cylinder 1 starts contracting. Due to the contraction movement of the boom cylinder 1, the pressure P in the main pipe line T _a is reduced.
Since (t) starts reversing and starts increasing, ΔP / Δt> 0, and the controller 11 that has detected this has a drive current i _{ca
Is set} to 0 and the drive current i _cb is switched to i ₀ to switch the switching position of the discharge direction switching valve 12 from the left switching position to the right switching position.

As a result, the hydraulic oil in the main pipe line T _b flows out to the oil tank 9, so that the pressure P _r (t) in the main pipe line T _b rapidly drops. Therefore, due to the decrease in the pressure P (t) in the main pipeline T _{a for} retracting and contracting the boom cylinder 1, the vibrations of the pressures P (t), P _r (t) in the main pipelines T _a , T _b , that is, the boom The stretching vibration of the cylinder 1 quickly converges.

FIG. 11 is a boom cylinder drive hydraulic circuit diagram according to the third embodiment of the present invention. In the figure, 1
4a and 14b are provided in the pilot oil inflow pipes that flow into the left and right pilot receiving portions of the directional control valve 4, and when the drive currents i _ca and i _cb are output, the flow rates of the pilot oil that pass through are restricted. It is a switching valve with a throttle. The operation of this embodiment is similar to that of the second embodiment, and the operation value θ at the current time is
The first operation value counter value θ ₁ of the absolute value registered the value of (t) | θ ₁ | a, operation value of time after the first operation value counter value θ ₁ and the time t has elapsed by the time Δt θ ( The difference from the second operation value counter value θ ₂ that registered the value of (t) (θ ₁ −
The product of θ ₂ ) and sign (θ ₁ ) is investigated, and | θ ₁ | ≧ θ
_{If min} and (θ ₁ −θ ₂ ) sign (θ ₁ ) ≧ δ ₁ , the sign (θ ₁ ) is checked for positive or negative.

If this is positive, the drive current i _{ca is set} to i ₀ to switch the throttle-equipped switching valve 14a to the throttle position side, and a sudden return operation of the operating rod 7 causes the directional switching valve 4 to move from the left pilot receiving portion. The flow rate of the pilot oil that returns to the pilot valve 8a through the switching valve with throttle 14a is regulated to suppress an abrupt switching operation from the left switching position of the direction switching valve 4 to the neutral position. If sign (θ ₁ ) is negative, the drive current i _{cb is set} to i ₀ to switch the throttled switching valve 14b to the throttle position side, and the operation rod 7 is suddenly returned to the right of the direction switching valve 4. The flow rate of the pilot oil that returns from the pilot receiving portion to the pilot valve 8b through the throttled switching valve 14b is regulated to suppress an abrupt switching operation from the right switching position of the direction switching valve 4 to the neutral position.

FIG. 12 is a boom cylinder drive hydraulic circuit diagram according to the fourth embodiment of the present invention. In the figure, 1
5 is a DC power supply, 16 is a potentiometer type manipulated variable detector connected to the operating rod 7 and detecting the operating value θ (t) of the operating rod 7 as a DC detection voltage v _c value, 17 a changeover switch, and 18 an integrating A delay circuit F (s), 19 composed of a circuit or the like, which converts a steep fluctuation of the operating value θ (t) to a delayed operating value θ ′ (t), 19 is an input operating value θ (t) signal or delay It is an amplifier that amplifies the manipulated value θ '(t) signal. In the present embodiment, the direction switching valve 4 is configured by a solenoid valve, and the switching valve with throttle 14a, 1 for suppressing the rapid pilot pressure change applied to the left pilot receiving portion of the direction switching valve 4 in the third embodiment.
4b is replaced with a delay circuit F (s) 18, and an input signal to an amplifier 19 that outputs a drive current i _c output to a solenoid that controls the switching operation of the directional control valve 4 by a changeover switch 17 is used as a manipulated variable detector 16 The operation value θ (t) signal detected by or the delay operation value θ ′ (t) signal relaxed by the delay circuit F (s) 18 can be switched to the boom of the third embodiment electrically. It has the same function as a cylinder drive hydraulic circuit.

