JPH0672438B2 - Boom vibration suppressor for hydraulic excavators - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a device for suppressing vibration of a hydraulic excavator when a boom is raised at a high speed.

(Prior Art) Conventionally, in a hydraulic excavator, a flow rate (speed) command by operating a boom operation lever is input to a flow rate control mechanism,
By operating this flow rate control mechanism, the discharge flow rate of the variable displacement pump is controlled to control the operating speed of the boom cylinder, that is, the boom.

However, according to the conventional device that controls the pump flow rate only by the lever command as described above, there is a problem in that the boom vibrates due to a sudden change in the flow rate when the boom rises at a high speed, and a smooth boom raising operation cannot be obtained.

In order to solve this problem, the pump flow rate may be controlled based on a factor other than the lever command, for example, a change condition of the pump pressure, but in this case, the following new problem occurs. .

That is, in a hydraulic excavator, generally, the hydraulic pressure from one pump is supplied to the boom cylinder and the bucket cylinder in parallel. Therefore, if the bucket is operated during boom operation, the pump pressure is also affected by the bucket load pressure. Therefore, if the pump pressure is used as control data for suppressing boom vibration, the control becomes inaccurate.

(Object of the Invention) Therefore, the present invention is a vibration control of a boom in a hydraulic working machine capable of controlling the vibration when the boom is raised at a high speed by controlling the flow rate according to the vibration state of the boom regardless of whether or not the bucket is operated. A device is provided.

(Structure of the Invention) The present invention relates to a boom cylinder that drives a boom, an arm cylinder that drives an arm, a bucket cylinder that drives a bucket, a boom cylinder, an arm, and a bucket that output an operation command signal to each of these cylinders. Operation levers, two first and second pumps, and a first pump and a second pump that separately control the discharge flow rates of the two pumps based on command signals from the operation levers. A flow rate control mechanism and a boom control valve, an arm control valve, and a bucket control valve that operate based on command signals from the operation levers are provided, and the pressure oil supply line of the first pump is branched into two. One branch line is connected to the boom cylinder hydraulic line via the boom control valve, and the other branch line is connected to the bucket control valve. While being connected to the hydraulic line of the bucket cylinder via the valve, the pressure oil supply line of the second pump is connected to the hydraulic line of the arm cylinder via the arm control valve, and is connected to the arm control valve. A boom cylinder sub-hydraulic line is provided between the extension side hydraulic line of the boom cylinder and the arm control valve that is connected to the hydraulic supply line of the second pump via the valve when the arm control valve is stopped or in the low speed position. In the hydraulic excavator in which the boom cylinder sub-hydraulic line is provided with a boom cylinder sub-control valve that operates based on a high-speed rising command signal from the boom operation lever, the first and second hydraulic excavators are provided.
It is provided with first and second pump pressure detection means for detecting the discharge pressure of both pumps, and a controller to which the detected pump pressure and the command signal from each of the operation levers are inputted. The pump pressures of both pumps detected by the pump pressure detecting means are differentiated to obtain the rate of change of the pump pressures, and the above-mentioned pump pressures are almost equal to the condition that the high speed command signal is input from the boom operation lever. When they are equal, the differential value of both pump pressures is set to the first
Separately for both the pump and the second pump flow control mechanism,
Further, when there is a difference between the pump pressures due to the bucket operation, there is provided means for outputting only the differential value of the pump pressure of the second pump to the second pump flow control mechanism as a command of the compensation flow rate for the vibration of the boom. Is.

With this configuration, the change state of the pump pressure is read as the boom vibration state and is added to the control element of the pump discharge flow rate with respect to the boom cylinder, so that the change of the pump pressure, that is, the vibration of the boom is suppressed. Moreover, when the bucket is operated while the boom is being raised at a high speed, the pump pressure of the second pump, which is hydraulically unrelated to the bucket, serves as the flow rate control element, so that accurate control that is not affected by the bucket operation is performed. be able to.

(Example) An example of the present invention will be described with reference to the drawings.

FIG. 1 shows the overall configuration of the apparatus according to this embodiment. In the hydraulic circuit shown in the figure, for simplification of the drawing, illustration of a check valve or the like normally equipped is omitted.

