JPH0312178B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a swing control device for a dredge boat that excavates earth and sand from the bottom of a water body.

When increasing the water depth of a navigation route or anchorage, or when digging a foundation for the construction of an underwater structure, a dredge boat is used to dig up the earth and sand from the bottom of the water. FIG. 1 is a plan view showing the outline of such a dredger. In this figure, 1 is a hull, 2 is a cutter for excavating earth and sand on the bottom of the water, and 3 is a rudder that projects forward of the hull 1, and the cutter 2 is provided at the tip of the rudder. 4 is a rod-shaped spud that extends from the hull 1 to the bottom of the water, and is provided at the rear of the hull 1.
It is configured to serve as a fulcrum when swinging (rocking). 5a and 5b are anchors fixed to the bottom of the water, and each is connected to wires 6a and 6b. 7a and 7b are sheaves (pulleys) provided on the rudder 3, and the wire 6a is wound around the winch drum 8a via the sheave 7a.
The wire 6b is wound around the winch drum 8b via the sheave 7b. DCM1
DCM2 is a DC motor that drives the winch drum 8b via the reducer 9b, and DCM2 is a DC motor that drives the winch drum 8a via the reducer 9a.

When the above-mentioned dredger is to be swung to the right from point B to point A, for example, the wire 6a is wound up by the winch drum 8a while applying a regenerative brake to the DC motor DCM1 and applying appropriate tension to the wire 6b. Rotate it to the point. At the same time, the cutter 2 is used to excavate the bottom of the water for dredging. Then, each time the position of the spud 4 is moved forward (upward in the drawing) little by little, shaking is performed while swinging to the right or to the left, and the entire target area is shaken.

FIG. 2 is a block diagram of a conventional swing control device that controls the swing motion described above. In addition,
In this figure, parts corresponding to those in FIG. 1 are given the same reference numerals.

In this figure, SW1 is a switch that is turned ON when the motor swings to the left, and a speed signal _S1 that commands the rotational speed of the DC motor DCM1 is supplied as an addition signal to the deviation detection point _a1 via this switch SW1. In addition, at the deviation detection point _a1 , there is a direct double electric motor DCM.
The output signal of the indicator generator PG, which outputs a voltage corresponding to the rotation speed of 1, is supplied as a subtraction signal, and the deviation obtained at this deviation detection point a ₁ is sent to the controller.
Supplied to CL ₁ . The controller CL ₁ controls the DC motor DCM based on the deviation obtained at the deviation detection point a ₁
Outputs a signal Sa that commands an armature current value of 1.
In this case, the signal Sa output by the controller CL ₁ is a signal that makes the deviation at the deviation detection point a ₁ zero. SW ₂ is a switch that contacts contact L during left swing and contact R during right swing, and its common terminal is connected to deviation detection point a ₂ . Deviation detection point
The feedback value Iaf of the armature current supplied from the current transformer CT is supplied to _a1 as a subtraction signal, and the signal Sa is supplied as an addition signal during left swing, and the armature current set by variable resistor VL1 during right swing. A current set value (constant value) is supplied as an addition signal. CL ₂ is a forward converter that can switch between forward and reverse based on the deviation obtained at deviation detection point _A1 .
This controller calculates the firing angle of CH and supplies the resulting firing angle signal S _G to the gate pulse generator GPG1. Gate pulse generator GPG
1 supplies a firing pulse _GP to the forward converter CH based on the firing angle signal S _G. AC ₁ is the power supply for the armature circuit of the DC motor DCM1. F ₁ is DC motor DCM
1 field winding, and from power supply AC ₂ to thyristor 1
Current is supplied via 5. Note that the common line of the field winding circuit is not shown. _a3 is a deviation detection point, to which the field weakening reference signal DS is supplied as an addition signal and the armature voltage feed buffer signal Va is supplied as a subtraction signal. CL ₃ is calculated when the deviation obtained at the deviation detection point a ₃ becomes negative, that is, Va≧
A pulse generator gates the firing angle signal to reduce the field current to protect the motor when DS occurs.
In other cases (when Va<DS), a firing angle signal that makes the field current constant is supplied to the gate pulse generator GPG2. The left swing control circuit LS is configured by each of the above-mentioned components. Further, a right swing control circuit RS is configured in the same manner as the left swing control circuit LS. To describe the correspondence of the main components of the left swing control circuit LS and the right swing control circuit RS, controllers CL ₁ to _{CL 3} correspond to controllers CR ₁ to _{CR 3} , respectively, and deviation detection points a ₁ to a ₃ correspond to Deviation detection point b ₁ ~
b ₃ correspond to each, switch SW2, variable resistor VL
1. Thyristor 15, switch SW4, variable resistance
VL2 and thyristor 16 correspond to each other. Also,
F ₂ is the field winding of the DC motor DCM2, and SW
3 is a switch that turns on when swinging to the right.

Next, the operation of the above-mentioned conventional swing control device will be explained using an example when swinging to the left.

