JPH0726414B2 - Excavator speed control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excavator speed control device for an excavator, which controls the descending speed of an excavator suspended by a winch drum, that is, the excavating speed.

[0002]

2. Description of the Related Art For example, in a so-called continuous wall excavator for excavating a hole for forming a continuous wall as a foundation of a bridge pier in the ground, in order to excavate a deep hole straight with high precision,
As disclosed in Japanese Patent Application Laid-Open No. 1-278622, the electric excavator (electromill) is lowered at an extremely low speed and a constant speed.

[0003]

However, according to the conventional excavation speed control method, only the constant speed control is performed regardless of the hardness of the formation, so that when the excavation device reaches a hard formation, the teeth of the excavation device are The self-weight component of the device acting first becomes large, which causes an excessive load on the addendum, resulting in damage to the addendum.

Therefore, the present invention provides a speed control device for an excavator capable of preventing damage to the addendum by limiting the load on the addendum of the excavator while basically performing constant speed control. is there.

[0005]

According to a first aspect of the present invention, there is provided an excavator in which a winch drum for suspending an excavator is rotationally driven by a hydraulic motor, and a motor rotation speed is adjusted by adjusting a pressure oil supply amount to the hydraulic motor. A flow control valve for controlling
Excavation speed detecting means for detecting the actual excavation speed by the excavator, tooth tip load detecting means for detecting the tooth tip load of the excavator, and controlling the excavation speed by giving a flow rate command to the flow rate control valve during excavation. Excavation speed control means is provided, and the excavation speed control means obtains a deviation between the actual excavation speed detected by the excavation speed detection means and a preset target excavation speed, and determines the deviation to be zero. A constant speed control unit that outputs a speed command signal, and a deviation between a preset limit value and the actual tooth tip load detected by the tooth tip load detecting means is obtained, and when the deviation is a negative value, the deviation is zero. So as to output a deceleration command signal, and when the actual tooth tip load exceeds the limit value, the control system of the flow control valve is controlled by the over signal from the constant speed control section. Tip load control And switching means for switching to, it is made of an output unit for outputting a control signal for the flow control valve based on the output signal from the constant speed control section or the tooth load controller.

According to a second aspect of the present invention, in the structure of the first aspect, the constant speed control unit sets a target excavation speed and a speed at which the rotational speed of the hydraulic motor at the time of setting the target excavation speed is set as a control reference value. A control amount including a setter, which adds a PI calculation value based on a deviation between the set target excavation speed and the actual excavation speed detected by the excavation speed detection means and the feedforward control reference value. Is obtained, and this control amount is output to the output unit.

According to a third aspect of the present invention, in the structure of the first or second aspect, an actual motor speed detecting means for detecting an actual motor speed is provided, and the output section is a constant speed control section or a tooth tip load control section. Control value is calculated from the deviation between the output value of the motor speed and the actual motor speed detected by the motor speed detection means, the output value is added as a feedforward amount to this control amount, and the added value is controlled for the flow control valve. It is configured to output as a signal.

[0008]

According to the above construction, when the load acting on the addendum of the excavator is below the limit value, constant speed control is performed, and when the addendum load exceeds the limit value, the switching means automatically controls the addendum load. Since the deceleration control is switched to the part, the tooth tip load is limited and damage to the tooth tips is prevented.

Further, according to the second aspect of the invention, in the constant speed control, the motor rotation speed at the time of setting the excavation speed is fed forward as the control reference value (base of the control amount), so that it is compared with the case of only the PI control. The control response is improved.

On the other hand, according to the third aspect of the invention, the output section detects not only the feedback control of only the excavation speed but also the rotation speed of the motor and adds this to the feedback control, so that the control accuracy is improved.

[0011]

Embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 is a winch drum mounted on a main body of a mobile crane (crawler crane or wheel crane) not shown, and an electric continuous wall excavation is performed on a suspension rope 2 pulled out from the winch drum 1. The device 3 is suspended so that it can be lifted and lowered, and the excavation device 3 excavates a hole H for a continuous wall. Reference numeral 3a denotes an excavating tooth of the excavating device 3, and 4 denotes a rope guide sheave provided on the top of a crane boom (not shown).

Reference numeral 5 is a hydraulic motor for driving a drum. A motor drive circuit for supplying pressure oil from the pump P to the motor 5 is provided with a servo valve 6 for converting an electric signal into a flow rate.
An electric signal (flow rate command signal) from the controller 7 as the excavation speed control means is input to the servo valve 6 to control the rotation speed of the motor 5.

A speed reducer 8 as a mechanical speed reducer is provided on the output side of the motor 5, and the rotation speed of the motor 5 controlled by the servo valve 6 is reduced to an ultra-low speed range by the speed reducer 8. It is transmitted to the winch drum 1.

Here, the flow rate control system using the servo valve 6 is compared with the case of a conventionally known system in which the tilt angle of the pump is adjusted to control the flow rate (see, for example, Japanese Patent Laid-Open No. 2-13600). The speed control range is significantly widened.