That is, the controller 11 determines the operation value θ of the operation rod 7 from the DC detection voltage v _c from the operation amount detector 16.
(t) is calculated, and | θ ₁ | ≧ θ _min and (θ ₁ −θ ₂ ) ・ si
Whether or not gn (θ ₁ ) ≧ δ ₁ is satisfied is always determined, and if the determination result is correct, the changeover switch 17 is changed over to the delay circuit F (s) 18 side. Since the delay operation value θ ′ (t) signal, which is obtained by relaxing the change in the operation value θ (t) whose absolute value is rapidly decreased, is input to the input terminal of the amplifier 19, the directional switching valve 4 is neutralized from the left and right switching positions. It is possible to suppress a sudden switching operation to the position.

[0035]

As described above, according to the invention of claim 1, the operating speed of the operating rod is checked, and when the operating speed is equal to or higher than a predetermined value, the actuator is actuated via the direction switching valve. Pressure oil of the hydraulic oil in the inflow side pipeline is opened by opening the switching valve connected to the inflow side pipeline and discharging the hydraulic oil in the inflow side pipeline to which the hydraulic oil is supplied. When the valve is fully lowered, the switching valve is closed, so it is possible to make the operation of the actuator follow the operation of the operating rod promptly while preventing the impact and vibration caused to the actuator by the sudden return operation of the operating rod. it can. Claim 2
According to the invention described above, the outflow side pipe line for outflowing the hydraulic oil from the actuator is the low pressure side pipe line, so that the structure of the hydraulic circuit for preventing the vibration of the actuator can be simplified. According to the third aspect of the present invention, since the pipeline that is constantly connected to the oil tank in which the hydraulic oil recirculates is the pipeline on the low pressure side, it is possible to move to a quick stop operation of the actuator. According to the invention of claim 4, when the operating speed of the operating rod is equal to or higher than a predetermined value, the switching valve is switched to one switching operation position to discharge the hydraulic oil in the inflow side pipe line,
As a result, when the pressure of the hydraulic oil in the inflow side pipe once drops and then rises, the switching valve is switched to the other switching operation position so that the hydraulic oil in the outflow side pipe is discharged. The amount of displacement of the actuator after the sudden return operation of the operating rod can be reduced as much as possible, and the pressure vibration of the hydraulic oil in the outflow side pipe line can be quickly converged.

According to the invention of claim 5, the operating speed of the operating rod is checked, and when the operating speed is equal to or higher than a predetermined value, the switching operation speed of the directional switching valve is switched according to the operation of the operating rod. Therefore, the switching operation of the direction switching valve can be swiftly switched following the operation of the operating rod. According to the invention of claim 6,
Since the switching operation speed of the directional switching valve was moderated by switching the switching valve with throttle provided in the pilot line connected to the pilot receiving part of the hydraulically operated directional switching valve, a general-purpose hydraulic circuit element was used. The directional switching valve can be smoothly switched. According to the invention described in claim 7, the electromagnetically operated directional control valve is switched based on the delay signal obtained by delaying the detection signal for detecting the operation amount of the operation rod by the delay circuit, thereby the switching operation speed. Since the above is alleviated, the switching operation of the directional control valve can be smoothly performed with good responsiveness.

[Brief description of the drawings]

FIG. 1 is a boom cylinder drive hydraulic circuit diagram according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing how to obtain an operation value according to an operation direction of an operation rod.

FIG. 3 is a flowchart of vibration prevention control during a sudden stop of a boom cylinder according to the first embodiment.

FIG. 4 is a flow chart of vibration prevention control at the time of sudden stop of the boom cylinder following FIG.

FIG. 5 is a waveform diagram showing pressure fluctuations in the main pipeline and output values of drive current when the operating rod is operated in the forward direction.

FIG. 6 is a waveform diagram showing pressure fluctuations in the main pipeline and output values of drive current when the operating rod is operated in the negative direction.

