JPH1162902A - Actuator vibration isolating device for hydraulic working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To isolate vibration in a wide range unlimited to specific vibration by increasing the quantity of discharge oil for the specified time. SOLUTION: The pressure fluctuation of damped waveform is generated to oil chambers 2a, 2b according to inertial load 2e of a hydraulic cylinder 2 and the changeover speed of an operating lever 18a due to oil stagnated in oil passages 14, 16 and a directional control valve 6 in addition to the oil chambers 2a, 2b and the elastic deformation of a line. A displacement controller 4a of a variable displacement pump 4 is therefore actuated by an output signal from a control means 28 to increase discharge oil by the specified quantity for the specified time. The increased discharge oil from the variable displacement pump 4 flows to a return passage 10 to which makeup oil passages 25, 26 are connected. According to the pressure increase-decrease pulsation of pressure fluctuation waveform of the oil chambers 2a, 2b, discharge oil from the variable displacement pump 4 is supplied from the makeup oil passages 25, 26 to the oil chambers 2a, 2b through check valves 25a, 26a, and the unevenness of fluctuating waveform is reduced to damp pressure fluctuation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator damping device for a hydraulic working machine such as a hydraulic shovel or a wheel loader, and more particularly, to stop the operation of an actuator such as a boom cylinder which holds a large inertial load. In this case, the present invention relates to an actuator damping device for a hydraulic working machine, which attenuates vibration due to pressure fluctuations occurring in an actuator at an early stage.

[0002]

2. Description of the Related Art A typical hydraulic working machine, for example, a hydraulic shovel, is equipped with a hydraulic working device driven by a hydraulic cylinder as an actuator. This hydraulic working device is composed of a boom mounted on the excavator body so as to be swingable in the vertical direction, an arm mounted on the tip of the boom so as to be swingable in the vertical direction, and a swingable vertically on the tip of the arm. The boom cylinder is interposed between the excavator body and the boom, the arm cylinder is interposed between the boom and the arm, and the bucket cylinder is interposed between the arm and the bucket. I have. In these hydraulic cylinders, the direction switching valve is switched by operating an operation lever provided in the driver's seat, and the discharge oil from the hydraulic pump is selected to one of the rod-side oil chamber or the head-side oil chamber of the hydraulic cylinder. Is supplied, the oil in the other oil chamber is discharged, and the expansion or contraction operation is performed. By this expansion and contraction operation, the bucket at the tip of the hydraulic working device is moved to perform operations such as excavation of earth and sand, movement of the excavated earth and sand, and loading into a dump truck.

In order to stop the expansion / contraction operation of these hydraulic cylinders, the operation lever is switched from the operating position to the neutral position to stop the supply of the discharge oil to the hydraulic cylinder and the discharge of the oil from the hydraulic cylinder. At this time, for example, when the operation lever is rapidly operated to the neutral position to quickly stop the supply and discharge of the discharge oil and the hydraulic cylinder is suddenly stopped, the oil chambers on both sides of the piston in the hydraulic cylinder are provided with pistons. As a reaction to stop the inertial load of the hydraulic cylinder acting on the hydraulic cylinder, pressure fluctuation of a damping waveform occurs. The pressure fluctuation causes vibration in the hydraulic cylinder in the expansion and contraction direction. The pressure fluctuation and vibration increase as the operation of the hydraulic cylinder is suddenly stopped, and as the inertial load in the operation direction of the hydraulic cylinder increases. Since the boom cylinder of the hydraulic shovel holds most of the mass load of the hydraulic working device, when stopping the boom cylinder during the lowering operation, large pressure fluctuations occur in the boom cylinder oil chamber, and the boom cylinder Large vibrations are likely to occur. This vibration causes the hydraulic working device, and further the hydraulic excavator body to which the hydraulic working device is attached to vibrate, making it difficult to perform a positioning operation of the hydraulic working device, for example, a bucket, deteriorating the ride comfort of the worker, and Increases worker fatigue.

In order to attenuate the pressure fluctuation and the vibration at an early stage, a vibration preventing device (a damping device) provided in a hydraulic circuit of a hydraulic cylinder is provided, for example, in Japanese Utility Model Laid-Open No. 6-14.
No. 504. This anti-vibration device
A type of movable accumulator that connects the head-side oil chamber and the rod-side oil chamber of a hydraulic cylinder, and is installed in each of the spaces formed at both ends of the movable piston. The head side oil chamber is connected. Then, the hydraulic oil of the hydraulic cylinder passes through the orifice to absorb the energy of the vibration, and the movement of the movable piston replenishes the hydraulic oil to the rod-side oil chamber or the head-side oil chamber to attenuate the cylinder vibration.