Reference numeral 1 is a boom cylinder for raising and lowering (raising and lowering) a boom, 2 is a bucket cylinder for rotationally driving a bucket, and 3 is an arm cylinder for pushing and pulling an arm. Further, 4 is the first control valve for the boom, 5 is the second control valve for the bucket, 6 is the third control valve for the arm, and these control valves 4, 5 and 6 are
Boom, bucket, and arm operation levers (hereinafter, these are referred to as boom lever, bucket lever, arm lever) 7,8,9 pilot pressure by operation (hereinafter,
The operation is controlled by the lever command value), and each cylinder 1, 2, 3 is activated by the operation of each control valve 4, 5, 6.
The supply of the pressure oil from the first and second pumps 10 and 11 is controlled.

The pressure oil supply line 12 of the first pump 10 is branched into two, and one branch line 12a is connected to the hydraulic lines 13 and 14 of the boom cylinder 1 via the first control valve 4. Further, the branch line 12a is stopped when the first and second control valves 4 and 5 are stopped and the passages 4a and 5a opened at the low speed position, and the fourth branch line 12a which operates when a high speed pulling command is issued from the arm lever 6. Control valve 15,
In addition, it is connected to an extension side (arm pulling side) hydraulic line 17 of the arm cylinder 3 via an arm auxiliary hydraulic line 16.

In addition, the other branch line 12b of the first pressure oil supply line 12
Are connected to the hydraulic lines 18 and 19 of the bucket cylinder 2 via the second control valve 5.

On the other hand, the pressure oil supply line 20 of the second pump 11 is connected to both the extension side and contraction side hydraulic lines 17 and 21 of the arm cylinder 3 via the third control valve 6, and at the same time the stop and low speed of the control valve 6 are stopped. The passage 6a opened at the position, the fifth control valve 23 that operates when a high speed rising command is issued from the boom lever 7, and the extension side (boom rising side) of the boom cylinder 1 via the boom auxiliary hydraulic line 24. It is connected to the hydraulic line 13.

Therefore, the relationship between each cylinder 1, 2, 3 and both pumps 10, 11 is as follows.

(A) For the boom cylinder 1, only the pressure oil from the first pump 10 is supplied except when the boom is raised at a high speed, and when the arms are being driven at a high speed even at the time of a high speed rise. When the boom is moving up at high speed and the arm is not driven at high speed, the pressure oil from the first pump 10 is expanded by the pressure oil from the second pump 11 via the boom cylinder auxiliary hydraulic line 24. It joins the side hydraulic line 13 and a large flow rate is supplied to the extension side of the boom cylinder 1.

(B) For the bucket cylinder 2, always the first pump
Only 10 pressure oils are supplied.

(C) With respect to the arm cylinder 3, only the pressure oil from the second pump 11 is supplied except when the arm high speed pulling drive is performed, and when the arm high speed pulling drive is performed and the boom and the bucket are not being driven at high speed, the second The pressure oil from the first pump 10 joins the pressure oil from the pump 11 to the arm cylinder extension side hydraulic line 17 via the arm cylinder sub-hydraulic line 16, and a large flow rate is supplied to the extension side of the arm cylinder 3. It

The lever command value by operating each of the levers 7, 8 and 9 is transmitted via the high pressure selection valves 25 to 30 to the first flow rate control mechanism for the first pump 10.
31 and the second flow rate control mechanism 32 for the second pump 11, and both pumps 10, 1 are basically based on this lever command value.
The discharge flow rate of 1 is controlled.

Also, the lever command value from the lever 7 and the high pressure selection valve
The lever command value from the levers 8 and 9 selected by 26 and 27 is set by the hydraulic-electric converters 33a, 33b, 34 and 35, and both pumps 10 and 11 are set.
The discharge pressures P ₁ and P ₂ are converted into electric quantities by hydraulic pressure-electric converters 36 and 37 as pump pressure detecting means, and are input to the controller C. This controller C is provided with differentiating means and coefficient means, and both pump pressures P ₁ , P
₂ is differentiated by the differentiating means, and differential values dP ₁ and dP ₂ as the rate of change of pump pressure caused by boom vibration are obtained. Further, the coefficient means, to the differential value dP ₁ , dP ₂ ,
The control current output is obtained by multiplying the coefficients (gains) K ₁ and K ₂ that are determined by the characteristics of each machine such as the boom length.
K ₁ dP ₁ and K ₂ dP ₂ are converted into hydraulic pressure by the electro-hydraulic converters 38 and 39 and are sent to the flow rate control mechanisms 31 and 32 as command values of the compensating flow rate for controlling the boom vibration. . In the differentiating means, an upper limit and a lower limit of the differential value are provided in order to avoid an excessive response due to disturbance, and the differential value is regulated within these ranges. The action of this controller C is the second
Further description will be given with reference to the flowchart of the figure.