FIG. 7 is a boom cylinder drive hydraulic circuit diagram according to a second embodiment of the present invention.

FIG. 8 is a flowchart of vibration prevention control during a sudden stop of the boom cylinder according to the second embodiment.

FIG. 9 is a flow chart of vibration prevention control at the time of sudden stop of the boom cylinder following FIG.

FIG. 10 is a waveform diagram showing the output value of the drive current, the fluctuation of the pressure in the main pipeline, and the displacement of the boom cylinder in comparison with the conventional example.

FIG. 11 is a boom cylinder drive hydraulic circuit diagram according to a third embodiment of the present invention.

FIG. 12 is a boom cylinder drive hydraulic circuit diagram according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1 boom cylinder 2 pressure sensor 3 electromagnetic on-off valve 4 directional switching valve 5 actuating hydraulic pump 7 operating rod 8 (a, b) pilot valve 9 oil tank 10 operation value sensor 11 controller 12 discharge direction switching valve 13 throttle 14 (a, b) ) Changeover valve with throttle 17 Changeover switch 18 Delay circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Morio Oshina 650 Jinrachicho, Tsuchiura City, Ibaraki Prefecture Hitachi Construction Machinery Co., Ltd. Tsuchiura Factory

Claims (7)

[Claims] 1. An actuator, to which hydraulic oil is supplied via a direction switching valve that is switched based on the operation of the operating rod after a predetermined amount of operation from the neutral position and then a sudden return operation. In a vibration prevention device for a hydraulic actuator that prevents shock and vibration, check the operating speed of the operating rod, and when the operating speed is equal to or higher than a predetermined value, hydraulic oil is applied to the actuator via the direction switching valve. The supplied hydraulic oil in the inflow side conduit is opened into the low pressure side conduit by opening the switching valve connected to the inflow side conduit, and the pressure vibration of the working oil in the inflow side conduit is sufficient. A vibration preventing device for a hydraulic actuator, wherein the switching valve is closed when the pressure drops. 2. The vibration preventing device for a hydraulic actuator according to claim 1, wherein the low pressure side pipe line is an outflow side pipe line for letting out the hydraulic oil from the actuator. 3. The low-pressure side pipe line is a pipe line which is always connected to an oil tank in which hydraulic oil flows back.
Anti-vibration device for the hydraulic actuator described. 4. The switching valve is a switching valve having two switching operation positions, and when the operating speed of the operating rod is equal to or higher than a predetermined value, the switching valve is switched to one of the switching operation positions and the inflow side is provided. When the hydraulic oil in the pipeline is discharged to the pipeline side that is always connected to the oil tank, the pressure of the hydraulic oil in the inflow pipeline is once reduced and then rises, and the switching valve is turned to the other side. 4. The vibration preventing device for a hydraulic actuator according to claim 3, wherein the hydraulic oil in the outflow side pipeline is discharged to the side of the pipeline that is always connected to the oil tank by switching to the switching operation position of. 5. An actuator to which hydraulic oil is supplied via a direction switching valve that is switched based on the operation when the operation rod is operated from the neutral position for a predetermined operation amount or more and then is rapidly returned. In a vibration prevention device for a hydraulic actuator that prevents shock and vibration, the operating speed of the operating rod is checked, and when the operating speed is equal to or higher than a predetermined value, the direction switching valve that is switched according to the operation of the operating rod. The vibration prevention device for a hydraulic actuator is characterized in that the switching operation speed of the is reduced. 6. The direction switching valve is a hydraulically operated type,
6. The hydraulic pressure according to claim 5, wherein the switching operation speed of the direction switching valve is moderated by switching a throttled switching valve provided midway in a pilot line connected to a pilot receiving portion of the direction switching valve. Anti-vibration device for actuator. 7. The directional control valve is of an electromagnetically actuated type,
6. The switching operation speed is relaxed by switching the directional switching valve based on a delay signal obtained by delaying a detection signal for detecting the operation amount of the operation rod by a delay circuit. Anti-vibration device for hydraulic actuator.