JP2904376B2 - Vibration suppression device for hydraulic actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration suppressing device for a hydraulic actuator, and more particularly to a hydraulic circuit device for suppressing vibration generated when the operation of a hydraulic cylinder is stopped in a construction machine.

[0002]

2. Description of the Related Art A conventional hydraulic actuator drive circuit of a construction machine will be described with reference to FIGS. FIG. 5 shows a boom cylinder drive circuit of the hydraulic shovel. A pilot operated directional control valve 5 is provided in main pipelines 3 and 4 connecting a hydraulic cylinder 1 for boom drive and a hydraulic pump 2. The direction control valve 5 is controlled by a pilot operation unit 6, and switches in conjunction with the movement of an operation lever 7 of the pilot operation unit 6, so that the elevation angle of the boom of the excavator can be operated. Reference numeral 8 denotes a pilot hydraulic pump.

Next, the operation of the boom cylinder drive circuit will be described.
6 will be described according to the timing chart. Hydraulic excavator
Operator is t₁At the time of operation lever 7 in the left of FIG.
To the side, t_TwoAt the spool of the directional control valve 5
Starts moving from the neutral position C to the R position, and t_ThreeAt
Reach the maximum displacement position. Start of operation of operation lever 7 ₁
Of the response from when the directional control valve 5 is activated (t_Two−
t₁) Indicates the pilot system pressure loss and pilot hydraulic pressure
It occurs due to the elasticity of the base.

When the directional control valve 5 switches from the neutral position C to the R position, the pressure oil from the hydraulic pump 2 receives the directional control valve 5,
The hydraulic cylinder 1 is supplied to the piston rod side oil chamber 1a of the hydraulic cylinder 1 through the main conduit 3, and the hydraulic cylinder 1 contracts. Returning to the operator t ₄ when in the neutral position the operating lever 7, the directional control valve 5 behind the start of the operation back in t _5, the neutral position C at t _6.

[0005] large hydraulic excavator boom total mass of the hydraulic cylinder 1 is driven, because the inertia is large, when the return operation direction control valve 5 at t ₅ starts shrinking speed of the hydraulic cylinder 1 is lowered by a hydraulic cylinder The pressure in the bottom oil chamber 1b of FIG. ₁ rises rapidly due to the inertia of the boom (P _{1 in} FIG. 6). And that the reaction force, the pressure of the piston rod 1c of the hydraulic cylinder 1 is extended piston rod side oil chamber 1a by the extending movement is increased (P _2). Subsequently, the hydraulic cylinder 1 contracts by the reaction force of the surge pressure P ₂ of the piston rod side oil chamber 1a. Then, contraction and extension are repeated sequentially, and the pressure in the bottom-side oil chamber 1b and the pressure in the piston-rod-side oil chamber 1a rise alternately, causing the piston rod 1c to vibrate, gradually attenuating the pressure fluctuation and stopping the vibration. .

[0006]

In the conventional hydraulic actuator drive circuit described above, when stopping the operation of a large-mass movable part such as a boom of a hydraulic shovel, vibration occurs in the hydraulic cylinder due to inertia of the boom or the like. There is a problem in operability. In addition, the vibration of the hydraulic cylinder causes the vibration of the hydraulic equipment main body, which increases the operator's fatigue and lowers the work efficiency.

In view of the above, vibrations generated when the hydraulic actuator stops are suppressed to improve operability.
There are technical problems to be solved in order to reduce the physical burden on the operator and improve the work efficiency, and an object of the present invention is to solve the above problems.

[0008]

SUMMARY OF THE INVENTION The present invention has been proposed to achieve the above object, and has a pilot operating section for deriving a pilot pressure in a rotating direction of an operating lever.
In the hydraulic circuit which controls the hydraulic actuator by the directional control valve is switched by the pilot pressure, the two main conduit for connecting the directional control valve and the hydraulic actuator connected by solenoid valves, O of the operating lever
A first sensor for detecting on / off or an operation amount , and a second sensor for detecting one pressure of the main line,
The solenoid of the first and second sensors and the electromagnetic on-off valve connected to the respective control unit, the detection signal of the first sensor
Signal is off, and the pressure of one main line reaches the operating pressure or the holding pressure, and the second sensor outputs a predetermined detection signal.
An object of the present invention is to provide a vibration suppression device for a hydraulic actuator configured to open the electromagnetic on-off valve for a certain period of time when led to a control unit .