For this reason, by combining with the speed reducer 8, it becomes possible to perform excavation control at an ultra-low speed, which is impossible with the prior art in this type of excavator. Specifically, in the past, the rope speed was limited to the range of 5 m / Hr to 30 m / Hr.
Speed control in the range of / Hr to 30 m / Hr is possible.

The controller 7 includes an actual excavation speed signal from an excavation speed detector 9 which detects an actual excavation speed based on the moving speed of the suspension rope 2, and a motor rotation which detects an actual rotation speed (rotation speed) of the motor 5. The actual motor rotation speed signal from the number detector 10 and the actual load signal from the actual load detector 11 that detects the suspension load are input, and the speed control of the motor 5 is performed based on these input signals and the like.

Encoders are used as the excavation speed detector 9 and the motor rotation speed detector 10, and a load cell for detecting the tension of the suspension rope 2 is used as the suspension load detector 11, for example.

FIG. 2 shows the internal structure of the controller 7.

The controller 7 includes a constant speed controller 12
, The addendum load control unit 13, the switching unit 14, and the output unit 15
And consists of.

The constant speed controller 12 has a speed setter 16,
Teaching by the speed setter 16, that is, after the start of excavation, a proper excavation speed is searched while observing the excavation condition on a monitor, and a target excavation speed (hereinafter, referred to as a target value) Vt is set by operating a switch in the optimum excavation state.

Simultaneously with the setting of the target value Vt, the motor rotation speed Nt at this setting is set as a control reference value for feedforward.

At the time of excavation, the target value Vt and the actual excavation speed Vr detected by the excavation speed detector 9 are added at a point 1
Then, the deviation ΔV is obtained and the PI calculation is performed based on this deviation ΔV.

That is, as a proportional operation, the multiplier 18 multiplies the deviation .DELTA.V by a constant proportional gain kp to obtain a proportional value kp.
-ΔV is required. In addition, the deviation ΔV
Is integrated by the integrator 19, and the calculated value ΣΔ is calculated by the multiplier 20.
V is multiplied by a constant gain ki to obtain an integrated value ki · ΣΔV
Is required.

The proportional value kp · ΔV and the integral value Σki
-ΔV is sent to the addition point 21. In addition, the speed setter 16
The control reference value Nt set by is fed forward to this addition point 21, and these are added to obtain the basic control amount (command motor speed) Nb for constant speed control.

As described above, the deviation ΔV between the target excavation speed Vt and the actual excavation speed Vr is obtained, and the PI calculation is performed based on the deviation ΔV to absorb the change in the excavation speed due to the change in the rope winding layer on the winch drum 1. can do. Moreover, not only the PI calculation but also the control reference value Nt is added to this as the feedforward amount to obtain the basic control amount Nb, so that so-called hunting that occurs when only the PI calculation is performed is suppressed, and the convergence to the control value occurs. The control response is quick and good.

The tooth tip load control unit 13 is provided with an excavator self-weight setting device 22 for setting the self-weight of the excavator 3, and at the time of excavation, the actual load detector 11 detects from the set self-weight W0 at the addition point 23. The actual load Wt is subtracted to obtain the actual load (actual tip load) Wk acting on the tip of the excavating tooth 3a.

The real tooth tip load Wk thus obtained is sent to the addition point 24, where the deviation ΔW between the preset tooth tip load limit value WL and this actual tooth tip load Wk (the limit value is exceeded. The value = WL-Wk) is determined.

This deviation ΔW is sent to the multiplier 25 and the sign discriminator 26, and a proportional operation in the multiplier 25 calculates a speed value Kpw · ΔW proportional to the deviation ΔW, while the sign discriminator 26 is used. (+) (-), That is, the actual tooth tip load Wk
Is over the limit value WL.

The figure shows (+), that is, the case where the actual tooth tip load Wk is smaller than the limit value WL. At this time, the basic control amount Nb which is the output value of the constant speed control unit 12 is added by the output unit 15. It is sent to point 27, and added point 28
At the addition point 27, which is fed forward to, the deviation ΔNb between the basic control amount Nb and the actual motor rotation speed Nr detected by the motor rotation speed detector 10 is obtained, and then the multiplier 29 is proportional to this deviation ΔNb. The gain kp ′ is multiplied to obtain the control amount kp ′ · ΔNb.

Then, the control amount kp '· ΔNb and the feed-forward basic control amount Nb are added at the addition point 28.
Is added to obtain the final control value Nc for constant speed control, and this final control value Nc is transferred via the constant current amplifier 30 to the servo valve 6
Output as a control current.

The constant current amplifier 30 keeps the control current constant regardless of fluctuations in the power supply voltage.

On the other hand, when the sign discriminator 26 discriminates (-), that is, the actual tooth tip load Wk exceeds the limit value WL, the switching unit 14 receives an over signal from the discriminator 26. From the constant speed control side in the figure, the tip load control unit 1
3 is switched to the tooth tip load control side.

Simultaneously with this switching, the excavation speed Vm at that time is stored in the memory 31, the stored excavation speed Vm is sent to the addition point 32, and the speed value Kpw.multidot. ΔW is subtracted, and the value is sent to the output unit 15 as a deceleration command signal.