[0005]

SUMMARY OF THE INVENTION Conventional actuator dampers for hydraulic working machines of the above-described type include:
There were the following problems to be solved. (1) The damping effect is small except for specific pressure fluctuation and vibration. That is, since the size of the orifice, the size of the piston, the stroke of the piston, and the like are determined values, the pressure fluctuation and vibration of the vibration damping target are determined. (2) The damping effect is small except for the sudden stop of the operation of the actuator. That is, since the vibration is suppressed by restricting the hydraulic oil flowing through the orifice, when the actuator is stopped relatively slowly, the flow rate flowing through the orifice is small and the effect is small.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and its technical problem is that it is possible to suppress a wide range of vibrations without being limited to a specific vibration, and to perform various types of stop / stop operations of an actuator. An object of the present invention is to provide an actuator damping device for a hydraulic working machine, which can cope with the above.

[0007]

According to the present invention, in order to solve the above-mentioned technical problems, an actuator damping device is configured as follows. (1) Neutral discharge oil of the variable displacement pump returned to the oil tank from the direction switching valve when the actuator is stopped,
By increasing the amount by a predetermined time, the actuator is supercharged, and the vibration waveform of the pressure fluctuation generated in the actuator is attenuated at an early stage. (2) The increase of the discharge oil of the variable displacement pump is controlled in accordance with the hydraulic pressure of the actuator and the switching speed of the direction switching valve. (3) The degree of increase of the discharge oil of the variable displacement pump is controlled according to the type of the actuator. (4) A pressure detector is provided for the actuator, and an operation detector is provided for the direction switching valve. Based on detection signals from these detectors, the controller controls the discharge oil amount of the variable displacement pump.

That is, according to the present invention, a variable displacement pump, an actuator actuated by oil discharged from the variable displacement pump, A direction switching valve interposed between the displacement pump and the actuator, the directional switching valve having an operating position for supplying the discharge oil to the actuator and a neutral position for returning the discharge oil to the oil tank via a return oil passage; In the hydraulic working machine, between the actuator and the return oil passage, a check valve that branches the return oil passage and connects the actuator to the actuator, and allows only a flow from the return oil passage in the direction of the actuator. A replenishing oil passage provided with the pump, and when the directional control valve is switched from the operating position to the neutral position, the amount of the discharge oil of the variable displacement pump is increased for a predetermined time. Control means are provided for, the actuator damping device for a hydraulic working machine is provided, characterized in that.

That is, in the actuator vibration damping device of the hydraulic working machine according to the present invention, the discharge oil of the variable displacement pump returning to the oil tank from the directional switching valve has a vibration waveform of a fluctuating pressure generated in the actuator when the actuator is stopped. Is increased for a predetermined period of time and resupplied, and the vibration waveform is damped and damped early.

[0010] In a preferred embodiment, the control means includes:
The discharge oil amount is controlled according to the hydraulic pressure of the actuator and the switching speed of the direction switching valve to the neutral position.

Therefore, the increase of the discharge oil of the variable displacement pump is controlled according to the load applied to the actuator, which is a factor of the pressure fluctuation, and the speed at which the hydraulic oil flowing through the directional control valve is stopped.

In a preferred embodiment, the control means further comprises: a pressure detector for detecting a hydraulic pressure of the actuator;
An operation detector for detecting the switching speed of the directional control valve, and a controller for outputting an increase amount and an increase time of the discharge oil to a displacement controller of the variable displacement pump based on the detected oil pressure and the switching speed. And

Therefore, the increase in the discharge oil of the variable displacement pump is appropriately controlled by the pressure detector, the operation detector and the controller.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a hydraulic working machine according to a preferred embodiment of the present invention.

Referring to FIG. 1, the hydraulic circuit of the hydraulic cylinder 2 will be described with a typical actuator used in a working device of a hydraulic working machine represented by a hydraulic cylinder indicated by reference numeral 2. The discharge oil from the variable displacement pump 4 is selectively supplied through the directional switching valve 6 to be expanded and contracted.