[0009]

The first sensor provided in the pilot operation section detects whether or not the operation lever has been operated and outputs a signal to the control section. A second sensor provided in one main conduit of the hydraulic actuator detects a hydraulic pressure on the bottom side of the hydraulic actuator and outputs a signal to the control unit. When the operating lever is turned to derive the pilot oil and the direction control valve is switched to another position, the hydraulic oil from the hydraulic pump flows into one of the main lines of the hydraulic actuator to operate the hydraulic actuator Let it. At that time, the control unit stores the information that the operation lever has been operated, and closes the electromagnetic on-off valve.

Then, when the operation of the hydraulic actuator is stopped by returning the operating lever to the neutral position, the hydraulic pressure of the one main pipeline temporarily increases, and the second sensor increases the hydraulic pressure on the bottom side of the hydraulic actuator. Is transmitted to the control unit. Further, the first sensor transmits to the control section that the operation lever has returned to the neutral position. At that time, the control unit opens the electromagnetic on-off valve for an arbitrary fixed time, connects the two main lines, and allows the hydraulic oil in one main line to escape to the other main line.

Accordingly, the unbalance of the main line hydraulic pressure caused by inertia when the hydraulic actuator is stopped is eliminated, and the hydraulic actuator stops smoothly without vibration to suppress the generation of the reaction force.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIGS. For convenience of explanation, the same components as those of the related art will be described at the same time. FIG. 1 shows a boom cylinder drive circuit of a hydraulic shovel of a construction machine, in which a hydraulic cylinder 11 is provided as a hydraulic actuator for driving the boom, and a main pipe line 13 connecting the hydraulic cylinder 11 and a hydraulic pump 12 is provided.
14 is provided with a pilot-operated directional control valve 15. The directional control valve 15 is controlled by a pilot operation unit 16, and the operation lever 17 of the pilot operation unit 16 is rotated in any direction on the extension side or the contraction side of a boom (not shown), so that the pilot valve 18 is rotated. Or 19 from the pilot hydraulic pump 20 to the pilot oil passage 21
Alternatively, the pilot oil is led to 22. Then, pilot pressure is applied to either the pilot port 23 or 24 of the direction control valve 15, and the spool of the direction control valve 15
Is switched to the R or L position.

Here, a bypass pipe 25 is provided between the two main pipes 13 and 14, and an electromagnetic on-off valve 26 is interposed between the bypass pipes 25. When the solenoid 27 is off, the solenoid on-off valve 26
And the bypass line 25 is in a closed state. The solenoid 27 is connected to a control unit 29 via a signal line 28. Further, the pilot operation unit 16 is provided with a pressure switch type first sensor 30 for detecting the operation of the operation lever 17; The first sensor 30 and the control unit 29 are connected by a signal line 31. Further, a second sensor 32 for detecting the pressure P on the bottom side of the hydraulic cylinder 11 is provided in one of the main pipelines 14.
And the control unit 29 are connected by a signal line 33.

Next, the operation of the vibration suppressing device for a hydraulic actuator according to the present invention will be described. Referring to the flowchart of FIG. 2 and the timing chart of FIG. 6 together, the determination unit of the control unit 29 sets a flag f as to whether the solenoid 27 of the electromagnetic on-off valve 26 has been operated through the signal line 28. In the initial state, since the electric signal i _C is not output to the solenoid 27 of the electromagnetic on-off valve 26, the flag f is set to “0” (step 101). Then, the detection value of the first sensor 30 of the pilot operation unit 16 is read into the control unit 29 via the signal line 31 and the one main line 1
The control unit 29 reads the detection value P of the second sensor 32 provided in the control unit 4 through the signal line 33 (step 102), and determines whether or not the operation lever 17 is in the operating state by the determination means of the control unit 29. A judgment is made (step 103).

