JPH0786243B2 - Excavator ultra-low speed controller - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-low speed control device for an excavator which controls the descending speed of an excavator suspended by a winch drum in an ultra-low speed range.

[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,
Excavation control at ultra-low speed is required.

Conventionally, as a method for controlling such an excavation speed, as disclosed in Japanese Patent Application Laid-Open No. 1-278622, the actual excavation speed is detected, and the detected value and a preset target value are set. A method of controlling the braking force of the winch based on the deviation of is known.

Further, as disclosed in Japanese Patent Laid-Open No. 2-13600, a tilting of a variable displacement pump for supplying pressure oil to a hydraulic motor, which is a drive source of a winch, based on a deviation between a detected value and a target value. A method of controlling the angle to control the supply flow rate to the motor, that is, the rotation speed of the motor is also known.

[0005]

However, in the method of controlling the braking force of the winch, the low-speed controllability deteriorates because the pulsation of the winch rotation occurs in the low-speed range. Further, in the method of controlling the tilt angle of the pump, the control range of the flow rate is narrow, and therefore the speed control of the motor is limited to the narrow range. Therefore, in any of the methods, the lower limit speed of the ultra-low speed control is relatively high (about 5 m / Hr), and improvement in excavation accuracy beyond the present situation cannot be expected.

Therefore, the present invention provides an ultra-low speed control device for an excavator capable of performing constant-speed excavation control at an ultra-low speed and improving excavation accuracy.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an excavator in which a winch drum for suspending an excavator is rotationally driven by a hydraulic motor, and an electric control signal is supplied to a motor drive circuit for supplying pressure oil to the hydraulic motor. A flow rate control valve for controlling the rotation speed of the motor by changing the flow rate is provided, and the speed control range of the motor by the flow rate control valve is set to an ultra-low speed range between the hydraulic motor and the winch drum. A speed reducer is provided, and constant speed control means for controlling the flow rate control valve so that the excavation speed by the excavation device is constant is provided, and the constant speed control means sets a target excavation speed and Set the speed setting device that sets the rotation speed of the hydraulic motor when setting the target excavation speed as the control reference value, the excavation speed detector that detects the actual excavation speed, and the actual motor speed. It is composed of a motor speed detector for outputting and a calculation section, and this calculation section obtains a deviation between the set target excavation speed and the actual excavation speed detected by the speed detector, and performs a PI calculation based on this deviation. Value and the feedforward control reference value are added to obtain the basic control amount, the deviation between the basic control amount and the actual motor speed detected by the motor speed detector is obtained, and the gain is added to this deviation. The control amount is multiplied to obtain the basic control amount as a feedforward amount, which is added to the control amount, and the added value is output as a control signal for the flow control valve.

[0008]

According to the above construction, since the motor speed control is basically performed by the flow rate control valve, the speed control range becomes wider than that in the case where the tilt angle of the pump is controlled. Then, by further decelerating this motor rotation with the speed reducer, control in the ultra-low speed region becomes possible. That is, the combination of the flow rate control valve and the speed reducer enables speed control at a much lower speed.

In this ultra-low speed control, (I) 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).
The responsiveness of control is improved as compared with the case of only I control.

(II) Not only the feedback control of the excavation speed but also the rotation speed of the motor is detected and added 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 the main body of a mobile crane (crawler crane or wheel crane) not shown.
Is hung up and down so that the hole H for the continuous wall is excavated by the excavator 3. 3a is an excavating tooth of the excavating device 3, 4
Is 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 a constant speed control means is input to the servo valve 6 to control the rotation speed of the motor 5.

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

According to the flow rate control system using the servo valve 6, the speed control range is compared with the conventional system in which the tilt angle of the pump is controlled as disclosed in Japanese Patent Laid-Open No. 2-13600. Will be much wider.

Therefore, by combining with the speed reducer 8, it becomes possible to perform excavation control at an extremely low speed, which is impossible with the prior art including the one disclosed in Japanese Patent Laid-Open No. 1-278622. Specifically, conventionally, the rope speed is 5 m / Hr ~
While limited to the speed range of 30 m / Hr, this method enables speed control in the range of rope speed of 0.2 m / Hr to 30 m / Hr.

The controller 7 includes a motor for detecting an actual excavation speed signal from an excavation speed detector 9 for detecting an actual excavation speed based on the moving speed of the suspension rope 2 and an actual rotation speed (rotation speed) of the motor 5. The actual motor rotation speed signal from the rotation speed detector 10 is input, and the speed of the motor 5 is controlled based on these input signals. Encoders are used as both detectors 9 and 10, for example.

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

The controller 7 comprises a speed setter 11, an arithmetic unit 12, and a constant current amplifier 21.

The speed setter 11 searches for an appropriate excavation speed while teaching, that is, after monitoring the excavation and watching the excavation condition on the monitor, and sets a target excavation speed (hereinafter referred to as a target value) Vt by operating a switch in the optimum excavation state. To do. 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, and these are sent to the calculation unit 12 as calculation information.