A discharge port of the variable displacement pump 4 is connected to an inlet port of the directional control valve 6 by an oil passage 8, and an oil discharge port of the directional switch valve 6 is connected to an oil cooler 10 by a return oil passage 10.
a to the oil tank 12. The two output ports of the direction switching valve 6 are connected to the rod-side oil chamber 2a of the hydraulic cylinder 2 by an oil path 14 and to the head-side oil chamber 2b of the hydraulic cylinder 2 by an oil path 16, respectively.
The variable displacement pump 4 has a displacement controller 4a.

The direction switching valve 6 is of a pilot operated type operated by pilot pressure oil. The directional control valve 6 is selectively operated by the pilot pressure oil from the pilot operation valve 18 being selectively supplied to the spool end of the directional control valve 6 via the oil passage 20 or the oil passage 22. In a neutral state in which the pilot pressure oil is not supplied to the direction switching valve 6 and the pilot operation valve 18 is not switched, the direction switching valve 6 is neutralized by the neutral return springs 6a provided in the direction switching valve 6 itself. It is returned and held at the position (the state of FIG. 1).

The actuator damping device generally designated by reference numeral 36 includes a supply oil passage 24 and a control means 28.

The supply oil passage 24 branches the return oil passage 10 and supplies a supply oil passage 25 connecting the head side oil chamber 2b of the hydraulic cylinder 2 and a supply oil connecting the rod side oil chamber 2a of the hydraulic cylinder 2. A road 26 is provided. The replenishment oil passage 25 is provided with a check valve 25a so that only the flow from the return oil passage 10 in the direction of the hydraulic cylinder 2 is allowed. Similarly, the supply oil passage 26 is provided with a check valve 26a so that only the flow in the direction from the return oil passage 10 to the hydraulic cylinder 2 is permitted. The check valve 25a and the check valve 26a may be substantially the same.

The control means 28 includes a pressure detector 30a for detecting the oil pressure of the rod-side oil chamber 2a of the hydraulic cylinder 2 in the supply oil passage 30a, and a pressure detection for detecting the oil pressure of the head-side oil chamber 2b of the hydraulic cylinder 2. The container 30b is provided in the supply oil passage 25. The control means 28 also controls the switching speed of the directional control valve 6 from the operating position to the neutral position by controlling the pilot operation valve 18.
An operation detector 32 for detecting the operation state of the pilot operation valve 18 is provided at the rotation center of the operation lever 18a of the pilot operation valve 18. The operation detector 32 detects an operation speed at which the operation lever 18a is operated from an operation position indicated by a two-dot chain line to a neutral position indicated by a solid line, that is, a switching speed.

The control means 28 further controls the displacement controller 4 of the variable displacement pump 4 based on the detected hydraulic pressure and the switching speed.
a includes a controller 34 for outputting the increase amount and the increase time of the discharge oil. The controller 34 includes the arithmetic unit 3
4a and a timer 34b. Arithmetic means 34a
Calculates the amount of increase in the discharge oil amount of the variable displacement pump 4 based on the outputs from the pressure detectors 30a and 30b and the output from the operation detector 32. Conveniently, the increase in discharge oil is as shown in FIG. That is, the pressure in the rod-side oil chamber 2a of the hydraulic cylinder 2 and the pressure in the head-side oil chamber 2b
When both the cylinder load pressure obtained from the difference with the pressure and the switching speed of the operation lever 18a exceed a prescribed value, an instruction to increase the discharge oil amount of the variable displacement pump 4 is issued. The magnitude of the substantial load applied to the hydraulic cylinder 2 is detected by the cylinder load pressure, and the speed of the operation stop of the hydraulic cylinder 2 is detected by the switching speed of the operation lever 18a. In a state where only one of the cylinder load pressure and the switching speed of the operation lever 18a exceeds the specified value, the vibration due to the fluctuation of the hydraulic pressure is substantially small, so that the instruction to increase the discharge oil amount of the variable displacement pump 4 is not issued. If both values are less than the specified values, no instruction to increase the amount of oil discharged from the variable displacement pump 4 is issued. This prescribed value is calculated in advance by the arithmetic means 3 in accordance with the size of the hydraulic working device of the hydraulic working machine, the working mode, and the like.
4a. When the increase amount of the discharge oil is calculated, the time for increasing the variable displacement pump 4 is instructed by the timer 34b. The larger the amount of increase, the longer the amount of time may be. However, it is convenient to set the increase time to a fixed time, for example, one second, because the system can be simplified.