If the operating lever 17 is in the neutral position and is not in the operating state, the process proceeds to step 104, where the determining means of the control unit 29 determines whether the flag f is "0" or "1". Then, it is determined whether or not the solenoid 27 of the electromagnetic switching valve 26 has been operated. When f = 0, it means that the solenoid 27 of the electromagnetic on-off valve 26 is not operated, and when that is the case, the calculating means of the control unit 29 increases the bottom pressure P based on the detection value of the second sensor 32. The gradient dP / dt is calculated, and it is determined whether dP / dt> 0 (step 105). When the aircraft is stopped in the initial state, the operation lever 17 is in the neutral position, and since hydraulic oil is not drawn out from the hydraulic pump 12 to both the main pipelines 13 and 14, dP / dt = 0 and dP / dt. >
0, the processing advances to step 106 because it is not, the pressure P _R of a predetermined bottom-side set in advance by the setting means of the control unit 29, to the pressure P ₁₁ at that time read in step 102.
At that time, the signal line 2 is output by the output means of the control unit 29.
The electric signal i _C is not output to the solenoid 27 via 8 (step 107). That is, the spool of the solenoid on-off valve 26 is at the position S, the bypass line 25 is closed, and the process returns from step 107 to step 101.

Next, the operator operates the operating lever 17 to lower the boom (not shown) of the excavator.
1 is rotated to the left in FIG. 1, the discharge oil of the pilot hydraulic pump 20 is drawn out to the pilot oil passage 21 through the pilot valve 18 and the pilot pressure is supplied to the pilot port 23 of the direction control valve 15 in FIG. And the spool switches to the R position. Accordingly, the hydraulic oil of the hydraulic pump 12 is led out to the main pipeline 13, contracts the hydraulic cylinder 11, and the boom of the hydraulic shovel descends. According to the flowchart of FIG. 2, steps 101 to 10
2 to step 103, the first sensor 30
The control unit 29 determines that the operation lever 17 is in the operating state on the basis of the detection value, and proceeds to step 108. Calculate the gradient dP / dt and calculate dP / dt
It is determined whether or not = 0. At the start of the operation of the operation lever 17, since the pressure of the main pipelines 13 and 14 increases, d
Since P / dt> 0 and dP / dt = 0, the process proceeds to step 106, and the control unit 29 does not output the electric signal i _C to the solenoid 27 as described above (step 1).
07) Return to step 101.

If the operator continues to rotate the operation lever 17 to the left in FIG. 1, the process proceeds from step 101 to step 103 via step 102, and proceeds to step 103.
In 8, the operating oil of the constant pressure P ₁₂ is continuously drawn out from the hydraulic pump 12 to one of the main pipelines 13 or 14, so that the calculating means of the control unit 29 calculates the operating oil based on the detection value of the second sensor 32. The calculated rising gradient of the bottom pressure P is dP
/ Dt = 0, and the routine proceeds to step 109. Here, the pressure P _R of a predetermined bottom-side set in advance by the setting means of the control unit 29, and read the pressure P ₁₂ at that time in step 102, the process proceeds to step 107, in the same manner as described above, the control unit 29 The process returns to step 101 without outputting the electric signal i _C from the output means to the solenoid 27. If the operator continues to rotate the operation lever 17, step 103
From step 108 to step 109, return to step 101 via step 107, and loop the process. Hydraulic oil is continuously drawn from the hydraulic pump 12 to the main line 13, and the contraction operation of the hydraulic cylinder 11 is continued to reduce the hydraulic pressure. The shovel boom continues to fall.

Here, when the operator returns the operation lever 17 to the neutral direction in order to stop the lowering of the boom, the introduction of the hydraulic oil to the main pipeline 13 starts to decrease. On the other hand, due to the inertia of the boom, the pressure in the main line 14 starts to rise once, and the rising gradient of the pressure P on the bottom side becomes dP / dt.
> 0, so that dP / dt = 0 is not satisfied in step 108 and the process proceeds to step 106, and the control unit 29
Does not output the electric signal i _C to the solenoid 27 (step 107) and returns to step 101.

Thus, when the operation lever 17 is returned to the neutral position, the process proceeds from step 103 to step 105 via step 104. Here, the pilot oil is not led out to the pilot oil passage 21, and the spool of the direction control valve 15 switches from the R position to the C position. At that time, the rising gradient of the pressure P on the bottom side becomes dP / dt <0 and is not dP / dt> 0, so the process proceeds to step 106, and the electric signal _ic is transmitted from the control unit 29 to the solenoid 27 in the same manner as described above. The process returns to step 101 without outputting (step 107). Further, when the rising gradient of the pressure P on the bottom side becomes dP / dt> 0 due to the recoil on the rod side, the process proceeds from step 105 to step 110, and the pressure P on the bottom side at that time read in step 102 is set in advance. comparing the predetermined the pressure P _R.