As described above, when the tooth tip load Wk exceeds the limit value WL, the constant speed control is automatically canceled and the tooth tip load control is switched to, and the excavation speed is reduced according to the over amount and the tooth speed is reduced. The tip load is reduced. For this reason, damage to the tooth tips is reliably prevented.

If the actual tooth tip load Wk becomes smaller than the limit value WL by this tooth tip load control, the sign discriminator 26
And the switching unit 14 switches to the constant speed control side, and the original constant speed control is resumed.

By the way, the flow control valve for controlling the speed of the motor 5 is not limited to the servo valve shown in the above-mentioned embodiment, in short, any valve capable of converting an electric signal into a flow rate may be used. For example, an electromagnetic proportional valve is used. May be.

[0038]

As described above, according to the present invention, as a control unit for controlling the rotation speed of the motor for driving the winch drum, a constant speed control unit for keeping the excavation speed constant and a tooth tip load within a constant range. And a tooth tip load control section to keep the tooth tip load control unit configured to automatically switch from constant speed control to tooth tip load control by the switching means when the tooth tip load exceeds the limit value.
It is possible to prevent the tooth tip load from becoming excessive and damaging the tooth tips.

Further, according to the invention of claim 2, in the constant speed control, the motor rotation speed at the time of setting the excavation speed is fed forward as the control reference value (base of the control amount), so that it is compared with the case of only the PI control. Control responsiveness can be improved.

On the other hand, according to the third aspect of the invention, the output section detects not only the feedback control of only the excavation speed but also the rotation speed of the motor and adds this to the feedback control, so that the control accuracy can be improved. .

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an entire apparatus according to an embodiment of the present invention.

FIG. 2 is a block configuration diagram showing a configuration of a controller in the embodiment.

[Explanation of symbols]

1 Winch Drum 2 Suspended Rope 3 Excavator 3a Excavator Teeth of Excavator 5 Hydraulic Motor for Driving Winch Drum 6 Servo Valve as Flow Control Valve for Controlling Rotational Speed of the Motor 7 Controller (Excavation Speed Control Means) 9 Excavation Speed Detector 10 Motor rotation speed (motor speed) detector 12 Constant speed control unit of controller 16 Speed setter of constant speed control unit 17 Addition point for PI calculation in constant speed control unit 18 Multiplier for proportional calculation 19 Integration Unit 20 Multiplier for integration calculation 21 PI Addition point for calculating control amount by adding a calculated value and control reference value 13 Tooth tip load control unit 11 Actual load detector 22 for detecting actual tooth tip load 22 Excavator Self-weight setter 24 Addition point for obtaining deviation between actual tooth tip load and limit value 25 Multiplier for calculating speed value according to deviation 26 Code for outputting over signal Discriminator 14 Switching unit (switching unit) 15 Output unit 27 Output unit 27 Addition point for obtaining the deviation between the output value from the constant speed control unit or the tooth tip load control unit and the actual motor rotation speed 29 The control amount is determined based on the deviation. Multiplier for calculating 28 Addition point for obtaining final control value by adding control amount and output value

Claims (3)

[Claims] 1. An excavator in which a winch drum that suspends an excavator is driven to rotate by a hydraulic motor, and a flow rate control valve that adjusts a pressure oil supply amount to the hydraulic motor to control a motor rotation speed, and the excavator. Excavation speed detection means for detecting the actual excavation speed by means of the above, tooth tip load detection means for detecting the tooth tip load of the excavator, and excavation speed control for controlling the excavation speed by giving a flow rate command to the flow rate control valve during excavation The excavation speed control means obtains a deviation between the actual excavation speed detected by the excavation speed detection means and a preset target excavation speed, and a constant speed command signal is set so that the deviation becomes zero. A constant speed control unit for outputting the difference between the preset limit value and the actual tooth tip load detected by the tooth tip load detecting means is calculated so that the deviation becomes zero when the deviation is a negative value. Reduced to A tip load control section for outputting a speed command signal and a control system for the flow control valve from the constant speed control section to the tip load control by the over signal when the actual tip load exceeds the limit value. Excavation speed of an excavator, characterized by comprising a switching means for switching to a section Control device. 2. The speed control device for an excavator according to claim 1, wherein the constant speed control unit sets a target excavation speed and a rotation speed of the hydraulic motor at the time of setting the target excavation speed as a control reference value. Control is performed by adding a PI calculation value based on a deviation between the set target excavation speed and the actual excavation speed detected by the excavation speed detection means to the feed-forward control reference value, which has a speed setter. An excavation speed control device for an excavator, which is configured to obtain an amount and output the control amount to an output unit. 3. The excavation speed control device for an excavator according to claim 1 or 2, further comprising an actual motor speed detection means for detecting an actual motor speed, and the output part has a constant speed control part or tooth tip load control. The control amount is obtained from the deviation between the output value from the section and the actual motor speed detected by the motor speed detecting means, the output value is added to this control amount as a feedforward amount, and the added value is added to the flow control valve. It is configured to output as a control signal to the excavator.