In the calculation unit 12, during the excavation, the first addition point 1
In 3, the deviation ΔV between the target value Vt and the actual excavation speed Vr detected by the excavation speed detector 9 is obtained, and the PI calculation based on this deviation ΔV is performed.

That is, as a proportional calculation, the deviation ΔV is multiplied by a constant gain kp in the multiplier 14 to obtain a proportional value kp · Δ.
V is required. Further, as an integral calculation, the deviation ΔV is integrated by the integrator 15, and the multiplier 16 multiplies the calculated value ΣΔV by a constant gain ki to obtain an integrated value ki · ΣΔV.

The proportional value kp · ΔV and the integral value Σki
-ΔV is sent to the second addition point 17. Further, the control reference value Nt set by the speed setter 11 is fed forward to the second addition point 17, and these are added to obtain the basic control amount (commanded motor speed) Nb.

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 basic control amount Nb is sent to the third addition point 18 and is fed forward to the fourth addition point 19. At the third addition point 18, the basic control amount Nb and the motor speed detector 10 detect it. The deviation ΔNb from the calculated actual motor rotation speed Nr is obtained, and then the deviation ΔNb is calculated by the multiplier 20.
b is multiplied by the proportional gain kp ′, and the control amount kp ′ · ΔN
b is required.

Then, the control amount kp '· ΔNb and the feed-forward basic control amount Nb are added at the fourth addition point 19 to obtain the final control value Nc in the arithmetic unit 12, and this final control value is obtained. Nc is output as a control current to the servo valve 6 via the constant current amplifier 21.

The constant current amplifier 21 keeps the control current constant regardless of fluctuations in the power supply voltage.

In this way, the servo valve 6 is controlled by the controller 9, the motor speed is controlled by the servo valve 6, and constant speed excavation control is performed at an ultra-low speed.

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 embodiment, but any valve capable of converting an electric signal into a flow may be used, for example, an electromagnetic proportional valve is used. May be.

[0030]

As described above, according to the present invention, as a basic configuration, the motor speed is controlled by the flow rate control valve having a wide speed control range, and the rotation of the motor is reduced to the ultra-low speed range by the speed reducer. Since the configuration is such that it is transmitted to the winch drum, it is possible to control the excavation speed at an ultra-low speed as compared with the conventional device, and it is possible to improve the excavation accuracy.

In this ultra-low speed control, since the motor rotation speed at the time of setting the target excavation speed is fed forward as the control reference value (base of the control amount), the response of the control is improved as compared with the case of only the PI control. In addition to improving the feedback control of only the excavation speed, the rotation speed of the motor is detected and this is added to the feedback control, so the control accuracy can also 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 5 Hydraulic Motor for Driving Winch Drum 6 Servo Valve as Flow Control Valve for Controlling Rotational Speed of the Motor 7 Controller (Constant Speed Control Means) 8 Reducer 9 Excavation Speed Detector 10 Motor rotation speed (motor speed) detector 11 Speed setter of controller 12 Calculation unit 13 First addition point for PI calculation in calculation unit 14 Multiplier for proportional calculation 15 Integrator 16 Multiplier for integral calculation 17 PI Second addition point 18 for obtaining the basic control amount by adding the calculated value and the control reference value Third addition point 20 for obtaining the deviation between the basic control amount and the actual motor speed 20 Multiplier 19 for obtaining the control amount based on the deviation 19 Fourth addition point for adding control amount and feedforward basic control amount to obtain final control value

Claims (1)

[Claims] 1. In an excavator in which a winch drum that suspends an excavator is driven to rotate by a hydraulic motor, a motor drive circuit that supplies pressure oil to the hydraulic motor is controlled by changing a flow rate according to an electric control signal. Is provided with a flow control valve for controlling the rotation speed of the motor, and a speed reducer is provided between the hydraulic motor and the winch drum to set the speed control range of the motor by the flow control valve to an ultra-low speed range .
The above-mentioned excavation equipment to keep the excavation speed constant.
It is equipped with a constant speed control means for controlling the flow control valve.
The speed control means sets the target excavation speed and
Controlling the rotation speed of the hydraulic motor when setting the target excavation speed.
The speed setter set as a quasi value and the actual excavation speed are detected.
Detects excavation speed detector and actual motor speed
It consists of a motor speed detector and a calculation unit.
The target excavation speed set above and the speed detector above
The deviation from the detected actual excavation speed is calculated, and the PI calculated value based on this deviation and the feedforward
The above-mentioned control reference value is added to obtain the basic control amount, and this basic control amount and the motor speed detector detect
Deviation calculated between the actual motor speed which determines the control amount by multiplying the gain to the deviation, the controlling the basic control amount as a feed forward quantity
It is added to the flow rate and this added value is output as a control signal for the flow control valve.
An ultra-low speed control device for an excavator characterized by being configured to exert force .