The variable displacement pump 4 provided with the displacement controller 4a is a well-known one used for a hydraulic working machine such as a hydraulic excavator, and usually operates at the same time when a plurality of actuators are simultaneously operated. The discharge oil amount is variably controlled so as not to slow down, or to increase or decrease the operation speed of a specific actuator. For example, when a swash plate type variable displacement piston pump is adopted, the displacement controller 4a drives the swash plate tilting mechanism to change the tilt angle of the swash plate when the control signal is input, thereby controlling the discharge oil amount. Let me change.

The operation of the actuator damping device 36 as described above with reference to FIG.

(1) Operation of Hydraulic Cylinder: In the neutral position (shown by a solid line) in which the operating lever 18a of the pilot operating valve 18 is not operated, that is, in the state where the direction switching valve 6 is in the neutral position (the state of FIG. 1). The oil discharged from the variable oil pump 4 through the oil passage 8 is not supplied to the hydraulic cylinder 2 but passes through the return oil passage 10 and the oil cooler 10.
a to the oil tank 12. Operation lever 1
8a from the neutral position to the operating position indicated by the two-dot chain line, for example, to flow the pilot oil through the oil passage 20;
And the oil discharged from the variable displacement pump 4 is
When the oil is supplied to the rod-side oil chamber 2a of the hydraulic cylinder 2 via 4, the piston 2c of the hydraulic cylinder 2 and the integrated rod 2d are moved in the direction of arrow 3, and the hydraulic cylinder 2 contracts. At this time, the oil in the head-side oil chamber 2 b flows through the oil passage 16 and the return oil passage 10 via the direction switching valve 6.

(2) Stopping operation of the hydraulic cylinder and occurrence of vibration: When the operating lever 18a of the pilot operating valve 18 is operated from the operating position shown by the two-dot chain line to the neutral position shown by the solid line, the flow of the pilot oil in the oil passage 20 Stops, and the directional control valve 6 returns to the neutral position by the neutral return spring 6a.
The supply of the discharge oil from the variable displacement pump 4 to the hydraulic cylinder 2 via the pump 4 is stopped, and the flow from the hydraulic cylinder 2 to the return oil passage 10 via the oil passage 16 and the direction switching valve 6 is stopped. Thus, the piston 2c of the hydraulic cylinder 2 during the contraction operation is stopped by being caught by the oil whose flow in the oil chambers 2a and 2b has stopped. At this time, the oil chambers 2a and 2b are
a, oil passage 2, oil passage 14, oil passage 16, directional control valve 6
Due to the elastic deformation of the oil, the pipeline, and the like that accumulates in the hydraulic cylinder 2, the pressure fluctuation of the attenuation waveform occurs according to the inertial load 2 e of the hydraulic cylinder 2 and the switching speed of the operation lever 18 a.

(3) Control means: The oil pressure of the rod-side oil chamber 2a and the oil pressure of the head-side oil chamber 2b of the hydraulic cylinder 2 are detected by the pressure detector 30a and the pressure detector 30b of the control means 28, respectively. Further, the operation detector 32 detects the switching speed of the direction switching valve 6 from the operating position to the neutral position at the operation lever 18a. Based on these output signals, the controller 34 calculates
The increase amount of the discharge oil of the variable displacement pump 4 is calculated by 4a, the increase time of the discharge oil is set by the timer 34b,
An instruction signal is output to the displacement controller 4a of the variable displacement pump 4. The calculation means 34a is in a state where only one of the load pressure of the hydraulic cylinder 2 and the switching speed of the operation lever 18a exceeds a specified value, for example, to slowly stop a large inertial load or to suddenly stop a small inertial load. In the case of (1), the amount of discharge oil is not increased, and the variable displacement pump is not operated when the amount of increase is not required.

(4) Increase of pump discharge oil: control means 28
, The displacement controller 4a of the variable displacement pump 4 is operated, and the discharge oil is increased by a predetermined amount for a predetermined time.

(5) Replenishment oil passage, attenuation of vibration: The increased discharge oil of the variable displacement pump 4 flows to the return oil passage 10 to which the supply oil passages 25 and 26 are connected. And oil chamber 2
The discharge oil of the variable displacement pump 4 is supplied from the supply oil passages 25 and 26 to the oil chambers 2a and 2b via the check valves 25a and 26a in accordance with the pulsation of the increase and decrease of the pressures of the pressure fluctuation waveforms a and 2b.
And the irregularities of the fluctuation waveform are reduced, and the pressure fluctuation is attenuated. The check valves 25a and 26a are provided in order to prevent the pressure oil of the hydraulic cylinder 2 from dropping into the return oil passage 10 in a normal expansion and contraction operation.