Lever command value in step S _1, the pump pressure P ₁ in step S _2, P
₂ are read, and the pump pressures P ₁ and P ₂ are read in step S _3.
Is differentiated. Next, in step S ₄ , it is determined whether or not the boom is operated at high speed by the lever command value input via the hydraulic-electrical converter 33a, and whether or not the arm is operated in high speed in step S ₅ . Is judged respectively,
When it is determined that the boom is being raised at high speed and the arm is stopped or the operation is performed at low speed (at this time, the pressure oils from both pumps 10 and 11 are supplied to the boom cylinder 1 in a confluent manner), further step S ₆ is performed. It is determined whether the bucket is stopped or operating at low speed. Then, as a condition the bucket stop or low speed operation, the differential value dP in step S _7
1, each coefficient K ₁ · K ₂ to dP ₂ is multiplied control current K ₁ · d
P ₁ , K ₂・ dP ₂ is obtained, and this control current K ₁・ dP ₁ , K ₂・ dP ₂
But is limited processed during the predetermined upper limit value and the lower limit value (step S _8), is output to both the flow control mechanism 31, 32 (step S _9, S _10).

In this manner, the rate of change (differential value) of the pump pressures P ₁ and P ₂ is read as the boom vibration state, and this differential value is fed back to the flow rate control mechanisms 31 and 32. Therefore, the flow rate control mechanisms 31 and 32 are input with the lever command value by the lever operation and the feedback value, and the pump flow rate is controlled by the flow rate command by these, and the boom cylinder,
That is, the operation of the boom is controlled.

FIG. 3 shows an example of the step response situation of the pump pressure as a result of this control in comparison with the case of the conventional device having no vibration suppressing function. In the figure, a shows the control result by this device, and b shows the control result by the conventional device.
According to this device, the change in pump pressure is read, the pump flow rate is decreased when the pump pressure rises, and the pump flow rate is increased when the pump pressure decreases, so that the pump flow rate is controlled in a direction to calm the change in pump pressure. By doing so, after the boom operation rises, the pump pressure quickly settles to the rated level determined by the load conditions (for example, the amount of scooped soil and boom attitude in the case of a hydraulic excavator),
Boom vibration is effectively suppressed.

However, if the buckets are simultaneously operated when the boom rises at a high speed, the pump pressure will be affected by the bucket load pressure. At this time, the following processing is performed.

That is, when the bucket operation is determined in step S ₆ , both pump pressures P ₁ and P ₂ are compared in step S ₁₁ . At this time, since the load pressure of the bucket cylinder 2 is smaller than the load pressure of the boom cylinder, all of the discharge flow rate of the first pump 10 flows to the bucket cylinder 2 and a difference occurs between the pump pressures of the pumps 10 and 11 (P ₁ <P ₂ ). Therefore, at this time, the process proceeds to step S ₁₂ , the output to the first flow rate control mechanism 31 is set to O, and the control current K ₂ · dP to the second flow rate control mechanism 32 is set.
Only ₂ is output.

In this way, when the bucket is operated when the boom rises at a high speed, the discharge flow rate of the second pump 11, which is not affected by the bucket load pressure, is controlled by the differential value of the discharge pressure of the pump 11, and therefore, when the bucket is stopped. The vibration of the boom can be suppressed in the same manner as.

When the discharge pressures of both pumps 10 and 11 are almost equal,
Is the same condition as the bucket stop time bucket stopped Similarly, proceeds from step S ₁₁ to step S _7, the control current K ₁ · dP ₁ toward both flow control mechanism 31,32, K ₂ · dP ₂ is output It

Further, when the boom is moving up at a low speed and when the boom is descending, steps S ₄ to S ₁₃ are performed, and when the arm is driven at high speed when the boom is moving up at a high speed, steps S ₄ to S ₅ are performed and then step S ₁₄ is performed. Move. At this time, since the boom cylinder 1 is driven only by the first pump 10, only the control current K ₁ · dP ₁ based on the differential value of the discharge pressure of the pump 10 is input to the first flow rate control mechanism 31.