When the pressure P on the bottom side is a predetermined pressure P
_{If R} has not been reached, the process proceeds to step 107, where the electric signal i _C is not output to the solenoid 27, and
Return to In step 110, the process proceeds to step 111 if the pressure P of the bottom is equal to or greater than a predetermined pressure P _R, any time t setting means of the control unit 29 is set in advance
Only, an electric signal i _C is output from the output means of the control unit 29 to the solenoid 27 via the signal line 28 (step 11).
1). Accordingly, the spool of the solenoid on-off valve 26 is switched to the position O, the bypass line 25 is opened, and the main line 13
And the main pipeline 14 are communicated with each other, whereby a sudden pressure increase and reaction force on the main pipeline 14 side are suppressed, and the vibration of the piston rod 11c of the hydraulic cylinder 11 can be prevented. And
Since the solenoid 27 of the electromagnetic on-off valve 26 has been operated, the flag f is rewritten to "1" (step 112) and the process returns to step 102.

FIG. 3 shows another embodiment, in which a first sensor 30 provided on the operating lever 17 of the pilot operating section 16 is provided with a pressure for detecting the presence or absence of a mechanical operation of the operating lever 17. Although a switch-type sensor is used, in the present embodiment, a third sensor 34 that continuously detects the operation amount of the operation lever 17 of the pilot operation unit 16 is provided. Therefore,
When the operation lever 17 of the pilot operation unit 16 is turned, the third sensor 34 outputs an electric signal corresponding to the operation amount of the operation lever 17, and the control unit 29 notifies that the operation lever 17 has been operated. Inform The other configuration is the same as that of the hydraulic circuit shown in FIG. 1 and the resulting functions and effects are substantially the same. Therefore, the flowchart of the operation is shown in FIG. 4 and the description is omitted.

The present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified ones.

[0023]

According to the present invention, as described in the above embodiment,
The surge pressure generated in one main line when the operation of the hydraulic actuator is stopped is communicated with the other main line and absorbed by opening the electromagnetic on-off valve for a certain time. Therefore, the vibration of the hydraulic actuator and the hydraulic device main body is suppressed, and the operability is improved. In addition, the present invention has various effects, such as a reduction in vibration, whereby the degree of physical fatigue of the operator can be reduced, and the workability can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a vibration suppression device for a hydraulic actuator according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation of a vibration suppression device for a hydraulic actuator.

FIG. 3 is a hydraulic circuit diagram of a vibration suppression device for a hydraulic actuator according to another embodiment of the present invention.

FIG. 4 is a flowchart for explaining the operation of a hydraulic actuator vibration suppression device according to another embodiment.

FIG. 5 is a conventional hydraulic actuator drive circuit diagram.

FIG. 6 is a timing chart of each part by a hydraulic actuator drive circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Hydraulic cylinder 13, 14 Main pipeline 15 Direction control valve 16 Pilot operation part 17 Operation lever 26 Electromagnetic on-off valve 27 Solenoid 29 Control part 30 First sensor 32 Second sensor

Claims (1)

(57) [Claims] 1. A hydraulic circuit for controlling a hydraulic actuator by a pilot operating unit for deriving a pilot pressure in a direction of rotation of an operating lever and a directional control valve switched by the pilot pressure, wherein the directional control valve and the hydraulic actuator are controlled. Are connected by an electromagnetic on-off valve, and a first sensor for detecting ON / OFF or an operation amount of the operation lever, and detecting one pressure of the main line. a second sensor is provided, the solenoid of the first and second sensors and the electromagnetic on-off valve connected to the respective control unit, the detection signal is off of the first sensor, and the pressure of one main line the second of but reaches the working pressure or holding pressure
When the sensor derives a predetermined detection signal to the control unit
A vibration suppressing device for a hydraulic actuator, wherein the electromagnetic on-off valve is opened for a predetermined time.