(6) As described above, the vibration of the hydraulic cylinder 2 is stopped because the operation of the hydraulic cylinder 2 is stopped, and the discharge oil of the variable displacement pump 4 is replenished in a supercharged state and is attenuated. Shaken. Therefore, the positioning of the bucket or the like of the hydraulic working device can be facilitated, and the hydraulic working machine does not wobble.

(7) In the case where the supply of the discharge oil to the rod-side oil chamber 2a or the head-side oil chamber 2b, for example, tends to be insufficient while the hydraulic cylinder 2 during the extension or contraction operation is stopped. Since hydraulic oil is easily supplied from the return oil passage 10 via the supply oil passage 25 or 26, the hydraulic cylinder 2 operates smoothly.

FIG. 3 shows another embodiment of the present invention. Depending on the type of the hydraulic working machine, combination relief valves 36 and 37 in which an overload prevention relief valve and a vacuum prevention valve are integrated with the hydraulic cylinder 2 are provided in the oil chambers 2a and 2b.
, Or only one of them, the combination relief valves 36 and 37 are provided in the supply oil passages 25 and 26, respectively, and the variable displacement valves are provided via check valves 36a and 37a as vacuum prevention valves. Pump discharge oil can be supplied.

As described above, the present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above-described embodiments, and can be variously modified or modified within the scope of the present invention. It is. (1) In the embodiment of the present invention, the supply oil passage is connected to each of the rod-side oil chamber and the head-side oil chamber of the hydraulic cylinder. In addition, it may be provided only in one oil chamber. (2) In the embodiment of the present invention, one hydraulic cylinder is provided. However, when a plurality of hydraulic cylinders are provided in the hydraulic working machine and discharge oil is simultaneously supplied to the plurality of hydraulic cylinders, the vibration control is performed by the control means. The number and operating state of the hydraulic cylinders to be shaken may be identified, and the amount of increase may be determined according to the number. (3) In the embodiment of the present invention, a hydraulic cylinder is used as an actuator, but the present invention can be similarly applied to other actuators, for example, a hydraulic motor, a hydraulic oscillating motor, and the like. .

[0033]

According to the actuator damping device for a hydraulic working machine constructed in accordance with the present invention, a wide range of vibration can be damped without being limited to a specific vibration, and various stop / slow operations of the actuator can be performed. It is possible to provide an actuator damping device for a hydraulic working machine that can respond to an operation.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of an actuator of a hydraulic working machine including an actuator damping device configured according to the present invention.

FIG. 2 is a diagram showing a relationship between an increased amount of discharge oil of a variable displacement pump, a cylinder load pressure, and an operation lever switching speed.

FIG. 3 is a hydraulic circuit diagram showing another embodiment of a supply oil passage.

[Explanation of symbols]

 2: Hydraulic cylinder (actuator) 4: Variable displacement pump 6: Directional switching valve 10: Return oil path 12: Oil tank 24, 25, 26: Supply oil path 25a, 26a: Check valve 28: Control means 30a, 30b: Pressure detector 32: Operation detector 34: Controller 36: Actuator damper

Claims (3)

[Claims] 1. A variable displacement pump, an actuator operated by a discharge oil from the variable displacement pump, and an operation position interposed between the variable displacement pump and the actuator to supply the discharge oil to the actuator. And a directional control valve having a neutral position for returning the discharge oil to the oil tank via a return oil passage, wherein the return oil passage is provided between the actuator and the return oil passage. A replenishing oil passage is provided that is branched and connected to the actuator and that includes a check valve that allows only the flow from the return oil passage in the direction of the actuator, and the direction switching valve switches from the operating position to the neutral position. A control device for increasing the amount of the discharge oil of the variable displacement pump for a predetermined time when provided. 2. The actuator vibration damper of a hydraulic working machine according to claim 1, wherein said control means controls said discharge oil amount according to a hydraulic pressure of said actuator and a switching speed of said directional switching valve to said neutral position. apparatus. 3. The control means includes a pressure detector for detecting a hydraulic pressure of the actuator, an operation detector for detecting the switching speed of the directional control valve, and a control unit based on the detected hydraulic pressure and the switching speed. The actuator damping device for a hydraulic working machine according to claim 1 or 2, further comprising: a controller that outputs an increase amount and an increase time of the discharge oil to a displacement controller of the variable displacement pump.