During left swing, switch SW1 is ON, SW3
is turned OFF, switch SW2 contacts the L side, and SW4 contacts the L side. As a result, the DC motor DCM
1 rotates based on the speed signal _S1 , and the wire 6b is wound around the winch drum 8b. on the other hand,
The armature current of the DC motor DCM2 is constantly controlled to the armature current value set by the variable resistor VL2, and therefore the DC motor DCM2 rotates in response to the difference between its output torque and the tension of the wire 6a. (normally rotates in the opposite direction) and applies regenerative braking in the swing direction (left side). In this manner, the swing control device swings to the left while applying braking on the starboard side of the hull 1 (FIG. 1).

By the way, in the conventional swing control device described above, for example, when swinging to the left (or swinging right), the DC motor DCM2 on the braking side
When the rotational speed of (DCM1) exceeds the rated rotation, the field current decreases under the control of controller CR ₃ (CL ₃ ), the output torque of DC motor DCM2 (DCM1) decreases, and the regenerative braking force weakens. However, the output torque of the braking motor is generally
Wire 6 caused by disturbances such as cutter reaction force and tidal current
It is set to the optimum value that can prevent rolling, etc., where the hull 1 swings due to loosening of the parts a and 6b and the rotation of the cutter 2, so a decrease in output torque during operation is caused by rolling. This was extremely problematic as it caused the wire to become loose.

In view of the above-mentioned circumstances, the present invention provides a swing control device that can perform stable swing operation without reducing the output torque of the braking-side electric motor. The control is performed based on the field current and the set torque value.

Embodiments of the invention will be described below with reference to the drawings, but first the principle of the invention will be described.

In the case of a DC motor, it is known that the armature current a is expressed by the following equation, where T is the torque and Kφ is the torque constant.

a=T/Kφ......(1) Here, Fig. 3 shows the characteristic curve of field current f and magnetic flux Φ.If the slope of the linear part of this characteristic curve is _k1 , then the magnetic flux Φ is a straight line. Within the area, it can be expressed as φ=k ₁・f (2). Also, the torque constant Kφ can be expressed as Kφ=k ₂・Φ ………(3) (where k ₂ is a constant), so from equations (2) and (3), Kφ=k ₁・k ₂ f ……… (4) becomes. Therefore, from equation (4), equation (1) above becomes Ia=T/Kφ=T/k ₁・k ₂・f (5), and from equation (5), it is possible to keep torque T constant. If desired, it is understood that the armature current a should be changed in accordance with the change in the field current f. Then, the present invention performs the calculation shown in equation (5) to control the armature current of the braking-side DC motor.

FIG. 4 is a block diagram showing the configuration of essential parts of an embodiment of the present invention. In the figure, VL3 is a variable resistor for setting the torque T of the DC motor, and 25 is the torque T set by the variable resistor VL3, the field current value f, and preset constants k ₁ , k ₂
This calculation unit calculates the control target value of the armature current a by calculating the right-hand side of equation (5) based on the above, and outputs the armature current control signal SIa corresponding to the calculation result. In this case, the torque T set by the variable resistor VL3 is input to the input terminal 25a of the calculation unit 25, and the signal corresponding to the field current value f is input to the input terminal 25b. In addition, this calculation section 25 and the variable resistor
VL3 constitutes a constant torque control section 30. In this embodiment, the constant torque control section 3
0 are provided, and each armature current control signal SIa is supplied to the terminal R of the switch SW2 and the terminal L of the switch SW4 shown in FIG. Detects the field current value and generates a feedback signal S as a result of this detection.
f to the input terminal 25 of each constant torque control section 30
supply to b.

According to such a configuration, as is clear from the above explanation of the principle, the output torque of the DC motor on the braking side is always maintained at the value set by the variable resistor VL3, so the field weakening control is activated. Even if the field current decreases, the output torque of the braking-side DC motor does not weaken.

As explained above, according to the present invention, the armature current of the DC motor on the braking side is controlled based on the field current of the DC motor and the set torque value. Even if the field current of the side motor decreases, the output torque of the DC motor does not decrease, and stable swing operation can be performed, thereby preventing the wire from loosening or rolling.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing the outline of a swing boat, Fig. 2 is a block diagram showing the configuration of a conventional swing control device, Fig. 3 is a characteristic diagram showing the characteristics of magnetic flux Φ against field current f, and Fig. 2 is a block diagram showing the configuration of a conventional swing control device. FIG. 4 is a block diagram showing the configuration of essential parts of an embodiment of the present invention. 25...Arithmetic unit, VL3...Variable resistor, 30...
...Constant torque control section.

Claims (1)

[Claims] 1. In a swing control device for a dredge boat that swings the dredge boat from side to side, the armature current of the DC motor is adjusted so that the output torque of the DC motor on the braking side is equal to the set torque value. 1. A swing control device for a shoveling boat, characterized by comprising a constant torque control section that performs control based on a field current value.