(Effects of the Invention) According to the present invention as described above, by detecting and differentiating the pump pressure, the change status of the pump pressure is read as the vibration status of the boom, and this differential value is applied to the flow control mechanism to detect the boom vibration. Since the configuration is such that the command value of the compensation flow rate for suppression is input, it is possible to effectively suppress vibration when the boom rises at a high speed.

Moreover, in the configuration in which the boom cylinder and the bucket cylinder are connected in parallel to one pump, and the combined flow rate from the two pumps is supplied to the boom cylinder when the boom rises at a high speed, the bucket moves when the boom rises at a high speed. When operated at the same time, the flow rate of the pump is controlled based on the differential value of the discharge pressure of the pump that is not affected by this bucket operation. The flow rate can be accurately controlled.

Further, in order to detect the pump pressure, for example, when an acceleration sensor is attached to the boom, and the sensor detects a change in boom acceleration as a boom vibration condition, the sensor is damaged or malfunctions due to contact with soil or the like. There is no fear, and the device becomes highly durable and reliable.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention, FIG. 2 is a flow chart for explaining the operation of the embodiment, and FIG. 3 is a comparison of control results according to the embodiment with a conventional device. FIG. 1 ... Boom cylinder, 2 ... Bucket cylinder, 3 ... Arm cylinder, 4 ... Boom control valve, 5 ... Bucket control valve, 6 ... Arm control valve, 7 ... Boom control lever, 8 ... Bucket control lever, 9 ... Arm control lever, 10 ... First pump,
11 ... Second pump, 31, 32 ... Flow control mechanism of both pumps, 12
... 1st pump pressure oil supply line, 12a, 12b ... same line branch line, 20 ... 2nd pump pressure oil supply line, 24 ... boom cylinder auxiliary hydraulic line, 23 ... boom cylinder auxiliary control valve, 36 , 37 ... Hydraulic-electrical converter as pump pressure detecting means, C ... Controller.

Claims (1)

[Claims] 1. A boom cylinder for driving a boom, an arm cylinder for driving an arm, a bucket cylinder for driving a bucket, and boom, arm, and bucket operation levers for outputting operation command signals to these cylinders. A first pump and a second pump, and a first pump and a second pump dual flow rate control mechanism that separately control the discharge flow rates of the two pumps based on command signals from the operation levers. , A boom control valve, an arm control valve, and a bucket control valve that operate based on command signals from the operation levers, and the pressure oil supply line of the first pump is branched into two, and one branch line is provided. Via the boom control valve to the boom cylinder hydraulic line, and the other branch line via the bucket control valve. While being connected to the hydraulic lines of the bucket cylinder, the pressure oil supply line of the second pump is connected to the hydraulic line of the arm cylinder via the arm control valve, and the arm control valve and the boom cylinder are connected to each other. A boom cylinder sub-hydraulic line connected to the pressure oil supply line of the second pump via the valve when the arm control valve is stopped or in the low speed position is provided between the extension hydraulic line and In the hydraulic excavator in which the boom cylinder sub-hydraulic line is provided with a boom cylinder sub-control valve that operates based on a high-speed rising command signal from the boom operation lever, the first and second hydraulic excavators are provided.
It is provided with first and second pump pressure detection means for detecting the discharge pressure of both pumps, and a controller to which the detected pump pressure and the command signal from each of the operation levers are inputted. The pump pressures of both pumps detected by the pump pressure detecting means are differentiated to obtain the rate of change of the pump pressures, and the above-mentioned pump pressures are almost equal to the condition that the high speed command signal is input from the boom operation lever. When they are equal, the differential value of both pump pressures is set to the first
Separately for both the pump and the second pump flow control mechanism,
Further, when a difference occurs between the two pump pressures due to the bucket operation, there is provided means for outputting only the differential value of the pump pressure of the second pump to the second pump flow rate control mechanism as a command of the compensation flow rate for the vibration of the boom. Vibration suppression device for booms in hydraulic excavators.